Method and system for providing demand assigned multiple access of asynchronous signals

Method and system for providing unsynchronized signal demand assignment type multiple access

The above and other situations, features and advantages of the present invention will be more clearly understood by the following and more clear descriptions presented in the accompanying drawings, in which:

Figure 1 is a diagram of a specific form of point-to-multipoint microwave radio system architecture according to the present invention;

Figure 2 is a block diagram of network components of the specific form of the point-to-multipoint microwave radio system shown in Figure 1;

Figures 3A and 3B are diagrams of the channelization effect used in the specific form of the point-to-multipoint system shown in Figure 2, illustrating the reuse of frequencies in the channels supporting multi-level modulation modes;

Figure 4 shows the frame-to-air interface format of the TDMA used in the point-to-multipoint system of Figure 2;

Figure 5 is a diagram of the air interface format used by one of the single frame formats in Figure 4;

6 is a traffic packet formatted for use in the frame format of the air interface of FIG. 5, illustrating a split preamble according to a specific form of the present invention.

Figures 7A and 7B are diagrams of four clusters and single clusters respectively, which are part of the data segments of the traffic cluster shown in Figure 6;

Figure 8 is a diagram of the header (header) section of Figure 5 on the empty interface frame format;

FIG. 9 is a functional block diagram of the multi-modal remote terminal with a dedicated user interface (SSI) module attached to the above-mentioned FIG. 2;

10 is a functional block diagram of the timing recovery system used in the multi-modal remote terminal of FIG. 9 to recover the timing sent by the multi-modal hub terminal of FIG. 2;

FIG. 11 is a functional block diagram of the multi-mode remote terminal of FIG. 9 or the multi-level modulation function modulator ASIC used in the multi-mode hub terminal of FIG. 14;

FIG. 12 is a functional block diagram of the multi-modal remote terminal of FIG. 11 executing and using the features of the split presynchronization signal shown in FIG. 6;

FIG. 13 is a block diagram of the specific form of the hub part containing the multi-modal hub terminal and transmission equipment described in FIG. 2;

FIG. 14 is a functional block diagram of the multi-modal hub terminal with the dedicated interface module attached to the user interface described in FIG. 2 and FIG. 13;

FIG. 15 is a diagram showing the format of a multi-transport modal unit bus frame used in a specific form of the multi-transport modal unit bus and how it relates to the empty interface frame format in FIG. 5.

16 is a block diagram of an inter-module communication unit format transmitted on the multi-transmission modal unit bus of FIG. 15;

FIG. 17 is a block diagram of a unit bus data unit format transmitted on the multi-transmission modal unit bus of FIG. 15;

FIG. 18 is a timing block diagram of the multi-transmission modal unit bus of FIG. 15;

FIG. 19 is a flowchart illustrating the steps of performing data transfer between indoor units of the multi-modal hub terminal and indoor units of the multi-modal remote terminal on the specific form of communication shown in FIG. 2;

Figure 20 is a block diagram of the four DS1AAL1 user interface modules used in the specific form of the point-to-multipoint system of Figure 2;

Figure 21 is a block diagram of the TDMDS3 user interface module used in the preferred specific form of the point-to-multipoint system of Figure 2;

Figure 22 is a block diagram of the ATMOC3c user interface module used in the preferred specific form of the point-to-multipoint system of Figure 2;

Figure 23 is a block diagram of the DS3 transparent user interface module used in the preferred specific form of the point-to-multipoint system of Figure 2;

Figure 24 is a diagram of data units formatted by the DS3 transparent SSI module in the specific form of Figure 23;

Figures 25A and 25B are respectively a multi-transmission modal user interface module with 8 T1 ports and a multi-transmission modal with 4 T1 ports and 4 LAN ports used in the point-to-multipoint system of Figure 2 The functional block diagram of the dedicated interface module for receiving accounts;

Figure 26 is a diagram of the ATM converter used in the ATM OC3c SSI module of Figure 17 for the multi-level modulation environment of the point-to-multipoint system of Figure 2, illustrating a request assignment multiple access (DAMA) technology and An ATM address filtering technology;

FIG. 27 is a flowchart illustrating the request assignment multiple access technology and the ATM address Lubo technology described in FIG. 26;

Figure 28 is a block diagram of the structure of a standard ATM cell;

Figure 29 is a block diagram of the structure of an ATM cell, which is formatted to include a header section containing an ATM dedicated header and signaling data used according to the specific form of a point-to-multipoint system, and a header section containing a pulse code modulation Change data

FIG. 30 is a block diagram of the ATM address filtrate technology of the ATM unit of FIG. 28 and the TDM unit Lubo of FIG. 29 that will be received from a mixed transmission modal source executed by the user-specific interface module;

Figures 31A and 31B are flowcharts illustrating the steps performed in two variations of the ATM address filtrate technology described in Figure 30;

Fig. 32 is a block diagram of an expanded indoor unit of the indoor unit coupled to the multi-modal remote terminal of Fig. 9;

FIG. 33 is a functional block diagram of a fiber expansion module used to connect the indoor unit of the multi-module remote terminal of FIG. 9 and the expansion indoor unit of FIG. 2 through an expansion fiber link;

Figure 34 is a time sequence diagram illustrating the delay involved in transferring data from the indoor unit of the multi-modal remote terminal in Figure 9 to the extended indoor unit in Figure 32;

FIG. 35 is a diagram illustrating a request-assigned multiple access (DAMA) technique used in a specific form of the point-to-multipoint system of FIG. 2 to dynamically change bandwidth based on channel conditions;

FIG. 36 is a flowchart illustrating the steps performed in the request assignment multiple access technique shown in FIG. 25;

Figure 37 is a block diagram of the 1:N redundant system used in the central part of the specific form of the point-to-multipoint system of Figure 2;

38 is a flowchart of the steps taken by the backup hub terminal shown in FIG. 37 to detect a failure of the hub terminal on one line in the 1:N redundant system of the point-to-multipoint system of FIG. 2;

Figure 39 is a specific form of the present invention used to buffer pulse code modulation (PCM) data and signal for use in Figure 20, 21, 25A and 25B in the TDM-based user interface module dedicated to the memory structure ;

FIG. 40 is a code modulation mapping control structure memory used for the memory structure pulse of FIG. 39 for TDM buffering in the TDM-based user interface module used in a specific form of the present invention;

Figure 41 is a diagram of compressed pulse code modulation (PCM) data in the TDM buffer in the TDM-based user interface module according to the specific format shown in Figures 39 and 40 and signaled into the TDM unit by a single DS0. Unit format for TDM unit;

Figure 42 is a diagram of compressing pulse code modulation (PCM) data in the TDM buffer in the TDM-based user interface module according to the specific format shown in Figures 39 and 40, and sending signals from multiple DS0s into a single TDM unit Unit format for TDM unit;

FIG. 43 is a unit format for compressing multiple DS0 TDM units with embedded frames in the TDM buffer in the TDM-based user interface module according to the specific format shown in FIGS. 39 and 40;

Figures 44A and 44B are flowcharts illustrating the TDM buffer described in Figures 39 to 43. The TDM-based SSI module completed in the point-to-multipoint system is also used for traffic flow in and out of the TDM-based user interface module.

This case is based on 35U.SC§119(e) claiming that Kay et al.s U.S. Provisional Patent Application No. 60/094,106 "MULTI-MODE, MULTI-MODULATION POINT TO MULTIPOINT MICRO-WAVE RADIO SYSTEM" filed on July 24, 1998 Priority, the US patent provisional application is incorporated herein by reference.

This patent document relates to a point-to-multipoint communication system described in the following patent documents proposed at the same time as this case. The related patent applications are: the US patent application "MULTI-MODE, MULTI-MODULATION POINT TO MULTIPOINT COMMUNICATIONS" filed by Kay et al. in July 1999; it is now US Patent No. _; Kay et al. filed in July 1999 U.S. Patent Application "MULTI-MODU-LATION RADIO COMMUNICATIONS"; now U.S. Patent No. _; U.S. Patent Application "MULTI-TRANSPORT MODE RADIO COMMUNICATIONS" filed by Corrigan et al. in July 1999; now U.S. Patent No. _ No.; Lohman et al. filed a US patent application "SERVICESPECIFIC INTERFACING IN POINT TO MULTIPOINTCOMMU-NICATIONS" in July 1999; now it is US Patent No. _; Muhammad et al. filed a US patent application "EXTEN-" filed in July 1999 SION INTERFACE UNITS IN A cOMMUNIcATIONS SYSTEM"; now U.S. Patent No. _; U.S. Patent Application "AIR INTER-FACE FRAME FORMATTING" filed by Kay et al. in July 1999; now U.S. Patent No. _; filed by Muhammad et al. in July 1999 U.S. Patent Application "MULTI-TRANSPORT MODE BUS COMMUNICATIONS"; now U.S. Patent No.; U.S. Patent Application "1:N RE-DUNDENCY IN A COMMUNICATIONS SYSTEM" filed by Wendling et al. in July 1999; now U.S. Patent No. _; and the U.S. Patent Application "TDM BU-FFERING" filed by Muhammad et al. in July 1999; it is now U.S. Patent No. _; all of which are incorporated herein by reference.

The background of the invention

The present invention relates to digital communication networks, and more particularly to fixed radio networks including point-to-multipoint microwave radio communication parts. More specifically, the present invention relates to request assignment multiple access within a fixed radio network including point-to-multipoint microwave radio communication sites.

The point-to-multipoint radio communication system is generally known in the industry. Competitive local telephone exchanges or waves use point-to-multipoint systems to provide services to users in remote areas by reverse transmission equipment. Generally speaking, a point-to-multipoint system includes a central hub with several hub terminals, most remote terminals, and a central office. The head office manages the system and is coupled to each central terminal at the central location via a reverse transport substructure (such as a fiber network established in the entire city). The central office is connected to a number of other networks; such as the Public Switching Telephone Network (PSTN), Internet Switching or Wave (IXC), Internet Service Provisioning System (ISP), and other data transmission systems. Each hub terminal contains a radio system that communicates with the remote terminal at a remote user in the remote area surrounding the hub terminal. The remote terminal provides a network interface to remote users. Therefore, the point-to-multipoint radio system provides users with voice, video, and data connections to other networks that can be obtained through the central terminal and the central office.

Request Assigned Multiple Access (DAMA) is a method that allows many users to access point-to-multipoint radio networks from remote communication terminals in different locations. It is an agreement to establish how much bandwidth is allocated to each user, and then modify the bandwidth according to the needs of each user. Request assigned multiple access is accomplished in different ways depending on the type of traffic being transmitted.

In a TDM point-to-multipoint communication system, time division multiplexing (TDM) traffic detects off-hook or active calls of voice traffic, and the communication system automatically allocates bandwidth. Messages are required between each remote terminal and the hub terminal in order to request bandwidth, allocate bandwidth, and confirm the bandwidth location. Similarly, if data traffic requires more bandwidth, a message is needed.

For asynchronous traffic in the ATM point-to-multipoint communication system, such as asynchronous transfer mode (ATM), voice and data traffic are managed according to the established priority order using ATM standards. Therefore, unlike the message sent by the TDM communication system, the ATM communication system generates traffic in an asynchronous manner based on the type of traffic, and for example, gives voice traffic a higher priority than data traffic.

The known old point-to-multipoint system only supports TDM (synchronous) or only ATM (non-synchronous) transmission mode. ATM networks are not as popular as TDM networks because the underlying structure is expensive and not entirely appropriate; therefore, although some users obtain ATM services through independent networks, most users only obtain TDM services. In order to obtain both TDM and ATM services, users must reserve two different communication networks.

Summary of Wood Inventions

The present invention advantageously addresses the above requirements and other requirements. The method is to provide request assignment multiple access technology in a multi-level modulation environment and communication system supporting both TDM and ATM traffic.

In a specific form, the feature of the present invention may be a method for requesting the assignment of multiple access asynchronous signals in a multi-level modulation radio communication system, and for completing the setting of the method, including the following steps; receiving; Most asynchronous signals; buffer the majority asynchronous signals; place each of the majority asynchronous signals in each of the majority modulation buffers, wherein each of the majority modulation buffers is the same as the majority modulation buffer One of the variable modes is combined; and each of the plurality of asynchronous signals is transmitted to a multi-level modulation radio system during an appropriate time slot.

In another specific form, the feature of the present invention can be an asynchronous unit in a multi-level modulation radio communication system using a multi-level modulation request to assign a multiple access system, including a system for deflecting the asynchronous unit away A cell tracer for incoming traffic, a line and buffer manager coupled to the cell tracer for buffering each asynchronous cell to one of a plurality of modulation buffers, wherein the majority of modulation buffers Each of them is associated with one of the most modulation modes. The system also includes a unit formatter coupled to the circuit and the buffer manager, wherein the unit formatter includes a plurality of modulation buffers and each of the plurality of modulation buffers is coupled to the circuit and the buffer manager.

In an additional specific form, the feature of the present invention may be a method of constructing an asynchronous transfer modal chipset, which includes the following steps; configuring an asynchronous transfer modal chipset, including a buffer and line manager, and Coupled to the utopia bus of the buffer and line manager, and most phy addresses of the utopia bus; and combining one or more of the most phy addresses with one of the most modulation modes.

In another specific form, the feature of the present invention may be a method for selecting an asynchronous transfer modal unit in a path in an asynchronous transfer modal chip set, which includes the following steps: combining individual virtual path identifiers and individual virtual waves The channel identifier is assigned to an individual asynchronous transfer modal unit received from a communication subchannel, wherein the individual virtual path identifier and the individual virtual channel identifier correspond to each of the most modulated traffic streams ; And based on the virtual path identifier and the virtual channel identifier, the asynchronous transfer modal unit path is selected to each of the plurality of modulated traffic streams.

In a further specific form, the feature of the present invention can be a method for multiple sub-channel request assignment multiple access for providing asynchronous transfer modal units in a multi-level modulation radio communication system, including the following steps: The communication line receives a plurality of asynchronous transfer modal units, wherein each of the plurality of asynchronous transfer modal units comes from each of the plurality of communication sub-channels of the communication line; buffers the majority of asynchronous transfer modal units; Each of the synchronous transfer modal units is placed in an individual modulation buffer of each of the majority unit formatters, wherein each of the majority unit formatters contains a majority modulation buffer, and wherein the majority unit formatter Each of the plurality of modulation buffers in each of the plurality of modulation buffers is associated with one of the plurality of modulation modes, wherein each of the plurality of unit formatters is associated with one of the plurality of communication subchannels; and At an appropriate time, each of the plurality of asynchronous transfer modal units is transmitted to a multi-level modulation radio system.

In another specific form, the feature of the present invention may be that an asynchronous unit in a multi-level modulation radio communication system uses multiple sub-channels and multi-level modulation requests to assign a multiple access system, including a system for unsynchronized The synchronization unit extracts a unit tracer of an input traffic stream, a line and buffer manager coupled to the unit tracer for buffering each asynchronous unit to one of a plurality of modulation buffers, wherein the majority Each of the modulation buffers is associated with one of the most modulation modes. The system also includes a plurality of unit formatters coupled to the line and buffer manager, so that each of the plurality of unit formatters supports one of the sub-channels of the communication channel, and each of the plurality of unit formatters includes an individual The majority of modulation buffers. Each of the individual multiple modulation buffers is coupled to the circuit and the buffer manager.

In a more specific form, the feature of the present invention can be a request assignment multiple access method based on channel conditions in a multi-level modulation point-to-multipoint radio communication system, and the settings used to complete the method, including The following steps: configure a central communication terminal for use of one of the most modulations. On the basis of the cluster communication to the cluster communication, the cluster communication is transmitted to the most remote terminals located in most areas, where the majority of the areas are caused by and The distance between the central communication terminal is defined; a communication link is established between the central communication terminal and the plurality of remote terminals; one of the highest-order modulations in the majority is used to adjust during clear channel conditions Change the bundle signal containing the data signal for transmission, in which the bit error rate of the communication link included during the clear channel condition is less than or equal to 10 ^-8 During the period; using each of the pre-assigned types of the majority modulation to modulate the cluster signal containing the data signal for transmission during periods of severe channel conditions, wherein each of the majority modulations corresponds to each of the majority areas , Where the bit error rate of the communication link is greater than 10 ^-8 ; And transmit the modulated bundle of messages via the communication link.

In another specific form, the feature of the present invention may be a method for receiving various communications in a time-division multiple access communication link in a time-independent scheme, including the following steps: communicating via the time-division multiple access The link transmits traffic clusters, where the traffic clusters are sent according to a first time plan, and each of the traffic clusters is individually modulated by one of a plurality of modulation modes; and is independent of the The method of the first time scheme receives individual traffic packets in individual communication terminals, wherein the individual communication terminals use only one of the pre-assigned multiple modulation modes to demodulate the traffic packets.

Schematic description

The above and other situations, features and advantages of the present invention will be more clearly understood by the following and more clear descriptions presented in the accompanying drawings, in which:

Figure 1 is a diagram of a specific form of point-to-multipoint microwave radio system architecture according to the present invention;

Figure 2 is a block diagram of network components of the specific form of the point-to-multipoint microwave radio system shown in Figure 1;

Figures 3A and 3B are diagrams of the channelization effect used in the specific form of the point-to-multipoint system shown in Figure 2, illustrating the reuse of frequencies in the channels supporting multi-level modulation modes;

Figure 4 shows the frame-to-air interface format of the TDMA used in the point-to-multipoint system of Figure 2;

Figure 5 is a diagram of the air interface format used by one of the single frame formats in Figure 4;

6 is a traffic packet formatted for use in the frame format of the air interface of FIG. 5, illustrating a split preamble according to a specific form of the present invention.

Figures 7A and 7B are diagrams of four clusters and single clusters respectively, which are part of the data segments of the traffic cluster shown in Figure 6;

Figure 8 is a diagram of the header (header) section of Figure 5 on the empty interface frame format;

FIG. 9 is a functional block diagram of the multi-modal remote terminal with a dedicated user interface (SSI) module attached to the above-mentioned FIG. 2;

10 is a functional block diagram of the timing recovery system used in the multi-modal remote terminal of FIG. 9 to recover the timing sent by the multi-modal hub terminal of FIG. 2;

FIG. 11 is a functional block diagram of the multi-mode remote terminal of FIG. 9 or the multi-level modulation function modulator ASIC used in the multi-mode hub terminal of FIG. 14;

FIG. 12 is a functional block diagram of the multi-modal remote terminal of FIG. 11 executing and using the features of the split presynchronization signal shown in FIG. 6;

FIG. 13 is a block diagram of the specific form of the hub part containing the multi-modal hub terminal and transmission equipment described in FIG. 2;

FIG. 14 is a functional block diagram of the multi-modal hub terminal with the dedicated interface module attached to the user interface described in FIG. 2 and FIG. 13;

FIG. 15 is a diagram showing the format of a multi-transport modal unit bus frame used in a specific form of the multi-transport modal unit bus and how it relates to the empty interface frame format in FIG. 5.

16 is a block diagram of an inter-module communication unit format transmitted on the multi-transmission modal unit bus of FIG. 15;

FIG. 17 is a block diagram of a unit bus data unit format transmitted on the multi-transmission modal unit bus of FIG. 15;

FIG. 18 is a timing block diagram of the multi-transmission modal unit bus of FIG. 15;

FIG. 19 is a flowchart illustrating the steps of performing data transfer between indoor units of the multi-modal hub terminal and indoor units of the multi-modal remote terminal on the specific form of communication shown in FIG. 2;

Figure 20 is a block diagram of the four DS1AAL1 user interface modules used in the specific form of the point-to-multipoint system of Figure 2;

Figure 21 is a block diagram of the TDMDS3 user interface module used in the preferred specific form of the point-to-multipoint system of Figure 2;

Figure 22 is a block diagram of the ATMOC3c user interface module used in the preferred specific form of the point-to-multipoint system of Figure 2;

Figure 23 is a block diagram of the DS3 transparent user interface module used in the preferred specific form of the point-to-multipoint system of Figure 2;

Figure 24 is a diagram of data units formatted by the DS3 transparent SSI module in the specific form of Figure 23;

Figures 25A and 25B are respectively a multi-transmission modal user interface module with 8 T1 ports and a multi-transmission modal with 4 T1 ports and 4 LAN ports used in the point-to-multipoint system of Figure 2 The functional block diagram of the dedicated interface module for receiving accounts;

Figure 26 is a diagram of the ATM converter used in the ATM OC3c SSI module of Figure 17 for the multi-level modulation environment of the point-to-multipoint system of Figure 2, illustrating a request assignment multiple access (DAMA) technology and An ATM address filtering technology;

FIG. 27 is a flowchart illustrating the request assignment multiple access technology and the ATM address Lubo technology described in FIG. 26;

Figure 28 is a block diagram of the structure of a standard ATM cell;

Figure 29 is a block diagram of the structure of an ATM cell, which is formatted to include a header section containing an ATM dedicated header and signaling data used according to the specific form of a point-to-multipoint system, and a header section containing a pulse code modulation Change data

FIG. 30 is a block diagram of the ATM address filtrate technology of the ATM unit of FIG. 28 and the TDM unit Lubo of FIG. 29 that will be received from a mixed transmission modal source executed by the user-specific interface module;

Figures 31A and 31B are flowcharts illustrating the steps performed in two variations of the ATM address filtrate technology described in Figure 30;

Fig. 32 is a block diagram of an expanded indoor unit of the indoor unit coupled to the multi-modal remote terminal of Fig. 9;

FIG. 33 is a functional block diagram of a fiber expansion module used to connect the indoor unit of the multi-module remote terminal of FIG. 9 and the expansion indoor unit of FIG. 2 through an expansion fiber link;

Figure 34 is a time sequence diagram illustrating the delay involved in transferring data from the indoor unit of the multi-modal remote terminal in Figure 9 to the extended indoor unit in Figure 32;

FIG. 35 is a diagram illustrating a request-assigned multiple access (DAMA) technique used in a specific form of the point-to-multipoint system of FIG. 2 to dynamically change bandwidth based on channel conditions;

FIG. 36 is a flowchart illustrating the steps performed in the request assignment multiple access technique shown in FIG. 25;

Figure 37 is a block diagram of the 1:N redundant system used in the central part of the specific form of the point-to-multipoint system of Figure 2;

38 is a flowchart of the steps taken by the backup hub terminal shown in FIG. 37 to detect a failure of the hub terminal on one line in the 1:N redundant system of the point-to-multipoint system of FIG. 2;

Figure 39 is a specific form of the present invention used to buffer pulse code modulation (PCM) data and signal for use in Figure 20, 21, 25A and 25B in the TDM-based user interface module dedicated to the memory structure ;

FIG. 40 is a code modulation mapping control structure memory used for the memory structure pulse of FIG. 39 for TDM buffering in the TDM-based user interface module used in a specific form of the present invention;

Figure 41 is a diagram of compressed pulse code modulation (PCM) data in the TDM buffer in the TDM-based user interface module according to the specific format shown in Figures 39 and 40 and signaled into the TDM unit by a single DS0. Unit format for TDM unit;

Figure 42 is a diagram of compressing pulse code modulation (PCM) data in the TDM buffer in the TDM-based user interface module according to the specific format shown in Figures 39 and 40, and sending signals from multiple DS0s into a single TDM unit Unit format for TDM unit;

FIG. 43 is a unit format for compressing multiple DS0 TDM units with embedded frames in the TDM buffer in the TDM-based user interface module according to the specific format shown in FIGS. 39 and 40;

Figures 44A and 44B are flowcharts illustrating the TDM buffer described in Figures 39 to 43. The TDM-based SSI module completed in the point-to-multipoint system is also used for traffic flow in and out of the TDM-based user interface module.

In the views of each figure, the corresponding reference symbol indicates the corresponding component.

Detailed description of preferred specific form

The following description of the best practice mode currently attempted by the present invention should not be considered as limiting, but the purpose is only to illustrate the general principle of the present invention. The field of the invention should be decided on the scope of each patent application.

First, refer to Fig. 1; shown is a multi-transmission mode, multi-level modulation point-to-multipoint microwave radio system (hereinafter referred to as a point-to-multipoint system) architecture according to a specific form of the present invention. The point-to-multipoint system 100 includes a central office 102, a public switched telephone network (PSTN) 104, an Internet service provision system 106, and other networks. The point-to-multipoint system 100 also includes a central part 110, each having a plurality of multi-mode central terminal 112 (hereinafter referred to as the central terminal) and its associated multiple multi-mode remote terminal 114 (hereinafter referred to as the remote Terminal). The multi-multimodal remote terminal 114 is placed in a sector 116 ("circular slice"). The hub terminal 112 is coupled to the multiple remote terminal 114 via the multiple communication link 118. The point-to-multipoint system 100 further includes a transmission network 120 and a component management system (EMS) 122.

The public switching telephone network 104, the Internet service provision system 106, the transmission network 120 (also referred to as reverse transmission), and other networks 108 are all coupled to the central office 102. The transmission network 120 couples the central office 102 to the central part 110 and to the component management system 122. Each central terminal located in the central part 110 communicates with the individual remote terminal 114 in a sector through a communication link 118.

Proper terms are used throughout this manual to describe the specific device or situation of the point-to-multipoint communication system. When the term "multi-level modulation (device)" is used, it refers to the ability of the device to use multiple modulations. When the term "multi-transmission mode (device)" is used, it refers to the ability of the device to support multiple transmission modal signals such as synchronous signals (such as TDM signals) and asynchronous signals (such as ATM signals). When the term "multimodal (device)" is used, it refers to both multi-level modulation and multi-transmission modal features. In addition, the proper nouns for the use of signals collectively describe the different typical traffic transmitted via the point-to-multipoint system.

According to this specific form of the present invention, a competitive intra-city telephone exchange or wave (CLEC) uses a point-to-multipoint system to provide various services to users who are connected to the remote terminal 114 of the point-to-multipoint system . The central office 102 provides voice and data converters and multiplexing equipment for the business use of the point-to-multipoint system 100, and the component management system 122 (hereinafter referred to as EMS) manages the point-to-multipoint system and controls the various components in the central office 102. The converter and various components at the hub 110 and the remote terminal 114. Therefore, the central office 102 is connected to the services provided to users, including the public switching telephone network 104, Internet services, and other networks 108, such as other switching or wave or data delivery systems. Therefore, the point-to-multipoint system 100 provides multimedia services, including data, voice, and video, to users at the remote terminal 114. The transmission network 120 distributes information between the central office 102 and each central terminal 112 of the central location 110.

Each sector 116 of the point-to-multipoint hub 110 includes one or more hub terminals 112, depending on the multiple channels and locations of the user industry including the remote terminal 114 (detailed in FIG. 2). Each hub terminal machine supports one of the sub-channels. Each sub-channel is a subset of the total frequency bandwidth or channel bandwidth. To simplify the description, each sector 116 in FIG. 1 only shows one hub terminal 112 (hereinafter referred to as sector radio). Each hub terminal 112 is a sector radio used to communicate with the remote terminal 114 in a specific sector 116. Each hub terminal 112 (sector radio) communicates with a remote terminal 114 (also a sector radio) via a communication link 118. The user can connect to the remote terminal 114 via a user interface or a dedicated user interface module (hereinafter referred to as an SSI module). T1 or E1 lines and other communication lines (further described below) extend from the SSI module to the user's equipment. Both T1 and E1 lines are well known in the telecommunications industry, so they will not be explained further in this article.

The specific form of the point-to-multipoint system 100 shown is advantageous for transmission on the communication link 118 in a time division multiple access/time division multiple access (TDMA/TDMA) manner. This means that in the downlink direction (from the hub terminal 112 to the remote terminal 114), the radio interface is a time-sharing multiple access link, and in the uplink direction (from the remote terminal 112) To the hub terminal 112), the radio interface is a time-sharing multiple access link. This is different from the old point-to-multipoint system using time division multiplexing (TDM) transmission, or continuous transmission in the downlink direction. The use of TDMA (also known as discontinuous transmission) in the downlink facilitates the deployment of switched directional antennas (which can be sector antennas) in the hub terminal. The switched directional antenna reduces interference and increases the transmission range, as detailed in Figs. 3A, 3B and 14. Alternatively, the point-to-multipoint system 100 can use continuous transmission in the downlink; however, the disadvantage is that the use of switched directional antennas is not as ideal as used in the preferred form.

In addition to operating in TDMA mode in the downlink, the point-to-multipoint system architecture of this specific form uses multiple transmission modes to carry signals. To be clear, the point-to-multipoint system of this specific form can interact with asynchronous signals (that is, asynchronous signals such as asynchronous transfer modal (ATM) transmission signals) and synchronous signals (that is, synchronous signals such as time division multiplexing ( TDM) transmission signal) interface. The transmission of the asynchronous signal does not need to worry about the specific time and is delivered based on the header information, but the synchronization signal is transmitted based on the specific time and is delivered based on the received time. The old point-to-multipoint system is fully synchronized (such as TDM) or fully asynchronous (range ATM), so according to the old method, two sets of redundant lower structures are required when using both TDM and ATM. It is particularly advantageous to have a system with two types of service delivery modes, because users can not only use fully established TDM-based voice services, but also high-speed data and multimedia ATM services. The advantage is that both of these transmission modes can be used, and a single substructure is used to make the point-to-multipoint system 100. The details of how the point-to-multipoint system can guide both ATM-based and TDM-based communications are further discussed below.

In this specific form of point-to-multipoint system, the hub terminal 112 (sector radio) and the long-distance terminal 114 (sector radio) are also beneficial to include a multi-level modulation modulator and demodulator. The air frame format of the multi-level modulation mode transmitted on the basis of the cluster signal connection. Therefore, a single hub terminal 112 can use one modulation mode to transmit one bunch of signals, and use another modulation mode to transmit the next bunch of signals. This enables the hub terminal 112 to transmit to all the remote terminals 114 within its specific sector 116, regardless of which remote terminal 114 adopts any modulation mode or in which area.

In the old point-to-multipoint system, in a sector 116, n modulation modes require n radios (central terminal 112), so each of the n radios uses a different modulation mode. However, the use of multi-level modulation modes in a given sector is an exception to the general implementation. Conversely, higher-order modulation modes can only be used under high-quality channel conditions. Therefore, these higher-order modulation modes are usually used to complete the communication with each remote terminal 114 that is closer to the hub terminal 112. On the other hand, when the remote terminal 114 is in a remote area, a more robust modulation mode is required to reduce the bit error rate. Therefore, two or more regions can be defined in each sector 116, and the remote terminal 114 in each region adopts the highest-order modulation mode (maximum number of bits/ Sec/Hz). As a result, the old point-to-multipoint system not only requires multiple hub terminals 112 for multiple transmission modes for each sector 116, but also requires multiple hub terminals 112 for each sector 116 to support multi-level modulation modes. Therefore, for example, each sector 116 may require six hub terminals 112 to support two transmission modes and three modulation modes per sector (redundancy is not considered, and it uses 1:1 redundancy for example). In the case of the system, the number of hub terminals will be doubled). The various components of the point-to-multipoint system in this specific form are configured to handle multiple transmission modes and multi-level modulation modes, etc., and are described throughout the specification of this case.

Therefore, the hub terminal 112 and the remote terminal 114 can use both asynchronous (ATM) and synchronous (TDM) to transmit modal transmission and reception signals. In addition, the hub terminal 112 and the remote terminal 114 can use multi-level modulation modes such as quadrature phase shift keying (QPSK), 16-quadrature amplitude modulation (16-QAM), and 64-quadrature amplitude modulation (64-QAM) , In the TDMA/TDMA air interface frame format, these signals are modulated and demodulated on the basis of the cluster communication connection. The system is not limited to these modulation functions, but can be configured to perform, for example, BPSK, 32-QAM, 128-QAM, and 256-QAM.

Typically, the point-to-multipoint system operates in a city or business park or other limited area in a metropolitan area. There are dense potential users in this area. A transmission network 120 such as a high-speed synchronous optical network (SONET) ring is spread throughout the limited area. The SONET ring is well known in the industry. The central part 110 is also scattered in the entire limited area and connected to the transmission network 120. The central office 102 transfers the service to be provided to the hub terminal 112 via the SONET ring. Each hub terminal 112 has an indoor unit (also called a channel processing unit), which is located in a central hub building containing the hub 110 and coupled to the transmission network 120. Each hub terminal 112 also has an outdoor unit (also called a transceiver unit), which is usually located on the roof of the hub building. The outdoor unit of the hub terminal 112 communicates with a corresponding outdoor unit of the remote terminal 114 usually located on the roof of the user's industry. The outdoor unit of the remote terminal 114 communicates with an indoor unit of the remote terminal 114 within the user's industry. The user connects to the point-to-multipoint system through a dedicated user interface module (SSI module) installed in most indoor units of the remote terminal 114.

The communication link 118 between each hub terminal 112 and its individual remote terminal 114 is a line-of-sight microwave radio communication link, so the communication link 118 is affected by the distance depending on the modulation mode selected by the hub terminal 112 limit. For example, a signal modulated by QPSK will usually only travel about 3 kilometers and have an acceptable bit error rate (BER), which is about 10 ^-12 Or smaller. The signal modulated by 64-QAM will travel a shorter distance (ie 1000 meters) with the acceptable bit error rate. In addition, microwave radio signals are limited by the transmission power output of outdoor units or transceiver units. Although the communication link 118 in this specific form is a microwave radio signal, it should be understood that this specific form is not limited to microwave signals in other variants, but may potentially include other media (or various combinations of media) known in the industry, for example, For example, wires, cables, and transmission line communication links. In addition, the point-to-multipoint system 100 is not limited by terrestrial applications. The point-to-multipoint system may include a hub and remote terminals, which are terrestrial stations with satellite links between them. Therefore, the concept of multi-transmission modal multi-level modulation communication extends to all forms of point-to-multipoint systems.

