INTEGRATED GATEWAY NETWORK ARCHITECTURE FOR LOOP EMULATION SERVICE ON ATM-over-DSL SERVICE

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

[Technical field to which the invention belongs]

The present invention relates to the field of communications, and more particularly to techniques for providing loop emulation services such as ATM-over-DSL services or voice over packets or cell transport.

【0002】

References The following documents are all incorporated herein by reference in their entirety.

【0003】

Nattkemper et al. "Distributed Telecommunications Switching System and Method" US Pat. No. 5,953,318 Stevenson, Method and MFP for Placing Time Division Multiplexed Telephony Traffic into an Asynchronous Transfer Mode Format, U.S. Pat. ATM Forum "ATM User-Network Interface Specification Version 3.1" (September 1994) ("UNI 3.1") ATM Forum "ATM User-Network Interface (UNI) Signaling Specification Version 4.0" (July 1996) ("UNI 4.0") ATM Forum "Utopia Level 2, Version 1.0, af-phy-0039.000 "(June 1995) ("Utopia Specification ") International Telecommunication Union (ITU), Broadband Integrated Services Digital Network (B-ISDN)-Digital Subscribers Signaling No. 2 (DSS2)-User-Network Interface (UNI) Layer 3 Specification for Basic Call / Connection Control "ITU-T recommendation Q.2931 (February 1995) ("Q.2931 ") ITU "ISDN User-network Interface Layer 3 Specification for Basic Call Control" Recommendation Q.931 (05/98) ("Q.931") ITU "B-ISDN ATM Adaptation Layer specification: Type 2 AAL "ITU-T Recommendation I.363.2 (1997) (I.363.2) ITU "Segmentation and Reassembly Service Specific Convergence Sublayer for the AAL type 2" ITU-T recommendation I.366.1 (1998) (I.366.1) ITU "AAL Type 2 Service Specific Convergence Sublayer for Trunking" ITU-T recommendation I.366.2, 02/99 ITU "Packet-based multimedia communications systems" ITU-T recommendation H.323 (02/98) ITU "Packet-based multimedia communications systems Annex D: Real-time facsimile over H.323 systems "Annex D to ITU-T recommendation H.323 (09/98) ATM Forum "ATM Trunking Using AAL2 for Narrowband Services" AF-VTOA-0113.000 (2/99) ("VTOA" specification) ADSL Forum "Recommended Interoperability Implementation Agreement for BLES" CopperCom and Alcatel, 99-204, August 1999 ATM Forum "Loop emulation service and new profile definition for voice over AAL2" Alcatel USA, 99-0392, July 1999 ("99-0392 Profile") ATM Forum "LAN Emulation Over ATM Version 1.0" (January 1995); ATM Forum "LAN Emulation Client Management Specification Version 1.0" (September 1995); ATM Forum "LAN Emulation Over ATM Version 1.0 Addendum" (December 1995) (Mon) and ATM Forum "LAN Emulation Servers Management Specification 1.0" (March 1996) (LANE-4) (all collectively referred to as LANE specifications in this specification) Telecordia, GR-303-CORE Issue 2 "IDLC Generic Requirements, Objectives, and Interface" December 1998 and related issues list Report: GR-303-ILR Issue 2A, December 1998; Telecordia, GR-303-IMD ,, IDLC System Generic Operations Interface (formerly TR-TSY-000303 Supplement 3), Issue 1, December 1998; Telecordia, GR-2833-CORE Issue 3, Revision 2 "Generic Operations Interfaces Using OSI Tools: List of Information Model for IDLC and FITL Systems and related issues Report: GR-2833-ILR Issue 3C, December 1998; and Telecordia, GR-29050-CORE, Issue 2, October 1997, Revision 1, "Generic" Requirements for EML Applications for Management of IDLC Systems and related issues List Report: GR-2905-ILR Issue 2B, December 1998 (all collectively referred to herein as GR-303 specifications). Telecordia "Digital Interface Between the SLC-96 (r) Digital Loop Carrier System and a Local Digital Switch" Document No. TR-TSY-000008 Issue 2, August 1987 (TR-08 specification) [0004]

[Conventional technology]

In the public switched telephone network (PSTN), narrowband (NB) traffic is carried over time domain multiplexing (TDM) links. PSTN utilizes a cross-connect switching system at the telephone company's facility and a digital loop carrier (DLC) to provide analog or TDM service lines to individual customers. Narrowband services are defined herein to include all TDM services and analog telephone services up to T1 data transfer rates. Narrowband services include, among other things, Simple Old Telephone Services (POTS), Integrated Services Digital Network (ISDN), and T1 Services.

【0005】

Asynchronous Transfer Mode (ATM) networks are networks of digital exchanges that carry and route traffic packaged in individual "ATM cells." ATM is defined within several specifications published by the ATM Forum, which includes UNI 3.1 and UNI 4.0. As used herein, the term "ATM" refers to a network protocol that conforms to these documents in all relevant respects, whether or not it conforms to the more up-to-date or other specifications. Within an ATM network, each cell contains addressing information that allows the ATM switch to route incoming calls to the next node towards the appropriate destination. A digital subscriber line access multiplexer (DSLAM) is used to provide a separate subscriber connection to an ATM. ATM services are commonly used to provide wideband (BB) services to individual customers. In the access loop, ATM is carried by twisted pair copper cable through the ADSL physical layer.