Refer to FIG. 2; shown is a block diagram of a point-to-multipoint microwave radio system 200 according to the specific form of FIG. 1. Each remote terminal 114 (multi-modal remote terminal) in the point-to-multipoint system 200 includes: an indoor unit 202, a dedicated interface module (hereinafter referred to as SSI module) 204, an outdoor unit 206, and equipment Inner link 208, and a communication link 210. Central part 110 Central hub terminal 112 (multi-modal hub terminal) includes: outdoor unit 212, central indoor unit 214, device internal link 216, a digital signal 3 TDM SSI module 218 (hereinafter referred to as TDM-DS3 SSI module) Group), an ATM optical carrier level 3c SSI module 220 (hereinafter referred to as ATM-OC3cSSI module), a DS3 line 222, an OC3c line 224, a DS3 transparent SSI module (not shown, but included in the central part 110 Inside), and including a TDM multiplexer (TDM MUX 226 and an optical ATM multiplexer (ATMMUX) 228 optical transmission equipment 252. The transmission equipment 252 is coupled to the central office 102 via a transmission network 246 (also referred to as reverse transmission). The central office 102 includes an optical TDM multiplexer 230, an optical ATM multiplexer 232, a data converter 234, a voice converter 236, an OC3c/OC12c line 240, a dedicated line 250, and a component management device 244 inside the EMS 122. The public equipment 248 includes the remaining hub terminal 112.

The user interfaces with the point-to-multipoint system 200 via a remote terminal 114 located in the user's industry. Insert an SSI module 204 into a dedicated user interface port or slot (hereinafter referred to as SSI port) provided on the chassis of the indoor unit 202 (or channel processing unit) of the remote terminal 114.

The indoor unit 202 (channel processing unit) of the remote terminal is located in the user's industry. The indoor unit 202 of the remote terminal 114 multiplexes the traffic between the user and the point-to-multipoint system through the SSI module 204. The indoor unit 202 is coupled to the internal link 208 of the device, and includes a multi-level modulation modulator and an empty frame formatting logic (in Figure 9 the multi-level modulation modulator and failure control In-device) and a user interface multiplexer function in one unit. Each indoor unit 202 (channel processing unit) of the remote terminal 114 has four SSI ports to allow for several different user interfaces such as T1 or E1 lines or dedicated user interface modules 204, as shown in Figure 20- Discussion of 25B. The SSI module 204 and the processor of the indoor unit 202 multiplexly convert synchronous signals (such as TDM) and asynchronous signals (such as ATM) into the indoor unit 202. The SSI module 204 multiplexes TDM and ATM traffic on a multi-transport modal unit bus (see Figure 15-18). In addition, each SSI module implements unique TDM buffering technology (refer to Figure 39-44B) and ATM address filtering technology (refer to Figure 30-31B), so that each SSI module will bus the ATM of the multi-transport modal unit. And TDM traffic formatting. The multi-transport modal unit bus has a bus frame format (see FIG. 15) to allow both the TDM unit and the ATM unit to be placed on it in an interchangeable manner.

Therefore, the rest of the point-to-multipoint system does not need to be modified to use TDM and ATM transmission modes to transfer signals. The unit formatter (also known as the signal formatter) of the SSI module (at the remote terminal 114 and the hub terminal 112) formats the TDM traffic or signal in the TDM unit, which is compatible with the standard ATM unit (ie 53 bytes) the same size. Therefore, the unit formatter of the SSI module 204 formats the TDM unit and the ATM unit in such a way that the rest of the point-to-multipoint system is obviously the same type of unit; however, each SSI module has the TDM unit And the ATM unit is formatted so that it is equal to the SSI module of the receiving communication terminal. Therefore, the multi-transport modal unit bus carries many units without distinguishing these units as TDM units or ATM units. The mixed traffic (TDM and ATM unit) on the multi-transport modal unit bus is directly mapped to a corresponding air interface frame format (refer to FIGS. 5 and 15) for transmission via the communication link 210. The mixed traffic is received via the communication link 210, and is mapped from the air interface frame format back to the multi-transport modal unit bus frame format (see FIG. 15). The multi-transport modal unit bus brings the mixed traffic to the SSI module 204, where the unit formatter (ie, the signal formatter) of the SSI module 204 selects the TDM unit and separates it from the ATM unit. Based on the time plan completed in the TDM system, the TDM unit is selected based on the time slot, and the ATM unit is selected based on the header information. Therefore, the point-to-multipoint system 200 can carry both ATM and TDM. The method is to format the TDM data and ATM cells in a unique frame structure, and convert them into and out of the point at the SSI module 204. For multipoint system 200 (refer to SSI module details in Figure 20-25B). The details of this assignment are discussed throughout this manual.

The indoor unit 202 of the remote terminal 114 also supports a fiber expansion module that plugs into an SSI port to allow connection to an expansion indoor unit. This allows linear growth in the number of user interfaces (ie, SSI modules) that can be supported by the indoor unit 202 of the remote terminal 114. Refer to Figure 32-34 for the fiber expansion module and expansion indoor unit.

The outdoor unit 206 (ODU) (or transceiver unit) of the remote terminal 114 is usually installed on the roof of the user's industry. The outdoor unit 206 of the remote terminal 114 communicates with the indoor unit 202 of the remote terminal 114 via the in-device link 208, and communicates with the central terminal 112 via a communication link (a microwave radio communication link 210). The outdoor unit 206 of the remote terminal 114 includes an antenna, a power amplifier, a low-noise receiver, a converter, an in-device link interface, and an alignment device, which are further illustrated in FIG. 9.

The intra-device link 208 (IFL) includes a single coaxial cable that connects the indoor unit 202 (also known as the channel processing unit) of the remote terminal 114 to the outdoor unit 206 (also known as the transceiver unit) of the remote terminal. User unit), and refer to Figure 7 for further explanation. The intra-device link 208 carries DC power to operate the outdoor unit 206 of the remote terminal 114, control signals, and a reference frequency. The frequency used by the intra-device link 208 is 70 MHz from the outdoor unit 206 of the remote terminal 114 to the indoor unit 202 of the remote terminal 114, and the indoor unit 202 of the remote terminal 114 to the outdoor unit of the remote terminal 114 206 is 160 MHz.

The communication link 210 or the air-to-air interface 210 is a 38 GHz microwave radio channel. The point-to-multipoint system 200 in this specific form supports the following frequencies: 5.2 GHz, 24 GHz, 28 GHz, and 38 GHz, although a wide range of frequency bands can be used. This specific form of channelization work divides a 50 MHz channel into four sub-channels, each with 12.5 MHz and each operating at a symbol rate of 10 Msps. In addition, the point-to-multipoint system can use multiple 50 MHz channels, so that there are more than one hub terminal 112 in each sector and use the same symbol rate of 10 Msps. Channelization is not limited to dividing the 50 MHz channel into four sub-channels using specific symbol rates. Various channel bandwidths can be selected and divided into various sub-channels using various symbol rates. Also, as described in Figures 3A and 3B, the frequency reuse capability can be used for multi-frequency channels.

As described above, the point-to-multipoint system 200 operates in both the uplink and downlink directions in a TDMA/TDMA format via the communication link 210. The transmitted signal includes both TDM and ATM traffic mixed in the same air interface frame format. These signals are modulated on the basis of the cluster signal connection with the cluster signal using a multi-level modulation mode. This specific form uses QPSK, 16-QAM (16-QAM), and 64-QAM (64-QAM) transmission. The point-to-multipoint system supports three typical clusters in the same TDMA frame. In practice, QPSK operates at a slower bit rate and is used to increase the range of the system; 64-QAM is used for closer remote terminals for better spectral efficiency; and 16-QAM is ideally used Long-distance terminal 114 at medium range. (It should be noted, however, that the features of this specific form, such as the use of multi-level modulation modes, are particularly advantageous in the microwave range, because the channels in this range tend to degrade rapidly with distance during the decay of the electron flow, and require the line of sight to start. Function.) In addition, the clusters on the blank interface frame format are made into different sizes to mix and match in the blank interface frame format (see Figure 5).

The hub 110 of the point-to-multipoint system 200 supports a multi-sector, multi-frequency unit, and each sector is served by at least one hub terminal 112 (sector radio) using a sub-channel. It is composed of two main components: a hub terminal 112 (also known as a multi-modal hub terminal) and a transmission device 252. The hub terminal 112 is further discussed with reference to FIGS. 9 and 10. FIG. 2 shows a hub terminal 112 and the remaining hub terminals are represented by a shared device 248. Each hub terminal 112 uses multi-level modulation modes (QPSK, 16-QAM and 64-QAM) to transmit and receive multiple transmission modal signals (such as ATM and TDM), just as the remote terminal 114 uses multiple transmission modalities And use multi-level modulation mode to transmit and receive signals. Each hub terminal 112 (sector radio) has a channel processing unit 214 (indoor unit 214) and a transceiver unit 212 (outdoor unit 212). A hub terminal 112 with an outdoor unit 212 can communicate with all remote terminals 114 in the specific sector, no matter where the remote terminal 114 is located outside the hub terminal 112 (ie radio distance) . This is an improvement of the traditional point-to-multipoint system that requires one radio for each sector and area. Therefore, the old point-to-multipoint system requires n radios, and the n is equal to the number of sectors multiplied by the number of zones in the sector. Regardless of the number of zones in this specific form, only one radio is required per sector.

The area within a sector ("circular slice") can generally be thought of as the area two distances away from the central terminal. However, these areas are more accurately defined by the channel quality that can be obtained by the receiver of the remote terminal and the receiver of the hub terminal. Therefore, remote terminals can be "classified" according to channel quality, and remote terminals that receive higher channel quality refer to those that are in the "closer" area and receive lower channel quality. Means in the "farther away" area. Since the channel quality is generally consistent with the radial distance, the two nouns are used interchangeably with the term "area". For example, a remote terminal that is very close to the central terminal (for example, up to 1000 meters) can be in one area, and a remote terminal that is far away (for example, 3 kilometers) is in another area. The two remote terminals are in the same sector, but they are at a different "distance" from the central terminal. Therefore, there may be a higher order of modulation (requiring a larger number of bits/second/Hz) between the closer remote terminal 114 and the hub terminal 112, while communication with the farther remote terminal requires a higher level of modulation. A lower-level modulation hub terminal 112 is used.

This specific form improves the old method in that there is no need for a hub terminal 112 for each area in each sector of the specific form. Conversely, each hub terminal 112 can use multi-level modulation modal transmission, so it can communicate with all remote terminals 114 in its sector, regardless of the region where the remote terminal is located.

The hub 110 may also include a transmission device 252 to the transmission network 246, the latter including a TDM multiplexer 226 and an ATM multiplexer 228. The transmission equipment 252 is arbitrary in this specific form, so if the transmission equipment 252 is not placed in the central position, similar equipment is placed in the central office 102.

In addition, no concentrator is required in the design of the hub terminal 112. In the old system, the concentrator splits the intensive traffic into multiple separate traffic streams, and each stream goes to the hub terminal 112 via a different modulation. Since the single hub terminal of this specific form uses multi-level modulation to transmit on the basis of a cluster of communications, no concentrator is needed. "Dense" traffic is simply sent directly to the hub terminal 112, which transmits the multiplexed traffic over the air.

The outdoor unit 212 (transceiver unit) of the hub terminal 112 is the same as the outdoor unit 206 of the remote terminal 114. The outdoor unit 212 of the hub terminal includes an integrated 38 GHz transceiver unit plus antenna. The transmission and reception frequency bands are exchanged with respect to the transmission and reception frequency bands of the outdoor unit 206 of the remote terminal 114. The outdoor unit 212 of the hub terminal 112 is usually located on the top of the building containing the hub 110. Similar to the indoor unit 202 of the remote terminal 114, the indoor unit 214 (channel processing unit) of the hub terminal 112 is connected to the outdoor unit 212 (transceiver unit) of the hub terminal 112 through an intra-device link 216 ). The intra-device link 216 is a single coaxial cable, which carries the power required by the outdoor unit 212, a reference frequency, uplink and downlink intermediate frequency signals, and a telemetry link.

The indoor unit 214 of the hub terminal 112 is similar to the indoor unit 202 of the remote terminal 114. The indoor unit 214 also uses multi-level modulation modes to support multiple transmission modal signals. The indoor unit 214 includes an intermediate frequency transceiver department, a channel and control processor, and three types of transmission equipment 252 interfaces. The first type of interface is the TDM-DS3 SSI module 218 (illustrated in Figure 21), which supports DS3 connection to a TDM multiplexer 226 for carrying TDM traffic. The second type is the DS3 transparent SSI module (not shown). The DS3 transparent SSI module (illustrated in Figure 23) is intended to be used for the point-to-point link between the hub terminal 112 and the remote terminal 114. This point-to-point link uses the entire bandwidth of the radio (for example, 12.5 MHz), and is unique because the point-to-point link can be generated in a point-to-multipoint system (see Figure 23). The third type is the ATM-OC3c SSI module 220 (illustrated in FIG. 22), which is used to carry the traffic of the ATM unit to an ATM multiplexer 228. The central part 110 and the central terminal 112 are described in detail with reference to FIGS. 13 and 14. It should be noted that DS3 is a digital signal level 3 and OC3c is a sequential (collocated) optical carrier level 3. Both are known in the communications industry.

The hub terminal 112 is supported by 1:1 redundancy conversion. Each hub terminal 112 has a one-to-one redundant outdoor unit (206, 212) and indoor unit (202, 214). For example, if the indoor unit 214 of the hub terminal 112 or the outdoor unit 212 of the hub terminal 112 fails, a backup hub terminal (not shown) including an outdoor unit (not shown) and an indoor unit (not shown) That is, it is automatically switched in to replace the faulty hub terminal 112. Therefore, each hub terminal 112 needs a backup hub terminal. The 1:1 redundancy system is shown in Figure 13.

Alternatively, a novel 1:N redundancy system can be used for the hub terminal 112 in the same sector and with the same antenna profile (refer to the description of FIG. 37).

The transmission equipment 252 multiplexes the traffic from the indoor unit 214 of each hub terminal 112 of the round-trip transmission network 246. The TDM-based and ATM-based multiplexing conversion is achieved by using the TDM multiplexer 226 and the ATM multiplexer 228. As mentioned above, the transmission network 246 may be a synchronous optical network (SONET) ring. The SONET ring is an optical fiber cable ring laid underground in the entire limited area. It is a high-speed carrier that carries synchronous (TDM) or asynchronous (ATM) traffic.

In another specific form, the reverse transmission line may be replaced by a radio communication link (not shown) from the transmission device 252 to the transmission network 246 (or reverse transmission structure). The radio communication link can be a microwave radio communication link very similar to the communication link 210 between the hub terminal 112 and the individual remote terminal 114. An antenna (such as a first 12-inch antenna) is coupled to the transmission device 252, and a corresponding antenna (such as a second 12-inch antenna) is coupled to the transmission network 246. The antenna will have a very narrow beam width (for example, 2-3 degrees), allowing a much larger range than a wider-angle antenna. This specific form allows the distance between the central part 110 and the transmission network 246 to be about 5 to 10 miles.

The central office 102 provides the conversion work of the point-to-multipoint system 200, and contains the component management system 122 (EMS). In another way, the transmission equipment is located in the central office and is tool-dependent. In another way, EMS 122 is not installed in the headquarters 102. The transmission equipment at the central office 102 is a TDM multiplexer 230 for TDM traffic, an ATM multiplexer 232 for ATM traffic, a data converter 234, a voice converter 236, DS1 or DS3 line 238 , OC3c/OC12c line 240, and STM-1 line (not shown). Other dedicated lines 250 are coupled to other data delivery systems, such as PSTN, Internet service delivery system, and Internet exchange or wave. The data converter 234 and the voice converter 236 control which data and voice go to the multiplexer 230 and the ATM converter 232. DS1 line 238 is a T1 line or E1 line, and DS3 line 238 carries or a group of 28 T1 streams. The OC3c and OC12c lines 240 are dedicated ATM lines. The STM-1 line is also used in the European version of the point-to-multipoint system 100. Each STM-1 line system composition operates in ATM or TDM mode. For example, TDM STM-1 lines will replace DS3 lines 222 and 238 and ATM STM-1 lines will replace OC3c lines 224 and 240. This transmission equipment and various lines are well known in the industry.

The component management system (EMS) 122 of the central office 102 includes a component management device 244, which performs the off-network management function of the point-to-multipoint system. The component management device 244 is physically a UNIX-based workstation commonly used in point-to-multipoint systems, and includes a large geographic display. The operator can construct and monitor the point-to-multipoint system by the EMS 122. In a specific form, the EMS 122 uses a wide area network (WAN) to communicate with all central locations 112 in the point-to-multipoint system. The WAN communicates with each hub 110 via an urban area network (LAN) path selector located at each hub 110, and the indicator couples the WAN to the LAN of each hub 110. EMS 122 manages the central part 110 is a conventional method. The LAN path selector is shown in Figure 13. The LAN in the central part and each indoor unit 214 of the central terminal 112 (refer to Figure 13). The transmission from the central LAN to the WAN is often a separate landline T1 line, or another method, which can be multiplexed into the DACS 230 as discussed below.

In another specific form, the component management system 122 uses a compliant frequency band network to communicate with the central part 110 of the point-to-multipoint system 200 via texts (information) sent through the transmission network 246 (reverse transmission). The text message is sent to TCP/IP or frame delay via the transmission network 246 and ATM multiplexer 228 using AAL5 (ATM conversion level 5). The ATM OC3c SSI module 220 receives the message, as shown in FIG. 22. This method is different from the old system of communication via an independent land line. This is more economical and eliminates the need to maintain a majority of separate land lines independent of the central location 110 for the wide area network to communicate with the central location 110's LAN.

In addition, it should be noted that the point-to-multipoint system is described in the preferred form throughout this article as having both multi-transmission modal capabilities and multi-level modulation capabilities. The point-to-multipoint system is not intended to be limited to a point-to-multipoint system with both capabilities. For example, a specific form of the point-to-multipoint system can be configured to transmit and receive multiple transmission modal signals (such as synchronous and asynchronous) without multi-level modulation capability. This specific form does not require a multi-stage modulation function modulation demodulator, but may include a single modulation function modulation demodulator known in the industry. In another specific form, the point-to-multipoint system may have multi-level modulation capability without multiple transmission modal capability. In this specific form, each specially designed SSI mode and multi-mode unit bus does not need to be modified and can work. Therefore, the hub terminal and the remote terminal may include multiple transmission modal radios in one specific form, and multi-level modulation radios in another specific form.

This specific form is completely compatible with conventional equipment, such as the transmission equipment 252, the transmission network 246, and the components of the central office 102. The point-to-multipoint system 200 still supports existing users and interfaces; however, the conventional SSI module must be modified to interface with the multi-transmission and multi-level modulation system. The specific forms of this point-to-multipoint system that can be used to operate the system are described below.

Refer to Figures 3A and 3B; the channelization effect used in a specific form of the point-to-multipoint system shown in Figure 2 is shown, illustrating that the frequency in the central part is reused to support the multi-channel multi-channel modulation mode . FIG. 3A illustrates the frequency reuse of two channels (for example, a 50 MHz frequency channel) indicated by a first frequency 302 and a second frequency 304. The first frequency 302 and the second frequency 304 are used by individual hub terminals in the hub to adjacent sectors, such as the first sector 306 and the second sector 308. Then, the first frequency 306 is reused in the interval sector, such as the third sector 310, and so on. Interval sectors refer to those next to adjacent sectors. For example, the third sector 310 using the first frequency 302 is an interval sector of the first sector 306, and the second sector 308 using the second frequency 304 is adjacent to the first sector 306. The first sector 306 and the second sector 308 shown in FIG. 3A are 90-degree sectors.

Each sector, such as the first sector 302 and the second sector 304, advantageously supports the individual frequency sub-channels of the first frequency channel and the second frequency channel. Each sub-channel supports multi-level modulation modes (such as QPSK, 16-QAM, and 64-QAM, but not limited to these modulation modes) within the 90-degree sector. On the contrary, the old method of frequency reuse only supports one modulation mode for each sub-channel, and does not support more than one modulation mode that uses the same frequency to be reused in the interval sector.

The frequency reuse in this specific form supports 64-QAM modulation, and this poses a special problem because 64-QAM modulation is extremely sensitive to interference. In order to achieve frequency reuse for higher-order modulation such as 64-QAM, a sector antenna must be used in each hub terminal, and a sub-channel in each sector, so as not to interfere with the interval sub-waves in adjacent sectors during transmission Road transmission. The sector antenna is used as the same antenna shown in the outdoor unit of each hub terminal in Figures 1 and 2. In addition, the sector antennas currently have reduced or low-level side lobes in order to transmit narrow beams without causing interference to the spaced sectors using the same frequency. The side lobes of the sector antenna must be sufficiently reduced to support the use of 64-QAM modulation. Therefore, the side lobes are reduced by 1.5 times the beam width of the sector antenna. In addition, the side lobe must be at a low level, for example, no more than 35dB under the peak gain of the sector antenna, so as not to interfere with the 64-QAM signal in the frequency used in each interval sector. Therefore, the side lobe feature enables frequency reuse to be used for higher-order modulation, such as 64-QAM.

The graph in FIG. 3B shows the same frequency reuse for 2 channels; however, the first sector 306 and the second sector 308 are 45 degree sectors. Similarly, the hub terminal in each sector must have a sector antenna whose side lobes are sufficiently reduced to use multi-level modulation modal transmission including 64-QAM to enter the 45-degree sector without using the same frequency Interference is introduced in the interval sector.

In another way, this specific form is not limited to 90-degree and 45-degree sectors, and other sector sizes can be selected, such as 22.5-degree sectors. In addition, the two sub-channels using different frequencies can be located in the same sector. Therefore, two hub terminals can transmit via sub-channels of different frequency channels in each sector.

Air interface

Refer to FIG. 4 again; shown is a diagram of the upper frame interface format 400 of the specific form of TDMA. The point-to-multipoint top frame format 400 for both uplink and downlink includes N frames 402. The meaning of frame 402 is explored as follows. The above frame format is generated in the multi-level modulation modulator described in FIG. 11.

Refer to Fig. 5 again; shown is one of the empty interface frame format diagrams corresponding to each of the N frames in the frame format of the specific form in Fig. 4. The air interface frame format 500 includes a header section 502, a backup section 504, and a traffic section 506. The traffic segment 506 may include QPSK quad-plex 508, 16-QAM quad-plex 510, QPSK single-plex 512, 64-QAM quad-plex 512, and 16-QAM single-plex 514.

The TDMA air interface frame format 500 in FIG. 5 corresponds to one of the N frames in the upper frame format shown in FIG. 4. In this specific form, the air interface frame format 500 is advantageously designed to provide both TDM and ATM transmission. The key to providing both TDM and ATM transmission on the same air interface frame format 500 is to format the TDM traffic into a TDM unit with the same size as an ATM unit (see Figures 28 and 29). This formatting is done at the SSI module of the indoor unit of both the remote terminal and the hub terminal. Both the TDM unit and the ATM unit contain header information for distinction. Therefore, the TDM unit and the ATM unit are multiplexed into a bus frame format, and the latter is directly mapped to the air interface frame format 500 (see Figure 15). The uniquely designed air interface frame format 500 provides the necessary structure to transmit mixed traffic, and a unique structure to exchange differently modulated traffic clusters. In addition, the capability of the radio communication link is a function of the modulation mode selected for the individual traffic bundle, since the air interface frame format 500 has different sizes of bundles depending on the modulation used. Multi-level modulation for indoor units of hub terminals and indoor units of remote terminals. Modulators and bus controllers contain the required air-to-air interface frame format 500 to generate the air-to-air interface frame format 500 Analyze the logic, and further explain Figures 9 and 11.

In practice, the air interface frame format 500 is the same in the uplink and the downlink, while the old point-to-multipoint system is used in the downlink (TDM) to support continuous transmission and in the uplink. Continuity (TDMA) to the space frame format. The air interface frame format 500 has a header section 502 for system management and dynamic bandwidth allocation. The manifold section 502 contains m time slots containing QPSK packets. The header section 502 contains QPSK bundles, because QPSK is the lowest-order modulation (minimum number of bits/second/Hz) of the modulation mode used in this specific form; therefore, it has the farthest range. Therefore, all remote terminals in the point-to-multipoint system are designed to receive at least QPSK-modulated clusters so that they can receive master messages. The manifold section 502 further refers to the discussion of FIG. 8. The backup section 504 separates the main section 502 from the traffic section 506.

The traffic segment 506 of the TDMA blank frame format 500 carries the effective negative OR (ATM unit and TDM unit) to and from the remote terminal and the central terminal. The TDMA air frame format is used for both the uplink and the downlink, and supports traffic modulated by the cluster communication method. The point-to-multipoint system of this specific form supports QPSK quad-plex 508, 16-QAM quad-plex 510, QPSK single-plex 512, 64-QAM quad-plex 512, and 16-QAM single-plex 514. This specific form is not limited to the above modulation, but can also be configured to support other modulations known in the industry, such as BPSK, 128-QAM, 256-QAM, and 32-QAM.

The traffic clusters in the traffic segment 506 are made in different sizes, and depending on the modulation selected for a particular cluster, it is convenient to design them as integer multiples of each other. Alternatively, the clusters can be designed to be multiples of each other, rather than integer multiples. The frame format of the air-to-air interface generally holds n QPSK four-packets in the traffic segment 506. The number of clusters n is a function of the frequency used, as described further below. Therefore, as known in the industry, the QPSK quad-plex 508 is x symbols long and supports one quadruplet DS0. The 16-QAM quad-plex 510 is x/2 symbols long and supports one quadruplet DS0. QPSK single-plex 512 and 64-QAM quad-plex 512 are x3 symbols long and support a single DS0 and a quadruplet DS0 respectively. 16-QAM single-plex 514 is x/6 symbols long and supports one Single DS0. DS0 or digital signal level 0 is a term known in the telecommunications industry; therefore, no further explanation is required.

The advantage is that the relationship between the sizes of the clusters enables the point-to-multipoint system to use different modulation modes to mix and match different clusters within the same fixed-size air interface frame format 500. QPSK quad-plex 508 is twice the length of 16-QAM quad-plex 510, three times the length of QPSK single-plex 512 or 64-QAM quad-plex, and six times the length of 16-QAM single-plex 514. Moreover, if the frame format of the air interface can hold n QPSK quad-plex 508, it can hold 2n 16-QAM quad-plex 510, 3n QPSK single-plex 512 or 64-QAM quad-plex 512. , And 6n 16-QAM single-cluster 514. These size relationships enable the bandwidth available in the air interface frame format 500 to be used extremely efficiently. This is different from the blank frame format used in conventional point-to-multipoint systems that contain fixed-size bundles using only one modulation mode.

In addition, because the air interface frame format 500 uses a variety of multi-level modulation modes to produce proportionally large-scale traffic clusters, there is no need to re-allocate a new time plan for any change in the transmission of any remote terminal. In the old system, the remote terminal was instructed to "listen" to which time slot through the use of a time plan. Therefore, if a new remote terminal is added or removed, or the demand for one of the remote terminals has been increased or decreased, the time plan changes and a new time plan must be allocated to all remote terminals.

The advantage is that the specific form does not need to re-allocate a new time plan for individual remote terminals to receive individual traffic clusters. Each remote terminal simply demodulates the structured parts of the traffic segment 506 for demodulation. For example, a remote terminal in the closest area will only demodulate traffic packets using 64-QAM instead of using QPSK or 16-QAM. Please note that 64-QAM is irrelevant in the time slot in the traffic segment 506, because the remote terminal will receive it regardless of the time slot in which it is located. So there is no need for a new time plan, and in fact there is no need for a time plan at all. Therefore, the long-distance terminal function can receive the cluster information, and has nothing to do with the time plan. This represents a request assignment multiple access technology that does not require the use of a time scheme or has nothing to do with the time scheme.

This specific form provides text messages via the QPSK modulation bundle in the master section 502, to be sent once the traffic bundle is demodulated at the indoor unit of the remote terminal. All long-distance terminals are constructed to demodulate the master bundle signal. It should be noted, however, that the transmission of the new time plan is for the SSI module to determine which unit of the multi-transport modal unit bus will be used (see Figure 20-25B), but there is no need for a new time plan for each remote terminal to pass through the air The interface receives certain traffic bundles. In addition, the required waiting time frame is one less than the conventional time scheme.

In a preferred specific form, the length of the air interface frame format 500 is 6 milliseconds, and there are 8 frames in the 48 millisecond upper frame format in FIG. 4. The 6 millisecond frame length corresponds to the 48-byte DS0 samples of the TDM data taken every 125 microseconds (8 kHz). As briefly mentioned above and explained more fully below, in order to allow the use of multiple transmission modal features, TDM data is formatted into a TDM unit similar to a standard ATM unit (see Figures 28 and 29). Therefore, it is necessary to fill the appropriate data segment of the TDM unit for the 48-byte DS0 sample, so the length of the blank interface frame format 500 must be at least 48×125 microseconds = 6 milliseconds to collect enough TDM bits Tuples to fill a traffic bundle. Therefore, a total of 57 QPSK quad-plex 508, 114 16-QAM quad-plex 510, 171 QPSK single-plex 512 or 64-QAM quad-plex 512, or 342 16-QAM can be installed in traffic segment 506. Single cluster 514, or various combinations of the above traffic clusters. Similarly, the length provided is a function of the frequency used and the length of the data unit formatted into the traffic bundle, so the specific form is not limited to these specific lengths.

Since the air-to-air interface frame format 500 supports three modulation modes in a cluster-to- cluster communication mode, a single hub terminal (sector radio) can transmit to all remote terminals in a sector, regardless of the remote terminal Where is the machine located in the sector. For example, the hub terminal will use QPSK to transmit to each remote terminal in an area up to 3 kilometers away, and the hub terminal will use 64-QAM to transmit to the nearest remote terminal, and use 16 -QAM is a long-distance terminal in a medium-distance area, all in the same air-to-air interface format 400. This allows the use of the highest possible modulation (maximum number of bits/second/Hz) of each remote terminal and the most effective use of the communication channel, while still retaining satisfactory quality. Therefore, the remote terminal in the farthest area uses the lowest-order modulation available (such as QPSK), and the remote terminal in the closest area uses the highest-order modulation available (such as 64-QAM) .

Refer to Figure 6 again; shown is a diagram of the traffic packet format used in the frame format of the air interface of Figure 5 including a split preamble feature. The traffic cluster 600 includes: a preamble 602, including a protection device 606, a ramp 608, a first unique word 610, a second unique word 611, a first data/backup section 612, and a second data/ Backup section 614; data section 604; and a parity 616. The split length 613 of the preamble is also displayed.

The traffic cluster is always shown in a format, but it is intended to describe the format of a QPSK four cluster, 16-QAM single cluster, and so on. The data section 604 and the first data/backup section 612 and the second data/backup section 614 are divided differently according to the typical cluster used (as described in Figures 7A and 7B), and the traffic cluster 600 The length will depend on the selected modulation mode. Therefore, the traffic cluster represents one of the formats of the traffic cluster shown in FIG. 5. In a specific form, the data section 604 and the first and second data/backup sections 612 and 614 are designed to carry small-sized data units; for example, the 53-byte ATM cell in Figure 28 and the one in Figure 29 53-byte TDM unit.

The pre-synchronization signal 602 of the traffic cluster 600 contains a segment including the protection device 606 and the ramp 608 that are fully known. However, the uniqueness of the preamble signal 602 is that the preamble signal is a "split preamble signal", in which a unique word is divided into a first unique word 610 and a unique word 611, instead of the one used in the old preamble A unique word. The first unique character 610 and the second unique character 611 are separated by a first data/backup section 612.

The first unique word 610 and the second unique word 611 are split as shown, so that the multi-stage modulation modulator of FIG. 11 can accurately estimate the channel characteristics, including the frequency offset and the frequency offset in the received packet. Phase shift. The frequency and phase estimation is performed by the multi-level modulation modulator, and the specific functions of the first unique word 610 and the second unique word 611 are shown in FIG. 12. The first unique word 610 and the second unique word 611 are advantageously separated by a first data/backup section 612 constituting the preamble split length 613.

The preamble 602 precedes each TDMA and provides synchronization symbols and guard time between uplink TDMA clusters. As discussed in Figure 12, the traffic throughput is optimized because the traffic is contained in the data section 604, the first data/backup section 612, and the second data/backup section 614. Depending on the specific cluster type (shown in Figures 7A and 7B) and size (shown in Figure 5) of the traffic cluster, and depending on the modulation mode used, the traffic cluster 600 may not include the first The second data/backup section 614, or the second data/backup section 614 may only contain backup but no data. Similarly, the first data/backup section 612 may contain partial or no data, but only backup. The advantage is that the first and second data/backup sections 612 and 614 should contain data (or traffic) in order to optimize the traffic throughput. In addition, the traffic cluster 600 includes a parity 616, which can be at the end of the traffic cluster 600 as shown or included in the preamble (not shown). A post-synchronization signal (not shown) including a downward ramp and protection device can be attached to the traffic cluster 600. The clusters are not limited to four clusters and single clusters, but may include other types of clusters known in the industry.

Refer to Figures 7A and 7B; the diagrams of four clusters and single clusters are shown respectively, which are part of the data segment and data/backup segment of the traffic cluster shown in Figure 6. The quad cluster 700 shown in FIG. 7A has a backup 702 and a majority of data fields 704 containing a header 706 and a data segment 708. The single cluster 710 shown in FIG. 7B has a backup 702 and a single data field 704 containing a header 706 and a set of material segments 708.

In implementation, the four-cluster 700 shown in FIG. 7A is the first of the two-cluster types, and the second is the single-cluster 710 shown in FIG. 7B. As shown in FIGS. 28 and 29, the four clusters 700 has 4 data fields 704 with 4 data units, and the single cluster 710 has 1 data fields 704 with 1 data unit. Each data unit contains a header 706 and a data section 708. The data unit in the data field 704 can be an ATM unit (Figure 28) or a specially formatted TDM unit (Figure 29).

An important feature of the air interface frame format is that it is structured to carry both ATM and TDM data. Since a standard ATM cell has a length of 53 bytes of 5 bytes for identifiers and 48 bytes for data, each data field 704 in the empty interface frame format (regardless of whether it is in quad-plex or single In the cluster), the length must be 53 bytes or more. Therefore, if the TDM data is carried in the empty interface frame format, the length of the TDM unit installed in the data field is also 53 bytes or more. As will be discussed in FIG. 29, a TDM unit contained in the data field 704 advantageously uses 5 bytes for header information and 48 bytes for data, similar to an ATM unit. The 48 bytes of the DS0 sample of the TDM data required to fill the data field 508 specifies the length of the blank interface frame format. As mentioned above, the length must be at least 6 milliseconds to take enough data to fill the data field 704 (corresponding to 48 125 microseconds (8 kHz) pulse code modulation (PCM) during the 6 millisecond blank frame period ) Frame). It should be noted that the designer can change the sampling rate, so the minimum-to-air interface frame format will be changed. Refer to Figures 28 and 29 for the structural details and advantages of ATM cells and specially designed TDM cells.