【0006】

Recently, there has been a lot of interest in providing narrowband loop emulation services or voice over ATM interfaces. Such services can provide a narrowband line in the subscriber's home, sometimes referred to as a "derived line", without the need for additional twisted pair. The "free incoming line" service typically leverages the existing ATM over ADSL access loop infrastructure to provide additional narrowband services to customers.

【0007】

FIG. 1 is a block diagram of a corresponding part of a conventional network architecture that provides a loop emulation service in a customer's home using a stand-alone gateway. In the customer's home, the data network 110 is connected to the data port of the ADSL terminal unit (ATU-R) 112, also known as the integrated access unit (IAD). Data networks typically carry data contained within packets, such as IP packets, over Ethernet. In the uplink, the ATU-R112 extracts IP packets from the Ethernet frame, rewraps them in the ATM cell, and digitally subscribes to the service provider's central office (CO) 113 over the ADSL link 118. Send to multiplexer (DSLAM) 114. In the downward direction, the opposite processing is performed. Both IP packets and ATM cells used herein are examples of "packets." Optionally, insert a splitter 116 into the ATM-over-ADSL link 118 in the customer's home, insert a corresponding splitter 119 into the central station 133, and insert a conventional analog POTS signal (analog POTS). The analog POTS signals can be carried through the same twisted pair 118 to the position of DSLAM114 where signals) are distributed and provided to the line connector of class 5 switch 129. DSLAM114 transports IP-over-ATM traffic to ATM network 120, and IP-over-ATM traffic can be routed over ATM network 120 to other DSLAM122, Internet Service Provider (ISP) 124, or both. It is clear that the overall architecture includes traditional POTS services within the same customer home and can be connected to Class 5 switch 129 via separate analog and TDM links and equipment not shown. Utilization of ATM network 120, which carries IP-over-ATM data between multiple data networks, is typically achieved according to the Local Area Network Emulation (LANE) incorporated above. Further, the embodiment shown in FIG. 1 uses an ADSL (Asymmetric Digital Subscriber Line) link connected between the ATU-R and the DSLAM114, but with other types of Digital Subscriber Line (DSL) links. It can also be used instead. At the central station, the ADSL link 118 is usually terminated by the ADSL terminator-central station (ATU-C) card in the DSLAM114.

【0008】

To provide toll-free line service, the ATU-R112 is modified to provide one or more narrowband POTS ports 128. The ATU-R112 digitizes the POTS signal from port 128, encapsulates it in the ATM cell, and merges it with the IP-over-ATM cell generated from the data network 110 in the ATM cell. Therefore, the stream of ATM cells carried over the ATM-over-ADSL link 118 contains both the ATM cells carrying traditional data and the ATM cells carrying TDM voice traffic. However, ATM cells that carry TDM traffic are carried within a virtual circuit (VC) that terminates at the standalone gateway 130. The DSLAM 114 routes all ATM cells arriving from the ATM-over-ADSL link 114 into the ATM network 120, which eventually routes these cells carrying TDM traffic to the gateway 130. Gateway 130 retrieves TDM information from the incoming ATM cell, converts it back into TDM format, and sends it, for example, over the GR-303 link to a second class 5 switch 126. In the opposite direction, TDM traffic from switch 126 arrives at gateway 130, where it is encapsulated in an ATM cell and sent to ATM network 120. The ATM network 120 routes the cells to the appropriate DSLAM114, which further routes those cells to the ATU-R112 over the ATM-over-ADSL link 118. The ATU-R112 retrieves TDM data from these ATM cells and forwards it to line port 128.

【0009】

Since there is no direct analog connection between the POTS port of the free incoming call line in the customer's home and the TDM switch at the far end of the gateway 130, normal POTS notification operations such as on-hook and off-hook do not have the desired effect. Therefore, to complete the loop emulation service provided by gateway 130, the ATU-R112 detects such behavior, encodes it into a special notification ATM cell, and sends it to the gateway. The gateway then decrypts the notification ATM cell and notifies the Class 5 switch for an incoming free POTS line. Any downlink notification is transported in the corresponding form.

【0010】

The usual specifications for encapsulation and retrieval of both TDM voice band signals and POTS notification information are described in the VTOA specifications incorporated above and in ITU-T Recommendations I.363.2 and I.366.2. ATM cells that meet these specifications in all applicable respects, whether or not they meet other specifications, are referred to herein as AAL Type 2 ATM cells or simply AAL-2 or AAL2 cells. As used herein, the term "user traffic" refers to the content of traffic to or from a user (voice, data, etc.), while the term "notification or management traffic" operates a communications network. Refers to the content of the traffic transport notification and other content to be used.