It is also important to show that the data field 704 and the backup 702 occupy the space in the traffic cluster in Figure 6, including the data section 604, the first data/backup section 612, and the second data/backup section 614. When the traffic cluster is received through the air-to-air interface, the data in the first and second data/backup sections 612 and 614 and the data section 604 of the traffic cluster are modulated by the multi-level modulation function. They are connected in sequence and divided into four clusters 700 and single cluster 710. Therefore, the backup 702 data field 704 of FIGS. 7A and 7B is mapped to the data section 604 and the first and second data/backup sections 612 and 614 of FIG. 6.

In addition, the data segment 708 (also referred to as the sub-slot) of the data field 704 of the four-cluster 700 and the single-cluster 710 can carry data of multiple DS0s in one of several modes. In the specific forms shown in FIGS. 29 and 42 to 43, data obtained from a number of DS0s can be carried in the data field 704 by the TDM unit. In the TDM mode, the 48 bytes of PCM samples of DS0 are carried by an appropriate header 706. The header 706 contains signaling, such as channel-associated signaling. In addition, the header 706 of the TDM unit uses an ATM header (VPI) to distinguish it from the ATM unit, and is discussed in FIG. 29. The four-cluster format 700 can also be used as an ATM traffic for DS0 carrying an ATM unit (53 bytes). Another method can gather 25 data fields 704 to carry a DS1 in ATM conversion layer 1 (AAL1). The bandwidth will be sufficient to handle the +/-200ppm clock skew between the network frame timing and the user's (potentially different) clock rate.

As mentioned, the air interface frame format is formatted to carry both ATM and TDM traffic. However, the old system requires separate air frame formats for ATM and TDM communication links. The TDM data is also formatted in a specially designed TDM unit with the same size as the ATM unit, so the empty frame format cannot distinguish between ATM and TDM units. The SSI module formats the TDM unit and multiplexes it with the ATM unit into a multi-transport modal unit bus. Then, the multi-transmission modal unit bus frame format is directly mapped to the TDMA air interface frame format. Therefore, the SSI module distinguishes ATM and TDM traffic. For details on how the ATM and TDM units on the multi-transport modal unit bus are mapped to the air interface frame format, refer to the discussion in FIGS. 15 to 18. This specification further discusses the details of how to format the ATM cell and TDM cell for the cell bus frame format of the multi-transport modal cell bus. These features provide a method of how to implement the frame format of the air interface in the point-to-multipoint system.

Refer to Figure 8 again; shown is the diagram of the manifold segment 800 in Figure 5. The manifold segment 800 includes m time slots containing a plurality of manifold clusters. Shown are a maintenance tank 802, a remaining three-hour tank 804, and a collection tank 806.

Each pair of empty interface frames in the above frame has m header time slots. The master cluster information only uses QPSK to transmit in various maintenance slots 802 to ensure a constant size header segment, and because QPSK provides the maximum transmission range of the modulation currently used in this specific form. Therefore, all remote terminals, even the remote terminals in the farthest area, can receive and transmit the master bundle.

Each remote terminal is assigned a maintenance slot 802 in the top frame format of Figure 4; therefore, for example, if there are 9 maintenance slots 802 and 8 frame in the top frame structure, it can Supports 72 remote terminals (9 maintenance slots×8 frames) in the above frame structure. The remaining three slots 804 are used for other purposes in frames 1 to N-1 of the upper frame format in Figure 4, such as random access via the ALOHA protocol, acknowledgement, and a remote terminal dedicated wave road. In the frame N of the frame format on FIG. 4, three header time slots 804 are combined to form a collection time slot 806 in the uplink direction. A collection packet is transmitted during the long collection time slot 806, and a mechanism for calibrating the transmission timing is provided to the remote terminal.

The collecting tank 806 is also used in a specific form of the present invention that uses a 1:N redundancy system, as described in FIGS. 37 and 38.

The header section 800 contains several types of clusters, including: maintenance clusters, random access clusters, response clusters, and a shortened calibration cluster. The maintenance cluster (in the maintenance slot 802) provides a communication path between the remote terminal and the hub terminal, regardless of whether the remote terminal carries traffic. The random access packet in the uplink (in the remaining time slot 804) allows the remote terminal to request bandwidth in a request assigned multiple access (DAMA) operation (see Figure 35). The response packet in the uplink (the remaining time slot 804) is used by the remote terminal to acknowledge the protocol message sent by the central terminal. The collection packet (in the collection slot 606) is used by the remote terminal during installation to find the correct timing offset.

The advantage is that the main management section 800 allows remote terminals to transmit control information without contention. Therefore, each remote terminal is in regular contact with the point-to-multipoint hub terminal to report an alarm and perform real-time power control once for each of the above frame formats.

Remote terminal

Refer to FIG. 9 again; it is a block diagram illustrating the remote terminal 900 (multi-modal remote terminal) in the specific form of the present invention shown in FIGS. 1 and 2 as originally described. The remote terminal 900 is a radio system and includes an outdoor unit (ODU) 902 (also called a transceiver unit) with an antenna 904. The remote terminal 900 also includes an intra-device link (IFL) 906 and an indoor unit (IDU) 908 (also referred to as a channel processing unit). The indoor unit 908 contains a maintenance port 910, a multiple transmission module 912, four user-specific interface modules 914 (SSI modules), and a channel and control module 916 (CCM). The channel and control module 916 includes: an intermediate frequency (IF) transceiver section 918 and a base frequency section 920. The IF transceiver section 918 includes an IFL interface 922, an up converter 924, and a down converter 926. The baseband section 920 includes a multi-level modulation modulator 928, a bus controller 930, a control processor 932, and control signals 934.

The outdoor unit 902 (transceiver unit) communicates with the indoor unit 908 (channel processing unit) via the intra-device link 906. The IF transceiver section 918 is coupled to the intra-device link 906 via the IFL interface 922. The up-converter 924 and the down-converter 926 are coupled between the multi-level modulation modulator 928 and the multi-transmission modal unit bus 912. The bus controller 930 is coupled to the multi-level modulation modulator 928 and the multi-transmission modal unit bus 912. The multi-transport modal unit bus 912 is also coupled to the four SSI modules and the control processor 932. The control processor 932 is coupled to the maintenance port 910 and sends a control signal 934 to the IFL interface 922, the up converter 924 and the down converter 926.

In practice, the remote terminal 900 includes two secondary systems: an outdoor unit 902 and an indoor unit 908. The outdoor unit 902 is an integrated unit with an antenna, an uplink converter, a power amplifier, and a downlink converter (all known in the industry). The antenna is a circular antenna with a protective ray cover. The outdoor unit 902 of the remote terminal 900 communicates with the outdoor unit 902 of the hub terminal through the antenna 904 via the 38 GHz radio frequency communication channel. Therefore, the outdoor unit 902 functions as a transceiver unit. There are two transmission frequency bands for the transmission function of the outdoor unit 902. The low frequency band is from 38.6 to 38,95 GHz, and the high frequency band is from 38.95 to 39.3 GHz. The reception frequency band used by the outdoor unit 902 is a low frequency band of 39.3 to 39.65 GHz and a high frequency band of 39.65 to 40.0 GHz. The outdoor unit 902 receives its timing reference from the hub terminal via the air interface. Each signal is received and down-converted into an intermediate frequency (IF) for transmission to the indoor unit 908 on the intra-device link 906 (IFL). The intra-equipment link 906 is a single cable that is a low-loss cable, such as the third type VSAT cable produced by Comscope. The support is up to 1000 feet with IFL906.

The intra-device link 906 carries the following: DC power from indoor unit 908 to outdoor unit 908, intermediate frequency transmission data, intermediate frequency reception data, a reference frequency and telemetry, IFL link 906 occupies 12.5 MHz in each direction The uplink and downlink bandwidths are concentrated in 160 MHz and 70 MHz, respectively.

The indoor unit 908 of the remote terminal 900 is usually installed inside the user industry, typically in a wiring closet. The indoor unit 908 includes the following modules: channel and control module 916 (CCM), SSI module 914, and backplane power supply unit (not shown) and chassis (not shown). It is an independent unit that accommodates up to 4 user interface modules 914 (SSI modules) ^O The indoor unit 908 is powered by 110 volt AC input. Can include an optional 48V DC input. The channel and control module 916 includes an IF transceiver section 918 and a digital baseband section 920. The IF transceiver section 918 contains an IFL interface 922, an up converter 924, and a down converter 926, while the digital baseband section 920 contains a multi-stage modulation modulator 928 and a bus controller. 930 and control processor 932. The multi-transport modal unit bus 912 (or SSI bus) provides connections to the four SSI modules 914, the control processor 932, and the bus controller 930.

The IF transceiver section 918 of CCM916 supports a 12.5 MHz sub-channel with 0PSK, 16-QAM or 64-0AM modulation. The upconverter 924 is in the transmission path to the outdoor unit 902 via the intra-device link 906. The up-converter 924 receives the modulated data from the multi-stage modulation modulator 928, and transforms it into analog, Lubo and frequency shift. The down converter 926 receives the signal of the outdoor unit 902, Lubo, provides automatic gain control, converts the signal into a digital signal, and then carries the signal to the multi-stage modulation demodulator 928. The IFL interface 922 functions as a multiplexer, allowing multiple signals to be carried between the indoor unit 908 and the outdoor unit 902 on a single coaxial cable. The purpose of the IFL interface 922 is to divide the signal from the outdoor unit 902 to its individual circuits in the indoor unit 908. It also combines the signal from the indoor unit 908 with the coaxial cable going to the outdoor unit 902. The signals from the indoor unit 908 are the synthesizer reference point, DC power, telemetry, and transmission intermediate frequency. The signals received by indoor units are intermediate frequency and telemetry. The components and implementation of the IF transceiver section are well known in the industry.

The main functions of the channel and control module 916 of the digital baseband section 920 are as follows: modulator function, air frame formatting, air interface protocol, internal SSI bus interface and multiplex conversion, maintenance port , Control processing, SSI monitoring, and control and operation administration and management functions.

Multi-level modulation function Modulation demodulator 928 is implemented as an ASIC (application specific integrated circuit), including modulation, demodulation, air frame formatting, air interface protocol, and Reed-Solomon encoder/decoding Device and other functions. The multi-level modulation function modulator 928 supports the use of QPSK, 16-QAM, and 64-QAM TDMA cluster types on the basis of the cluster communication connection. The demodulator also contains a tracking section to compensate for multipath conditions in 16-QAM and 64-QAM. The modulator contains the correct formatting logic for the blank frame. The multi-level modulation and demodulator 928 is described in further detail with reference to FIG. 11.

The control processor 932 is a reduced instruction system code (RISC) processor and functions as the main processor of the indoor unit 908. The control processor 932 is a controller for the main functions of the indoor unit 908, such as configuration, alarm monitoring, and reporting to the component management system (EMS) via the air control channel (management section in FIG. 8). The control processor 932 also sends signals to the IF transceiver section 918 for gain control as known in the industry. The maintenance port 910 can be connected to a modulator component provided by the customer, for the operator to remotely access the remote terminal through a simple old telephone call (POTS) circuit. The status of the remote terminal 900 can be updated or reset via this interface.

The bus controller 930 is a field gate array (FPGA) or customer logic. The bus controller 930 moves the main pipe section away from the air interface frame format once demodulated, and reinserts an intermediate module communication section (IM-Com) on the multi-transport modal bus 912 used, Used for messages between the bus controller (such as formatter) of the SSI module and the local processor (such as the central processing unit). Refer to Figures 15 and 16 for further discussion of the IM-Com message segment. Therefore, as described above, the bus controller 930 maps the traffic in the air interface frame format in FIG. 5 to the multi-transport modal bus frame format in FIG. 15. The bus controller 930 also maps the traffic on the air interface frame format in FIG. 5 to the dedicated cluster type of FIGS. 7A and 7B used in the air interface frame format in FIGS. 5 and 6. As far as the air interface frame format is concerned, the header segment is used for messages between the channel of the remote terminal 900 and the control module 920 and the channel of the hub terminal and the control module (illustrated in Figure 14 ). The available space on the frame format after the blank frame format header section is removed can be used for the remote terminal's channel and the control module 920 and the intra-city processor of the SSI module to report. Text (ie IM-Com section). The bus controller 930 also includes an air interface frame format and a time scheme of the multi-transmission modal unit bus 912. The format of the pair of empty interface frames is illustrated in the above FIGS. 4-8, and the multiple transmission unit bus is illustrated below with reference to FIGS. 15-18.

The remote terminal 900 carries both synchronous (TDM) and asynchronous (ATM) traffic on the multi-transport modal unit bus 912. The unit bus format uses the bus controller 930 to map to a pair of empty interface frame formats. The following refers to the SSI module to explain the details of how to use different types of traffic formatting for the same unit bus frame format.

It should be noted that the ATM and TDM traffic in the frame format of the air interface has been routed by the remote terminal 900, and there is no need to distinguish the mixed traffic. The mixed traffic on the air interface frame format is directly mapped to the multiple transport modal bus frame format to be sent from the remote terminal 900 to the SSI module 914. The SSI module 914 distinguishes ATM traffic and TDM traffic. The advantage is that the remote terminal 900 does not need to classify mixed traffic. The remote terminal 900 uses a unique air interface frame format and a unique corresponding multi-transport modal bus frame format to transport traffic to carry mixed traffic (ATM and TDM) in the same radio system. Similarly, this is different from a radio system in a point-to-multipoint system that actually requires a separate radio system for each transmission mode (ATM and TDM).

It should be noted that all the functional blocks of the remote terminal are not described in further detail. Their operations and implementation are all well understood by those skilled in the industry.

Refer to FIG. 10 again; it shows a functional block diagram of the timing recovery system used in the remote terminal of FIG. 9 to recover the timing sent by the hub terminal of FIGS. 2 and 14. The chart 1000 includes a multi-stage modulation demodulator 1002 with a cluster detector 1004; a bus controller 1008 with a time comparison unit 1010 and a remote time base counter 1020; and a second stage Loop wave generator 1014, a digital-to-analog converter 1016 (D/A converter), and a voltage controlled oscillator 1018 (VCO). It also shows the start 1006 of the signal in the upper frame, the remote start 1022 of the signal in the upper frame, the timing offset signal 1012, and the clock input 1024.

The cluster signal detector 1004 of the multi-level modulation modulator 1002 is coupled to the time comparison unit 1010, and the latter is coupled to the second-order loop wave device 1014. The second-stage loop wave device 1014 is coupled to the D/A converter 1016, the latter is coupled to the VCO 1018, and the latter is coupled to the remote time base counter 1020.

In practice, the remote terminal in the point-to-multipoint system recovers the timing of the signal sent from the hub terminal via the air interface. Therefore, the long-distance timing recovery is one of the methods for the remote terminal function to recover the timing from the central terminal. This timing recovery is necessary so that the indoor unit of the remote terminal can correctly demodulate the cluster signal received by the central terminal. Therefore, the timing of the remote terminal and the hub terminal does not need the timing rate switching function of the modulator. The timing of the remote terminal has the same frequency and phase as the timing of the central terminal.

In addition, the remote terminal uses the recovered timing to send the air-to-air cluster back to the hub terminal. Therefore, the advantage is that the hub terminal does not need to recover the long-distance timing to demodulate the cluster signal of the long-distance terminal. The hub terminal only needs to locate the activation of the cluster. Therefore, there is no additional timing to resume work at the hub terminal.

Therefore, the remote terminal in FIG. 9 uses the timing recovery system shown in FIG. 10 to restore the timing of the hub terminal. This is unique because the timing is from a discontinuous transmission from a hub terminal to a remote terminal (ie TDMA) rather than recovering from continuous transmission. Therefore, the hub terminal may not place all the time slots for transmission in order to reduce interference, or the remote terminal may be located far away from the hub terminal and only be able to modulate some of the lowest-order modulation packets (such as the one in this specific form). QPSK) decoding. Recovering the timing from discontinuous transmission will cause various problems. Because the timing is measured once for each frame above, a large amount of errors are accumulated during it. In continuous transmission, the timing of the measurement is much more frequent and the error between each measurement is relatively large. few.

The timing used at the hub terminal must be a very stable clock signal, such as a level 1 source known in the industry, and further refer to the discussion in FIG. 13. Level 1 timing sources are extremely expensive, so this point-to-multipoint system eliminates the need for a separate level 1 source at the remote terminal by restoring the timing of the hub terminal in the air interface. Therefore, the timing at the remote terminal is extremely accurate and stable.

Timing recovery is accomplished with a phase-locked loop (PLL). The hub terminal sends the first cluster of each upper frame in the farthest range modulation (for example, QPSK in this specific form), and puts a built-in Sync word in the upper frame in the pre-synchronization signal of this cluster. The cluster signal detector 1004 of the multi-level modulation modulator 1002 detects the upper frame activation Sync word, and generates an upper frame activation signal 1006 and sends it to the timely comparison unit 1010. The cluster detector 1004 corresponds to the cluster detector and parameter estimator 1146 in FIG. 11. The remote time base counter 1020 generates a remote upper frame signal start 1022 for each upper frame once, and the latter is also sent to the timely comparison unit 1010.

The timely comparison unit 1010 counts the time offset between the upper frame signal activation 1006 and the remote upper frame signal activation 1022. The time offset is sent to the second-order loop wave device 1014 (located in the control processor in the channel and control module in Fig. 9) with a timing offset signal 1012. At the second-stage loop wave device 1014, a second-stage phase-locked loop eye algorithm runs on the timing offset signal 1012. The second-order loop wave device 1014 slows down the wave work required to accurately restore the timing in the discontinuous transmission, thereby compensating for the error in the discontinuous measured value. The timing recovery in continuous transmission does not use the second-order loop wave filter 1014. The use of the second-stage loop wave device 1014 is novel in this case. The second-stage loop wave device 1014 then outputs a digital number, which is translated into a voltage level by the D/A converter 1016. This voltage controls VCO1018. The output of VCO1018 is the clock input 1024, or the timing used at the remote terminal. The clock input 1024 is also fed back into the remote time base counter 1020 to generate the remote upper frame signal to start 1022. This timing (clock input 1024) is also distributed to all SSI modules to be used as their stable clock source.

Therefore, it is advantageous for the remote terminal of the point-to-multipoint system to restore the timing of the discontinuous transmission of the hub terminal. The old point-to-multipoint system has its own timing source at the remote terminal, and the transmission in the downlink is continuous. In addition, since the remote terminal and the central terminal use the same timing, the central terminal does not need to perform independent timing recovery work to demodulate the cluster signals received from each remote terminal.

The various components and the second-order phase-locked loop algorithm are known to those skilled in the industry, so no further explanation is needed.

Multi-level modulation function modulation demodulator

Refer to Fig. 11 again; it shows the functional block diagram of the multi-level modulation modulator of the indoor unit in the remote terminal of Fig. 9 and the hub terminal of Fig. 10. The multi-level modulation function modulator and demodulator 1100 includes a modulator 1102 and a demodulator 1104. The modulator 1102 includes: transmission data 1106, a transmission buffer interface 1108, a scrambler 1110, a Reed-Solomon encoder 1112, and a modulation selector unit 1114. The latter includes a byte-to-symbol converter 1116, a cluster Signal formatter 1118 and constellation lookup table 1120. The modulator 1102 also includes a pulse shaper 1122, a half-band wave device 1124, a ramp wave 1126, a linearizer 1128, an IF modulator 1130, a sinc distortion compensation wave device 1132, and a transmission intermediate frequency 1134. The demodulator 1104 includes a receiving intermediate frequency 1136, a matching wave device and down converter 1138, and a collection section 1140. The latter includes a pre-correlation wave device 1144 and a cluster signal detector and parameter estimator 1146. The cluster detector and parameter estimator 1146 outputs a gain estimation value signal 1148, a timing estimation value signal 1150, a phase estimation value signal 1152, and a frequency offset estimation value signal 1154. The demodulator 1104 also includes a tracking section 1142, including an automatic gain control 1156 (AGC), an equalizer and phase rotator 1158, a multi-stage modulation limiter 1160, and a carrier recovery loop 1162. In the demodulator 1104, a coefficient memory 1164, a symbol-to-byte converter 1166, a Reed-Solomon decoder 1168, a descrambler 1170, and an output buffer 1172 are displayed.

The multi-level modulation function modulator and demodulator is an application-specific integrated circuit specially generated to perform cluster signal modulation (QPSK, 16-QAM, and 64-QAM) using three different modulations (QPSK, 16-QAM, and 64-QAM) ASIC). The multi-level modulation modulator 1100 is not limited to these modulations, but can be configured to support, for example, BPSK, 32-QAM, 128-QAM, and 256-QAM. The advantage is that the multi-level modulation function modulator can switch between various modulations on the basis of cluster signal connection. In another way, the multi-level modulation modulator can be configured to convert various modulations on the basis of frame by frame. The multi-level modulation function modulator 1100 generates the frame format of the air interface as described above with respect to FIGS. 4-8. Therefore, the multi-level modulation function modulation demodulator switches between differently modulated traffic clusters and different types of traffic clusters. It is advantageous to enable a single hub terminal of a point-to-multipoint system to communicate with all remote terminals within a specific sector, regardless of the area where the remote terminal is located. In addition, this enables effective use of the available bandwidth, because communication with remote terminals closer to the hub terminal in the radial direction can use a modulation mode (such as QPSK) modulation mode (such as 64-QAM) is completed. In addition, the same multi-level modulation modulator 1100 can be used at the remote terminal and the hub terminal.

The multi-level modulation and demodulator 1100 has two main systems: a modulator 1102 and a demodulator 1104. The modulator 1102 has a design target of up to 10 megapods (or 10 MSps) and 12.5 pods. The IF center frequency is twice the Bode rate, or 20 MHz nominal. When the transmission data 1106 enters the modulator from the bus controller of the indoor unit (refer to FIGS. 9 and 14), it is input through a transmission buffer interface 1108. The transmission buffer interface 1108 is an alternating buffer that allows back-to-back packets. Secondly, the data is scrambled by the scrambler 1110 to disperse the energy. The scrambler is coupled to the Reed-Solomon encoder 1112, which encodes the data. The Reed-Solomon encoder 1112 is coupled to the byte-to-symbol converter 1116 of the modulation selector unit 1114.

The modulation selector unit 1114 is a component of the multi-level modulation function modulation demodulator 1100 that can use multi-level modulation. The symbol-to-byte converter 1116 is coupled to the cluster formatter 1118. The byte-to-symbol converter 1116 is programmable, and converts the byte to a specific modulation (such as QPSK) that will be used for each cluster. , 16-QAM, and 64-QAM) required modulation symbols. The cluster formatter 1118 is coupled to the constellation lookup table 1120. The cluster formatter 1118 formats the symbols into a cluster type, such as four clusters or single clusters as discussed in FIG. 7A or 7B. The cluster formatter 1118 can also be used to add the preamble and postamble to the cluster. The constellation search table 1120 is programmable, and formats the cluster information according to one of the three constellations constructed by it: 4 (QPSK), 16 (16-QAM), and 64 (64-QAM). Each constellation is programmable and not limited to square constellations. Various constellations can be used, such as a multi-level circular 64-point constellation. Therefore, it is advantageous for the modulation selector 1114 to use multiple modulations to format the cluster on the basis of connecting the cluster to the cluster. This represents an improvement over the old method using only one modulation modulator.

Secondly, each symbol is passed through a programmable pulse shaper 1122 that interpolates each signal, such as a cosine square wave device. Secondly, the signal passes through the half-band waver 1124. The ramp wave 1126 (which is a programmable ramp wave) applies a ramp wave to the start and end of the cluster. The linearizer 1128 is coupled to the ramp wave 1126 and compensates for nonlinear distortion. Secondly, the IF modulator 1130 modulates the signal to an intermediate frequency (IF). Secondly, the sinc distortion compensation wave device 1132 (which is an FIR wave device) compensates the sinc distortion when the transmission IF 1134 leaves the multi-level modulation function modulator 1100. Alternatively, the transmission of IF1134 can go to a regression for self-testing. The entire functional block diagram of the modulator part 1102 receives the cluster signal and timing control signals, and a table access interface is coupled to the transport buffer interface 1108, the cluster formatter 1118, and the constellation lookup table 112. , Ramp wave 1126, and linearizer 1128. Transmit IF1134 to the IF transceiver section of the indoor unit of the remote terminal and the central terminal (refer to Figures 9 and 14).

The demodulator 1104 feeds composite bandpass signal samples or receives the intermediate frequency 1136. These samples use a matching Lubo device and down converter 1138 Lubo. The output of the matched wave device and the down converter 1138 is a composite fundamental frequency I/Q signal. The demodulator is divided into two sections (collection section 1140 and tracking section 1142). The down-converted samples are sent to these two sections.

Collection section 114. It includes a pre-correlation wave detector 1144 and a cluster detector and parameter estimator 1146. The received clusters are one of two types: maintenance clusters (manager) and traffic clusters. When the maintenance cluster is activated, the pre-correlation wave device 1144 (which is an FIR wave device) is charged or preset coefficients from the coefficient memory 1164. The preset coefficient is a preset interpolation coefficient from the coefficient memory 1164. When the pre-correlation wave device 1144 has preset coefficients, the cluster detector and parameter estimator 1146 will provide the true timing offset, as seen by the demodulator 1104. The timing estimation value is sent to the equalizer and phase rotator 1158 as the timing estimation value signal 1150. The timing estimate is used by the equalizer and phase rotator 1158 of the tracking section 1142 to select a set of interpolator coefficients. These interpolation coefficients are used for all possible timing offsets of different channels (used by each remote terminal), and then stored in coefficient memory 1164 to be used in the following traffic packets received from different channels . When the traffic cluster is activated, the pre-correlation wave device 1144 charges or stores the coefficient in the coefficient memory 1164 (determined by the maintenance cluster). This enables the cluster detector and parameter estimator 1146 to provide the best parameter estimates when the samples arriving at the cluster detector and parameter estimator 1146 have been equalized for channel distortion. A set of independent internal interpolation coefficients corresponding to each channel of communication by each remote terminal is stored in the coefficient memory 1164. Therefore, the pre-correlation wave device 1144 may be a coefficient of the long-distance terminal set (or the central terminal set) originated from the traffic bundle.

This is different from the old method because the demodulator of the old method typically does not contain a pre-correlation wave device at all. The I/Q signal is sent directly to a cluster detector. In addition, the pre-correlation wave device uses a unique method to load or use coefficients, so that each parameter (timing, gain, frequency offset, and phase) can be estimated more accurately at the cluster detector and parameter estimator 1146, because The channel has been equalized for distortion.

Therefore, the maintenance cluster of individual remote terminals passes through the pre-correlation wave filter 1144 with preset coefficients (non-equalizers), so as to select the equalized coefficients for each individual remote terminal. When a remote terminal receives the traffic packet, it loads the pre-correlation wave device 1144 back. The selection of the equalization coefficient is based on maintaining the timing offset of the cluster. This procedure enables the cluster detector and parameter estimator 1146 to obtain better parameter estimates of the traffic cluster of the cluster detector and parameter estimator 1146, because the individual channel is entering the cluster detector and The parameter estimator 1146 has previously been equalized by the pre-correlation wave device 1144 with the preload and the individual interpolation coefficients.

The output of the pre-correlation wave device 1144 then proceeds to the cluster detector and parameter estimator 1146, which detects the unique word of the preamble signal to indicate the existence of a cluster. The cluster detector can detect the activation of a cluster, or the activation of a frame or the above frame. This ensures that the demodulator 1104 knows when the air interface frame format is activated. Once a cluster of signals is detected, initial parameters including timing offset, gain estimate, phase estimate, and frequency offset estimate are estimated. Figure 11 shows how to use the split preamble as shown in Figure 6 to find the details of frequency offset and phase offset. Then, the cluster detector and parameter estimator 1146 sends the following signals: gain estimation value 1148 to automatic gain control 1156, timing estimation value signal 1150 to equalizer and phase rotator 1158, frequency offset estimation value signal 1154 and phase estimation The value signal 1152 is sent to the carrier recovery loop 1162.

In the tracking section 1142, the down-converted symbols are sent to the automatic gain control 1156. Automatic gain control 1156 (AGC) uses the initial gain estimate obtained from the gain estimate signal to measure the power of the received I/Q sample, and equals it to a programmable threshold level to generate an instantaneous power level. At this moment, the power error is provided by a nonlinear wave device (in the AGC1156) to the wave device, and then used to close a negative feedback loop, which drives the received signal power level to the programmable threshold level.

Then, the I/Q output of the AGC 1156 is fed into the equalizer and phase rotator 1158. The equalizer of the equalizer and the phase rotator 1158 interferes with the inter-symbol caused by the non-ideal phase/amplitude response of the channel. In addition, the equalizer and phase rotator 1158 are loaded with coefficients in two different ways, depending on the type of cluster. During the maintenance of the cluster, the equalizer load of the equalizer and the phase rotator 1158 is stored in the interpolator coefficients in the coefficient memory 1164. The timing estimate provided by the collection section 1140 is used to select a set of interpolator coefficients stored in the coefficient memory 1164. The equalizer then tracks the channel changes and stores the equalizer coefficients back into the coefficient memory 1164 at the end of the burst. Only the coefficients corresponding to the remote terminal to which the cluster belongs will be updated. During the traffic congestion, the equalizer load is pre-correlated with the coefficients used by the wave filter 1144. Therefore, the equalizer and the pre-correlation waver 1144 will work on the same set of coefficients.

The equalizer coefficients are modified by the least mean square algorithm (LMS). Other algorithms such as recursive least squares (RLS) can also be used. The equalizer may have only the front-pass coefficient, or both the front-pass and feedback coefficients. In addition, the precedent coefficient can be a score or a symbol as a basis.

The carrier recovery loop 1162 tracks and suppresses the carrier QAM signal. Therefore, the demodulator can support both QAM and QPSK modulation. When tracking the activation of each cluster, the carrier recovery loop 1162 is loaded to collect the phase estimation value signal 1152 and the frequency offset signal 1154 provided in the segment 1140. The carrier recovery loop 1162 uses a second-stage phase-locked loop to track the phase and frequency. The phase error is obtained by using the input of the multi-level modulation limiter 1160 (the output of the equalizer and phase rotator 1158) and the output of the multi-level modulation limiter 1160. Then, the output of the carrier recovery circuit 1162 is sent back to the equalizer and phase rotator 1158, so that the output can be rotated before being sent to the multi-stage modulation limiter 1160. Also, using this phase will update the error of the equalizer coefficient to rotate. The equalizer error is also obtained using the input and output of the multi-level modulation limiter 1160.

The programmable multi-level modulation limiter 1160 transforms the output of the equalizer and phase rotator 1158 into demodulation bits. Therefore, the multi-level modulation limiter 1160 maps the received data to the third modulation mode One of the corresponding three-star seats (4, 16 and 64 points) in one of the states (QPSK, 16-QAM, and 64-QAM, respectively)

. In addition, the multi-level modulation limiter 1160 supports various variations of 64-QAM modulation, such as a multi-level circular constellation. Therefore, the multi-level modulation limiter 1160 facilitates the multi-level modulation capability of the multi-level modulation demodulator 1100. The multi-level modulation limiter 1160 is similar to the constellation lookup table 1120 of the modulator 1102. In addition, the output of the multi-level modulation limiter 1160 is converted from sign to byte by the sign-to-byte converter 1166. The symbol-to-byte converter 1166 supports three star seats, each for one of the modulation modes used by the modulator section 1102. The output of the symbol-to-byte converter 1166 is sent to the Reed-Solomon decoder 1168 for decoding. The data then proceeds to a descrambler 1170, which cancels the scrambling effect inserted by the scrambler 1110 of the modulator 1102. Then load the descrambled data byte into the output buffer 1172. The output buffer 1172 is an alternating buffer, so when one buffer is written by the demodulator 1104, the other is read by the baseband interface to the bus controller. This causes back-to-back bursts at the output buffer 1172. Therefore, the output data 1174 is the signal output of the bus controller in the digital baseband section of the remote terminal and the central terminal from the multi-level modulation modulator 1100 (refer to Figures 9 and 14).

It is also necessary to note that a table access interface provides information about the frame format and cluster type of each modulation used by the multi-level modulation modulator demodulator 1100, and is coupled to the transmission buffer Interface 1108, cluster formatter 1118, constellation lookup table 1120, ramp 1126, linearizer 1128, cluster detector and parameter estimator 1146, and output buffer 1172.

The demodulator 1104 is controlled via a serial register in a main interface. The register is written by the life microprocessor, that is, the control processor of the remote terminal and the central terminal. In addition, the real-time control of the demodulator 1104 is accomplished by the provided cluster signal and timing controller logic.

It should be noted that not all functional blocks are fully explained, because their functions and implementations are understood by those skilled in the industry, so no further explanation is needed.

As shown, the multi-level modulation function modulation demodulator 1100 advantageously modulates and demodulates multiple modulation modes on the basis of the cluster signal connection. The multi-level modulation and demodulator 1100 can convert various modulations, and then convert various types of clusters. The multi-level modulation and demodulator 1100 is implemented as an application specific integrated circuit (ASIC) as a unit of a single modulation and demodulator. In addition, it is designed so that it can be used for remote terminals and hub terminals of point-to-multipoint systems. The multi-level modulation and demodulator can be programmed so that when the multi-level modulation and demodulator 1100 is used in a specific remote terminal in a specific area of a sector, only certain modulations are used. Variable modal demodulation.

Alternatively, the multi-level modulation function modulation demodulator 1100 can be implemented by three independent modulation demodulators, each supporting a single modulation and providing a conversion device between the three independent modulation demodulators. Although therefore, the multi-level modulation modulator 1100 is different from the old modulator that supports single modulation, and facilitates the multi-level modulation of the specific form of the point-to-multipoint system shown in Figures 1 and 2. situation.