【0011】

[Problems to be Solved by the Invention]

The gateway 130 is a stand-alone device that resides in a separate central station behind the ATM network and supports a large number of DSLAMs. In another configuration, the gateway 130 resides only behind one DSLAM and can be located within the central station 133 of the local service provider, in which case the gateway 130 requires a separate class 5 switch 126 instead of a local class 5 Can be connected to switchboard 129. In both configurations, the gateway 130 is a separate device from the various ATM and PSTN exchanges and access multiplexers. As a stand-alone device, the gateway 130 detects failures and protects them. It must be managed as a separate network element for a variety of purposes, including switching) and repair, configuration and telephone service provision, performance monitoring, security, connectivity and billing. Standalone gateways are typically not manufactured by companies that manufacture other network equipment that the service provider must manage, so the controller that manages such gateways manages all other equipment within the central office. Cannot integrate well with the control device. Thus, as shown in FIG. 1, gateway 130 is managed by one element management system (EMS) 131, while DSLAM114 is managed by another different EMS123. Standalone gateways also need to be managed as separate communication nodes to establish the necessary interconnects for network traffic in both ATM and TDM networks. The problem remains in this case as the provision of telephone service requires coordination between the assignment of a gateway class 5 switch and the allocation of another free incoming POTS line. In addition, maintenance procedures also require line traceability between many network elements. Testing and turn-up processing for free incoming POTS lines requires coordination with many more network elements. This is because standalone gateways usually do not have a telephone test access point. In addition, there is currently no element manager that supports the network elements of many vendor-made toll-free lines. Therefore, in order to mix and match DLC and stand-alone gateways, it is necessary to test the conformity of management functions for each element.

【0012】

Standalone gateways also pose a potential disruption to network reliability. In addition, as a stand-alone device, Gateway 130 occupies a valuable central station floor and has additional power and cooling requirements. It also requires a separate dedicated battery backup system, which is a significant cost increase. Moreover, since the gateway 130 is a stand-alone device, it may be uneconomical to install it for a small number of free incoming POTS lines.

【0013】

Therefore, existing TDM-ATM gateways are valuable in providing toll-free line services, and thus increase the value provided to DSL service subscribers, but this is costly and indispensable for service providers. It may not be possible to make up for the increased revenue from providing free incoming line services. It is highly desirable to find a way to provide toll-free line service over DSL lines at a much lower cost without the need to install a stand-alone gateway device.

【0014】

[Means for solving problems]

According to the present invention, in general, a TDM-ATM gateway that performs a loop function for one or more narrowband toll free lines is incorporated into a device that performs the routing of network traffic. Routing includes exchange and / or multiplexing and consists of ATM cell routing and / or TDM traffic routing. In a preferred embodiment, the gateway is embedded in a device that routes both TDM and ATM traffic, such as an Alcatel USA Litespan terminal. In this case, the gateway's TDM port is multiplexed with other TDM subscriber traffic on the network-side TDM interface, and the gateway's ATM port is one or more virtual from one or more subscriber remote ATM terminations. It acts as the end point of the ATM of the line.

【0015】

By integrating the TDM-ATM gateway with other network devices that route ATM, TDM, or both traffic, the gateway no longer needs to be managed as a separate network element. Instead, the gateway can be managed as a mere component or sub-component of the routing device. Also, in some embodiments, the integrated gateway does not cause further potential failures. This is because in such an embodiment the gateway is already integrated on the control card, which is already part of the protection group and is already the smallest replaceable component in the event of a failure. Also, the integrated gateway does not occupy any additional central station floor space, nor does it significantly compromise existing power and cooling requirements. In addition, since most of the fixed costs incurred to support integrated gateways are already incurred by the host-side network equipment, service providers initially support only a few lines and gradually offer toll-free line services. It can be rolled out economically, or the transition from a TDM service transported over the PSTN to a TDM service transported over the ATM can be made gradually as needed, or both.

【0016】

Hereinafter, a specific embodiment of the present invention will be described with reference to the drawings.

【0017】

BEST MODE FOR CARRYING OUT THE INVENTION

Figure 11 is a block diagram of the gateway network architecture that can be used to implement the loop emulation service. The customer home equipment is the same as the equipment shown in Fig. 1. However, instead of providing the gateway function in the centralized device behind the ATM network, the gateway function is provided locally on the DSLAM before the cell is provided to the ATM network 120. TDM access multiplexers such as digital loop carriers (DLCs) are also integrated within the same equipment as the DSLAM, and the gateway function operates between these two functions. Basically, the gateway function is integrated within the integrated DLC / DSLAM node.