Refer to FIG. 12 again; it shows a functional block diagram of the parameter estimation performed in the multi-level modulation function modulator and demodulator of FIG. 11 and using the characteristics of the split preamble shown in FIG. 6. The frequency offset estimator 1200 includes a pre-correlation wave device (Figure 11), a first correlator 1204, a delay buffer 1206, a second correlator 1208, a first phase estimator 1212, a second phase estimator 1210, and The I/Q signal 1202 of the frequency offset estimation value 1218 and the frequency offset 1214, the scaler 1216, and the frequency offset 1218.

The I/Q signal 1202 enters the first correlator 1204, which is coupled to the delay buffer 1206 and the first phase estimator 1212. The delay buffer 1206 is coupled to the second correlator 1208, which is coupled to the second phase estimator 1210. The outputs of the first phase estimator 1212 and the second phase estimator 1210 are connected to an adder 1214, and the latter is coupled to a scaler 1216. The scaler 1216 outputs the frequency offset estimated value 1218.

In practice, the specific form reflected in FIG. 12 uses the split preamble shown in the traffic packet of FIG. 6 to provide an accurate frequency offset estimate. The traffic cluster has been optimized to have a specified size, so that the traffic clusters with different modulations can be mixed and matched in the format of the air interface frame in FIG. 5. However, in order to maximize the traffic throughput of each individual traffic cluster, each traffic cluster should have as small a preamble as possible. In the old demodulator, the preamble is used to estimate the frequency offset of the received traffic packet. Specifically, it is typical to insert a unique word into the preamble. The phase is estimated over the length of the unique word portion of the preamble to determine the frequency offset. The length of the unique character can be, for example, about 32 symbols or 40 symbols. This symbol length should produce an accurate phase estimate to provide an accurate frequency offset. If the unique word is quite long, the estimated value will not be equally accurate, because the phase will change too much in the length of the unique word. If the unique word is much shorter, the phase estimation value will be inaccurate, and the phase cannot be accurately estimated because the symbol interval is too short.

The specific form shown in Figures 6 and 12 splits the unique character into a first unique character 610 and a unique character 611, with data (traffic) and/or backup in the middle (the first data shown in Figure 6/ Backup section 612). The first data/backup section 612 separates the first unique word and the second unique word by a number of symbols defined as a preamble splitting length 613. The first unique character 610, the second unique character 611 and the first data/backup section 613 in between constitute a total length equal to a typical unique character. Therefore, the two shortened unique characters and the data between them replace the unique characters of the old law; therefore, shorter unique characters are used in the preamble, and the traffic throughput of the traffic cluster is increased due to the amount of symbols in between. For example, a unique character of 32 symbols can be replaced by a first unique character of 8 symbols, data of 16 symbols, and a second unique character of 8 symbols. Moreover, the first unique character does not need to be the same length as the second unique character. For example, the second unique word may have 16 symbols, and the first unique word may have 8 symbols.

When the I/Q signal 1202 (composite fundamental frequency) enters the bundle detector and parameter estimator 1146 of the demodulator, it enters a first correlator 1204. The first correlator 1204 then searches for the first unique word. For example, if the first unique word is 8 symbols, the first correlator 1204 detects the first unique word including 8 symbols, and then sends the I/Q output of the first unique word to the first phase estimationDevice1212. The correlation is done at the symbol rate so that every sample that is separated is ignored. The first correlator is actually two correlators, one for the in-phase component sample (I) and the other for the right-angle component sample (Q). The correlators are well known in the industry, so no further explanation is needed.

The I/Q signal also advances to the delay buffer 1206, which is responsible for the number of symbols in the first data/backup section between the first unique word and the second unique word. The delay buffer 1206 stores the 16 symbols of the first data/backup section. The second correlator 1208 then searches for the second unique word (for example, 8-symbol unique word), and sends the I/Q signal of the second unique word to the second phase estimator 1210. The second correlator 1208 is actually two correlators. The first phase estimator 1212 and the second phase estimator 1210 respectively estimate the phase of the first unique word and the second unique word. The adder 1214 obtains the difference between the two phases and uses the calibrator 1216 to calibrate it to generate an estimated frequency offset 1218. The calibrator 1216 divides the phase difference by the distance between the midpoints of the first unique character and the second unique character. For example, the distance in the example is 4 symbols ten 16 data symbols ten 4 symbols = 24 symbols. These symbols are multiplied by the symbol rate to get the distance. This is different from the frequency estimator of the old method, which only contains a correlator instead of a first correlator 1204 and a second correlator 1208.

Therefore, the frequency offset estimator 1200 uses the unique split preamble shown in FIG. 6 to estimate a small preamble that is close to the Cramer-Rao boundary and has as few as 16 symbols in total between the first unique dictionary and the second unique word. Frequency deviation within the synchronization signal. The traffic throughput is maximized while maintaining accurate frequency estimation. These functional block diagrams are understood by those skilled in the industry, so no further explanation is needed.

Hub terminal

Refer to Fig. 13 again; it shows a block diagram of the central part of the specific form of the point-to-multipoint system shown in Fig. 2. The central part 1300 has a radio system 1301 including a plurality of central terminals. Each terminal has a main outdoor unit (ODU) and antenna 1306, a backup outdoor unit 1308 and antenna 1310, inter-device link (IFL) 1312, main Indoor unit (IDU) 1314 and spare indoor unit 1316. The transmission equipment 252 system is also shown, including a TDM multiplexer 1318, ATM multiplexer 1320, and timing source 1322. Also shows DS3 line (digital signal 3) and OC3c line 1326 (sequential optical carrier level 3), a LAN path selector 1328, a wide area network line 1330 (WAN line), reverse transmission line 1332 and a timing source signal 1334.

Each hub terminal 1302 (sector radio) includes a main outdoor unit with an antenna 1306, coupled to a main indoor unit 1314 via an inter-device link 1312 (IFL). It is also shown that the backup outdoor unit 1308 with an antenna 1310 is coupled to the backup indoor unit 1316 via an inter-device link 1312. The spare indoor unit 1316 (IDU) has the same connection device as the main IDU 1314, so only the main indoor unit 1314 will be discussed. Each main indoor unit 1314 has a DS3 line 1324 to the TDM multiplexer 1318 and an OC3c line 1326 to the ATM multiplexer 1320. The TDM multiplexer 1318 and the ATM multiplexer 1320 each have a reverse transmission line 1332, allowing connection to a transmission network (not shown). Each main indoor unit 1314 of each hub terminal 1302 is coupled to the LAN hub 1328 and timing source 1322. The timing source 1322 sends the timing reference signal 1334 to each hub terminal 1302. The LAN path selector 1328 has a random WAN line 930 to the EMS.

In practice, the central part 1300 is the heart of the point-to-multipoint system. The central part 1300 supports a multi-frequency, multi-sector central. The radio channel is divided into multiple sub-channels. For example, a 50 MHz channel can be divided into four 12.5 MHz sub-channels. Each central part 1300 supports one channel, and each central terminal 1302 supports one sub-channel (sector). In addition, each sector (the "circular slice" in FIG. 1) may contain more than one hub terminal 1302, depending on the location of the multiple channels of the 1300 megabits of the hub and the remote terminal. Each hub terminal 1302 (sector radio) of the radio system 1301 includes an outdoor unit 1304, which has an antenna 1306, an inter-device link 1312, and an indoor unit 1314.

The outdoor unit 1304 (also known as the transceiver unit) is an integrated 38 GHz transceiver and antenna 1306. The outdoor unit 1304 of the hub terminal 1302 is the same as the outdoor unit of the remote terminal described in FIG. 9, except that the transmission and reception frequency bands are exchanged with respect to the transmission and reception frequency bands of the outdoor unit of the remote terminal. The outdoor unit 1304 up-converts the signal of the inter-device link 1312 into the transmission frequency, and down-converts the signal of the air interface into the inter-device frequency. It is usually located on the top of the building at the central part 1300. In addition, the outdoor unit 1304 can be connected to a surge protector at the entrance of the building.

Alternatively, since the hub terminal 1302 uses discontinuous transmission (TDMA) transmission, the outdoor single megabit 1304 may include a converted wave beam antenna (not shown) as the antenna 1306, so that a converter is coupled to several antennas. Each antenna transmits to a narrow sub-sector, such as a sub-sector of 15-22 degrees. The converted wave beam antenna must be converted between the TDMA clusters in the air interface frame format. Therefore, only one antenna is used for transmission at a time, thereby reducing interference in other sectors and the hub terminal 1302. This also expands the range of the point-to-multipoint system by transmitting more energy/bit in a narrower wave beam than required by the antenna 1306 covering the entire sector. Therefore, the size of the multi-channel is reduced, and the operation of higher-level modulation is better. Similarly, the phased array antenna system will achieve the same result.

The inter-device link 1312 connects the outdoor unit 906 to the indoor unit 1314, and is the same as the inter-device link 1312 used in the remote terminal set in FIG. 9.

The indoor unit 1314 (channel processing unit) of the hub terminal 1302 is very similar to the indoor unit of the remote terminal. The indoor unit 1314 of the hub terminal 1302 also supports multiple transmission modes, such as asynchronous (such as ATM) and synchronization (such as TDM), and supports multi-level modulation modes such as QPSK, 16-QAM and 64-QAM. It interfaces with the device link 1312 and includes a channel and request module (CCM), which contains an IF transceiver section, a baseband section, a multi-transport modal unit bus, and four SSI ports . The internal work of the indoor unit 1314 of the hub terminal 1302 is similar to that of the indoor unit of the remote terminal, and further reference is made to the discussion in FIG. 14. Advantageously, the indoor unit 1314 of the hub terminal 1302 uses the same multi-level modulation modulator as the indoor unit of the remote terminal. Therefore, it is advantageous that only one multi-level modulation function modulator ASIC needs to be designed for all hub terminals and remote terminals of the point-to-multipoint system.

Some differences between the indoor unit 1314 of the hub terminal 1302 and the indoor unit of the remote terminal are the type of SSI module used in the SSI port, and there are a few additional interfaces in the indoor unit 1314 of the hub terminal 1302 (see figure 14). The indoor unit 1314 of the hub terminal 1302 only uses three types of interfaces to the transmission equipment: the TDM-DS3SSI module connected to the DS3 line 1324 (see Figure 21), and the ATM-OC3cSSI module connected to the OC3c line 1326 ( Refer to Figure 22), and the DS3 transparent SSI module connected to the DS3 line 1324 (refer to Figure 24).

In this specific form, each hub terminal 1302 uses a 1:1 redundancy system when one of the hub terminals 1302 fails. If the main outdoor unit 1304 or the main indoor unit 1314 fails, the backup outdoor unit 1308 and the backup indoor unit 1316 are converted into use. The interruption to user services is minor. The spare outdoor unit 1308 and spare indoor unit 1316 have the same composition as the main outdoor unit 1304 and main indoor unit 1314. The remote terminal in Figure 9 also uses a 1:1 redundancy system.

Alternatively, the central part 1300 can use a 1:N redundancy system, as shown in Figures 37-38.

The transmission device 252 is the same as described with respect to FIG. 2. The TDM multiplexer 1318 and the ATM multiplexer 1320 are used to transmit TDM and ATM traffic to and from the transmission network (not shown), respectively. The reverse transmission line 1332 connects the TDM multiplexer 1318 and the ATM multiplexer 1320 to the transmission network, and includes, for example, DS3, OC3c, and OC12c lines.

In addition, a timing source 1322 provides a synchronization solution for the hub terminal 1302. The important thing is that the timing source must be a stable and accurate source. The level 1 timing source is known in the industry, because the timing at the hub terminal 1302 is used for each remote terminal and the SSI coupled to the remote terminal. Module. The timing source 1322 can be an external DS1 source reference (GPS-source or other DS1 reference), a DS3 line, or a DS1 embedded in the DS3. The timing source 1322 is then used for the symbol rate used by the radio interface of each hub terminal 1302. The timing reference is also mentioned in Figure 14. If the timing source is DS1 in a DS3 (that is, a T1 in a DS3), the timing is usually provided by the converter of the central office, which is coupled to the transmission equipment 252 via the transmission network (see Figures 1 and 2 ). In this case, if the time sequence drifts due to an error condition of the central office, all the hub terminals will drift the same without data loss.

In addition, a LAN path selector 1328 is provided to allow communication between the hub terminals of the hub part 1300 and to connect to a wide area network (WAN) via a WAN line 1330 at will. In a specific form, the element management system (EMS) 122 uses the WAN to communicate with each hub terminal via the LAN path selector 1328. The WAN line 1330 can be provided as an Ethernet10BaseT line. Therefore, the component management system can communicate with the hub terminal 1302 via the LAN path selector 1328 at the hub 1300. The LAN path selector 1328 also allows the hub terminal 1302 to communicate with each other. Alternatively, the EMS can communicate with the central terminal 1302 by sending text messages via the transmission network and the reverse transmission line 1323. This advantageously eliminates the need for wire connections from the EMS to the central part 1300. This further refers to the description of FIG. 22.

The following is an overview of the traffic flowing from the central office through the central terminal. The traffic is routed through a transmission network (such as a SONET ring) to the central part 1300 by the component management system located in the central office. The traffic reaches the TDM multiplexer 1318 or the multiplexer 1320, depending on the type of traffic. ATM traffic is routed to the desired hub terminal via OC3c line, and TDM traffic is routed to the desired hub terminal via DS3 line. The individual traffic is multiplexed by the indoor unit 1314 to a multi-transport modal unit bus at the individual SSI module. The multi-transport modal unit bus is discussed in Figures 15-18. Then the mixed traffic is formatted for the radio interface and tuned to the intermediate frequency in the indoor unit 1304. The IFL 1312 carries the traffic to the outdoor unit 1304, where it is down-converted to the transmission frequency of the radio interface. Therefore, the long-distance terminal set within the coverage of the antenna sector of the outdoor unit 1304 of the traffic transmission. The data stream reaches the outdoor unit 1304 in the reverse direction. Therefore, the hub terminal 1300 in this specific form carries both ATM and TDM traffic, while the old law system requires a single lower structure for ATM and TDM transmission.

Another unique feature of the central part is that the central part is a modular central part structure. In the old point-to-multipoint system, when the hub is located, the hub architecture is designed as a chassis that includes the plug-in boards for all the different hub terminals that will be supported by the hub. Each board (used in the hub terminal) is known in the industry to share a common processor, common SSI interface module, common backplane interface, common power supply, and so on. In other words, each hub terminal in the old system is not solely located in the public equipment for operation. Therefore, when setting the central part, it is necessary to set the structure for the entire system.

On the contrary, in this specific form of the present invention, the system designer can construct a central part with only one channel sub-channel by installing a modular central terminal including an outdoor unit 1304 and an indoor unit 1314 . The indoor unit is a small unit with only two plug-in boards supporting one channel. To add more sub-channels, simply install another modular hub terminal for each sub-channel in the chassis. The modular hub terminal does not need to share a common processor, a common SSI interface module, a common backplane interface, or a common power supply. Therefore, the operation of the modular hub terminal (ie, the hub terminal 1302) has nothing to do with other modular hub terminals and other public equipment. Therefore, it is not necessary to set up a framework for the entire old point-to-multipoint system supporting a whole channel with as few as only one central part of the channel.

This is particularly advantageous because the old method uses only one channel and sub-channel point-to-multipoint system to install the cost extremely high. In practice, many service providers will set up point-to-multipoint systems that only serve one or two sub-channels, because many users are located very close to each other, or the point-to-multipoint system has very few users, or hinders many Physical barriers (such as mountains) used by the central terminal (each using an independent sub-channel). The advantage is that the modular hub allows the point-to-multipoint system to grow with the user's requirements, without forcing the service provider to pay for the entire point-to-multipoint system architecture supporting a whole channel in the initial stage.

In another specific form, the line to the reverse transmission line 1332 can be provided by a radio communication link from the transmission equipment 252 to the transmission network (shown in Figures 1 and 2) or the reverse transmission substructure (shown by that). Substitute. The radio communication link can be a microwave radio communication link very similar to the communication link between the hub terminal 1302 and individual remote terminals. An antenna such as a 12-inch antenna is coupled to the transmission device 252, and a corresponding antenna such as a second 12-inch antenna is coupled to the transmission network. This specific form allows the distance between the central part and the transmission network to be approximately 5 to 10 miles.

Refer to Figure 14 again; it shows the block diagram of the hub terminal (multi-modal hub terminal) in the specific form shown in Figures 2 and 13. The hub terminal 1400 includes an outdoor unit (ODU) 1402 (also called a transceiver unit) with an antenna 1404 and an indoor unit (IDU) 1406 (also called a channel processing unit). The indoor unit 1406 is coupled to an inter-device link 1408, maintenance port 1410, urban network (LAN) interface line 1412, T1 reference line 1414, multi-transport modal unit bus 1416, TDM DS3 SSI module 1418, ATM OC3c SSI module 1419, optional DS3 transparent SSI module 1421, and a channel and request module 1420. The channel and request module (CCM) 1420 includes: an IF transceiver section 1422, including an inter-device (IFL) interface 1424, an uplink converter 1426, and a downlink converter 1428; a digital baseband section 1430 , Including a multi-level modulation modulator 1432, bus controller 1434, control processor 1436, control signal 1437, maintenance port interface 1438, LAN controller 1440, and timing logic 1442; and a LAN interface 1444 and T1 interface 1446.

The outdoor unit 1402 is coupled to the indoor unit 1406 via the inter-device link 1408 coupled to the IFL interface 1424 in the IF transceiver section 1422 of the CCM module 1420. The IFL interface 1424 is coupled to the up converter 1428 and the down converter 1426. The up-converter 1428 and the down-converter 1426 are each coupled to the multi-level modulation demodulator 1432 of the digital baseband section 1430. The multi-level modulation modulator 1432 is coupled to the bus controller 1434, which is coupled to the multi-transmission modal unit bus 1416. The maintenance port 1410 is coupled to the maintenance port interface 1438, which is coupled to the control processor 1436. The LAN interface line 1412 is coupled to the LAN interface 1444, which is coupled to the LAN controller 1440. The T1 reference circuit 1414 is coupled to the T1 interface 1446, which is coupled to the timing logic 1442 of the baseband section 1430. The maintenance port interface 1438, the LAN controller 1440, and the sequential logic 1442 are coupled to the control processor 1436, respectively. The internal sequential logic and the control processor are also coupled to the multi-transmission modal unit bus 1416. The control processor 1436 sends the control signal 1437 to the IFL interface 1424, the up converter 1428 and the down converter 1426.

In implementation, the indoor unit 1406 (IDU) of the hub terminal (sector radio) is very similar to the indoor unit (IDU) of the remote terminal. The components of the IF transceiver 1422 are exactly the same as those described in FIG. 19. The multi-level modulation function modulation demodulator 1432 of the hub terminal 1400 can use multi-level modulation modes to transmit on the basis of cluster communication, and supports QPSK, 16-QAM, and 64-QAM as mentioned above. The bus controller 1434, the control processor 1436, and the multi-transmission modal unit bus are also the same as those in the indoor unit of the remote terminal (see the previous figures for details).

However, the control processor 1436 in the digital baseband section 1430 of the hub terminal 1400 is constantly in contact with the component management system. Therefore, the control processor 1436 completes the assignment of all time slots to the multi-transport modal unit bus 1416 and the traffic on the air interface. It also generates a time plan for mapping DS0 from the SSI module to the frame format of the multi-transport modal bus frame and the frame format of the air interface at the appropriate time slot. The control processor 1436 instructs each user-specific interface such as the TDMDS3SSI module 1418 when (via a time scheme) to transmit and copy the traffic of the multi-transport bus, and what kind of header information will be mixed for the traffic assignment. The control processor 14S6 uses the master message in the format of the air interface frame to communicate with each processor of the indoor unit of the remote terminal.

The maintenance port 1410 is similar to the maintenance port of the indoor unit of the remote terminal. The maintenance port 1410 is used to support the PC serial port connection on the top of the stack for maintenance and testing of the indoor unit 1406. The maintenance port 1410 uses a maintenance interface 1438 (such as an RS232 port) to interface with the control processor 1436.

The LAN controller 1440 is not in the remote terminal, but is a PCI bus-based controller that provides an interface to the component management system of the central office. The LAN interface 1444 is connected to the LAN interface circuit 1412, which is usually an Ethernet10BaseT circuit. The LAN interface line 1412 allows connection with a wide area network (WAN). The component management system uses the WAN to communicate with the LAN controller 1440. The component management system sends operation, administration, and management signals to the control processor 1436 of the CCM 1420. The LAN controller 1440 also allows the control processor 1436 to communicate with the control processors 1436 of other central terminal computers 1400 in the same central location.

The timing logic 1442 receives the timing reference source from a single terrestrial-based T1 (DS1) reference circuit 1414 via the T1 interface 1446, and translates it into a symbol rate for use in the entire point-to-multipoint system. Therefore, the timing logic 1442 generates the timing for the remote terminal including the SSI module (see Figure 20-25B) and the fiber expansion module (see Figure 32-34) coupled to the remote terminal. Alternatively, the reference clock pulse at the hub terminal 1400 can come from several sources, including a DS3 line clock retrieved from the DS3TDMSSI module or DS3 transparent line source; the DS1 line 1 or line 28 of the DS3-TDM SSI module is embedded in the DS3 -DS1 source of TDM SSI module; an OC3c line clock recovered by OC3c ATMSSI module; or a DS1 reference line 1414 as shown in Figure 14.

The clock pulse at the hub terminal is transmitted to the remote terminal via the air interface. This is accomplished by deriving the symbol rate clock of the sequential logic 1442 from the input reference clock, and then using the symbol rate received by the remote terminal unit to generate the required network interface clock. The important thing is that the transmitted reference clock pulse matches the stability of the land line, and also meets the relevant standards for jitter, wander, retention, and clock tracking capabilities. Therefore, the aforementioned source of the reference clock should be a level 1 level or equivalent timing source in order to provide the stability required by a point-to-multipoint system.

The control processor 1436 is a reduced command system code (RISC) processor that operates the channel and control module, and coordinates the maintenance port 1410, the LAN controller 1440, the sequential logic 1442, and the multiple transmission modal unit bus 1416. It also generates a control signal 1437, which is sent to the IF transceiver unit 1422 for gain control.

The multi-transport modal unit bus 1416 is a synchronous TDM unit bus, which can transmit both ATM and TDM traffic of the bus controller 1434 to and from the SSI module. The multi-transport modal unit bus 1416 is described in detail with reference to FIGS. 15-18. The advantage is that the multi-transport modal unit bus 1416 is an improvement over the old method using one bus to transmit ATM traffic and a single other bus to transmit TDM traffic.

The indoor unit 1406 has four SSI ports, but only three SSI modules, including the TDM-DS3SSI module 1418 described with reference to Figure 21, the ATM-OC3c SSI module 1419 described with reference to Figure 22, and the reference Figure 23 The DS3 transparent SSI module 1421. The TDM-DS3SSI module 1418 is used to transmit TDM traffic via a DS3 line which is a 28T1 line (28DS1). The ATM-OC3c SSI module 1419 is used to transmit ATM traffic via an OC3C line. The DS3 transparent SSI module 1421 uses the entire bandwidth of the sub-channel (sector), such as 12.5 MHz, to transmit asynchronous (such as ATM) or synchronous (such as TDM) data required by the point-to-point link in the point-to-multipoint system.

Multi-transport modal unit bus

Refer to Figure 15 again; shown is the bus frame format for the multi-transport modal unit bus, which provides the channel and control module of the indoor unit between the central terminal and the remote terminal shown in Figures 9 and 14 (CCM) The interface between the SSI module shown in Fig. 20-25B, and the relationship between the frame format of the air interface in Fig. 5 is exemplified. Diagram 1500 shows the multi-level modulation modulator 1502, the bus controller 1504, the SSI module 1506, the air interface frame format 1508, and the multi-transmission modal unit bus 1510 (also known as the multi-transmission modal) Bus), and multi-transmission modal bus frame format 1512. The multi-transmission modal bus frame format 1512 (hereinafter referred to as the bus frame format 1512) has a synchronization slot 1514 and an inter-module communication segment 1516 (hereinafter referred to as IM-Com Section 1516), and a unit bus data section 1518 (hereinafter referred to as CB-data section 1518) containing most data time slots 1526. The corresponding air interface frame format 1508 (as shown in FIG. 5) is also shown, which has a header section 1520, a backup section 1524, and a traffic section 1522.

The SSI module 1506 is coupled to the bus controller 15040 via the multi-transport modal unit bus 1510. The bus controller 1504 is coupled to the multi-level modulation modulator 1502, which is coupled to the IF transceiver of the indoor unit (Not shown). The multi-transport modal unit bus 1510 uses the bus frame format 1512, and the multi-level modulation function modulator 1502 outputs the air interface frame format 1508.

In practice, the multi-transport modal unit bus 1510 carries both asynchronous signals (such as ATM traffic) and synchronous signals (such as TDM traffic), which is different from the old one that requires a separate bus for TDM and ATM traffic. Method bus. The multi-transport modal unit bus 1510 provides a link between the channel and control module of the indoor unit and each SSI module 1506 (see Figure 20-25B). The multi-transport modal unit bus 1510 is an 8-bit synchronous TDM unit bus, using a fixed-length bus frame format 1512. The first time slot is a synchronized time slot 1514, which is used for synchronization between the indoor unit of the remote terminal and an extended indoor unit (EIDU). Refer to Figures 32-34 for further discussion. The remaining text time slot 1528 in the IM-Com section 1516 of the bus frame format 1512 has a fixed length, depending on the length of the bus frame. In addition, the diagram shown corresponds to both the hub terminal and the remote terminal. The dedicated SSI module 1506 will be changed depending on whether it is in a remote terminal or a hub terminal and its coupled reception.

The length of the bus frame format 1512 is selected so that the bus frame format 1512 can be directly mapped to the air interface frame format 1508, as shown in Figure 4-8. For example, if the frame format of the air interface is 6 milliseconds in length, the length of the bus frame format 1512 is also 6 milliseconds, and it matches with the air interface frame format 1508. The CB-data segment 1518 of the bus frame format 1512 is mapped to the traffic segment 1522 of the air interface frame format 1508. In addition, the different amount of data time slots 1526 of the CB-data segment 1518 can be assigned to the traffic cluster of the traffic segment 1522 of the air interface frame format 1508 with different inner diameters. For example, 12 data segments 1526 of CB-data segment 1518 can be mapped to a QPSK four-traffic cluster on the air interface frame format 1508, or 6 time slots can be mapped to a 16-QAM four-traffic. Cluster, or 4 time slots can be mapped to a 64-QAM four-traffic cluster.

The header section 1520 of the air interface frame format 1508 is only required for the communication between the indoor units of the remote terminal and the indoor units of the central terminal. Therefore, the main pipe section 1520 is deleted by the bus controller 1504 of the CCM of the indoor unit, so that the slot 1514 and the IM-Com section 1516 can be easily inserted into their positions during synchronization. Therefore, the IM-Com segment 1516 and the synchronization slot 1514 contain a necessary length to allow the bus frame format 1512 to directly correspond to the air interface frame format 1508.

This kind of bus frame format mapping operation is different from the old method, which often uses two separate bus frame formats to convey messages and data. In addition, the known old method bus frame format does not directly correspond to the air interface frame format 1508.

The multi-transport modal unit bus 1510 also operates at a fixed frequency that matches the symbol rate of the air interface. For example, if the air-to-air interface operates at a symbol rate of 10 Msps, the multi-transport modal unit bus 1510 operates at 10 Mbps (megabits per second). At the hub terminal, the timing of the multi-transport modal unit bus 1510 is derived from a timing reference or a link to the transmission network, as shown in FIG. 13. At the remote terminal, the timing of the multi-transport modal unit bus 1510 is derived from the signaling sent by the hub terminal. The CB-data section 1518 contains a fixed-length data time slot 1526. The data slot 1526 is advantageously constructed so that it can carry both specially formatted TDM units and ATM units (described in FIGS. 28 and 29) on the same bus frame format 1512. Likewise, this is different from the prior art that uses separate bus frame formats for ATM and TDM transmissions. The structure of the IM-Com unit installed in each message slot 1528 of the IM-Com section 1516 and the structure of the CB-data unit in each data slot 1526 of the CB-data section 1518 are individually referenced in Figure 16 and Discussion of 17. Therefore, as will be described in FIG. 12B, the CB-data unit in the data slot 1526 of the CB-data section 1518 is designed to carry an ATM unit or a specially designed TDM unit.

In addition, the multi-transmission modal unit bus 1510 combines the message (that is, in the IM-Com section 1516) and the data (that is, in the CB-data section 1518) on the same bus, and usually in the old In the legal system, a separate bus is used for both message and data transmission. The advantage of using only one unit bus bar is to reduce the number of pins used in the unit bus bar structure.

The data time slot 1526 has been selected to correspond to the empty interface frame format 1108. The data time slot 1526 can include different numbers of bytes; however, the length of the data time slot 1526 of the CB-data segment 1518 cannot be less than 53 bytes, because it is designed to fit the standard 53 bytes ATM unit and 53-byte TDM unit. The length should ideally not be less than 55 bytes in order to contain the control bytes shown in FIGS. 16 and 17. The timing signal or clock is also a part of the multi-transmission modal unit bus 1510. Referring to FIG. 18, a dedicated circuit or signal of the multi-transmission modal unit bus 1510 is constructed.

The IM-Com section 1516 message time slot 1528 system composition has a specific assignment. There is a dedicated text time slot 1528 available for each SSI module to be connected to the indoor unit. In addition, each fiber expansion module (both master and slave) has a text time slot 1528 (described in Figure 33), and each of the four SSI ports of the expansion indoor unit or EIDU has a text time slot 1528 (described in Figure 32). In addition, there may be additional time slots 1528 that can be dynamically assigned to any SSI module 1506 as needed.

Refer to Fig. 16 again; it shows a diagram of the structure of the IM-Com unit 1600 used in the multi-transport modal unit bus of Fig. 15. The IM-Com unit 1600 has a header 1602, including an SSIID 1606, a message signal column 1608 known in the industry, and an unused segment 1610. The IM-Com unit 1600 also contains a text segment 1604. The header 1602 includes the bytes used by the SSI ID 1606, which is used to resolve conflicts between different SSI modules while trying to place data in the same time slot. The second byte is used for the message signal column 1608, while the third byte is not used.

SSI ID 1606 is a field containing many bits, such as 8 bits. The lower 4 bits of SSI ID 1606 are used for SSI modules coupled to indoor units, while the higher 4 bits of SSI ID 1606 are used by individual expansion indoor units (see Figure 32). Therefore, each SSI module and each expansion indoor unit that interfaces with the multi-transport modal unit bus is assigned a bit. In operation, when a specific SSI module transmits into a time slot, a "0" bit is placed in its SSI ID 1606 bit, otherwise the SSI ID 1606 bit is "1". Since a message time slot is only assigned to one SSI module, for any given time slot in the IM-Com section, only one bit in SSI ID1606 should be "0". Therefore, if the third bit of SSI ID 1606 is assigned to the SSI module in SSI port #3, the lower four bits of SSI ID 1606 are transmitted into a time slot for the SSI module in SSI port #3. It should be "1011". The channel and control module (CCM) of the indoor unit resolve conflicts with a specific time slot in the IM-Com segment. If the SSI ID There is more than one "0" bit in each of the upper and lower 4 bits of 1606. The remaining m bytes constituting the message segment 1604 are used to report between the CCM control processor and the SSI module's local processor. This message job tells the SSI module which message time slot to use when transmitting and receiving, as well as other control information. The IM-Com unit 1600 is formatted by the bus controller or control processor of the indoor unit, or the city processor of each SSI module.

Refer to Fig. 17 again; it shows the structure diagram of a CB-data unit (also called a traffic unit) traveling on the multi-transmission modal TDM unit bus of Fig. 15. The traffic unit 1700 has a header 1702, a data unit 1704 (also referred to as a valid negative OR unit), and a backup section 1706. The header 1702 includes the first byte for SSI ID 1708 (refer to FIG. 16) and the second byte for payload status 1710.

The traffic unit 1700 fits into the data time slot 1526 of the CR-data section 1518 in the bus frame format. The traffic unit 1700 can be designed to match the length of the IM-Com unit 1600. In addition, the length of the traffic unit 1700 is such that one or more traffic units 1700 can be advantageously mapped to the traffic packet in the air interface frame format. For example, two traffic units 1700 can form a 16-QAM single traffic cluster, or 12 traffic units 1700 can form a QPSK quad cluster.

The data unit 1704 in the traffic unit 1700 has a length of 53 bytes, which is the size of a standard ATM unit. This facilitates the transmission of an asynchronous signal in the data unit 1704, such as a 53-byte ATM cell, or a synchronization signal, such as a 53-byte TDM data formatted in a specially designed 53-byte TDM unit (see Figure 29). ). Therefore, ATM and TDM units are multiplexed on the multi-transport modal unit bus by the SSI module (clearly the formatter of the SSI module). This feature eliminates the need to use one TDM unit for TDM traffic and another unit for ATM traffic.

The backup section 1706 contains any remaining bytes used in this specific form. The backup section 1706 includes a length so that the bus frame format can be made to match the air interface frame format, so that the bus frame format will be easily mapped to the air interface frame format. Depending on the design of the blank interface frame format and other system parameters, the data unit 1704 in the traffic unit can contain more bytes, but it cannot contain less than 53 bytes and still compares with 53 bits. Tuple ATM standard cells remain compatible.

In addition, the traffic unit 1700 includes n bytes. The size of the traffic unit 1700 depends on the length of the air interface frame format, the frequency used, and the minimum data unit size. As shown in FIG. 17, the traffic unit 1700 should be at least 55 bytes, so as to be responsible for the 53-byte data unit 1704 and the header section 1702. It should also be noted that the data unit can carry both an ATM unit and a TDM unit, and when the length of a standard ATM unit is replaced by a new standard length, the size of various units can be adjusted.

Refer to FIG. 18 again; shown is a timing diagram 1800 of the multi-transmission modal unit bus in FIGS. 15-17. The following unit bus signals constitute the multi-transmission modal unit bus: CB_CLK 1802, CB_TX_FS 1804, CB-TX-TSS 1806, CB-TX-DATA(7:0) 1808, CB-RX-DATA(7:0 ) 1810, CB_RX_FS 1812, CB_RX_TSS 1814, and CB_TX_SFS 1816 and CB_RX_SFS 1818.