【0018】

In Figure 11, in particular, for example, in the Nattkemper et al. Patent incorporated above, the DLC and DSLAM are the single Litespan described above. Both exist in the ADSL system. As shown in Figure 11, the ATM-over-ADSL118 is connected to an integrated DLC / DSLAM1110 that has been modified to include a dedicated gateway function 1112. The gateway function 1112 is integrated with the DLC / DSLAM access node 1114. At access node 1114, a subscriber ATM cell carrying TDM data is routed to gateway 1112, which retrieves TDM data and contains the same CO1113 containing access node 1114, for example via a GR-303 or TR-08 link. Send to class 5 exchange 129 on the local side located at. No connection to a Class 5 switch such as 126 (Fig. 1) is required. In the opposite direction, TDM traffic from Class 5 switch 129 for toll-free line 128 arrives at gateway 1112, which encapsulates the TDM traffic in an ATM cell and the appropriate ATM via DLC / DSLAM1110. Over-Send over ADSL subscriber link 118. The DLC / DSLAM will continue to route traditional ATM cells between the ATM network 120 and the ATM subscriber DSL link 118. Gateway 1112 and ATU-R112 use standard profiles to perform standard AAL-2 encapsulation and notification, enclosing loop traffic and notification information within ATM cells.

【0019】

As used herein, the term "exchange" refers to the transport of traffic from one of a plurality of interfaces to another selectable one of a plurality of interfaces. The set of input interfaces may be the same, completely different, or partially overlapped with the set of output interfaces. The term "exchange" usually incorporates or refers to a database that indicates the correspondence of an input channel to an output channel. For ATM exchanges, the database shows, among other things, which ATM output interface to use to forward incoming cells with a particular ATM destination address. For TDM exchanges, the database shows, among other things, which TDM output interface and which time slot on that TDM output interface to use to transfer incoming data within each time slot of the incoming TDM interface.

【0020】

Also, as used herein, the term "multiplexing" refers to the process of merging data from a number of input interfaces with a low bit rate onto a smaller number of output interfaces with a higher bit rate. The term "demultiplexing" refers to the opposite process. Typically, a telephone traffic multiplexer multiplexes data from N input interfaces onto a single outgoing and connected interface that has a bit rate N times that of the input interface. The telephone service multiplexer may or may not perform the exchange. Also, the telephone exchange may or may not perform multiplexing.

【0021】

Also, as used herein, the term "routing" is a comprehensive term that includes exchange, multiplexing, or both.

【0022】

FIG. 3 is a block diagram showing an embodiment of an integrated gateway loop emulation service that utilizes the integration of TDM and ATM processing in the Litespan ADSL system. The Litespan ADSL system includes a Litespan central station terminal (COT) 310 located within the service provider's central station 312 and multiple remote terminals (RT) 314 and 316 located at remote locations outside the central station 312. .. Each Litespan terminal 310, 314 and 316 participating in the loop emulation service includes at least one Litespan ADSL channel bank (CBA). Litespan An ADSL channel bank contains zero or more narrowband line connectors and one or more ADSL line interconnects (ADLUs), all with an ADSL bank controller (ABCU) over the backplane. connect. ABCU performs both the TDM Timeslot Transformation (TSI) function and ATM access multiplexing for ADLU in the channel bank that contains the ABCU. Each terminal is a separate device and is managed as a separate network node, but both TDM and ATM access multiplexing functions are integrated within the node. According to the embodiment of FIG. 3, another gateway function is each Litespan in each terminal in the Litespan system. It is built into each ABCU in the ADSL channel bank. Alternatively, in another embodiment, the gateway function can be provided on only one ABCU per Litespan terminal in the entire Litespan system. Figure 4 shows another embodiment that includes only a single gateway function throughout the Litespan system. In FIG. 4, the required gateway function is located on the ABCU in the COT, and the gateway function on the ABCU in the remote terminal is optional.

【0023】

The gateway function shown in the embodiments shown in FIGS. 3 and 4 can be seen as an ATM node that can be simply addressed from the core ATM network 120 and the ATM switch fabric in the Litespan system. Thus, in general, any gateway function within the Litespan system can perform gateway services for subscribers connected to any other ATM port that the gateway function can reach. For example, FIG. 3 shows another DSLAM 318 connected to the Litespan system of FIG. 3 via the ATM network 120, which itself does not provide any original TDM routing. With such a configuration, any gateway function 320, in the same way that the standalone gateway 130 in Figure 1 provides toll-free line service for ATM-over-ADSL customers connected to any DSLAM 114 and 122, The 322 or 324 can provide a toll-free line service to any subscriber connected to the DSLAM 318 via an ATM link. DSLAM 318 in Figure 3 is Litespan Although shown to be located at the same central station 312 as the COT310, in another embodiment the DSLAM318 may be physically located at a different location.

【0024】

In Figure 4, the DSLAM318 connects directly to the ATM port of the Litespan COT310 rather than through the ATM network 120 (eg, continuing the Litespan ADSL daisy chain).

【0025】

FIG. 5 shows another aspect of one embodiment of the present invention in a Litespan ADSL terminal. The terminal includes a common controller 510, a Litespan ADSL channel bank (CBA) 512, and a TSI (time slot conversion) cable 514 that interconnects them. The Litespan common controller 510 includes a TSI card 516, a terminal control processor (TCP) 518, and a database (DB) 520. Litespan The CBA 512 includes an ADSL line connector (ADLU) 522 connected to the ABC U524 via the backplane. ADLU522 provides an ATM-over-ADSL service line 118. Gateway function 526 is integrated on ABCU card 524. The network-side TDM traffic of ABCU524 is connected to TDM network 133 via the TSI cable 514 and the Litespan common controller 510, while the network-side ATM traffic of ABCU524 is connected to ATM network 120. It can be seen that the free incoming voice VC528 is generated between the TDM port 128 in the customer's home and the gateway function 526, and the gateway function 526 provides the gateway to the TDM network 133 via the TSI cable 514 and the common controller 510. It can be seen that another free incoming voice VC530 is provided between the customer premises equipment (CPE) and the gateway function 526 via another DSLAM318 and optionally via the ATM network 120.

【0026】

Figure 5 also shows that ADSL is not the only physical layer protocol that can carry toll-free line ATM cells. For example, the Litespan CBA512 further includes an HDSL Line Connector (HDLU) 532 that provides an HDSL2 port that carries ATM cells to and from other downlink devices such as another ATM multiplexer, customer in-home device 534, or both. I'm out.

【0027】

Figure 5 also shows that the traditional analog POTS port is not the only type of user port available for toll-free line services. In FIG. 5, the IP H.323 phone 536 is connected to a personal computer (PC) 538, and the personal computer (PC) 538 is connected to the ATU-R112 via the IP data network 110. The IP H.323 phone 536 complies with the ITU-T H.323 recommendations incorporated above. ATU-R112 ATMs IP H.323 data Convert to AAL2 free incoming POTS line cell and vice versa. In the embodiment of FIG. 5, the gateway function 526 can enable the toll-free line service by the IPH.323 telephone 536. In another embodiment, the toll-free line can be supported via a PC speaker and microphone connected to the PC538, or an RJ11 jack for a simple old-fashioned telephone. This can be achieved with the built-in network interface card or through software in the PC. In yet another embodiment, some IP-based telephones can be connected directly to the data network 110 without going through PC538, in which case the H.323 telephone digitizes the analog signal and goes through IP-over-Ethernet. Transferred to ATU-R112, ATU-R112 takes out the voice signal, re-encloses it in the ATM AAL2 cell, and sends it to gateway 526. In the downward direction, the opposite function is executed.

【0028】

FIG. 6 shows the Litespan CBA512 of FIG. 5, showing the conventional voice path 610 and the conventional data path 612 via the CBA512. Figure 6 also shows some specific functions performed by Litespan. In particular, the ATM switch fabric 616 on the ABCU524 routes the TDM-over-ATM cell from the toll-free voice path 614 to the gateway 526, as well as the gateway 526 from the ATM network and further the gateway 526 from the chained ABCU or DSLAM. Route TDM-over-ATMVC to. Gateway 526 is TDM-over-ATM Terminate the VC and retrieve the TDM data. Gateway 526 then puts the TDM data into one or more suitable 64kbps time slots on the SBI (Subscriber Bus Interface) bus 620. Gateway 526 also performs echo cancellation and cell compression / decompression with silence and 64kbps audio. In addition, any POTS notification encoded in the AAL-2 cell is converted to an out-of-band (OOB) ABCD notification on the SBI 620 towards the Litespan Common Controller 510 via a dedicated TCP message channel 624. In this way, gateway 526 executes TDM notifications towards the common controller for the customer home device connected to the toll-free POTS port.

【0029】

The TSI map function 622 is the same as the TSI map function that existed in the ABCU prior to the integration of gateway 526. This feature makes the time slot on the TSI cable 514 correspond to both the traditional SBI bus 610 on the CBA backplane and the time slot on the SBI bus connected to the TDM side of the gateway 526. In addition, database 520 (Figure 5) in Litespan Common Controller 510 can be extended to provide virtual POTS ports or other TDM services provided by the toll-free line function.

【0030】

Figures 7 and 8 compare embodiments of the present invention on Litespan-2000 terminals with embodiments on Litespan-2012 terminals. FIG. 7 shows an embodiment on a Litespan-2012 terminal. In Litespan-2012 terminals, the common controller 710 can include the STS interface 712. Therefore, the toll-free voice path 714 is carried on the TSI cable only once per direction of traffic flow. FIG. 8 shows an embodiment on a Litespan-2000 terminal. In the Litespan-2000 terminal, the common controller 810 does not include an interface to the TDM network. Instead, a connection to the TDM network is made via the DS1 card 812 in the Litespan CBA814. In this case, the free incoming voice path 816 reciprocates via the TSI cable 818 for each direction of traffic flow.

【0031】

As mentioned above, with the loop emulation service described herein, TDM traffic is encapsulated within an ATM cell using standard AAL-2 encapsulation. The AAL-2 standard defines a number of "profiles" that carry audio in different encoding schemes, such as the PCM-64, ADPCM-32 and ADPCM-40, and 99-0392 incorporated above. All such standard profiles or other profiles that are not currently part of AAL-2 are considered to be within the scope of the invention.