The CB_CLK 1802 signal is a clock with a frequency corresponding to the symbol rate of the air interface, and is a line. CB_RX_TSS 1814 means that each time slot has a single clock receiving time slot sync, and it is 1 line. CB_RX_FS1812 is a receiving frame Sync with a single clock pulse for each frame, and it is 1 line. CB_RX_SFS 1818 is the receiving frame Sync with a single clock pulse for each frame above, and it is 1 line. CB_RX_DATA(7:0)1810 is an 8-bit data unit bus with 8 lines. In another way, the unit bus can be 16, 24, 32, etc. bit unit bus. The unit bus structure can be corrected according to the license. CB_TX_TSS 1806 is a transmission time slot Sync with a single clock for each time slot, and it is 1 line. CB_TX_FS 1804 is a transmission frame Sync with a single clock for each frame and 1 line. CB_TX_SFS 1816 is the transmission of the upper frame Sync with a single clock for each upper frame, and it is 1 line. And CB_TX_DATA(7:0) 1808 is an 8-bit transmission data unit bus with 8 lines. Therefore, the multi-transmission modal unit bus includes 23 lines in total and has a timing as shown in FIG. 18.

The multi-transport unit bus is used as a link between the channel of an indoor unit (no matter at a central terminal or a remote terminal) and the control module and SSI module (the user's interface). Advantageously, the multi-transport modal unit bus replaces two separate buses used to transmit ATM and TDM traffic, and combines inter-module communication and data units on the same unit bus frame format.

Data flow through the air interface

Refer to Fig. 19 again; shown is a flowchart illustrating the main steps performed by the point-to-multipoint system shown in Fig. 2 on the data flow between the indoor unit of the hub terminal and the indoor unit of the remote terminal. Although referring to the specific steps in Figure 19, other related drawings will still be referred to. The above-mentioned steps are in a broad sense, and are intended to provide data transfer via a communication link of a point-to-multipoint system.

Both synchronous (TDM) and asynchronous (ATM) traffic (or signals) are routed from the central office to each SSI module at the central terminal through the transmission network. Each SSI module uses the multi-transport modal bus frame format to format and multiplex the mixed traffic on the multi-transport modal unit bus (step 1902). The specific technology used by the SSI module to format and multiplex mixed traffic into a single format on the multi-transport modal unit bus will be described in the following manual, instead of this flow chart. As mentioned, the multi-transport modal unit bus carries both asynchronous traffic (such as ATM) and synchronous traffic (such as TDM), but the way is that the remaining hub terminals and remote terminals do not know that they both carry ATM And TDM unit. Therefore, the point-to-multipoint system supports multi-traffic types through the formatting of the data required by the multi-transmission modal unit bus and the mapping of the multi-transmission modal unit bus data required by the empty interface frame format.

Continue with procedure 1900; by removing the inter-module communication segment (IM-Com) and replacing it with a corresponding header segment for the air interface frame format, the multi-transport modal unit bus is converged The layout frame format is converted to the empty interface frame format (step 1904). The bus controller described in Figures 9, 13 and 14 performs this step. This IM-Com segment is used by the channel and control module (also known as CCM) of the indoor unit of the central terminal to interact with each dedicated SSI module (such as TDM-DS3 SSI module and ATM OC3c SSI module). Group) communication. The main pipe section is used for the CCM of the central terminal to communicate with each CCM of the remote terminal. The bus controller also converts the bus frame format to the air interface frame format by converting the time slots of the multi-transmission modal unit bus into the correct number of air interface clusters. As shown in Figures 7A and 7B, the bus controller also determines that the cluster will be a four-cluster or a single-cluster.

Once formatted into a pair of empty interface frame format (step 1904), use one of the three available modulation modes as described above to modulate each signal on the basis of the cluster signal connection (step 1906). It is advantageous to enable a single hub terminal (sector radio) to communicate with each remote terminal within a specific sector, regardless of the area where the remote terminal is located. This also provides efficient use of available bandwidth. Secondly, the modulated signal in the air interface frame format is up-converted to the radio frequency of the communication link (step 1908). This is described in detail in the operation of the IF transceiver section in Figure 14. The latter converts the modulated signal to the IF of the indoor unit, and then up-converts to the radio frequency of the radio communication link (i.e., Figure 2 38 GHz in specific form).

Each signal then uses the 12.5 MHz sub-channel of the 50 MHz channel to propagate through the air interface (step 1910) to all remote terminals. It should be noted that the signals traveling through the air-to-air interface are both synchronous signals (such as TDM) and asynchronous signals (such as ATM) carried in the same air-to-air interface frame format. Each traffic flow is modulated by QPSK, 16-QAM, and 64-QAM. Traffic flow modulated by higher order modulation (larger bits/second/Hz) such as 64-QAM will be better than signals with lower order modulation (smaller bits/second/Hz) such as QPSK Degenerate faster. Therefore, QPSK streams will travel farther than 16-QAM. This is different from the known old method in which a single sector radio uses only one modulation for transmission, and only uses a single transmission mode in the empty frame format to carry traffic. Therefore, a single hub terminal (sector radio) of this specific form replaces the n hub terminals (sector radio) of the old point-to-multipoint system with n areas in each sector.

At the remote terminal, the modulated signal is received by a communication link, such as a radio communication link (step 1912). Note that the long-distance terminal will receive all the signals on the communication link (the ones that are not completely degraded). The received signal is then down-converted to the baseband signal to be demodulated (step 1914). Then demodulate the received signal on the blank frame (step 1916). Each signal is used in the same multi-level modulation modulator that modulates the signal by the hub terminal, and is demodulated on the basis of the cluster signal connection; however, the multi-level modulation function modulation solution The modulator system is configured to demodulate only the specific traffic packet that is demodulated by the configured specific remote terminal. For example, the remote terminal located in the area closest to the hub terminal will demodulate the QPSK modulated master bundle, and only the traffic bundle modulated by 64-QAM instead of 16-QAM Or the traffic bundle modulated by QPSK. Note that all remote terminals will demodulate the master bundle modulated by QPSK. In this specific form, 64-QAM is the highest order modulation, but the modulation is not limited to the specific modulation described.

Once each signal is demodulated according to the pre-structured set of the remote terminal, the signal on the empty interface frame format is transformed into the bus frame format of the multi-transport modal unit bus (step 1918). This is done at the bus controller of the CCM of the indoor unit. Remove the header section of the empty interface frame format, and add the IM-Com section of the bus frame format. In addition, each cluster of the air interface frame format is mapped to the corresponding time slot of the bus frame format of the multi-transmission modal unit bus. Finally, the traffic on the bus of the multi-transport modal unit is transmitted to each SSI module (step 1920), so that the SSI module can distribute the mixed traffic to the appropriate users. The reverse data flow is simply the opposite situation as described in steps 1902 to 1920.

Dedicated user interface module

The point-to-multipoint system allows a variety of standard interfaces for user specific needs, such as TDM-DS3 SSI module, ATM-OC3c SSI module, quad DS1/AAL1 SSI module, and DS3 transparent SSI module. However, each of these standard interfaces must be configured to interface with the multi-transport modal unit bus, because both of them carry both asynchronous traffic (ATM) and synchronous traffic (TDM). Therefore, the SSI module must be able to transmit different types of traffic on the multi-transmission modal unit bus, so that the correct traffic unit can be separated and sent to each user. In addition, each of these interfaces must be specially designed to format the traffic carried by it for transmission on the multi-transport modal unit bus. Figures 20 to 25B discuss the different types of SSI modules used in some point-to-multipoint systems and the technology used to interface with the multi-transport modal unit bus, and to format the traffic for transmission in the multi-transport mode. Technology on the unit bus.

Refer to Figure 20; it shows a block diagram of four DS1/AAL1 SSI modules. The four DS1/AAL1 SSI module 2000 includes the multiple transport unit bus 2002 described with reference to FIGS. 15 to 18, a unit control section 2004, an ATM processor section 2006, a timing section 2008, and a processing section 2010 , And a circuit interface section 2012. The unit control section 2004 includes a unit formatter 2014 (also known as a signal formatter), a transmission buffer 2016, a reception buffer 2017, a control logic 2018, and a PCM interface logic 2020. The ATM processor section 2006 includes an AAL1 (ATM conversion layer 1) SAR 2022 and an ATM buffer 2024. The timing section 2008 contains the timing logic 2026. The processing section 2010 includes a microprocessor 2028 and a message buffer 2030. The circuit interface section 2012 contains four T1/E1 framers 2032 and four T1/E1 ports 2034. Several connection buses are also shown, including a TDM bus 2036, Utopia bus 2038, pulse code modulation bus 2040 (also known as PCM bus 2040), and CP bus 2042.

The Quad DS1/AAL1 SSI module 2000 is a module that allows four T1 lines or E1 lines to interface with a point-to-multipoint system. The quad DS1/AAL1 SSI module is a dual transmission mode SSI module, which means that it can be configured to work in TDM mode or ATMAAL1 mode, depending on user preferences, such as the quad DS1 TDM SSI module or DS1/AAL1 ATM SSI module. The data is converted to DS1 (T1 line) containing 20 DSOs by multiplexing at the DSO level. The prior art has four DS1TDM SSI modules and DS1/AAL1 ATM SSI modules; however, a single old method four DS1 TDM SSI modules cannot be constructed as DS1/AAL1 ATM SSI modules, and four DS1/AAL1 SSI modules 2000 You can. In addition, the four DS1/AAL1 SSI modules 2000 used must be configured to interface with the multi-transport modal unit bus 2002. Once configured to serve one of the two data transmission types, the four DS1/AAL1 SSI module 2000 only processes the traffic type. Therefore, the operation of the four DS1/AAL1 SSI module 2000 will be explained in two modes. Alternatively, four DS1/AAL1 SSI modules 2000 can be configured to support both types of traffic at the same time.

When operating in ATM mode, the traffic from the indoor unit of the remote terminal enters the quad DS1/AAL1 SSI module 2000 via the multiple transmission unit bus 2002 to the unit formatter 2014. The multi-transport unit bus 2002 carries both ATM group TDM traffic, so the unit formatter 2014 (also known as the bus controller) needs to be able to separate the ATM units and discard the TDM units at the same time. In addition, the cell formatter 2014 must be able to identify the ATM cell of the specific user that is connected to the SSI module and the unnecessary TDM cell. As previously discussed, the traffic from the radio or air-to-air interface into the remote terminal is performed in one of three modulation modes. A specific remote terminal only demodulates one of the modulation modalities used in the traffic segment of the air interface frame format, so only certain traffic will be received and put on the multi-transmission modal unit bus 2002. In addition, the demodulated traffic needs to be split into multiple corresponding SSI modules.

The unit formatter 2014 listens to the configured time slot of the IM-Com segment of the multi-transport modal unit bus, and copies the appropriate message unit to the message buffer 2030, which is a dual-port RAM. Refer to Figure 15; it can be seen that each SSI module coupled to the multi-transport modal unit bus has a dedicated IM-Com segment time slot for its use. Therefore, the unit formatter 2014 only reads the specific IM-Com segment time slot. The message of the IM-Com unit is then routed to the microprocessor 2028, so that the four DS1/AAL1 SSI module 2000 can coordinate various activities with the CCM of the indoor unit. The microprocessor 2028 is a reduced instruction system code (RISC) processor.

The unit formatter 2014 uses an ATM address filtering technique to determine which traffic units of the CB-data segment from the multi-transport modal unit bus are discarded, and which units will be retained. Refer to the description of Figures 26-31B for the ATM address filtering technology. The vCI lookup table described in FIG. 30 is located in the receiving buffer 2017, which is a static RAM.

If the traffic unit contains an AAL1 ATM unit that has been properly filtered as described in Figure 26-31B, the AAL1 ATM unit is decompressed from the traffic unit and routed to AAL1 SAR2202 via Utopia bus 2036 (segmented And recombination), the AAL1 ATM unit is converted into a serial data stream for transmission to the T1/E1 framer 2032. Note that the PCM interface logic is not used in ATM mode. ATM buffer 2024 (static RAM) is used to buffer ATM cells, so they can be reassembled into small packets, and then sent to individual T1/E1 framer 2032 to be framed for individual user T1 lines (or E1 lines) ) Is transmitted via a T1/E1 port 2034. The microprocessor 2028 controls the data flow from the T1/E1 framer 2032 to the unit formatter 2014 and AAL1 SAR 2022.

The data flow is the reverse of the traffic from the T1 line (or E1 line) into the T1/E1 port 2034 and the T1/E1 framer 2032. The data flows from the T1/E1 framer 2032 to the AAL1 SAR 2022, which divides the traffic into multiple ATM units. The ATM cell is then sent to the cell formatter 2014 via the Utopia bus 2036 to wait for multiplexing to be converted on the multi-transport modal cell bus 2002. The message buffer 2030 also contains the mapping operation required to place the ATM cell in the multi-transport modal cell bus 2002.

When operating in the TDM mode, each unit arrives on the multi-transport modal unit bus 2002, so that each multi-transport modal unit bus slot carries one unit. The unit formatter 2014 determines which units are reserved by the unit bus 2002. The inter-module communication message (IM-Com) received by the multi-transport modal unit bus 2002 delivers the time plan to the unit formatter 2014 via the message buffer 2030. Therefore, the unit formatter 2014 knows which unit should be copied by which time slot in the multi-transport modal unit bus 2002, so only the TDM unit of its specific user is copied. Then the TDM unit is copied to the receiving buffer 2017 (this is a static RAM), if the TDM unit is a data unit. When the unit formatter 2014 copies each unit, it decompresses it into DS0 (both PCM data and signaling data), as explained with reference to the TDM buffer in FIGS. 39 to 44B.

In addition, the cell formatter 2014 re-compresses the data into the receiving buffer 2017 (this is a static RAM) according to the cell type, and is further described in FIGS. 40 to 43. The receiving buffer 2017 also contains a time scheme for mapping the unit bus time slots to individual T1/E1 time slots. At the correct time, the PCM interface logic 2020 separates the correct data (PCM and signaling) for each T1/E1 line and each time slot, compresses it into DSO, and sends it to the PCM bus 2040 T1/E1 framer, and frame the data for transmission on the T1/E1 line.

The data flow is the opposite of the TDM data reaching the four DS1/AAL1 SSI module 2000 via the T1/E1 line.

The timing section 2008 contains timing logic 2026. The sequential logic 2026 typically includes a complex programmable logic element (CPLD) and a phase locked loop (PLL). The four DS1/AAL1 SSI modules receive their timing from the multiple transmission modal unit bus 2002, which is restored by the timing of the hub terminal as described. Note that not all block diagrams are fully explained, because their operations and implementations are easily understood by those skilled in the industry.

Note that the quad DS1/AAL1 SSI module 2100 or any other SSI module shown actually contains the multi-transport modal unit bus 2002, not an interface to the multi-transport modal unit bus. For ease of understanding, the multi-transport modal unit bus shown is a part of the quad DS1/AAL1 SSI module 2100 or other SSI modules in Figure 22-25B. Note that the unit formatter 2014 formats TDM traffic and ATM units into units for transmission via a point-to-multipoint system, so it is also called a signal formatter. The signal formatter has different descriptions in this manual, for example, it is used as a unit formatter in the SSI module. However, in other specific forms, the signal formatter may be located in other components of the point-to-multipoint system, such as the multi-level modulation modulator or the bus controller of the hub terminal and the remote terminal. In general, a signal formatter (especially a unit formatter) formats signals of different transmission modes into a format (unit) suitable for transmission via a point-to-multipoint system.

Refer to Figure 21; it shows the block diagram of the TDM-DS3 SSI module 2100 used by the indoor unit of the hub terminal in Figure 2. TDM _- DS3 SSI module 2100 contains a unit formatter 2102 (also known as signal formatter), text buffer 2104, control logic 2106, central processing unit (CPU) 2108, processor bus 2110, transmission PCM buffer 2112, transmission Signaling buffer 2114, receiving PCM buffer 2116, receiving signalling buffer 2118, PCM interface 2120, system bus 2122, octal T1/E1 framer 2124, 28 T1/E1 lines 2126, one M13 multiplexer 2128, transmission/reception line interface unit (TX/RX LIU) 2130, loop 2132, and DS3 interface 2134. The multi-transport modal unit bus 2136 is also shown.

The TDM-DS3SSI module 2100 is a TDM-based SSI module, which is used for each hub terminal of a point-to-multipoint system to interface with the high-speed DS3 line to the transmission network. The TDM-DS3 SSI module 2100 demultiplexes the DS3 lines containing 28 T1/E1 lines (28 DS1) into DSO levels to interface with the point-to-multipoint system. Therefore, the TDM-DS3 SSI module 2100 functions as a 3/1/0 multiplexer. The TDM-DS3 SSI module 2100 is designed to handle all round-trip point-to-multipoint system TDM traffic, while the OC3c ATM SSI module (see Figure 22) is designed to handle all round-trip point-to-multipoint system ATM traffic.

When the signal is received by the multi-transport unit bus 2136, the unit formatter 2102 is instructed to pass the inter-module communication message (IM-Com) between the CPU and CCM of the central unit in the hub terminal from the multi-transmission mode Which unit is copied by the unit bus. In this case, the cell formatter 2102 reserves the TDM cell and throws out the ATM cell. The unit formatter 2102 also copies the appropriate IM-Com unit to the message buffer 2104 (this is a dual-port RAM) for use by the CPU 2108. The TDM unit is decompressed into PCM data (or PCM samples) and signaling. The PCM data is stored in the receiving PCM buffer 2116, and the signal such as Call Association Signaling (CAS) is stored in the receiving signal buffer 2118.

As shown in Figures 29 and 39, each TDM unit is decompressed to both the receiving PCM buffer 2116 and the receiving signaling buffer 2118, because the TDM unit contains both PCM data and signaling data. The buffers (2116, 2118, 2112, and 2114) are dual-port random access memory (also known as DPRAM). Also note that the four buffers (2112, 2114, 2116, and 2118) can be part of the same memory structure described in FIG. 39.

The TDM unit is further decompressed according to which unit type is used as shown in Figures 41-43.

Then, the PCM interface 2120 compresses the PCM data in the receiving PCM buffer 2116 and the receiving signaling buffer 2118 into DS1, and then sends it to the octal T1/E1 framer 2124 via the system bus 2122 (PCM bus) as T1 Or E1 to be framed. The PCM interface 2120 contains custom logic specifically designed for the TDM-DS3 SSI module 2100. The 28 T1/E1 lines 2126 are then multiplexed to the DS3 line by the M13 multiplexer 2128. The M13 multiplexer 2128 is a standard DS3 to DS1 multiplexer. The TX/RX LIU 2130 is connected to the DS3 circuit on the DS3 circuit interface 2134. The CPU 2108 processes the necessary logic and controls the TDM-DS3 SSI module 2100 via the processor bus 2110. Customer logic. Loop 2132 is used for testing purposes. In addition, the timing required for receiving the TDM-DS3 SSI module 2100 from the multi-transport modal unit bus 2136.

The data flow from the direction of the transmission network to the direction of the multi-transmission modal unit bus 2136 is simply the opposite. DS3 lines are converted into DS1 lines by M13 multiplexer 2128 multiplexing. Use the octal T1/E1 framer 2124 to move the framing work away from the DS1. Then, the PCM interface 2120 decompresses the DS1 into DSO, which is sent to the transmission PCM buffer 2112 (for PCM data) or the transmission signaling buffer 2114 (for signaling). The unit formatter 2102 then compresses the DSO into the specially designed TDM unit described in FIGS. 29 and 41-43, which is pre-multiplexed on the multi-transport modal unit bus 2136.

In addition, the cell formatter 2102 places an ATM header (a virtual path identifier (VPI)) in the header section of the TDM cell. This is detailed in Figure 29. This enables the ATM formatter of the ATM-based SSI module at the remote terminal to distinguish between ATM units and TDM units received by mixed traffic input (ie, multi-transport modal unit bus). In another way, ATM units and TDM units can be further distinguished by a time scheme. However, this requires more messages, which is far more time-consuming and troublesome.

Depending on the cell type and the acceptable delay, the cell formatter 2102 also formats the TDM cell, as described in Figures 41 to 43. Similarly, not all functional block diagrams are fully explained, because those skilled in the industry understand their operations and implementations.

Refer to Fig. 22 again; shown is a block diagram of the ATM-OC3cSSI module available in a remote terminal or a hub terminal used in the preferred specific form of the point-to-multipoint system shown in Fig. 2. ATM-OC3c SSI module 2200 contains an OC3c port 2202, DS3c port 2204, optical transceiver 2206, DS3 line interface unit (LIU) 2208, Phy2210, ATM line and buffer manager 2211 (hereinafter referred to as ALBM2211), unit Processor 2212, unit processor buffer 2214, buffer manager 2216, buffer manager buffer 2218, Utopia II bus 2220, uP bus 2222, ATM formatter 2224 (also collectively referred to as signal formatter), formatter buffer 2226 , PCI bridge 2228, AAL5 SAR 2230, PCI bus 2232, central processing unit (CPU) 2234, and multi-transport modal unit bus 2236.

The OC3c port 2202 is coupled to the optical transceiver 2206, which is coupled to a Phy 2210. Phy 2210 is coupled to a unit processor 2212 via Utopia II bus 2220. Alternatively, a DS3c port 2204 is coupled to a DS3 LIU 2208, which is coupled to a Phy 2210. Then, Phy 2210 in the DS3c structure is coupled to the unit processor 2212 via the Utopia II bus 2220, and then coupled to the uP bus 2222.

In addition, the ATM-OC3c SSI module 2200 can be configured to support multiple sub-channels instead of one sub-channel (12.5 MHz). A separate ATM formatter 2224 is required for each sub-channel, as described in FIG. 26.

The unit processor 2212 is coupled to the uP bus 2222, the unit processor buffer 2214, and the buffer manager 2216. The buffer manager 2216 is coupled to the _u P bus and buffer manager buffer 2218. The uP bus 2222 is also coupled to an ATM formatter 2224 and PCI bridge 2228. The ATM formatter 2224 is coupled to the formatter buffer 2226, the Utopia II bus 2220, and the multiple transport modal unit bus 2236. The ATM formatter 2224 is coupled to the AAL5 SAR 2230 via the Utopia II bus 2220. The CPU 2234 is coupled to the AAL5 SAR 2230 and the PCI bridge 2228 via a PCI bus 2232. The ALBM 2221 is a standard current ATM chipset, which includes a cell processor 2212, a cell processor buffer 2214, a buffer manager 2216, and a buffer manager buffer 2218.

In practice, the ATM-OC3c SSI module 2200 is designed to handle all round-trip point-to-multipoint system traffic. It can be used for hub terminals as shown in Figure 2, or for remote terminals, depending on the needs of specific users. The ATM-OC3c SSI module 2200 can be constructed in one of two ways. First, the link (155 Mbps) to the OC3c line is a pure high-speed unit and interface flow at OC3c. Second, the ATM-OC3c SSI module can be configured to operate at 44.736Mbps, a DS3 line consisting of a simple ATM cell stream. An OC3c line is an optical carrier level 3-sequential connection line as known in the industry, which means that the line is a continuous stream of ATM cells. Therefore, the OC3c configuration will contain the OC3c port 2202, the optical transceiver 2206, and Phy 2210, and the DS3 configuration will contain the DS3c port 2204, DS3 LIU 2208, and Phy 2210. In addition, the ATM-OC3c SSI module uses a standard current ATM chipset (ALBM 2211) to form a multi-level modulation environment for processing point-to-multipoint systems. The structure of the ATM chipset provides a unique ATM address filtering technology and request assignment multiple access technology. Refer to the descriptions of FIGS. 26 and 27.

In addition, the ATM-OC3c SSI module 2200 is in one mode when operating in a remote terminal, and in another mode when operating in a hub terminal.

During the operation of the hub terminal, the data from the transmission network and the central office reaches the ATM-OC3c SSI module 2200 via an ATM MUX, and then goes to the OC3c port 2202 and the optical transceiver 2206. Phy2210 is a well-known component in the ATM industry that performs the physical layer function of the ATM chipset 2211. In this figure, Phy2210 is a cell tracer, which separates the ATM cell from each frame and passes through the Utopia II bus 222. Send to the unit processor 2212 of ALBM2211. The cell processor 2212 then reorganizes the arriving ATM cells according to the ATM standard. The rectification work simply inspects the ATM units and will not arrive too soon. The cell processor 2212 has a cell processor buffer 2214 (a static RAM) for buffering ATM cells. The cell processor 2212 sends the ATM cell to the buffer manager 2216 of the ALBM 2211, and queues the ATM cell to the buffer manager buffer 2218 (a static RAM). The buffer manager then releases the ATM unit on the basis of VP/VC (virtual path/virtual channel) based on the priority order of the structure to ensure QOS (Quality of Service). This procedure is well known in the industry. The ATM cell is looped back to the buffer manager 2216 and sent back to the cell processor 2212.

Secondly, the ATM unit is sent to the ATM formatter 2224 via the Utopia II bus 2220. The ATM formatter 2224 performs the queuing function described in the Lubo section of the ATM address (see Figure 26). The ATM formatter 2224 is a client logic containing a number of shallow FIFOs, each holding a majority of ATM units that use one of the three modulation modes (also called modulation buffers) for transmission. The formatter buffer 2226 (a static RAM) contains the time scheme for each modulation mode. The ATM formatter 2224 uses this time scheme to map the ATM cells to the appropriate time slots of the multi-transmission mode unit bus 2236, so that each unit will use the appropriate modulation mode for transmission. Therefore, the appropriate remote terminal will receive the appropriate ATM cell. In addition, the ATM formatter 2224 formats each ATM unit into a traffic unit (described in FIGS. 16 and 17 respectively) for transmission on the multi-transport modal unit bus 2236.

In addition, the CPU 2234 can communicate with the channel and the control module CCM via the inter-module communication slot (IM-Com unit) on the multi-transmission modal unit bus 2236. The IM-Com unit is placed on the bus 2236 of the multi-transport modal unit via the ATM formatter 2224. The IM-Com unit is sent back to the CPU 2234 via the PCI bus 2232 and the PCI bridge 2228.

The data flow from the central terminal room unit to the ATM-OC3c SSI module 2200 is simply a reversal. The ATM unit is copied from the multi-transport modal unit bus 2236 and placed on the hub terminal. The ATM OC3c SSI module 2200 does not need to implement the ATM address Lubo technology (Figure 30-31B), because all ATM units are sent and connected to the transport network OC3c line (reverse transmission).

The ATM unit is returned to ALBM2211. Specifically, the ATM cell is sent to the cell processor 2212, the buffer manager 2216, then returns to the cell processor 2212, and then to Phy221. The specific frame is used for transmission and leaves the ATM-OC3c SSI module 2200 via the optical transceiver or DS3 line interface unit 22.8, depending on the configuration.

AAL5 SAR 2230 (segmentation and reassembly) is used for compliant band signaling. This role is to make the operation, administration, and control (OAM) messages from the Component Management System (EMS) to the central terminal into a small package. For details of the component management system, refer to Figures 2 and 10 for further discussion. This provides an improved method for the component management system to communicate with the point-to-multipoint system. The component management system can communicate with the hub terminal via a reverse transport or transmission network, instead of the conventional component management system via a wide area network (WAN), and then communicate with the hub via the LAN of the hub. The advantage is that there is no need to maintain a separate land line between the component management system (EMS) of the central office and each central location.

Since the ATM unit that carries the message sent by the EMS of the central office is on the same medium, the control unit sent by the component management system must be separated from the traffic unit. In addition, both the unit processor 2212 and the buffer manager 2216 use the virtual path identifier (VPI) and virtual channel identifier (VCI) of each unit, and determine whether there is any control unit to the CPU 2234. The control unit pre-routes to AAL5SAR 2230 via Utopia II bus 2220. The AAL5 SAR 2230 then forms a small packet of each message and sends it to the CPU 2234 via a PCI bus 2232. Each packet is formed in accordance with the Transmission Control Protocol/Internet Protocol (TCP/IP). The CPU 2234 can send the signal to the ATM formatter 2224 and unit processing via the PCI bus 2232 coupled to a PCI bridge 2228 and to the uP bus 2222 Machine 2212, and buffer manager 2216.

When operating at the remote terminal, the data is received from the central terminal via the air and demodulated by the CCM of the indoor unit of the remote terminal. Then send the data of the unit on the bus 2236 as the multi-transport modal unit to interface with the ATM OC3c SSI module 2200. Since the ATM formatter 2224 is located at the remote terminal, it executes the ATM address filtering procedure as shown in FIG. 30.

The ATM address filtering function is different in the ATM OC3c SSI module 2200 of the remote terminal, because the throughput of the ATM OC3c SSI module 2200 is much higher than the throughput of other types of SSI modules used in the remote terminal. The OC3c line sends data at 155.52 Mbps (megabits per second), which is equivalent to about three DS3 lines. Therefore, the table lookup method as described with respect to Figs. 30 and 31B (not Figs. 30 and 31A) is executed.

When using the ATM address filtering technique described in Figures 30, 31A, and 31B, once the ATM cell is accepted, the ATM cell is sent to the cell processor 2212 via the Utopia II bus 2220, and then sent to the buffer manager 2216 according to the The priority order of the structure is based on the VP/VC using the buffer manager buffer 2218 (static RAM) to queue and cancel the return unit processor 2212 to ensure the quality of service (QOS). The ATM cell is sent to Phy 2210 (cell tracer), then it is framed and transmitted via the optical transceiver 2206 to the OC3c line at the OC3c port 2202.

At the remote terminal, the data flow from the user to the ATM OC3c SSI module 2200 is the same as that from the OC3c line to the central terminal at the central terminal. The main difference is the number of modulation buffers in the ATM formatter 2224, because the remote terminal will only use one modulation instead of the full-range modulation mode used by the hub terminal for transmission.

The components and functions of the ATM OC3c SSI module 2200 are well understood by those skilled in the industry. ALBM2211 is the current ATM chipset known in the industry. Not all functional block diagrams are fully explained, because those skilled in the industry understand their operations and implementations.

Refer to Figure 23; it shows the functional block diagram of the DS3 transparent SSI module. The DS3 transparent SSI module 2300 contains a multi-transmission modal unit bus 2302, a unit formatter 2304 (signal formatter), a buffer 2306, a byte stuffer 2308, a dither attenuator 2312, a central processing unit 2310 (CPU ), a DS3 circuit interface unit 2314, and a DS3 circuit 2316.

The multi-transport modal unit bus 2302 is coupled to the unit formatter 2304 and the CPU 2310. The unit formatter is coupled to the buffer 2306 and the byte stuffer 2308. The byte stuffer 2308 is coupled to the dither attenuator 2312 and the DS3 line interface unit 2314. The dither attenuator 2312 is coupled to the DS3 line interface unit 2314, which is coupled to the DS3 line 2316. The central processing unit 2310 is coupled to the DS3 line interface unit 2314, the byte packer 2308, and the unit formatter 2304.

In practice, the DS3 transparent SSI module 2300 is not specifically ATM-based or TDM-based, and is used to provide a point-to-point link in a point-to-multipoint system. Therefore, the DS3 transparent SSI module 2300 is used when the user requires the entire channel bandwidth (for example, 12.5 MHz) of the radio sector of the hub terminal. The DS3 transparent SSI module 2300 can carry asynchronous traffic (such as ATM) or synchronous traffic (such as TDM); however, the specific traffic type has nothing to do with the DS3 transparent SSI module 2300. The data is simply carried through the point-to-multipoint system, and has nothing to do with specific types of data. The received bits are routed from one point (DS3 line 2316 at the hub terminal) to another point (for example, users coupled to DS3 line 2316 at the hub terminal), regardless of the framing operation used and the control bits that exist .

The old method point-to-point link is common; however, for this specific form of the present invention, the point-to-point communication link in the point-to-multipoint system is unique and different from the old method. To complete this transmission, a DS3 transparent SSI module 2300 is required at the indoor unit of the hub terminal, and a matching DS3 transparent SSI module 2300 is required at the corresponding indoor unit of the corresponding remote terminal.

When the serial data comes from the DS3 line 2316 via the DS3 line interface unit 2314, the data goes to the byte stuffer 2308. The byte stuffer 2308 is similar to the bit stuffer known in the telecommunications industry, except that it buffers bits into bytes instead of just buffering bits. The byte stuffer 2308 collects the bits from the DS3 line 2316, forms a byte and buffers the byte to the unit formatter 2304, which compresses the byte into a data unit for transmission to a multiple transmission unit stream On row 2302. The byte stuffer 2308 and the cell formatter 2304 change the timing of the DS3 line to the multi-transmission modal cell bus 2302 and the point-to-multipoint, system timing or time base. The formed data unit for the multi-transport modal unit bus is the same as the 53-byte data unit 1704 designed to be embedded in the traffic unit 1700 as shown in FIG. 17. The data unit formatted by the unit formatter 2304 of the DS3 transparent SSI module 2300 is different from the ATM unit and TDM unit formatted by other SSI modules. Refer to the description of FIGS. 28 and 29. Therefore, the characteristics of the data unit formatted by the DS3 transparent SSI module 2300 will be briefly described.

Also refer to FIG. 24; it shows a diagram of the data unit 2400 formatted by the DS3 transparent SSI module in the specific form of FIG. 23. The length of the data unit 2400 is 53 bytes, and it contains a header section 2402 and a traffic section

Section 2404. The header segment 2402 is 1 byte and includes a control byte 2406. The size of the data unit 2400 is advantageously the same as the ATM unit of FIG. 28 and the TDM unit of FIG. 29. Therefore, the data unit 2400 is conveniently inserted into the CB-data section of the multi-transmission modal unit bus 2302. The main difference between the data unit 2400 and the one shown in Figures 28 and 29 is that the length of the header segment 2402 is only 1 byte, so the traffic segment 2404 includes the remaining 52 bytes instead of 48 bytes as shown in Figures 28 and 29. Since the communication link is a point-to-point link, the traffic segment 2404 is maximized within the unit size of 53 bytes.

The change in the number of bytes in the traffic segment 2404 compressed into the data unit 2400 is a function of the frequency difference between the clock rate of the DS3 line 2316 and the multi-transport modal unit bus 2302. For example, the DS3 line operates at 44.736Mbps. If the bus clock rate of the multi-transport modal unit is 10Mbps, the bus frame format is 6 milliseconds, and there are 684 time slots on the multi-transport modal unit bus 2302 and the traffic of 83 bytes is held. Unit (refer to Figures 15 and 17), a specified number (for example, 648) of data unit 2400 will have 49 bytes in the traffic segment 2404, and a specified number (for example, 33) of data unit 24 00 There will be 50 bytes in the traffic segment 2404, and the remaining number (for example, 3) of data units 2400 will have a variable number of bytes in the traffic segment 2404 (for example, 49, 50, or 51). Bytes). Therefore, to match the line rate of the DS3 line 2316, the unit formatter 2304 compresses a different number of bytes into the traffic segment 2404 of the data unit 2400.

In the above example, the unit formatter 2304 is composed of software to know which data unit 2400 contains 49 bytes and which contains 50 bytes; however, the remaining three data units 2400 contain a variable number of bits. The tuple (49, 50, or 51) depends on the line rate of each DS3 line 2316. If the DS3 line 2316 is "speed", there are more bytes in the byte stuffer 2308, and the remaining three data units 2400 will contain 51 bytes. If the DS3 line 2316 is "slow", the remaining three variable data units 2400 will contain 49 bytes. If the DS3 circuit 2316 is approximately as expected, the remaining three variable data units 2400 will contain 50 bytes. The unit formatter 2304 adds a control byte to indicate how many bits are contained in the traffic segment 2404 of the remaining three data units 2400 to the receiving DS3 transparent SSI module 2300 (for example, at a remote terminal) Group. The buffer 2306 is used for messages between the CPU 2310 and the channel of the indoor unit and the control module.

Once the data unit 2400 is placed on the multi-transmission modal unit bus 2303 by the unit formatter 2304, the data unit 2400 is sent to the air as a four-cluster signal with the structure shown in FIG. 7A. The four clusters are received at the remote terminal, and each unit path is selected to the corresponding DS3 transparent SSI module 2300 of the remote terminal.

At the remote terminal, the data unit 2400 arrives at the multiple transmission modal unit bus 2302 at the unit formatter 2304, where the data byte is decompressed by the data unit 2400. The unit formatter is pre-structured with software to know which data unit 2400 contains how many bytes, only the transmission of the DS3 transparent SSI module 2300 is caused by the line of the DS3 line that contains a variable number of data bytes. Except for the variable data unit 2400. The control byte 2406 supplies such information to the cell formatter 2304.

In addition, as described above, the DS3 transparent SSI module 2300 assigns the control byte 2406 to indicate whether the remaining data unit 2400 contains 49, 50, or 51 bytes in its individual traffic segment 2404. This implementation is completed in the DS3 transparent SSI module in the old point-to-point link; however, at the receiving end, the matched DS3 transparent SSI module must read the control byte of each data unit to determine the data unit The number of bytes contained in the traffic segment 2404 of 2400.

The advantage is that the specific format is constructed in a 64-QAM mode, for example, only 3 of the 171 64-QAM four clusters in a 6 milliseconds to the air interface frame format (an example in Figure 5) The possible data units 2400 can have a variable number of data bytes (for example, 49, 50, or 51). The three data units 2400 are located in the last three data fields of the last 64-QAM four clusters (ie, four clusters #171) as shown in FIG. 7A: data field 2704, data field 3706, and data field 4704 , And translated to the last three time slots on the multi-transport modal unit bus 2302. This is due to the clock rate of the point-to-multipoint system, the length of the blank frame format, the length of the four-cluster data field, and the operating speed of the byte stuffer 2308. Therefore, the advantage is that the cell formatter 2304 at the receiving DS3 transparent SSI module 2300 only needs to read the control byte 2406 of the last three data fields 704 of the last four clusters instead of all the received data cells 2400. The control byte 2406, the latter is the conventional method of DS3 transparent SSI module. This feature reduces processing requirements and increases the throughput of the DS3 transparent SSI module 1300. In addition, due to the unique traffic segment 2404 size of the data unit 2400 and only the last three control bytes 2406 are read, there are only two least valid bits in each control byte 2406 that need to be read by the unit. The formatter 2304 reads. The number of the remaining variable length data units 2400 is derived from the worst-case clock skew (for example, 89 ppm) between the clock of the multi-transport modal unit bus 2302 and the clock of the DS3 line 2316. This greatly reduces the processing work that the unit formatter must perform for each received data unit 2400.

When the bits are decompressed to the byte stuffer 2308, a variable number of bytes are received into the byte stuffer 2308 to be output to the DS3 line 2316, causing a clock delay. Therefore, the dither attenuator 2312 including a FIFO (first-in first-out) and a phase-locked loop (PLL) buffers the bit tuples for transmission on the DS3 line 2316. It stores the bits and transmits them on the DS3 line 2316 at the average clock rate at which data bytes are received into the DS3 transparent SSI module 2300. Therefore, the bits leaving the dither attenuator 2312 leave at a constant rate and are not affected by the potential intermittent timing when a received data unit 2400 contains a variable number of bytes. Therefore, the timing of the signal sent by the point-to-multipoint system is changed back to the timing of entering the DS3 line 2316 of the remote terminal.

The data buffered in the FIF0 of the dither attenuator 2312 is sent by the PLL of the dither attenuator 2312 due to the clock edge. The PLL is locked to a reference (ie, clock) supplied by the unit formatter 2304. The use of PLLs is known; however, the use of PLLs to reduce jitter is unique to this particular form of the invention.

The number of bytes in the FIFO causes the benchmark to be adjusted when necessary. The adjustment is done regularly by lengthening or shortening the PLL benchmark. The adjustment is related to the number of bytes in the FIFO of the dither attenuator 2312 and the control byte 2406. The number of bytes in the FIFO controls the parity of the adjustment. For example, less than the expected number of bytes (for example, 49) causes the benchmark to decrease, and more than the expected number of bytes (for example, 51) causes the benchmark to increase. The control byte 2406 of the remaining number of variable data units 2400 commands the adjustment of the benchmark. Therefore, the rate change of the byte output from the dither attenuator 2312 is actually limited; therefore, the dither on the output clock of the DS3 line input unit 2314 and the DS3 line 2316 is reduced.

Note that the data flow from the remote terminal back to the central terminal is the same except for the reversal. In addition, data transfer occurs simultaneously from the central terminal to the remote terminal and from the remote terminal to the central terminal. All the components used are known to those skilled in the industry, so no further explanation is needed.

Multi-transmission modal SSI module

Refer to FIGS. 25A and 25B; it shows the block diagram of the multi-transmission modal SSI module used by the remote terminal shown in FIG. 2. Multi-transport modal SSI module 2500 handles both synchronous traffic (TDM) and asynchronous traffic (ATM), and contains multi-transport modal unit bus 2502, TDM unit formatter 2504 (TDM signal formatter), ATM unit Formatter 2506 (ie ATM signal formatter), text buffer 2508, ATM time scheme and Lubo memory 2510, receiving buffer 2512, transmission buffer 2514, PCM buffer controller 2516, PCM serial bus 2518, First utopial bus 2520, second utopial bus 2521, input/output (IO) bus 2522, AAL5 SAR 2524, AAL5 buffer 2526, AAL1 SAR 2528, AAL1 buffer 2530, central processing unit (CPU) 2532 PCI bridge 2538, PCI bus 2540, high-level data link control (HDLC) controller 2542, ROM bus 2544, frame relay serial bus 2546, CES serial bus 2548, LAN controller 2550 ( As shown in FIG. 25B, SSI module 2501), timing multiplexer 2552, T1/E1 framer 2554 are used for multiple transmission modes.

The multi-transport modal unit bus 2502 is coupled to the TDM unit formatter 2504 and the ATM unit formatter 2506. The TDM unit formatter 2504 is coupled to the message buffer 2508, the IO bus 2522, the receiving buffer 2512, the transmission buffer 2514, and the PCM buffer controller 2516. The PCM buffer controller 2516 is coupled to the timing multiplexer 2552 via a PCM serial bus 2518, and is coupled to the ROM bus 2544. The ATM cell formatter 2506 is coupled to the ATM time scheme, Lubo memory 2510, and IO bus 2522. The AAL1 SAR 2528 and the AAL5 buffer 2526 are coupled to the ATM cell formatter via the first utopial bus 2520 and the second utopial bus 2521, respectively. The AAL1SAR 2528 is coupled to the AAL1 buffer 2530 and the timing multiplexer 2552 via the CES serial bus 2548. AAL5 SAR2524 is coupled to AAL5 buffer 2526 and PCI bus 2540. The PCI bus 2540 is coupled to the IO bus 2522 (via the PCI bridge 2538), the CPU 2532, the HDLC controller 2542, and the LAN controller 2550 (used in the multi-transport modal SSI module 2501 of FIG. 25B). The HDLC controller 2542 is coupled to the timing multiplexer 2552 via a frame relay serial bus 2546. The timing multiplexer 2552 is also coupled to the T1/E1 framer 2554.

In practice, the multi-transport modal SSI module 2500 (also known as the universal SSI module) has the ability to handle asynchronous traffic (such as ATM) and synchronous traffic (such as TDM) on the same card (SSI module) . This feature is different from the old method where the SSI module only handles one or the other of the two transmission modes.

In addition, the multi-transport modal SSI module 2500 is different from the above-mentioned conventional SSI module because it also only processes one or the other of the two traffic types. However, like the multi-transport modal SSI module 2500, the above-mentioned SSI module must still be able to interface with the multi-transport modal unit bus and format the data unit correctly for transmission on the unit bus. Therefore, the multi-transport modal SSI module 2500 is provided by the same card to users who need both TDM and ATM services. It has eight T1/E1 interfaces 2554 in Figure 25A, and the multi-transport modal SSI module 2501 in Figure 25B has four T1/E1 interfaces 2554 and four LAN controllers 2550, but it can be manufactured according to specific requirements. To be changed. Therefore, the advantage is that the DSO of the T1/E1 line can be transmitted in TDM mode or ATM (AAL1 or AAL5) mode, and it can be selected on the basis of a line. Data traffic is transmitted by TDM or ATM (AAL-1/AAL-5) for T1/E1 interface or ATM (AAL-5) for LAN interface (LAN controller 2550).

ATM and TDM traffic are received by the multi-transport modal SSI module 2500 via the multi-transport modal unit bus 2502. Since the traffic on the unit bus 2502 includes IM-Com units including text and telegrams and CB-data units including TDM and ATM units, the multi-transport mode SSI module 2500 must be able to distinguish mixed traffic. There are two controllers (unit formatters) at the interface with the multi-transport modal unit bus 2502: TDM unit formatter 2504 and ATM unit formatter 2506. The TDM unit formatter 2504 reads the time scheme provided by the IM-Com message in the message buffer 2508 (a dual-port RAM) and is told which time slot to listen to, so that it can be accessed from the unit bus 2502 Copy the appropriate TDM unit instead of the unnecessary TDM unit or ATM unit. The ATM cell formatter 2506 uses the ATM address filtering technique described in Figures 30-31B to extract only the ATM cells of the previous user.

The ATM cell formatter 2504 (customer logic) reads the time plan memory contained in the power buffer 2508 (for example, 8k×8 dual-port RAM) on each header time slot of the multi-transport modal TDM unit bus 2502 ( Refer to Figure 15). When assigned, the TDM unit formatter 2504 copies the IM-Com unit to the message buffer 2508, and pre-routes to the CPU 2532 via the IO bus 2522, the PCI bridge 2538, and the PCI bus 2540. Inter-module communication messages (from the IM-Com section) provide tools for communication between the channel and control module of the indoor unit and the multi-transmission modal SSI module 2500.

For TDM traffic, the TDM unit formatter 2504 reads the time plan memory from the message buffer 2508 on the data unit. When a unit is assigned, it is copied to an internal FIFO (first in first out). The destination buffer address is read from the time plan memory, and the unit is copied to the receiving buffer 2518 (for example, 32k×32 synchronous static RAM) to be sent to the PCM buffer controller 2516. The TDM unit formatter 2504 decompresses the specially formatted TDM unit (refer to Figures 29 and 41-43) into DSO, which includes PCM data and signaling data such as call-associated signaling (CAS). As will be described in Figure 29, the old TDM unit only contains PCM data or signaling data, rather than both data in the same TDM unit.

The TDM unit formatter 2504 further uses the TDM buffer technology to decompress each unit in the message buffer 2508 that uses the PCM mapping control structure (PMCS) according to the specific type of TDM unit. Refer to Figures 39 to 44B for a more complete description of this TDM buffering operation.

The PCM buffer controller 2516 extracts the DSO (PCM data and CAS data) from the receiving buffer 2512, and compresses the DSO into T1/E1 (or DS1). Therefore, the PCM buffer controller 2516 converts the byte-serial data stream into two bit-serial data streams for the timing multiplexer 2552, one for PCM data and one for signaling. The TDM unit formatter 2504, the receiving buffer 2512, and the PCM buffer controller 2516 function as a cross-port converter. Advantageously, this function allows any time slot of the unit bus 2502 to be mapped to any time slot in any T1/E1 line. The PCM buffer controller 2516 is a custom logic that allows design flexibility. The timing multiplexer 2552 multiplexes the DS1 data and signaling stream from the PCM buffer controller 2516 into one of the T1/E1 framers 2554 via the PCM serial bus 2518, and is to be framed for use via the T1 line One of them is used for transmission. The T1/E1 framer 2554 inserts signaling into the output of the T1/E1 line. The T1 framer 2554 supports standard timing, such as the extended frame (ESF). Note that the timing of the multi-transmission modal SSI module 2500 is received from the multi-transmission modal unit bus 2502, which in turn is restored from the timing sent by the hub terminal. The timing is further illustrated in Figures 13 and 14.

The data flow is exactly the opposite situation from the T1/E1 line to the multi-transport modal SSI module 2500 and to the multi-transport modal unit bus 2502. Remove the framing operation and use the T1/E1 framing device 2554 to move the signaling away from DS1. The timing multiplexer 2552 multiplexes the DS1 to the PCM buffer controller 2516. The PCM buffer controller 2516 decompresses the DS1 into DSO (that is, PCM data and signaling data), and then copies the DSO to the transmission buffer 2514 (for example, 32k×32 SRAM) according to the TDM buffer operation described in FIG. 39. The function of the transmission buffer 2514 is the same as that of the reception buffer 2512, except in the other direction. The TDM unit formatter 2504 compresses the DSO into the specially designed TDM unit shown in Figures 29, 41, 42 and 43, and transmits it to the multi-transport modal unit bus 2502 at an appropriate time according to the time plan stored in the message buffer 2508 superior. Depending on the data sent using the PCM mapping control structure (PCMS) in the message buffer 2508, the TDM unit formatter 2504 compresses the DSO into different unit types to minimize the delay. (Refer to the discussion of TDM buffer operations in Figures 39 to 44B.) Once the unit is on the multi-transport modal unit bus 2502, the remote terminal will modulate it and carry it through the air interface (radio interface) to the hub terminal as described above. machine.

For ATM units, the ATM unit formatter 2506 uses the ATM address Lubo technology described in Figure 30-31A to distinguish between ATM units and TDM units on the multi-transport modal unit bus 2502, and further distinguish between the ATM units and TDM units that are sent to users. ATM cells and ATM cells to be discarded. The ATM address Lubo technology also distinguishes AAL1 unit and AAL5 unit. The ATM time scheme and Lubo memory 2510 (a type of RAM) contain the necessary ATM address Lubo lookup table described in Figure 30-31A. The ATM time plan and Lubo memory 2510 also contain the time plan for inserting the ATM cell back on the multi-transport modal unit bus 2502. The fact that the ATM formatter 2506 uses a time scheme to map ATM cells on a cell bus is different from the old ATM-based SSI module. Normally, ATM cells are multiplexed on a bus when they arrive, regardless of the specific time slot assignment, because ATM cells are routed based on header information. This feature applies to all ATM-based SSI modules described in this article.

Once an ATM unit is accepted, AAL1 units such as Circuit Emulation Service (CES) are pre-copied to AAL1 SAR 2528 (segmentation and reassembly) via a first utopial bus 2520, and AAL5 units such as a frame relay unit via a second utopia II Bus 2521 is copied to AAL5 SAR 2524. AAL1SAR 2528 and AAL5 SAR 2524 use AAL1 buffer 2530 and AAL5 buffer 2526, respectively, to compress ATM cells into small packets and send them via T1/E1 lines. Both the AAL1 buffer 2530 and the AAL5 buffer 2526 are static RAMs. AAL1 contains CES and CAS signaling and is multiplexed to the timing multiplexer 2552 via the CES serial bus 2548. AAL1 SAR 2528 supports up to 256 two-way CES+CAS channels to be assigned to individual time slots within a maximum of 8 T1/E1 lines. For unframed, unchannelized links, AAL1 SAR2528 supports up to 8 bidirectional CES channels within 8 T1/E1 lines. AAL1 SAR2528 also supports Synchronized Residual Time Stamping (SRTS) for unchannelized, unframed T1 links.

AAL5 SAR 2524 converts ATM cells into frame relay packets, and sends them to a HDLC (High Level Data Link Control) controller 2542 via a PCI bus 2540. At this time, each frame relay packet passes through a frame relay packet. The box relay serial bus 2546 is sent to the timing multiplexer 2552. For channelized links, the HDLC controller 2542 supports up to 128 bidirectional HDLC channels within 8 T1/E1 lines. For unchannelized links, the HDLC controller 2542 supports up to 8 bidirectional HDLC channels within 8 T1/E1 lines. The frame relay packet is multiplexed by the timing multiplexer 2552 to the T1/E1 framer 2554, and the predetermined frame is for transmission via one of the T1/E1 lines.

For ATM traffic entering the SSI module 2500 in the multi-transmission mode from the T1/E1 line, the timing multiplexer 2552 sends each CES packet to the AAL1 SAR2528 for AAL1 traffic. The timing multiplexer 2552 sends frame relay traffic (ALL5) to the HDLC controller 2542 that manages different channels. Then, the frame relay packet goes to AAL5 SAR 2524, to be decompressed into ATM unit. The ATM cell goes to the ATM cell formatter 2506 from the AAL1 SAR 2528 via the first utopiaI bus 2520 or from the AAL5 SAR 2524 via the second utopiaI bus 2521. The ATM time plan and Lubo memory 2510 contain a time plan for copying each ATM cell to the multi-transport modal unit bus 2502. The ATM cell formatter 2506 does not have access to the inter-module communication slot (IM-Com) of the cell bus. In this specific form, only the TDM unit formatter 2504 formats IM-Com. Note that the units from AAL1 SAR 2528 are sent to the multi-transport modal unit bus in a higher priority order than those from AAL5 SAR 2524, because AAL1 units are more delay sensitive.

Alternatively, as shown in FIG. 25B, the multi-transmission mode SSI module has four T1 line interfaces 2554 and four LAN controllers 2550. The LAN controller 2550 supports 10/100base-T connection to the Ethernet network. This is provided to support users who need more bandwidth than the T1 line provides. The LAN controller 2550 controls the 10/100base-T traffic flow of the AAL5 SAR 2524. Note that not all the functional components of the multi-transport modal SSI modules 2500 and 2501 are described in detail. These components and their implementation are known to those skilled in the industry, so no further explanation is needed.

In addition, since any time slot from the multi-transport modal unit bus 2502 can be mapped to any DSO of the T1/E1 line, and since the timing multiplexer 2552 multiplexes both ATM packets and TDM packets, DSO can be used Decompose a single T1 line (or E1 line). For example, the first five DSOs (taken from the 24 DSOs in the T1 line) can be used for AAL5 traffic (frame relay), the next 10 DSOs are used for AAL1, and the last nine are used for TDM traffic . This advantageously provides users with high channel assignment flexibility.

ATM address filtering

Refer to Figure 26; shown as an example of a block diagram of ATM address Lubo technology, which is converted by ATM-OC3c SSI module when ATM traffic enters the point-to-multipoint system of Figure 2 at the central terminalDevice2600 is executed. In addition, FIG. 27 is a flowchart illustrating the steps involved in the ATM address Lubo technology associated with FIG. 26. Therefore, when discussing FIG. 26, reference will be made to the steps in FIG. 27. Figure 26 shows the ATM converter 2600, which is composed of a reverse transmission line 2602, Phy2604, ATM line and buffer manager 2606 (hereinafter referred to as ALBM2606), Utopia II bus 2608, ATM formatter 2610, The multi-level modulation environment of n modulation buffer 2612, multi-transmission modal unit bus 2614, and time plan/modulation look-up table 2616.

The ATM converter 2600 is connected to the Phy 2604 to the transmission line 2602. Utopia II bus 2608 couples Phy 2604 to ALBM 2606. The Utopia II bus 2608 also couples the ALBM 2606 to each of the n modulation buffers 2612 of the ATM formatter 2610, which is the structured Phy in the conventional ATM converter. Each multi-level modulation buffer 2612 is located in the ATM formatter 2610, and is coupled to the multi-transport modal unit bus 2614.

In practice, this ATM address filtering technology is used in the ATM-OC3c SSI module at the hub terminal (see Figure 22). The ATM address Lubo technology selects ATM traffic to different modulation buffers 2612 by routing, and filters the ATM traffic to the correct remote terminal, thus generating different modulation streams of ATM traffic. The modulation buffer 2612 buffers the ATM cells to be placed on the multiple transmission unit bus 2614. ATM cells in different modulation buffers 2612 will be modulated with a different modulation. Only those long-distance terminals that can demodulate a specific modulation effect will receive ATM cells.

The core of the ATM converter 2600 is ALBM2606, which is the current ATM chipset known in the industry. The ATM chipset is designed to be used in radio systems. The ATM chipset does not have the ability or knowledge of demodulation or timing schemes. It only knows that it supports n Phys, and each Phy is associated with a Utopia bus (here, Utopia II bus 2608).

Phy is the abbreviation of "Entity", and is a physical layer ATM element such as a cell drawer or buffer that performs the physical layer ATM function. This ATM address filtrate technology uses the ATM chipset (as ALBM 2606) in a unique way to replace a far more complicated method of generating a master message to split the ATM cell into one of the different modulation traffic streams.

In this specific form of the present invention, the ATM converter is structured so that each of the n Phy functions as a modulation buffer for different modulation types. Each modulation buffer 2612 corresponds to a modulation stream. Therefore, according to the individual modulation buffer 2612, the Phy address on the Utopia II bus 2608 has a unique mapping to a specific modulation type. n Phy becomes n modulation buffer 2612. In addition, each dedicated virtual path identifier (VPI) and virtual channel identifier (VCI) are uniquely associated with the individual modulation mode specific to each modulation buffer 2612. In this specific form, there are three modulation buffers 2612, so there are three sets of VPI/VCI. Each group is mapped to one of the modulation buffers 2612. The mapping of each group of VPI/VCI is determined by the modulation type of the target remote terminal. This ensures that the ATM cell arriving from the reverse transmission line 2602 is routed to the correct modulation flow, and therefore to the correct remote terminal.

ALBM 2606 monitors the depth of its own internal buffer and performs the ATM quality of the service function, and the ATM controller 2610 controls the time slot of each ice bath ATM unit sent to the multi-mode radio (central terminal or remote terminal), so it controls Modulation mode used. For example, the first modulation buffer 2612 will support QPSK, the second modulation buffer 2612 will support 16-QAM, and the third modulation buffer 2612 will support 64-QAMO. Therefore, the ATM cell will be routed in a dynamic manner. Select the appropriate modulation buffer 2612, depending on the header information (VPI/VCI). Therefore, VPI and VCI are used to map ATM cells to individually modulated traffic streams.

In operation, ATM traffic enters a Phy2604, which is a cell tracer connected from the reverse transmission line 2602. The reverse transmission line 2602 is typically an OC3c line, but may be another physical medium known in the industry. The ATM cell is depicted in Phy2604, so the payload (ATM cell) is extracted from the frame and sent to ALBM 2606. Utopia II bus 2608 carries each unit to ALBM 2606. The ATM chipset or ALBM 2606 guarantees the quality of service (QOS) on the basis of VC (Virtual Channel). It has built-in hardware to manage QOS in a very reactive way. Therefore, ALBM 2606 buffers the arriving ATM cells according to the structured priority order associated with each virtual channel (step 2702 in FIG. 27). ALBM2606 supports most Phys, and in this article, there are n Phys. Each of the n Phys is an extremely shallow FIFO (first in first out) with only two units.

The time plan/modulation lookup table 2616 contains the time plan for each time slot of the multi-transmission mode unit bus 2614, Phy (here, the modulation buffer 2612), and the modulation mode. The time plan/modulation lookup table 2616 is coupled to the ATM formatter 2610 and stored in a buffer or memory such as static RAM. ALBM2606 reads the header information (VPI or VCI) of the ATM cell to know to which to modulate the buffer 2612 to send the ATM cell. The ALBM 2606 then transmits the ATM cell to the modulation buffer 2612 of the ATM formatter 2610 when the ATM formatter 2610 makes instructions as follows. To ensure ALBM 2606 sends ATM cells at the correct rate, and ATM formatter 2610 only accepts ATM cells that match the rate of the corresponding modulation mode on a Phy basis. This is a kind of "back pressure" loading technique, in which the ATM formatter 2610 performs a search for each time slot of the multi-transport modal unit bus 2614 in the time plan/modulation look-up table 2616. The time scheme/modulation look-up table 2616 informs the ATM formatter 2610 which ATM cell from which modulation buffer 2612 enters which time slot of the multi-transport modal unit bus 2614. Therefore, the ATM formatter 2610 uses the time plan/modulation look-up table to determine when each modulation buffer 2612 is valid for a specific time slot (step 2704 in Figure 27), and then determines a handshake on the Utopia II bus 2608 Signal (step 2706 in Figure 27). At the same time, ALBM 2606 regularly queries all its Phys (including the modulation buffer 2612) to find a valid handshaking signal. When ALBM 2606 sees a valid handshake signal, ALBM 2606 transmits the appropriate ATM unit to the active Phy, and then to the active modulation buffer 2612 (step 2708 in Figure 27). Then, the ATM formatter 2610 sends the ATM unit from the modulation buffer 2612 to the appropriate time slot of the multi-transport modal unit bus 2614 (step 2710 in FIG. 27).

Therefore, in short, this architecture generates three independent ATM cell modulation streams, each for a modulation type. The ATM unit is copied from each modulation buffer 2612 to the multi-transmission modal unit bus as a CB-data unit (see FIG. 15). The CB-data unit is then sent to the channel and control module of the indoor unit of the hub terminal, where it is mapped to the corresponding air interface frame format (refer to Figures 5 and 15), and depends on when each unit is located Slot modulation is one of the three modulations of a multi-level modulation demodulator (see Figure 11). Therefore, each modulation stream is composed of multiple sets of time slots, and each set of time slots is modulated by a different modulation type. The time slots in each group need not be continuous. Therefore, it is advantageous for the ATM converter 2600 to conveniently construct the ALBM 2606 so that each Phy on the Utopia bus has a one-to-one association with a modulation type, so as to generate ATM cell streams with different modulations. In addition, each group of VPI and VCI is associated with a modulation type. It should be noted that the Utopia II bus is shown as two separate buses in Figure 26; however, it is physically one bus as the industry understands.

In another specific form, the ATM filtrate operation shown in Figure 26 can separate ATM cells from more than one sub-channel into separate modulated traffic streams. The above-mentioned specific form generates a plurality of ATM cell streams with different modulations for one sub-channel of a channel. To support more than one sub-channel, more than one ATM formatter 2610 is required, that is, one ATM formatter 2610 for each sub-channel (in this specific form, one sub-channel is 12.5 MHz). Therefore, there are n ATM formatters 2610 instead of one ATM formatter 2610 for n sub-channels. Utopia II bus 2608 can support up to 30 components in total. Therefore, a multiple sub-channel ATM converter 2600 with a single ALBM 2606 can support up to 9 sub-channels, that is, each of the nine ATM formatters 2610 has, for example, three modulation buffers 2612. In this multi-channel ATM converter, each Phy address will be uniquely associated with a specific sub-channel and a specific modulation type corresponding to a specific modulation traffic stream.

Another way to generate different modulation streams is to add a "tag" to each ATM cell. This tag is known in the industry and is similar to the header of ATM, cell routing to the desired location (for example, individual modulation buffer 2610). However, the tag is added to the ATM cell and added to the cell processing, so the structured priority order of the ATM chip set is not used.

Figure 26 corresponds to Figure 22 illustrating the ATM-OC3c SSI module, so ALBM 2606 in Figure 26 is the same as ALBM 2211, including the buffer manager 2216, buffer manager buffer 2218, unit processor 2212, and unit of Figure 22 Handler Buffer 2214. The ATM formatter 2224 of FIG. 22 is the same as the ATM formatter 2610 of FIG. 26 and includes each of n modulation buffers 2612. The time scheme/modulation lookup table 2616 is contained in the formatter buffer 2226 of FIG. 22.

Secondly, the introduction of the basic unit structure of the standard ATM unit and the specially designed TDM unit used in this specific form of the present invention will help to clearly understand the address Lubo technology implemented in the SSI module of the remote terminal.

Refer to Fig. 28 again; shown is the block diagram of the asynchronous transfer mode (ATM) unit 2800 used in the point-to-multipoint system of Fig. 2. The ATM cell 2800 is a standard cell known in the industry and has a header section 2802 and a data section 2804. The header section 2802 contains a virtual path identifier (VPI) 2806, a virtual channel identifier (VCI) 2808, and other headers 2810. The standard ATM cell 2800 has a length of 53 bytes. The header section 2802 is five bytes and the data section 2804 is 48 bytes. VPI2806 is octet and identifies the virtual path, while VCI2808 is 16-bit to identify the virtual channel on New Year's Day. The VPI and VCI are inserted in the ATM formatter of the ATM-based SSI module of the hub terminal, so that the ATM-based SSI module of the remote terminal can retrieve the correct ATM unit.

Refer to Figure 29 again; it shows a block diagram of the time division multiplexing conversion unit (hereinafter referred to as TDM unit 2900) used in the specific form of the point-to-multipoint system. The TDM unit 2900 has a data segment 2902, a header segment 2904 containing a virtual path identifier (VPI) 2906, and other headers 2908. Note that the TDM unit 2900 can also be referred to as a TDM packet; however, since it is modeled after an ATM unit, this specification will refer to it as a TDM unit. In addition, the ATM unit 2800 and the TDM unit 2900 are collectively referred to as ATM signals and TDM signals.

It is advantageous to design the TDM unit 2900 to be the same length as the standard ATM unit, so that the ATM unit 2800 and the TDM unit 2900 can be in the same data unit (data unit 1704 in Figure 17) and in the same data unit on the multi-transport modal unit bus. Interchange within the same data field (data field 704 in Figure 7A-7B) of the air interface frame format.

In addition, the TDM unit 2900 has a 5-byte header section 2902 and a 48-byte data section 2904, similar to an ATM cell. This is different from the old TDM unit structure. The old TDM unit structure does not require the header section 2902 regardless of the length, because it is transmitted and converted according to the time slot where the TDM unit is located. In addition, the TDM unit 2900 uses an ATM dedicated header (VPI 2906) inserted in its header section 2902. Therefore, the use of a header segment on the TDM unit 2900, especially the use of an ATM header VPI 2906 on the TDM unit 2900, is unique to this specific form of the present invention. The VPI2906 is inserted into the TDM unit 2900 by the unit formatter of the TDM-based SSI module at the hub terminal. The VPI2906 is placed in the header section 2902 of the ATM cell exactly where the VPI2906 will be found, and is used in the following address Lubo technology.

In addition, the data segment 2904 is usually used to carry a digital signal level zero (also referred to as DSO) pulse code modulated data (hereinafter referred to as PCM data). PCM data and DSO are well known in the industry, so no further explanation is needed. Signaling data such as channel-associated signaling (also called CAS) corresponds to the PCM data and is sent in an independent TDM unit. In this specific form of the present invention, the other headers 2908 in the header section 2902 are not wasteful, but beneficially used to carry signaling data, while the data section 2904 is used to carry PCM data. Putting signaling data and PCM data in the same TDM unit 2900 is different from conventional TDM units that only contain PCM data or signaling data. Therefore, there is no need to carry signaling data and PCM data in independent TDM units that are converted separately based on time slots. Note that the signaling data must still be separated from the PCM data. Refer to Figures 41 to 43 for a detailed description of the TDM buffer operation.

Another feature of this specific form is that the data segment 2904 can be decomposed to carry more than one DSO PCM data. A conventional TDM unit only carries the data of 1 DSO. Depending on the specific TDM unit type described in Figures 41 to 43, most DSOs of a T1 line can be multiplexed into the same TDM unit. This procedure is further explained in Figures 39 to 44B.

Refer to Figure 30; shown is the block diagram of the ATM address Lubo technology implemented by each ATM-based SSI module of the remote terminal (for example, as shown in Figures 20, 22, 25A and 25B). When referring to FIG. 30, reference will be made to the corresponding steps of FIGS. 31A and 31B. The last two figures illustrate the steps of the ATM-based SSI module performing the ATM address Lubo technology. The ATM address Lubo operation chart 3000 shows a multi-transmission modal unit bus 3002, containing a VPI comparison 3006, an optional VPI lookup table 3007, and optional VPI accept/discard bits 3009 (for ATM in Figure 22) -OC3c SSI module) ATM formatter 3004 (or ATM signal formatter), buffer 3008 containing a VCI lookup table 3010, a Utopia bus 3012, and a TDM unit formatter 3022 (or TDM signal formatter) . The VCI lookup table 3010 has a VCI accept/discard bit 3016, AAL1/AAL5 bit 3018, and a second 8-bit part 3020. The VPI comparison 3006 includes the separated VPI 3024, a register 3026, and a comparator 3028. It also shows an AAL1 SAR 3013 and an AAL5 SAR3014.

The multi-transport modal unit bus 3002 is coupled to the ATM formatter 3004 and the TDM unit formatter 3022. The ATM formatter 3004 contains a VPI comparison 3006 and an optional VPI lookup table 3007. The ATM formatter 3004 is coupled to the buffer 3008 and the Utopia bus 3012. The buffer 3008 contains a VCI lookup table 3010. Both the ATM formatter 3004 and the TDM unit formatter 3022 are client logic elements.