【0032】

The standard AAL-2 Service Dependent Convergence Sublayer (SSCS) notification method, preferably using the Line Individual Notification Method (CAS) as the narrowband default, is the notification method between the CPE and the gateway. Used as. It is based on an 8-byte notification PDU carried with audio information within each audio channel. The notification PDU carries the in-band ABCD notification bits for POTS. Nevertheless, if both ends of the interface support Signaling System No. 7 (CCS), the notification scheme described in ITU-T Recommendation Q.931 above can be used for narrowband notification.

【0033】

FIG. 9 shows the communication protocol used between the CPE 910 and the Class 5 switch 129 to support the toll-free line 528 of FIG. Referring to FIG. 9, the telephone or other CPE910 in the customer's home transmits an analog signal to the ATU-R112. The ATU-R112 converts the analog signal to pulse code modulation (PCM) format and then encapsulates the PCM data in AAL-2 via an ATM cell. The ATU-R112 then uses the ADSL physical layer protocol to send the ATM cell to the ADLU522 in the Litespan CBA512. ADLU522 takes the ATM cells and sends them upstream through the CBA512 backplane SBI bus to ABCU524, which inspects the ATM cells and decides to route the cells from the VCIs in those cells to gateway function 526. .. Gateway function 526 extracts PCM audio sample from AAL-2 ATM cell and Litespan It transmits to the TSI card 516 in the Litespan common controller 510 in the upward direction via the SBI bus and the TSI cable 514. The TSI card 516 sends an audio sample upstream to the class 5 switch 129 via the STS interface in the common controller 510 (see Figure 7) or the DS1 interface in the CBA 512 (see Figure 8). In the downlink direction, the opposite set of protocol conversions is executed.

【0034】

The ATU-R112 and ABCU gateway 526 are provided so that the ATM AAL-2 cell is transmitted between the two devices using an ATM fixed connection (PVC). In another embodiment, communication between these two endpoints can be performed over a selective connection (SVC) as described in ITU Specification Q.2931. Also, the CPE shown in FIGS. 5 and 9 consists of an analog telephone 910 that communicates with the ATU-R112 via an analog electrical signal, but in another embodiment the port on the ATU-R112 is instead purely digital with the CPE910. Can support N x 64kbps communication. In this case, the user traffic carried on the free incoming "voice" line 528 may be a line mode data service and does not need to be converted to PCM in the ATU-R112. In yet another embodiment, the user traffic consists of a frame mode data service that is digitally transmitted to the ATU-R112, which is the AAL-2 Data Service Dependent Convergence Sublayer (SSCS) described in ITU Recommendation I.366.1. ) Is used to enclose the frame mode data in an ATM AAL-2 cell.

【0035】

Looking back at the toll-free line 128 in Figure 5, unlike traditional POTS services, the CPE910 and Litespan in the customer's home It can be seen that there is no direct analog electrical connection to the CBA512. Therefore, the well-known POTS notification behavior, such as raising the handset to off-hook to initiate a call and returning the handset to on-hook after the call ends, is sent between endpoints on the free incoming line using different methods. There is a need to. In this embodiment, the ATU-R112 and gateway function 526 encode this information in a special notification ATM cell in full compliance with ITU Recommendation I.366.2 incorporated above. All narrowband calls consisting of audio, voice, voiceband data, and line mode data are included in accordance with I.366.2. For traditional POTS lines, subscriber notification is performed for the CPE by the traditional POTS narrowband line connector in the CBA towards the Litespan common controller on the Litespan bus. In the opposite direction, the POTS line connector provides the appropriate analog notification to the CPE in response to the notification code received from the Litespan common controller. In the free incoming line embodiment of FIG. 5, it is the gateway function 526 that performs analog notifications towards the common controller 510 for the CPE910 and towards the CPE910 for the downlink signal received from the common controller 510. It is the ATU-R112 that executes analog notifications. The notification cell carried between the gateway function 526 and the ATU-R112 carries not only the control notification but also the notification protocol for minimizing the bandwidth usage on the DSL line 118 as much as possible.

【0036】

All packet formats and procedures for encoding different information streams for narrowband voice, voiceband data and line mode data transmission are described in ITU-T Recommendation I.366.2 and are not repeated here. However, in general, all sender ends of the TDM-over-ATM route perform at least the following functions as described in I.366.2: a) Coding of audio samples into bit sequences b) Selection of voice coding algorithms based on call and resource state characteristics such as congestion display c) Silence compression by voice activity detection and intermittent transmission of silence insert descriptor d) Transparency of line mode data as a stream of one 8kHz octet per time slot e) Data frame retrieval and flag removal, bit stuffing and CRC (as appropriate) f) Detection and priority of facsimile and modem traffic, such as high-fidelity coding g) Extract dial numerals from multi-frequency audible signals h) Extraction of individual line notification bits and analysis of their transitions i) Facsimile baseband bit decoding for page control and image data j) Alarm detection k) Synchronous transfer of processed signals to SSCS l) Request and response of user state control operation [0037]