In implementation, the multi-transport modal unit bus 3002, as described with reference to Figures 15 to 18, interfaces with an ATM formatter 3004 and/or a TDM unit formatter 3022, depending on which SSI module is inserted into the remote terminal It depends on the SSI slot of the indoor unit of the machine. At the ATM SSI module of the indoor unit of the remote terminal, the ATM address Lubo technology is completed for the mixed traffic that flows from the central terminal to the remote terminal and leaves the point-to-multipoint system to the user. This technique is used to distinguish the TDM unit and the ATM unit received on the multi-transport modal unit bus 3002. Once the correct type of unit is classified, the unit needs to be further classified to determine which unit on the multi-transport modal unit bus 3002 goes to a specific SSI module.

Shown is a block diagram of a comprehensive ATMSSI module, rather than describing a specific SSI module, such as the four DS1/AAL1 SSI modules described in Figure 20, the ATM OC3c SSI module in Figure 22, or Figure 25A and Multi-transmission modal SSI module in 25B. Therefore, the block diagram of FIG. 30 and the flowcharts of FIGS. 31A and 31B represent the procedures implemented at each ATMSSI module of the remote terminal, regardless of the type. Note that only the multi-transport modal SSI module in Figures 25A and 25B actually contains both an ATM formatter 3004 and a TDM unit formatter 3022, while other ATM-based SSI modules only contain an ATM formatter 3004, but no TDM unit. Formatter 3022.

For an SSI module (ie, TDM-based SSI module) configured for TDM traffic, the Lubo procedure is relatively simple. The IM-Com message slot on the multi-transport modal unit bus 3002 (see Figure 15) provides the TDM unit formatter 3022 with the appropriate time slot to be followed. This time plan is stored in a message buffer (not shown). Therefore, the TDM unit formatter 3022 simply pulls the TDM unit away from the time slot in which it is configured. This ensures that the TDM unit formatter 3022 only copies the required TDM units instead of unnecessary TDM and ATM units.

For an SSI module used for ATM traffic (ie ATM-based SSI module), the Lubo procedure involves a comparison and table lookup structure. The ATM formatter 3004 receives each incoming unit containing both TDM and ATM units on the multi-transport modal unit bus 3002 (step 3100 in FIG. 31A), and temporarily stores it in an internal FIFO (first in first out). Then, the ATM formatter 3004 performs VPI extraction on the received unit, and then the VPI comparison 3006 compares the extracted VPI with a VPI stored for a specific SSI module, thus performing a VPI comparison task (step 3102 in Figure 31A) . The VPI comparison 3006 uses a comparator 3028 to compare the extracted VPI 3024 with an internal vPI stored in the register 2026 (step 2352 of FIG. 23A). If the VPI of the incoming unit matches the internal VPI (step 3104 in Figure 31A), then the unit is reserved. All other incoming units with mismatched VPIs are discarded (3106 in Figure 31A). Since all TDM units have a vPI that is unique to TDM units as shown in Figure 29, it is the same as ATM The position of the VPI header, so the VPI comparison 3006 of the ATM formatter 3004 simply reads the VPI of the TDM unit, and discards the TDM unit as an ATM unit. Therefore, only ATM units that go to a specific SSI module are reserved. Therefore, TDM cells are distinguished from ATM cells to be reserved by a specific SSI module. In addition, the VPI comparison can be constructed to specifically match the assigned VPI of the TDM unit, and the TDM unit can be discarded on this basis. Therefore, ATM cells are again distinguished from TDM cells.

In this procedure, once the ATM is reserved, the next step is to locate the reserved ATM cell in the VCI lookup table 3010 on the VCI header 2808 of the reserved ATM cell in the buffer 3008 (a static RAM) Perform a VCI search (step 3108 in Figure 31A). The VCI search step extracts the 14 least significant bits of the VCI, and applies these bits as an index to the VCI search table 3010. VCI Lookup Form 3010 Support 2 ¹⁴ Addresses, but can support up to 2 ¹⁶ Addresses. Once the indicator is applied, 16 bits are read from the VCI lookup table and latched in the ATM formatter 3004 in a single access. The first 8 bits of the lookup table contain a VCI accept/discard bit 3016 and an AAL1/AAL5 bit 3018. If the VCI accept/discard bit is "0" (Step 3110 in Figure 31A), there is no match and the ATM cell is discarded without further processing (Step 3106 in Figure 31A). If the VCI accept/discard bit is "1" (step 3110 in Figure 31A), there is a match and the ATM cell is reserved.

In addition, if the ATM unit is reserved, the VCI look-up table 3010 includes an AAL1/AAL5 bit 3018, which informs the ATM formatter 3004 that the ATM unit is an AAL1 ATM unit or an AAL5 ATM unit (step 3112 in Figure 31A) and should be passed through Utopia Bus 3. 12 route selection to AAL1 SAR 3013 or AAL5 SAR 3014. If a matching unit is an AAL5 unit (step 3112 in Figure 31A), it will be routed to AAL5 SAR 3014 via Utopia bus 3012, and will be processed as described earlier in the specification (step 3114 in Figure 31A).

If the matched unit is an AAL1 unit (step 3112 in Figure 31A), the unit will be sent to AAL1 SAR 3013 via Utopia bus 3012. However, this unit will be slightly modified. The lower 8 bits of VCI need to be translated by performing a lower VVI translation operation (Step 3116 in Figure 31A). The AAL1 chip used requires physical information in the lower 8 bits, not the standard ATM VCI. Advantageously, the VCI look-up table 3010 is constructed with software according to the specific user configuration load. Therefore, VCI is translated into a form that allows small users to have more flexibility in channel recognition. The advantage is that the lower VCI translation task is executed at the same time as the search step is completed, instead of having to perform a second independent search. If the AAL1 unit is accepted, the lower 8-bit VCI stored in the second 8-bit part 3020 of the VCI lookup table 3010 becomes the new lower VCI. The new lower 8-bit VCI is latched on the ATM cell before the cell is routed to AAL1 SAR 3013 (step 3118 of disconnection 31A). This is advantageous in that only one search is required and processing time is saved because it occurs simultaneously with the VCI search. Each accepted unit completes this procedure. If the unit is AAL5, the lower 8-bit VCI 3020 is discarded.

The person who wants to display combines several searches into one VCI search table 3010 for the VCI table search operation. An old method VCI search operation performs an accept/discard search, an AAL1/AAL5 search, and a lower VCI translation search. This specific form combines all three searches into a VCI search form 3010. Any combination of secondary search is different from the old ATM address filtering technology. Again, this saves processing time, and the ATM cell can be routed with the least delay.

Note that in some specific forms (not shown), the ATM-based SSI module can be designed to only support AAL1 or AAL5, but not both. Therefore, Figure 30 needs to be modified to remove one of AAL1 SAR 3013 or AAL5 SAR 3014. The AAL1/AAL5 bits are not required in this specific form.

The completion method of the ATM address filtering process is shown in Figure 22 for the ATM-OC3c SSI module of the remote terminal, which is different from other ATM-based SSI modules at the remote terminal, and is reflected in the flow chart of Figure 31B. Here, the reason for the different functions of the ATM address Lubo is that the throughput on the ATM-OC3c SSI module 2200 is much higher than the throughput of other types of SSI modules located in the remote terminal. The OC3c line sends data at 155.52 Mbps (megabits per second), which is approximately equal to three DS3 lines. The flowchart in Figure 31B also applies to the ATM-OC3c SSI module's choice of DS3.

In FIG. 31B, the first three steps are the same as those in FIG. 31A. Therefore, each unit is received from the multi-transmission modal unit bus (step 3150 in FIG. 31B), and as in steps 3102 and 3104 in FIG. 31A, it is completed between the detached VPI 3024 and the VPI stored in the register 3026 A VPI comparison (steps 3152 and 3154 of Figure 31B). If the VPI matches (step 3154 in FIG. 31B), the VCI lookup table 3010 is used as described above to perform the VCI search (step 3156 in FIG. 31B). Therefore, if the VCI accept/discard bit is equal to "1" (step 3158 of FIG. 31B), the ATM cell is accepted. If the VCI accept/discard bit is equal to "0" (step 3158 of FIG. 31B), the unit is accepted (step 3162 of FIG. 31B). It should be noted that the TDM unit does not go through the paths indicated in steps 3156 and 3158, because the VPI does match in step 3154.

If the VPI does not match (step 3154 of FIG. 31B), the cell is not discarded, but a VPI search is performed in the VPI lookup table 3007 of the ATM formatter 3004 (step 3164 of FIG. 31B). The VPI lookup table 3007 is an 8-bit table with 2 ⁸ The depth of each item. The extracted vPI is used as an index to enter the VPI lookup table 3007. If the VPI accept/discard bit 3009 is equal to "1" (step 3166 in Figure 31B), the unit is accepted (step 3162 in Figure 31B) ^。 If the accept/discard bit is equal to "0" (step 3166 in FIG. 31B), the cell is discarded (step 3160 in FIG. 31B). The VPI accept/discard bit 3009 has been assigned to the dedicated VPI of the ATM cell accepted by the constructed specific ATM-OC3cSSI module. Therefore, the TDM unit is discarded from the ATM unit during the VPI search operation. Because the VPI assigned to the TDM unit is unique to the TDM unit, the corresponding index entered into the VPT search table 3007 always has an acceptance/indicating that the unit is discarded. Bit 3009 is discarded. Therefore, all TDM units are discarded at the VPI lookup table 3007.

In addition, this provides a "VCI transparent" service, if the extracted VPI does not match the pre-assigned VPI dedicated to a specific SSI module. Therefore, the ATM cell passes through the SSI module without performing a VCI lookup. Therefore, all ATM cells with pre-structured VPI are issued to users through ATM-OC3c SSI module.

. In the specific form shown in FIGS. 30 and 31B, the ATM-based SSI module (such as the ATM-OC3c SSI module) advantageously performs a VPI comparison operation, and then executes a VPI comparison operation on each unit that enters the ATM-based SSI module VPI search or a VCI search. The advantage is that the ATM-based SSI module does not perform both VPI search and VCI search in every unit. Therefore, it is advantageous to use this specific form to shorten the processing time (which has attracted attention due to the throughput of the ATM-OC3cSSI module).

In addition, the ATM-based SSI module receives traffic from a mixed transmission modal interface such as a multiple transmission modal unit bus. However, the present invention is not limited to this description. The ATM-based SSI module can only receive ATM cells but not hybrid cells, and implement the same ATM address Lubo technology to correctly route the ATM cells to the desired location.

The address filtering technology is implemented in the SSI module of the multi-transmission modal multi-level modulation point-to-multipoint system. The components described are common in the industry and understood by skilled persons.

Expansion of indoor units and fiber expansion modules

Refer to Fig. 32 again; shown is the block diagram of the expanded indoor unit of each dedicated interface port of the internal unit of the remote terminal shown in Fig. 2 in the specific form. Chart 3200 includes: one of the remote terminal indoor unit 3204 (channel processing unit or IDU) coupled to one of the remote terminal outdoor unit 3202 (transceiver unit or ODU), 4 expansion indoor units 3208 (EIDU) ) Coupled to most fiber links 3206 of the indoor unit 3204. Each expansion indoor unit 3208 has four SSI modules (cards) 3210.

In order to allow more user interfaces and allow each user to interface with a point-to-multipoint system up to 2240 feet away from the indoor unit, the extended indoor unit 3208 (EIDU) is coupled to each SSI port of the indoor unit 3204 via a fiber link 3206 one. EIDU3208 allows up to 4 other SSI modules 3210 to interface with point-to-multipoint systems. The number of indoor units 3208 and individual SSI ports can be changed depending on the implementation method. Therefore, a maximum configuration allows up to 16 SSI modules 3210 to be inserted into a single indoor unit 3204 of a remote terminal.

This is different from the old method of expanding indoor units and expanding interfaces. An old system uses a bus repeater, such as a ribbon cable, which is a high-density copper cable that repeats (or expands) the bus that carries signals. However, the bus repeater can only extend the bus by a few feet, unlike the multi-mode fiber link 3206, which can extend the multi-transport modal unit bus by as much as 2250 feet. This is particularly advantageous because the user can interface with the remote terminal indoor unit that is up to 2250 feet away from the actual indoor unit. Therefore, the user can interface with the point-to-multipoint system at many different locations in the user's industry (usually a large building), and place the indoor unit 3204 in other places in the user's industry. With the old system, the user must be connected within a few feet of the actual indoor unit of the remote terminal.

EIDU3208 uses a set of fiber expansion modules as the "main" fiber expansion module (refer to Figure 33) to connect to the indoor unit 3204 of the remote terminal. The module is attached to the SSI port of the indoor unit 3204 and connected to a Multimodal fiber link 3206. The multimode bear fiber link 3206 is an optical fiber cable that functions as an extension line of a multi-transmission mode unit bus. The multi-mode fiber link 3206 is a 200 MHz link, which is connected to the expansion indoor unit 3208 with another fiber expansion module called a "slave" fiber expansion module (refer to Figure 23) inserted into the expansion indoor unit 3208. The "master" and "slave" fiber expansion modules are the same modules, but they are located in the indoor unit and expansion indoor unit of the remote terminal respectively. The fiber link 3206 is a multi-modal fiber known in the industry. The maximum length is 2250 feet, and the maximum length is 10 ^-12 Or less bit error rate transmission. In another way, the distance can be further extended, if a single-mode fiber is used instead of a multi-mode fiber for the fiber link 3206. Note that, as previously implied, the "multi-mode" used to refer to the cable does not refer to multi-level modulation and multi-transmission capabilities. The multi-mode cable is simply a commonly understood cable type.

The "main" fiber expansion module formats the signals on the multi-transmission modal unit bus for the fiber link 3206, and then transmits each signal via the fiber link 3206, including timing (this is guided from the hub via the air interface Terminal). Then, the "slave" fiber expansion module converts the signal from the fiber link 3206 back to the format of the multi-transport modal unit bus, and transmits the signal to another multi-transport modal unit bus of the EIDU 3208. The timing of each signal is advanced or delayed so that it matches the original signal timing of the indoor unit 3204. Therefore, the SSI module 3210 at the EIDU 3208 seems to be directly coupled to the indoor unit 3204 itself.

The actual expansion indoor unit 3208 only contains a fiber expansion module, a backplane bus including a multi-transport modal unit bus, and four SSI ports for the SSI module 3210. This simple function is like an extension of the multi-transport modal unit bus, so it can be used as an additional user interface. In addition, this is different from the old method expansion unit, because the old method expansion link (ribbon cable) and the old method expansion unit only support one type of traffic (ATM or TDM), while this specific form supports both types of traffic (ATM And TDM).

Refer to Figure 33; it shows a block diagram of a fiber expansion module in an SSI port of an indoor unit to be plugged into a remote terminal or an expansion indoor unit of Figure 32. The fiber expansion module 3300 diagram includes: a multi-transport modal unit bus 3302, fiber expansion module (FEM) formatter 3308, text buffer 3310, CPU 3312, data buffer 3314, parallel to serial converter 3316, serial to parallel converter 3318, divider 3320, fiber transmitter 3322, fiber receiver 3224, and fiber link 3326.

The multi-transport modal unit bus 3302 includes a timing bus and includes a backplane interface. The multi-transport modal unit bus 3302 is coupled to the FEM formatter 3308. The FEM formatter 3308 is coupled to the measuring buffer 3310 and the CPU 3312. The CPU 3312 is also coupled to the power buffer 3310. The FEM formatter 3308 is also coupled to the parallel-to-serial converter 3316, the serial-to-parallel converter 3318, the data buffer 3314, and the divider 3320. The parallel-to-serial converter 3316 is coupled to the fiber optic transmitter 3322, and the latter is connected to the fiber link 3326. The fiber link 3326 is also connected to the fiber receiver 3324, which is coupled to the serial-to-parallel converter 3318, which is also coupled to the data buffer 3314 and the divider 3320.

In practice, the fiber expansion module 3300 (FEM) (hereinafter referred to as IDU FEM or "main" FEM) at the unit in the remote terminal provides an interface to the fiber link 3326 connected to the EIDU. It also buffers the units coming in from the multi-transport modal unit bus 3302, buffers the data from the expansion indoor unit, and is embedded in the IM-Com master message and telegram in the bus frame format of the multi-transport modal unit bus 3302. The CCM communication of the indoor unit of the remote terminal. IDU FEM3300 uses the first IM-Com slot shown in Figure 15 to synchronize with the FEM at the EIDU and identify the EIDU.

Each unit arrives at the IDUFEM 3300 from the multi-transport modal unit bus 3302 to the FFM formatter 3308. The FEM formatter 3308 (customer design logic) also restores the timing of the multi-transport modal unit bus 3302. The FEM formatter 3308 inserts a unique word (for synchronization with the FEM at the EIDU), frame and frame identification codes, and an EIDU identification byte into the first IM-Com time slot. IM-Com messages are sent to the message buffer (dual-port RAM) for CPU3312 processing. The CPU3312 (BISC microcontroller) reads the message and the power buffer 3314 for use in configuration, alarms, etc. Finally, the FEM formatter 3308 transmits the frame received from the multi-transmission modal unit bus 3302 to the parallel-to-serial converter 3316. The parallel-to-serial converter 3316 is a high-speed converter that transmits the data frame to the optical fiber transmitter 3322 at 200 MHz. The fiber optic transmitter 3322 transmits the signal to the EIDU FEM (fiber expansion module or "slave" FEM at the expansion indoor unit) via the fiber link 3326.

In the opposite direction, the fiber optic receiver 3324 receives the data stream in the reverse direction from the EIDU via the fiber link 3326. The data is sent to the serial-to-parallel converter 3318, where the data stream is converted back to parallel format, and then sent to the data buffer 3314 (dual-port RAM). The data flow is slightly complicated due to timing and buffering requirements. Therefore, the FEM formatter 3308 restores the unique word assigned by the EIDU FEM so that the FEM formatter 3308 knows where the frame starts. This design ensures that the unique word arrives before the Synch signal of the unit bus TX frame (CB_TX_FS in Figure 18, indicating the unit bus 33D2). Therefore, the data is written into the data buffer 3314 before it is read by the FEM formatter 3308. Then, the FEM formatter 3308 reads the data from the data buffer 3314 at the beginning of the frame, and copies it to the multi-transport modal unit bus 3302. Therefore, the timing of the unit bus frame is advanced or lagging to compensate for the offset in the fiber link. The FEM formatter 3308 also restores the timing of the EIDU.

The Fiber Expansion Module (EIDU FEM) (sometimes referred to as "Slave" FEM) at 3300 of the expansion indoor unit uses the same block diagram shown in Figure 33. When the frame containing the IM-Com measurement and data is sent from the optical fiber transmitter of IDU FEM and passed through the multi-mode link, the signal enters the EIDU FEM3300 of its corresponding optical fiber transmitter 3324. The flow is the same as the IDU FEM described above. Note again that the unique codeword assigned to the frame is received in the FEM formatter 3308 so that it knows when the frame starts. Otherwise, there will be timing problems, because the FEM formatter will assume that the frame starts when it receives data instead of when the frame actually starts. This unique code word alleviates the timing problem between indoor units and EIDU. In addition, the CPU3312 of the EIDU FEM3300 uses the IM-Com manager to communicate with the CCM of the indoor unit of the remote terminal, and provides signals for each processor located in the attached SSI module. Therefore, the data in the frame format of the bus is transmitted on the multi-transport modal unit bus 3302 at the EIDU, and the extended SSI module can interface with the point-to-multipoint system.

Also note that the fiber expansion module does not actually distinguish the type of traffic it retransmits or supports. What separates the mixed traffic is to expand the SSI module of the indoor unit, and the fiber expansion module and the multi-mode fiber link simply provide the extension line of the multi-transmission modal unit bus. Therefore, fiber expansion modules and multi-mode fiber links support the use of multiple transmission types (such as TDM and ATM) signals. However, this is different from the old method of transmitting the multi-transmission modal signal to the expansion indoor unit via the expansion bus (fiber link).

The data flow from the 3300 SSI modules of EIDU FEM is the inverse of the data flow from the remote indoor unit to the expanded indoor unit. Each unit receives the multi-transmission modal unit bus 3302 at the FEM formatter 3308 (the latter copies the IM-Com message of EIDU FEM from the message buffer 3310), and inserts a unique word in front of the data frame so that IDUFEM knows this Where does the frame start, and copy each unit to the parallel-to-serial converter 3316 for transmission to the IDU FEM via the fiber link 3326. The IDUFEM formatter 3308 sequentially copies the data frames to the multi-transmission modal unit bus 3302, which is to be sent to the CCM of the indoor unit. Therefore, IDU FEM 3300, EIDU FEM 3300, and fiber link 3326 function as a multi-transport modal unit bus extension line. Note that not all the various signals are explained in detail, because their operations are understood by those skilled in the industry. Note that not all functional blocks and signals are described in detail. Skilled technicians understand these functions and can easily implement them, so no further explanation is needed.

Refer to Figure 34 again; it shows a delay timing chart involving the use of the fiber expansion module of Figure 33 to transfer data from the indoor unit of the remote terminal to the extended indoor unit (EIDU) of Figure 32. The effective delay is propagation delay 3402, guard time 3406 transmitted to reception offset 3406 and frame Synchro offset 3408. Various signals are also displayed: the unit bus receiving at the long-distance fiber expansion module, the upper frame Synchro3410 (CB_RX_SFS (at IDU FEM)), the unit bus receiving at the expansion fiber expansion module, the upper frame Synchro3412 (CB_RX_SFS (EIDU FEM) )), the unit bus transmission at the expansion fiber expansion module, the upper frame Synchro3414 (CB_TX_SFS (IDU FEM)), and the unit bus transmission, the upper frame Synchro3416 (CB_TX_SFS (EIDUFEM)).

Timing is extremely important in the design of the fiber expansion module in Figure 33. The timing diagram 3400 illustrates the delay of data transfer from the indoor unit of the remote terminal to the expanded indoor unit. The propagation delay 3402 is the delay from IDUFEM to EIDUFEM and vice versa. This illustrates the delay in the parallel-to-serial converter and the fiber optic transmitter and receiver of the Fiber Expansion Module (FEM) shown in Figure 33. EIDUFEM inserts a guard time 3404, which is usually a few microseconds, to ensure that the data arrives before being read. IDU FEM then resynchronizes the data arriving from the EIDU with the timing of the indoor unit. The transmission-to-reception offset 3406 and the frame Synchro offset 3408 are well known in the industry, so no further explanation is needed.

Request assignment multiple access

Request Assigned Multiple Access (DAMA) is a method of assigning bandwidth when changing requests for bandwidth within the system. Therefore, DAMA provides efficient use of the available spectrum. This point-to-multipoint system uses unique DAMA technology to allocate bandwidth in a multi-level modulation and multiple transmission environment.

Turn back to FIGS. 26 and 27; a block diagram and a corresponding flowchart are shown respectively, illustrating an ATM address filtering technique implemented by an ATM converter that has been configured for a multi-level modulation environment. In addition, Figures 26 and 27 also illustrate how bandwidth is assigned to ATM data traffic in the downlink direction (central to remote), and illustrates a DAMA technology.

Voice traffic is assigned in a conventional manner. The point-to-multipoint system detects a valid call (off-hook) and automatically assigns bandwidth. The remote terminal uses the assigned maintenance slot of the main management section in the air interface frame format to request bandwidth from the central terminal, as shown in Figures 4 and 6. The hub terminal uses TR-008 or GR-303 signaling to connect the call to the converter. The bandwidth is reallocated at the end of the call. If the converter initiates a call, the hub terminal will assign bandwidth and notify the remote terminal.

Data bandwidth is dynamically assigned in both directions (downlink and uplink). In the uplink, the remote terminal monitors its own buffer depth in each of the above-mentioned SSI modules. If the buffer depth exceeds a threshold and is higher than the amount of time that has been constructed, the remote terminal will request more bandwidth from the hub terminal. The hub terminal evaluates all requests and assigns different levels of bandwidth to all remote terminals according to the specified priority order.

In a specific form, the advantage is that the bandwidth used for ATM data traffic in the downlink is assigned by the unique method shown in Figure 26 above. As mentioned above, the ATM converter at the ATM-OC3c SSI module of the hub terminal can dynamically manage the ATM traffic flow from the OC3c line to the point-to-multipoint system. The ATM converter is pre-assembled for DAMA in the downlink direction (central to remote).

Each Phy of the ATM converter has already constituted n modulation buffers 2612. Each modulation type has a different modulation buffer 2612; for example, QPSK is used for the first modulation buffer 2612, 16-QAM is used for the second modulation buffer 2612, and 64-QAM is used for the third modulation buffer. Buffer 2612. ALBM2606 uses the well-known service agreement discussed in Figure 26 (step 2702 in Figure 27) to dynamically manage ATM cells on the basis of priority. In this regard, ATM cells with higher priority are sent out with a delay less than that of ATM cells with lower priority. In addition, the measurement of delay depends on VPI and VCI. Therefore, the advantage is that each VPI and VCI is also associated with a modulation type. The advantage is that each Phy is associated with a modulation type.

This architecture generates three independent ATM cell streams, each used for a modulation type within the same communication link. Each modulation stream includes multiple sets of time slots, where each set of time slots is subject to different modulations. Each modulation type requires more or less bandwidth, depending on the number of remote terminals of each modulation type and the number of subscribers; for generating different modulation streams of ATM data units, ATM data units The bandwidth is dynamically assigned within a modulation stream. The ATM formatter 2610 enters and exits the time slice/modulation lookup table 2616 and determines which modulation buffer is valid (step 2704 in Figure 27), and then sends a handshake signal to the ALBM 2606 (step 2706 in Figure 27). ALBM 2606 reads the handshake signal and transmits the ATM cell to the appropriate modulation buffer 2612 (step 2708 in Figure 27). Once the ATM units are in the respective modulation buffer 2612, the ATM formatter 2610 enters and exits the multi-transport modal unit bus frame format and the time scheme of each time slot corresponding to the air interface frame format, and transfers the ATM unit Transmit on the multi-transport modal unit bus (step 2710 in Figure 27). Therefore, three differently modulated ATM cell streams are generated. In this way, this technology using ATM chipset replaces a message generated from a hub terminal to a remote terminal or adds a "tag" known in the industry to the ATM unit to make the bandwidth dynamic in the downlink A far more complicated method of assigning ATM data traffic.

Refer to FIG. 35 again; it shows an example of a request-assignment multiple access (DAMA) technique to dynamically change bandwidth based on channel conditions. The corresponding steps in FIG. 36 (illustrating the steps performed in the DAMA technique based on the channel conditions as shown in FIG. 35) will be referred to when referring to FIG. 35. Shown is a hub terminal 3502 that transmits during a clear channel condition 3501 and a bad channel condition 3503. During the clear channel condition 3501, all remote terminals are in area 13504. During the bad channel conditions 3503, the remote terminals are located in the area 13504 to the area n3508. The sector 3506 supported by the hub terminal 3502 is also displayed.

In practice, this DAMA technology dynamically assigns bandwidth based on channel conditions. For example, in normal point-to-multipoint system operation, remote terminals in area 13504 require a lower bit of energy at an acceptable bit error rate (for example, 10 ^-8 ); therefore, higher-order modulation (larger bits/second/MHz) can be used, such as 64-QAM. In the farthest area, area n3508 (area 3 in this specific form uses QPSK modulation), the remote terminal requires a higher bit of energy, so lower order modulation (smaller number of bits per second) / MHz), such as QPSK. The specific implementation and benefits of this structure are explained throughout the specification.

Therefore, the hub terminal 3502 first selects the remote terminal to which it will transmit the traffic bundle. Secondly, monitor the channel conditions and determine whether the channel conditions are bad, for example, during a fading period in a rainy day. Rainy weather fading is the main damage to the microwave radio link. Channel conditions can be measured as a function of the received signal strength indicator (RSSI) or the bit error rate (BER) of the signal received via the communication link. For example, when the RSSI falls below the specific threshold of each of the different modulation modes supported by the hub terminal 3502 or the BER exceeds a threshold, the channel condition is considered bad. For example, the threshold BER can be 10 ^-8 . The hub terminal 3502 receives a maintenance packet from an individual remote terminal containing a signal quality indicator (SQI) (step 3606 in FIG. 36), which contains, for example, RSSI.

The hub terminal 3502 then selects the highest order modulation that can support individual remote terminals based on the channel conditions (step 3608 in Figure 36). During severe conditions 3503 such as rainy weather fading, the traffic is modulated and transmitted via the air interface using different modulations that have been configured according to the region, ie, region 13504 to region n3508.

However, during clear channel conditions, all remote terminals are considered to be in area 13504. Therefore, the traffic can be transmitted with the highest order modulation (step 3608 in Figure 36), which requires the minimum number of bits/second/Hz and uses the minimum bandwidth for transmission, that is, 64-QAM in this specific form. Note that the channel conditions will be clear for a high percentage of the time, allowing bandwidth to be dynamically assigned to a highest order modulation most of the time; and saving bandwidth. Therefore, the bandwidth is dynamically managed during clear channel conditions and is only converted back to the structured bandwidth allocation during bad channel conditions.

Then, the hub terminal 3502 checks whether there are any remote terminals to be communicated (step 3610 in FIG. 36). If yes, repeat steps 3604 to 3610. If not, the hub terminal will stop (step 3612 in Figure 36).

Although the bandwidth is dynamically managed based on channel conditions, this DAMA technology is ideal for low-quality traffic services such as an unspecified bit rate (UBR) Internet browsing data, although the technology can be used for other higher-quality calls. Service (such as voice). In this case, for voice and other high-quality services, the remote terminal is always located in its individual area, that is, area 13504 to area n3508. Therefore, an initial step is included to determine whether the traffic in transmission is a low-quality unspecified bit rate (UBR) service. If the services are high-quality services such as a specified bit rate, the traffic will be adjusted to normal using different modulations of remote terminals located in different areas, that is, area 13504 to area n3508. Therefore, the bandwidth used for high-quality services is not changed based on channel conditions. If the traffic in transmission is a low-quality service, the steps in Figure 36 are executed to dynamically assign bandwidth.

It should also be noted that FIG. 35 illustrates how different areas 3504 and 3508 are located in a sector 3506. This sector represents the aforementioned sector ("circular slice"). It should also be noted that Fig. 35 illustrates another DAMA technique, in which the signal received by the remote terminal is independent of the time scheme.

1:N redundancy

Refer to Fig. 37 again; shown is a block diagram of a 1:N redundant system 3700. Shown are hub terminal A3702, hub terminal B3704, backup hub terminal 3706, remote terminal 3710 (1A-nA), remote terminal 3712 (1B-nB), sub-channel A3714, sub-channel B3716 , DS3A line 3718, DS3B line 3720, spare DS3 line 3722, multiplexer 3724, and a reverse transmission line 3726.

The hub terminal A3702 communicates with each remote terminal 3710 via the sub-channel A3714, the hub terminal B3704 communicates with each remote terminal 3712 via the sub-channel B3716, and a backup hub terminal 3706 when the hub terminal B3704 fails It communicates with the remote terminal 3716 via the sub-channel B3716. The hub terminal machine A3702, the hub terminal machine B3704, and the backup hub terminal machine 3706 are coupled to the multiplexer 3724 via a DS3A line 3718, a DS3B line 3720, and a backup DS3 line 3722, respectively. The multiplexer 3724 has a reverse transmission line for connection to the transmission network (not shown).

In practice, the 1:N redundancy system 3700 is designed as described above to replace the 1:1 redundancy system used at the center of the point-to-multipoint system (see Figure 13). This system may or may not use central and remote terminals with multiple transmission modes and/or multi-level modulation capabilities, so it will be described in a comprehensive manner. In the 1:1 system, each communication terminal (or hub terminal) has a backup hub terminal to replace a specific hub terminal in case of failure. Therefore, a system with 10 hub terminals requires 10 spare hub terminals, which increases the cost of the system. Refer to the description of Figure 13 for the 1:1 redundant system.

In a point-to-multipoint system, due to the splitting of most channels and the location of remote terminals, several hub terminals can propagate to remote terminals within the same antenna sector. The 1:N redundancy system is designed to work when most hub terminals operate in the same sector and have the same antenna coverage. Therefore, the hub terminal machine A3702, the hub terminal machine B3704, and the backup hub terminal machine 3706 are all in the same sector, and their respective antennas point in the same direction. The central terminal A3702 can use the "50 MHz channel A" sub-channel A3714, and the central terminal B3704 can use the "50 MHz channel B" sub-channel B3716. The backup hub terminal 3706 can support its equivalent hub terminal A3702 or hub terminal B3704. Therefore, a small number of central terminals are needed at the central location to reduce the total cost of the point-to-multipoint system. The backup hub terminal 3706 must also have the same SSI module assembly or reverse transmission connection line as the hub terminal A3702 and the hub terminal B3704.

In a typical reality, both the hub terminal A3702 and the hub terminal B3704 operate normally to carry user traffic back and forth between the remote terminal 3710 and the remote terminal 3712, and the backup hub terminal 3706 is in the standby mode. state. If the hub terminal B3704 experiences a failure, such as an outdoor unit failure, the failure is detected and notified to the component management system (EMS) as described in Figure 38 below. A red alarm is generated on the DS3B Linear 3720. The backup hub terminal 3706 transfers to the replacement hub terminal B3704, and starts to transmit on the sub-channel B3716 to the remote terminal 3712. The multiplexer 3724 detects the red alarm, and performs the conversion of all connection lines from the DS3B line 3720 to the backup DS3 line 3722 based on the expectation that the backup DS3 line 3722 is used as the backup of the DS3B line. Then, the EMS informs the network operation center via a simple network management protocol (SNMP) message. The remote terminal 3712 detects a brief interruption in the transmission of the sub-channel B3716 and resynchronizes. The user at the remote terminal 3712 experiences temporary service quality degradation. The conversion downtime is kept as a statistical value. If the hub terminal machine A3702 fails, the backup hub terminal machine 3706 replaces it in the same way and propagates through the sub-channel A3714.

To ensure that the backup hub terminal 3706 works when a failure occurs, the application hub terminal 3706 must be tested regularly. If a backup hub terminal 3706 is idle for a long period of time, the backup hub terminal 3706 may have already failed when the call is executed. There is a test technique called "load sharing", in which the hub terminal B3704 transmits half of the load, and the backup hub terminal 3706 transports the other half of the load. If one hub terminal machine fails, the other hub terminal machines will take over. This requires additional frequencies for the backup hub terminal 3706, or the backup hub terminal 3706 shares the same frequency with the hub terminal B3704 in the TDMA frame. If they share the same frequency, the two terminals will have to transfer in and out bits that are difficult to complete with the symbol rate used by the point-to-multipoint system (for example, 10 MHz). Another backup test technique is to switch to the backup hub terminal 3706 once a day (in the middle of the night). Disadvantages cause an additional downtime once a day.

In this specific form of the present invention, the backup hub terminal 3706 simply transmits the test burst once to each upper frame (every 48 milliseconds) via the sub-channel A3714, and then transmits the test packet to each upper frame via the sub-channel B3716. Transmission test packet once. The test cluster is the first time in the last three time slots (hour slots m-2 to m) of the manifold segment in the last frame of the frame above the collecting slot 806 (as shown in Figure 8). Transmission during the slot (time slot m-2). Since the test cluster is sent during the first cluster, if the timing is slightly deviated, the test cluster will not collide with other clusters sent by the hub terminal B3704 or the hub terminal A3702. In addition, online hub terminals (hub terminal A3702 and hub terminal B3704) do not transmit during these three time slots. The test cluster is sent with QPSK modulation so that all remote terminals 3710 and 3712 can receive it (even in the farthest area). Each remote terminal receives the test packet and records whether the test packet has been received, and if so, records how far its signal strength and timing deviate from the position of the first packet. These statistical values are reported back to each online hub terminal. The reported value is stored and compared at any time to check whether the backup hub terminal 3706 has failed. If no reception is made or if the power level is significantly reduced, the backup hub terminal has failed. These values are also received in the backup hub terminal 3706 and used, as shown in Figure 38.

Refer to FIG. 38 again; it shows a flowchart of the steps taken by the backup hub terminal in FIG. 37 to detect the failure of the online hub terminal and test a backup hub terminal. Perform the following steps. The first step is to preset the backup hub terminal by collecting redundant information and receiving and transmitting timing (block 3802). Next, adjust the backup hub terminal to the frequency of the sub-channel (block 3804), and transmit it to the remote terminal of the sub-channel (block 3806). Secondly, each remote terminal reports the power level of both the backup hub terminal and the online hub terminal (block 3808), and transmits the information in the slot during its individual maintenance (block 3810) to the backup hub terminal. The backup hub terminal receives the information (block 3812), and finally performs fault detection (block 3814).

An initial step to be performed is to preset the backup hub terminal (block 3802) so that it can provide a 1:N redundancy to the online hub terminal (Figure 37, hub terminal A3702 and hub terminal B3704) . This requires the collection of the redundant information and the determination of the collection of the reception and transmission timing ^。 Specifically, the backup hub terminal is preset by communicating with the component management system (EMS) described in Figure 2 to obtain the redundant information such as the LAN address, frequency, main channel allocation, and the redundant information. The power settings of other hub terminals in the remaining group.

Secondly, as part of the preset work (block 3802), the backup hub terminal enters the receiving timing collection mode. The purpose of this mode is to determine the timing of the frame on the uplink for which it is tuned. The backup central terminal listens to the signal transmitted from the remote terminal to the central terminal to synchronize the timing and frame format of the backup central terminal with the rest of the point-to-multipoint system. The backup hub terminal waits until its local oscillator has been locked to the selected input source, then selects one of the sub-channels in the redundancy group and tunes it with the uplink (remote to hub). Then, the backup hub terminal sets its antenna to the opening and looks for the Sync word in the QPSK frame (this is sent by the remote terminal once per frame above). Detect the Sync word in the above frame and verify it. Secondly, demodulate the content of the bundle, and determine the number of time slots required for a specific remote terminal from the format information in the header. The backup hub terminal machine then calculates the frame and slot offset of the first cluster of the upper frame, and moves the upper frame timing to the same position as the received one. However, if the backup hub terminal does not detect and correct the sync word in the upper frame for a specified amount of time (for example, 8 frames above), the backup hub terminal will declare itself in a failure mode.

When the preset is still in progress, the backup hub terminal enters the transmission timing collection mode to determine the appropriate transmission to reception offset. The backup hub terminal starts with the transmission to receive offset value of 3.0 milliseconds (based on the format of the 6 milliseconds to the air interface frame), and transmits a time when the header segment of the last frame of the above frame is The header cluster in slot m-2 (refer to Figure 8). The remote terminal is programmed to search for the cluster in a slot in the last three time slots (also instant slots m-2, m-1, and m) of the last empty frame header section. If the cluster is not detected, the remote terminal does not act. If the cluster is detected, the remote terminal maintains independent timing offset and power parameters, and sends a message containing the information Back to the backup hub terminal (and hub terminal). The backup hub terminal therefore uses this information to adjust its timing and power. If the returned cluster is not detected within the specified time (for example, 8 frames above), the backup hub terminal will declare itself as a failure mode. Note that the timing adjustment is for a hub terminal on the current sub-channel individually, so the backup hub terminal must repeat the collection of reception and transmission timings for each hub terminal in the redundancy group.

As the last part of the preset work, the backup hub terminal enters the tracking mode to test the timing and detect faults. The backup hub terminal is continuously tuned to each sub-channel, and recalls the stored transmission and reception offsets, and verifies that the correct timing of the above frame has been obtained by reading the message header from the remote terminal (block 3804). If the timing of the above frame is inaccurate, the backup hub terminal must restart at block 3802.

Then, the backup hub terminal transmits a test packet transmission (block 3806) to the remote terminal as described above to form the last three time slots of the last frame in the frame header section above the collection tank 806 (time slot m- 2. m-1 and m) are in the first time slot (see also Figures 8 and 37). The test packet is the same as the test packet sent and described in FIG. 37. Therefore, the same test cluster is used to test the backup hub terminal and detect the failure of the online hub terminal. The online hub terminal does not perform transmission during this three-cluster communication period. The remote terminal in the sector knows to look for the bundle and measure its signal length (block 3808) and timing. Integrate the timing and power offset. Then, the remote terminal sends the power measurement value (such as the measured RSSI) to the backup central terminal and the central terminal back to the maintenance slot of the main section (block 3810). The backup hub terminal listens to the maintenance slot and receives the information stored in the remote terminal (block 3812). Note that the backup hub terminal knows which time slot should be listened to by the program of block 3802. When testing the backup hub terminal, the online hub terminal receives the information (block 3812).

Then, the backup hub terminal performs fault detection (block 3814). In order to detect failures, the backup hub terminal will receive the power level from the sub-channel of the remote terminal for itself and other on-line hub terminals and the power level of each hub terminal on the sub-channel in the redundancy group. Comparing with each other. If the power level of its own (backup hub terminal) exceeds a specified amount greater than the power level of some other hub terminal (usually 2 to 3dB), the backup terminal determines that the other hub terminal has failed, and Transfer to replace the faulty hub terminal. The backup hub terminal can be transferred immediately, because it contains all the transmission and reception information and the cluster communication time plan of all the online hub terminals in the redundant group. The remote terminal only noticed a short service interruption _。

The comparison of the average power levels between the backup central terminal and other central terminal is necessary to detect the failure of the power amplifier, because the radio channel is prone to fading and may be similar to the failure of the power amplifier. Therefore, compare the power levels, because the power level of both the main hub terminal set and the backup hub terminal set will decrease during fading.

This fault detection procedure must also explain the behavior of the remote terminal during rainy weather fading or the failure of the central terminal amplifier. If the power of a central terminal on a line is reduced, the automatic gain control (AGC) of the remote terminal will compensate. Similarly, the AGc will compensate for the power loss during the rainy fading period. Therefore, the information sent back to the backup hub terminal includes information on the RSSI of the power measurement values of both the online hub terminal and the backup hub terminal. Step 3814 monitors the strength of the test packet from the backup hub terminal when the backup hub terminal is tested as shown in FIG. 37.

Therefore, the 1:N redundancy system provides a backup hub terminal that can support more than one hub terminal in the hub. This is different from the old point-to-multipoint system, which has a backup hub terminal for each online hub terminal (1:1 redundancy). Therefore, the 1:N redundant system reduces the number of central terminal terminals in the central part, and is superior to the traditional point-to-multipoint system communication system. In addition, the 1:N redundancy system provides a unique method for testing backup hub terminals without the disadvantages of "load sharing" or periodic forced shutdowns, as shown in Figure 37. The method of FIG. 38 advantageously uses a unique air interface frame format to provide a fault detection method. The strength of the line hub terminal and the backup hub terminal is tested once for each frame above.

TDM buffer

The TDM buffering is completed in the TDM unit formatter of each TDM base user interface module. The TDM unit is assigned to the multi-transport modal unit bus slot, and the TDM data is minimized in a manner (Pulse code modulation data and channel-associated signaling) are uniquely compressed into the TDM unit.

Turn back to Figure 29; it shows a block diagram of a TDM unit formatted by the TDM unit formatter (or signal formatter) of the SSI module. The traffic segment 2904 (data segment) contains the TDM data or pulse code modulation (PCM). The header section 2902 of the TDM unit 2900 contains an ATM header or virtual path identifier 2906. This is different from the conventional TDM unit without header information, because the TDM unit is converted according to its time slot. In addition, the header section of the TDM unit includes an ATM dedicated header.

In addition, the TDM buffer technology uses header segments containing other headers 2908 for signaling bits, such as channel-associated signaling (CAS) bits. Traditionally, signaling (also known as signal bits) is carried in each independent TDM unit and converted by time slot. Therefore, the TDM unit 2900 of this specific form advantageously uses other header segments 2908 to carry signaling in the same TDM unit 2900 as PCM data (also referred to as PCM samples).

In practice, the SSI module is designed to interface with the T1 circuit (DS1) or E1 circuit known in the industry. Since different T1 and E1 lines use different framing modes, such as the expansion of the frame (ESF), the channel-associated signaling (CAS) information can be 2 bits or 4 bits, and it can be every 1.5, 2.0 steps Update in 3.0 seconds. In this way, because the T1E1 line operates in different framed modes and because the point-to-multipoint system can convert any DS0 at the hub terminal into a DS0 at the remote terminal, the signaling (such as CAS) is carried away Band (that is, not in traffic segment 2904). The signaling is extracted from the entry point (by the T1/E1 framer) and then transmitted using other headers 2908 in the header section 2202 shown in Figure 29, which is different from using a separate TDM unit to carry the signaling. Note that T1 and E1 lines (also known as digital signal level 1 or DS1) are well-known in the telecommunications industry. In addition, DS0 (or digital signal level zero) is well known in the telecommunications industry, so no further explanation is needed.

Simply turn back to FIG. 25A; shown is a multi-transport modal SSI module 2500. The multi-transport modal SSI module 2500 and other SSI modules (or synchronous modalities) configured to operate in TDM perform TDM buffering as follows. The multiple transmission SSI module of FIG. 25A will be described as an example of TDM buffering, so this operation does not need to be explained in each TDM-based SSI module. Therefore, FIG. 25A will be mentioned occasionally to illustrate how TDM buffering is applicable to TDM-based SSI modules.

As mentioned above, the PCM buffer controller 2516 receives PCM data and signaling (CAS) from the timing multiplexer 2552. The timing multiplexer 2552 receives PCM data and signaling (CAS) from the DS0 of T1/E1 via the T1/E1 framer 2554. The PCM buffer controller 2516 converts the PCM data and signaling into a parallel format, and stores them in the transmission buffer 2514. In other directions, the PCM buffer controller 2516 pulls the PCM data and signaling away from the receiving buffer 2512 . The receiving buffer 2512 and the transmitting buffer 2514 have a unique memory structure. Refer to the discussion in FIG. 39 below.

Refer to Figure 39 again; shown is a memory structure used to buffer pulse code modulation (PCM) data and signaling, such as channel-associated signaling (CAS), used in each TDM-based SSI in a specific form of the present invention Inside the module. The memory structure 3900 includes a receiving data buffer 3902, a transmission data buffer 3904, a receiving signaling buffer 3906, and a transmission signaling buffer 3908. The receiving data buffer 3902 and the transmission data buffer 3904 each have a plurality of line data buffers 3910. Each line data buffer 3910 is used for a corresponding T1 line and contains a DS0 data buffer 3912. Each DS0 data buffer 3912 contains PCM data bytes 3914 associated with a specific DS0 of each corresponding T1 line. Both the reception signaling buffer 3906 and the transmission signaling buffer 3908 contain a line signaling buffer 3916. Each line signaling buffer 3916 is used for a corresponding T1 line, and contains a DS0 signaling buffer 3918. Each DS0 signaling buffer 3918 contains a DS0 signaling byte 3920 (CAS) associated with a specific DS0 of each corresponding T1 line. Each DS0 signaling byte 3920 contains signaling.

The memory structure 3900 is implemented as a RAM, and the transmission buffer 2514 and the reception buffer 2512 of FIG. 25A are formed in a single memory structure 3900. The advantage is that the memory structure 3900 can be adjusted proportionally, allowing TDM-based SSI modules to interface with different numbers of T1 lines. For example, the four DS1 SSI modules (Figure 20) and the multi-transport modal SSI module (Figures 25A and 25B) allow four and eight T1 lines (DS1), respectively, while the TDM-DS3 SSI module (Figure 16) Allow 28 T1 lines (DS1). Therefore, the reception data buffer 3902, the transmission data buffer 3904, the reception signaling buffer 3906, and the transmission signaling buffer 3908 have different lengths depending on the implementation.

Each line data buffer 3910 supports a T1/E1 line, and contains 2048 PCM data bytes 3914 for PCM data compression into the 48-byte data segment 2904 of the TDM unit 2900 in Figure 29 (also called traffic Section). Each signaling line buffer 3916 contains 256 bytes for signaling to be compressed into other headers 2908 of the TDM unit in FIG. 29. Since each T1 line requires two line data buffers 3910 and two line signaling buffers 3916 (that is, one for transmission and one for reception), each T1 line requires 4098 bytes (4K) PCM data buffer and 512-byte signaling buffer memory.

Each line data buffer 3910 is a 2048 (2K) byte buffer containing most DS0 data buffers 3912, no matter how many DS0 and SSI modules are connected. Shown are 32 DS0 data lines for TDM-DS3 SSI modules (28 T1 lines plus 4 for online testing, or 32 E1 lines). Each DS0 data buffer 3912 contains PCM data bytes 3914 from a specific DS0. Advantageously, the DS0 data buffer 3912 is a 64-byte circular buffer. This allows the PCM data contained in the PCM data byte 3914 to be mapped into the 48-byte data segment 2904 of the TDM unit, with minimal memory requirements. As mentioned above, this specific format formats the TDM data into a cell structure the same size as an asynchronous transfer mode (ATM) cell. Therefore, PCM data is designed to fit within the 48-byte data segment.

The line signaling buffers 3916 each contain a DS0 signaling buffer 3918. Each DS0 signaling buffer 3918 contains a majority of signaling bytes 3920 (including CAS data) for a specific DS0. The DS0 signaling buffer 3918 is also a circular buffer, but has a length of 8 bytes.

In addition, the PCM samples are stored in each DS0 data buffer 3912 (circular buffer) every 125 microseconds, and the signaling is stored in the 8-byte DS0 signaling buffer 3918 every 1.0 milliseconds. The 64-byte DS0 data buffer 3912 and the 8-byte DS0 signaling buffer 3918 correspond to an 8 millisecond interval; however, the frame format of the multiple transport bus (Figure 15) and the frame format of the air interface ( Figure 5) In this specific form, for example, the 6 millisecond frame shall prevail.

During the first frame, the PCM data is written to the first 48 PCM data bytes 3914 of the 64-byte DS0 data buffer 3912. During the second frame, the PCM data is written to the last 16 PCM data bytes 3914, then wrapped (circular) and continued to be written to the first 32 PCM data bytes 3914 of the DS0 data buffer 3912. And so on. Therefore, the DS0 data buffer 3912 is continuously updated with new PCM data.

For the signaling buffer, during the first frame, the signaling bits are written to the first 6 signaling bytes 3920 of the DS0 signaling buffer 3916 in a similar manner. During the second frame, the last 2 signaling bytes 3920 of the DS0 signaling buffer 3916 and then the first 4 signaling bytes are written in a circular manner. Therefore, the PCM buffer and signaling buffer used in the memory structure 3900 are implemented in the "out" (multi-transport modal unit bus to the SSI module), such as reading from the DS0 data buffer 3912 in ring mode, and in the "in" (SSI module to multi-transmission modal unit bus) Write to the DS0 data buffer 3912 in a ring type.

Refer again to Figure 40; shown is a pulse code modulation mapping control structure memory used in a specific form of the present invention in the TDM-based user interface module. The pulse code modulation mapping control structure memory 4000 (hereinafter referred to as the PCM mapping control wire structure memory 4000) contains the pulse code modulation mapping control structure 4002 (hereinafter referred to as the PCM mapping control structure 4002). Each PCM mapping control structure 4002 contains a mapping structure effective 4004 (also known as MPA4004), T1/E1 bit 4006, line identification 4008, unit type 4010, PcM slot number/offset 4012, entry read offset 4014 , And write offset 4016 in appearance.

In practice, the PCM mapping control structure memory 4000 is coupled to the TDM unit formatter of the TDM-based SSI module, and is controlled by the control processor (CPU) of the TDM-based SSI module. The PCM mapping control structure memory 4000 controls the format of each TDM unit generated by the TDM unit formatter. The PCM mapping control structure memory 4000 contains the PCM mapping control structure 4002 so that the TDM unit will be formatted in a manner that carries the DS0 to be transmitted with minimal delay and without complicated hardware manipulation. The PCM mapping control structure memory 4000 contains a variable number of PCM mapping control structures 4002. The number of PCM mapping control structures 4002 depends on the number of T1/E1 lines (DS1) connected to the SSI module. Therefore, the TDM-DS3SSI module (Figure 21) requires 32*32=1024 PCM mapping control structures 4002 (32 T1/E1 lines are 28 lines for transmission and 4 for testing), and four DS1SSI modules (Figure 20) 32*4=128 PCM mapping control structures 4002 are required.

Each PCM mapping control structure 4002 is 4 bytes and contains an MPA4004. MPA4004 is a 1-bit field, indicating whether the PCM mapping control dimension 4002 is valid. The "0" bit indicates that the PCM mapping control structure 4002 is not valid, so the TDM unit formatter will ignore it. The "1" bit indicates that the PCM mapping control structure 4002 is valid, so the PCM mapping control structure 4002 will be used by the TDM unit formatter when formatting and compressing the TDM data unit for transmission on the multi-transport modal unit bus.

The PCM mapping control structure 4002 also contains a T1/E1 bit 4006, which indicates to the TDM formatter that the connected line is a T1 line or an E1 line ("0" is T1 and "1" is E1). The line identification 4008 is 5 bits, and the T1/E1 line is identified for the specific time slot of the multi-transmission modal unit bus. Since one of the time slots of the multi-transmission modal unit bus is connected to an established T1E1 line, DS0 from other T1E1 lines cannot be multiplexed to the same unit bus time slot.

The unit type 4010 indicates the type of dedicated unit to be used according to the specific PCM mapping control line structure 4002. Therefore, the unit type 4010 defines how many DS0s will be multiplexed into the data section of the TDM unit. The unit type 4010 is a 3-bit field. The TDM unit defined by the unit type 4010 will be placed in the data unit 1704 of the CB data unit 1700 and placed on the multi-transport modal unit bus (see Figures 15 and 17). Refer to the discussion in Figures 41 to 43 below for specific unit types.

The number of PCM slots/offset 4012 is a 5-bit field to identify the number of PCM slots used by a single DS0 mode or the first number of PCM slots used in each mode in a single TDM data unit to multiplex most DS0s. For the E1 line, all the values 0-31 (time slot 0 to 31) of the 5-bit field are valid, and for the T1 line, only the 0-23 (time slot 1 to 24) of the 5-bit field The value is valid. Therefore, the TDM unit formatter knows where to look in the memory structure 4000 to read or write PCM data to and from the dedicated data unit type.

The entry read offset 4014 is a 6-bit field, which is designated to form the read offset of the entry data field to be placed on the multi-transmission modal unit bus. This is because the DS0 data buffer 3912 of the memory structure in FIG. 39 is 64 bytes and the data segment of the TDM unit is 48 bytes. Therefore, each memory indicator needs to know which PCM data byte 3914 points to in the DS0 data buffer 3912 of the memory structure 3902 in FIG. 39. The 6-bit field corresponds to one of 64 PCM data bytes 3914. Similarly, the field write offset 4016 is a 6-bit field, which specifies the write offset used to compose the PCM data byte 3914 in the DS0 data buffer 3912 of the memory structure 3902. Therefore, the memory pointer is told which PCM data byte 3914 of the DS0 data buffer 3912 to write the PCM data to. The TDM units in a sequence are assigned different entry read offsets 4014 and exit write offsets 4016 based on the assignment of the multi-transport modal unit bus (which in turn is based on the air interface cluster assignment).

The signaling (such as CAS) is located at DS0 signaling byte 3920, and the corresponding PCM data is read/written by DS0 data byte 3914 at the same time it is read/written.

Refer to Figure 41; it shows the specific format shown in Figures 39 and 40, which is used to adjust the pulse code from a single DS0 (digital signal level zero) in the TDM buffer in the TDM-based user interface module. The unit format of the TDM unit that changes (PCM) data and signaling into the TDM unit. The TDM-based SSI module is shown in Figures 20, 21, 25A and 25B. The TDM unit 4100 includes a header section 4102 (also called a header) and a data section 4104 (the same as the data section 2904 in FIG. 29). The header section 4102 contains an even virtual path identifier 4106 (hereinafter referred to as an even VPI) and an odd virtual path identifier 4108 (hereinafter referred to as an odd VPI), and a backup section 4110. The even-numbered VPI4106 and odd-numbered VPI4108 also include ATMVPI2906 as shown in FIG. 29, which is used for ATM address Lubo as described above. The header section 4102 also contains a majority of signaling sets 4105, which are all 4-bit signaling (CAS) from a DS0.

In practice, the TDM unit 4100 is one of the unit types defined by the unit type 4010 of the PCM mapping control line structure 4002 in FIG. 40. When entering the field, the TDM unit formatter compresses the 48-byte PCM data of the DS0 data byte 3914 from a specific DS0 into the data segment 4104, and combines the data from the DS0 signaling byte 3920 of the specific DS0 The 3-byte signaling is compressed into the signaling set 4105 of the TDM unit 4100. Alternatively, the TDM unit formatter decompresses the PCM data and signaling from the unit 4100 and writes them to the correct DS0 data byte 3014 and DS0 signaling byte 3920 of the individual DS0. Once formatted, the TDM data unit 4100 is copied to the multi-transport modal unit bus (see Figure 15-17) in the previous CB data traffic unit (see Figure 17).

Note that both the signaling and PCM data are uniquely compressed into the TDM unit 4100, while the old TDM unit uses most independent TDM packets for signaling and PCM data checking. In addition, the TDM unit 4100 includes a unique header section 4102, and the old TDM packet does not include the header section, because the path selection is based on the time slot instead of the header information. In addition, the TDM unit 4100 uniquely includes one of the ATM headers used in the above-mentioned ATM Lubo technology in the specification, odd-numbered VPI4108, and even-numbered vPI4106 (that is, VPI).

For example, on the basis of a 6 milliseconds to the air frame, the TDM unit 4100 provides a 6 milliseconds buffer delay (that is, the length of the 6 milliseconds bus frame format) will come from a DS0 48 bit The group of PCM data is compressed into the TDM unit 4100. The header section 4102 includes 6 signaling data sets 4105 corresponding to 48-byte PCM samples (taken from the DS0 data buffer 3912 of the memory structure in Figure 39) or 3 byte signaling (including the signal from the Figure 39). 39 DS0 signaling buffer of memory structure 3918 CAS). The TDM unit 4100 can only be used for the constructed DS0. Both the constructed DS0 and the unstructured DS0 are well known in the digital telecommunications industry, so no further explanation is needed.

Refer to Figure 42 for the second time; it shows that according to the specific format shown in Figures 39 and 40, the pulse code modulation (PCM) data and information from most DS0s are used in the TDM buffer in the TDM-based user interface module. Make the unit format of the TDM unit compressed into a single TDM unit. The TDM unit 4200 includes a header section 4202 containing an even VPI 4206 and an odd vPI 4208, DS0#1 signaling set 4216, DS0#2 signaling set 4218, DS0 signaling set 4222, and DS0#n signaling set 4220. The TDM unit 4200 also contains a data section 4204, including a DS0#1 data section 4210, a DS0#2 data section 4212, and a DS0#n data section 4214.

In practice, the TDM unit 4200 is collectively displayed as a TDM unit that can carry PCM data and signaling from most DS0s in the same data segment 4204. This is different from the old method of compressing PCM data from a DS0 into a single TDM unit or packet. As mentioned above, this is also different from the old TDM unit, because PCM data and signaling are compressed into the same TDM unit 4200. The TDM unit 4200 has the same general design as that shown in FIG. 41, except that the TDM unit 4100 in FIG. 41 carries PCM data and signaling from only one DS0. Furthermore, the TDM unit 4200 represents several different unit types defined by the unit type 4010 of the PCM mapping control structure 4002 shown in FIG. 40. Therefore, the TDM unit formatter uses the PCM mapping control structure to determine which TDM unit type to format for each time slot on the multi-transport modal unit bus.

The TDM-based SSI module is advantageously pre-structured to format the TDM data unit into one of the available formats shown in FIGS. 41, 42 and 43. This minimizes the delay of certain types of traffic carried in certain DS0s. In this specific form, it is particularly important to generate several different unit types, because the TDM data unit is limited to this small size (that is, 53 bytes). The old TDM base point-to-multipoint system has nothing to do with this delay, because the TDM unit or packet system is designed to be much larger than 53 bytes, typically between 150 and 400 bytes.

The TDM unit 4200 can carry PCM data from more than one DS0 in the data segment 4204. The PCM data is compressed into DS0#1 data section 4210 to DS0#n data section 4214 of DS0#1 to DS0#n. For example, if only the data from two DS0s are compressed into the TDM unit 4200, they are only two segments (DS0 #1 data segment 4210 containing 24-byte PCM data from DS0 #1 And DS0#2 data section 4212) containing 24-byte PCM data from DS0#2. For each DS0, the corresponding header section 4202 will contain more than one signaling set. For example, there are three DS0#1 signaling sets 4216 and three DS0#2 signaling sets 4218. A backup section will contain extra bytes in the header section 4202. This backup section will be used when the header section 4202 needs to be full, so that the 5-byte header section 4202 is maintained in the TDM unit 4200.

Similarly, use <img file="TW484331B_D0001.tif" /><img file="TW484331B_D0002.tif" /> In the 6 millisecond frame format, the unit formatter compresses the PCM data and signaling from the two DS0s into the TDM unit 4200 at an interval of 3.0 milliseconds. Therefore, the buffer delay is reduced from 6.0 milliseconds in Figure 41 to 3.0 milliseconds in this example. Note that since only 3 milliseconds of PCM data is carried in the TDM unit 4200 of this example, two TDM units 4200 are sent during the same 6 millisecond frame. This allows the same amount of PCM data to travel within the same 6 millisecond frame, and at the same time helps to reduce the buffer delay of each TDM unit 4200. It should be obvious to skilled technicians that the more DS0 compressed into the TDM unit, the lower the buffer delay when compressing and decompressing the TDM unit 4200. This helps to minimize certain traffic.

Another example of the unit type shown in FIG. 42 is a TDM unit 4200, which compresses both PCM data and signaling from 8 DS0s into the TDM unit 4200. In this case, there are eight DS0 data sections in data section 4204: DS0#1 data section 4210 to DS0#8 data section 42140 Each data section (for example, DS0#1 data section 4210) contains 6 bytes of PCM data (also called PCM samples). This only provides a buffer delay of 0.75 milliseconds to compress/decompress PCM data and signaling to and from the TDM unit 4200. In this example, the corresponding header section 4202 will contain even-numbered VPI4206, odd-numbered VPI4208, and eight signaling sets (one for each DS0, that is, DS0#1 signaling set 4216, DS0#2 signaling set 4218, DS0#3-7 signaling set 4222 and DS0#8 signaling set 4214. There is no backup section in this example, because each signaling set completely fills the available space of header section 4202. In addition, in this example Since only 0.75 milliseconds of PCM data is sent in the TDM unit 4200, eight TDM units 4200 are assigned to carry the PCM data from the eight DS0s during the 6.0 millisecond frame period.

Therefore, using slightly different data segment 4204 and header segment 4202 structure, the TDM unit 4200 can be structured to carry PCM data and signaling from more than one DS0. This is beneficial to reduce the buffer delay, so as to minimize the delay of certain types of traffic. The two examples given (ie, 2 DS0 and 8 DS0) are only conceptual illustrations, so those skilled in the art can implement the TDM unit 4200 to compress other numbers of DS0s for different buffer delays. In addition, the DS0 compressed in the TDM unit 4200 can be both constructed and unstructured.

Refer to Figure 43 for the second time; it shows the unit format used to compress most of the TDM units with embedded DS0 compression in the TDM buffer in the TDM-based dedicated interface module according to the specific format shown in Figures 39 and 40 . The TDM unit 4300 has a data segment 4304 with a length of 50 bytes and supports up to 25 DS04312. Each DS04312 has 2 samples (2 frames) of PCM data (0.25 millisecond interval). The TDM unit 4300 provides a very low latency service for 24 Ds04312. The 25th DS04314 contains G.802 embedded frame (circuit emulation). The buffer delay of the TDM unit 4300 is reduced to 0.25 milliseconds. Since the 25th DS04314 is an embedded frame, the header section 4302 does not need to contain any signaling. Therefore, the header section 4302 is only three bytes containing the even-numbered VPI 4306, the odd-numbered VPI 4308, and the backup section 4310.

Therefore, it is advantageous that the different TDM unit types shown in the TDM unit 4100 can be generated by the TDM unit formatter of the TDM-based SSI module. This enables TDM data and corresponding signaling from one or more DS0s to be multiplexed on the multi-transmission modal unit bus in a variety of ways. Also, this is different from the known old method that only multiplexes a single DS0 into a TDM unit.

Refer to FIGS. 44A and 44B again; the flow chart is shown, illustrating the TDM buffer described in FIGS. 39 to 43, which is completed in the TDM-based SSI module of the point-to-multipoint system. Figure 44A illustrates the traffic that enters the TDM-based SSI module (at the hub terminal or remote terminal) via the transmission line (such as T1E1 or DS3) and is multiplexed on the multi-transport modal unit bus The steps implemented. Figure 44B illustrates the traffic received from the multi-transport modal unit bus at the TDM-based SSI module and converted to the user or reverse transmission line depending on the TDM-based SSI module being at a remote terminal or a hub terminal The steps implemented.

For traffic that flows from the T1 line through the TDM-based SSI module to the multi-transport modal unit bus of the point-to-multipoint system, the TDM-based SSI module performs the following steps. The first step is to convert the DS0 received from the T1 line with the frame removed from serial to parallel format, so that PCM data and signaling data (such as channel-associated signaling) can be recovered (Steps in Figure 44A) 4402). This step is performed using the PCM interface (such as the PCM buffer controller 2516) described in FIGS. 20, 21, 25A, and 25B. Therefore, the signaling data is separated from the PCM data of the received DS0. Secondly, PCM data (PCM samples) and signaling are buffered using a memory structure (step 4404 in Figure 44A). This memory structure is described with reference to FIG. 39, and can be implemented on each TDM-based SSI module.

Secondly, in the preparation of formatting the PCM data and signaling of the multi-transport modal unit bus, the TDM unit formatter obtains the correct PCM mapping control structure used by each multi-transport modal unit bus slot (Figure 44A) Step 4406). These PCM mapping control structures are contained in the PCM mapping control structure memory described in FIG. 40, and are typically contained in a message buffer coupled to a TDM unit formatter, such as the message buffer shown in FIG. 25ADevice2508. Then, the TDM unit formatter uses the PCM mapping control structure to determine the dedicated unit type of the TDM unit, which will be formatted for each multi-transport modal unit bus slot (step 4408 in FIG. 44A). These specific unit types are shown in Figures 41 to 43.

Secondly, the TDM unit is compressed into the dedicated unit type by PCM data and signaling (step 4410 in Figure 44A). The PCM mapping control structure further provides a TDM unit formatter with an appropriate offset in the memory structure of FIG. 39, so that the TDM unit formatter can place appropriate PCM data and signaling in the appropriate location of the TDM unit. In addition, for ATM address filtering, the TDM unit formatter inserts the ATM header (VPI) into the appropriate position of the header section (step 4412 in Figure 44A). Note that the advantage is that both the PcM data and the signaling are compressed and placed in the same TDM unit, and the PCM data from most DS0s is the same as the signaling. Again, this is different from the old TDM buffer technology. Finally, use the time scheme contained in the message buffer to multiplex the formatted TDM unit on the multi-transport modal unit bus (in the data section 1704 of the traffic unit 1700) (steps in Figure 44A) 4414).

To perform TDM buffering, perform the following steps for the traffic from the multi-transport modal unit bus of the point-to-multipoint system to the user or the reverse transmission of the T1 line through the TDM-based SSI module. Each unit (both ATM and TDM units) arrives at the multi-transport modal unit bus. First, the TDM unit formatter uses this timing scheme to extract the appropriate units, and only the TDM unit goes to the specific TDM-based SSI module (step 4416 in Figure 44B). Then, the TDM unit formatter enters and exits the PCM mapping control structure of each extracted TDM unit to determine which unit type the TDM unit corresponds to (step 4418 in Figure 44B).

Once the unit type is determined, the TDM unit formatter decompresses the PCM data and signaling from the received TDM unit as shown in Figure 39, and buffers them into the memory structure. Note that the PCM mapping control structure provides the appropriate offset in the memory structure, so the TDM unit formatter will know which data byte 3914 or which of the PCM data and signaling of each DS0 should be written into the memory structure Signaling byte 3920. Secondly, the PCM interface (such as the PCM buffer controller 2516) extracts the PCM data and signaling from the memory structure at an appropriate time and converts them back to the serial DS0 format (step 4424 in Figure 44B). Finally, the DS0 is framed for transmission and transmitted via the appropriate DS0 of the appropriate T1 line (Step 4426 in Figure 44B).

Although the invention disclosed in this document has been described by its specific specific form and application, those skilled in the industry can make various modifications and changes to it without departing from the scope of the invention listed in the scope of the patent application.