In addition, in another embodiment, the transmitting end can all perform one or more of the following functions as described in I.366.2. a) Inserting coded voice bits into the packet configuration b) Display of algorithms to use through packet header fields (eg UUI code points and length indicators) or packet payloads c) Insert SID bits and display SID to use, as with any voice algorithm d) Inserting an octet stream into a packet configuration based on time slots e) Segmentation of data frames into packet sequences with error protection f) Insert encoding bits for audio band data and display the algorithm used, as with any other audio g) Insert dial digit sign into the identified packet configuration h) Inserting a line-specific notification bit into the identified packet configuration i) Inserting a facsimile baseband bit into the identified packet configuration for this j) Inserting an alarm into a well-known packet configuration k) Packet sequence numbering to support isochronous reconstruction of the information stream on the receiving side l) Generate user state control message [0038]

All receiving ends of the TDM-over-ATM route can perform the following functions as described in I.366.2. a) Identification of the incoming packet type as determined by the fields in the packet header or packet payload b) Buffering of time-sensitive packets to reduce delay fluctuations (additional functionality for decoding) c) Timely release of packet content to the user, for example, treatment of sequence numbers when discarding old packets d) Algorithm identification and extraction of encoded voice bits from the packet configuration e) Display of any unrecoverable gap in the bitstream f) Extracting the octet stream from the packet configuration based on the time slot g) Rebuilding a data frame from a packet sequence with error detection h) Extraction of dial numeric code i) Extraction of line individual notification bit transition j) Facsimile baseband bit retrieval k) Retrieving the alarm l) Interpretation of user state control messages [0039]

In addition, all receiving ends may perform one or more of the following functions described in I.366.2: a) Recognition of the coding applied to the information stream b) Elimination of arbitrary delay fluctuations due to user decryption c) Synchronous transfer of coded information from SSCS d) Decoding audio bits into an audio sample that contains the comfort noise generation indicated by the silent insert descriptor. e) Attempts to perceptual masking errors in the absence of expected voice bits f) Playback of line mode data as a stream of one 8kHz octet per time slot g) Data frame playback and flag playback, bit stuffing and CRC (as appropriate) h) Extraction of multi-frequency audible signal from dial numeric sign i) Playback of individual line notifications from bit transitions j) Facsimile remodulation from baseband bits k) Interpretation of alarm l) Display and check user state control operation [0040]

The ATM AAL-2 specification allows senders and receivers to choose between several possible options on the user plane, control plane and management plane. On the user plane, gateway functions 526 and ATU-R112 are preferably predefined in ATM forums that specify AAL-2 to carry 32-byte 64kbps μ law PCM and ADPCM-32 as the default voice CODEC profile. Perform profile 7. In addition, gateway function 526 and ATU-R112 also implement a comprehensive means of negotiating other voice codec embodiments. It is also preferred that the CPE be designed such that the default means of clock synchronization between the CPE and Litespan is an adaptive clock algorithm based on the reception of downlink audio cells from Litespan. On the control plane, the gateway function 526 and ATU-R112 each support the Line Individual Notification Method (CAS), preferably as a default. Preferably, each also supports Common Line Notification Method (CCS) and includes a mechanism to determine if other support has extended CCS functionality. CAS The ABCD notification bit is included in AAL2 type 3 (UUI = 24) packets that have a specific value in the header field.

【0041】

On the management plane, the gateway function 526 and ATU-R112 preferably implement the loop start default service type. If the POTS port on the ATU-R112 is out of service or otherwise not provided, Litespan simply refuses to initiate a call from the ATU-R112 on that channel. Otherwise, CPE910 voice service is managed by Class 5 switch 129 via TR-08, GR-303, or V.52 interface with Litespan.

【0042】

FIG. 14 is a diagram showing a message transmission / reception flow of the conventional POTS service provided by Litespan. The CPE 1410 is connected to the POTS line connection device 1412 via an analog link, and the POTS line connection device 1412 is connected via the subscriber bus data link (SBDL) corresponding to the specific card slot containing the POTS line connection device 1412. Notification information is communicated between TCP1414 in Litespan and the common controller 1428. The message is transferred on the SBDL from the POTS line connector 1412 to the ABCU 1416 along the backplane bus, to the TSI card 1422 in the common controller 1428 via the TSI cable 1418, and to the TCP 1414 where the message arrives. The reverse route is used in the downlink notification method. For notification messages to a Class 5 switch 1420, standard TR-08 or GR-303 notifications are provided from TCP 1414 via TSI card 1422 to ABCU 1416 via TSI cable 1418. The ABCU1416 routes notification messages in TDM format to the DS1 card 1426 via the CBA1424 backplane, which further routes those messages to the Class 5 switch 1420. The downlink notification flow from the Class 5 switch 1420 to TCP 1414 follows the same route in reverse.

【0043】

US Pat. No. 5889773 incorporated above and TR- incorporated above for data and notification formats on the TSI cable 1418 between the POTS line connector 1412 and TCP 1414 and between TCP 1414 and a Class 5 switch It is not repeated here as it is detailed in the 08 and GR-303 specifications. However, in a nutshell, narrowband traffic within Litespan terminals goes into a 1ms superframe with eight 125 microsecond frames, each allowing the transfer of bit-oriented notification protocols corresponding to standard telephone traffic. It is put in and transported. Each frame has a subscriber bus interface (SBI) format that contains a 32-byte time slot data stream, and each time slot byte has a 16-bit alternating data format, alternating between two separate bits. Data streams placed in are supported by the SBI format. The odd bit positions in the 16-bit alternating data format carry the narrowband data that is actually transferred (in-band and out-of-band data), and the even-bit positions are not used on the TSI cable. On the backplane of the CBA1424, odd bit positions are used to carry upstream ADSL data. The SBI format carries internal system communication and user information with an out-of-band bit-oriented notification protocol for 24 DS-0 signals or one VT1.5 signal.

【0044】

The 32-byte time slot data stream in SBI format is reserved byte R, bit-oriented notification byte SIG, internal data link byte SQR (service request), framing byte overhead channel and digital signal level zero signal (DS0) channel byte 01- Divided into 24. Twenty-four DS0 data channel bytes are transported in pulse code modulation format during voice transport. These bytes distribute overhead channels over 125 microsecond frames and are 125 microseconds consisting of a set of three channels for minimal buffering when converting to digital signal level 1 (DS1) signals. Distributed via a second frame. The DS0 channel byte data is converted to the SBI format, which is the standard μ-law format inverted during voice transport, to provide noise-free pulse code modulation when the POTS line card is removed or not found. The bit-oriented notification byte SIG transports the standard AB or ABCD notification protocol used on the T1 system to provide 4-state and 16-state notification modes and the unique notification mode described in the Belcore TR-08 specification built above. to support. Data link bytes SRQ and SBDL provide communication functionality with TCP 1414. Unique byte values are transported within the R and SRQ bytes of the 8th frame of the superframe to identify the boundaries of each superframe.

【0045】

Figure 15 shows the flow of sending and receiving messages executed by the free incoming line loop emulation service in the Litespan terminal. With reference to FIG. 15, the message channel 1512 between the ATU-R1514 and the TCP 1516 in the Litespan common controller 1518 is described below. The notification method information is enclosed in the AAL2 ATM cell described above for the transfer between the ATU-R1514 in the ABCU1522 of the Litespan CBA1524 and the gateway 1520. The ATM cell is transported on the ADSL link 1526 between ATU-R1514 and ADLU1518 and then on the CBA backplane bus to ABCU1522 in CBA1524. The ATM route terminates at gateway 1520, but the message route extends through the common ABCU SBI / SBDL control channel via TSI cable 1418 to TCP 1516. There is no change in the notification between TCP 1516 and Class 5 Switch 1528. The downlink notification flow follows the same route in reverse.

【0046】

FIG. 16 is a simplified ladder diagram showing a conventional TR-08 calling flow using the configuration of FIG. At time 1610, when the customer offhooks the telephone 1410, the closure of the electrical circuit is detected by the POTS line connector card 1412, which is then the POTS line connector card 1412 via the out-of-band Litespan notification, DS1 card 1426 via TCP 1414. The DS1 card 1426 then sends an off-hook notification status to the Class 5 switch 1420. At time 1612, the Class 5 switch 1420 sends a dial tone to the DS1 card 1426 in response to an off-hook signal from Litespan. DS1 1426 returns the dial tone to the line card 1412, which sends the dial tone to the telephone 1410. At time 1614, the customer dials a number on the telephone 1410 and the dialed number is sent to the Class 5 switch 1420. Then, at time 1616, an end-to-end call is established between the Class 5 switch 1420 and the telephone 1410. Finally, when the conversation ends, the customer hangs up the phone 1410 (time 1618). An electrically open circuit is detected by the POTS line connector card 1412, which sends an on-hook notification to the DS1 card 1426 via the Litespan out-of-band notification, which eventually sends an on-hook signal. To class 5 switch 1420. On-hook and off-hook signal notifications from the DS1 card to the Class 5 switch are in-band notifications. TCP1414 does not intervene at all in sending and receiving messages between the Class 5 switch and the telephone 1410, except to provide the proper time slot mapping from the POTS card 1412 to the DS1 card 1426.

【0047】

FIG. 17 is a simplified ladder diagram showing a call flow from the POTS telephone 1510 using the free incoming call line configuration of FIG. At step 1710, the customer unhooks the handset on telephone 1510. At step 1712, the ATU-R1514 detects an off-hook condition and informs the gateway 1520 via an AAL2 ATM packet as described above. Gateway 1520 terminates the ATM route and sends off-hook notifications to Litespan TCP 1516 via ABCU SBDL as described above (step 1714). At step 1716, the gateway 1520 also sends an off-hook message to the DS1 card 1530 via TCP 1516 via Litespan out-of-band A / B notification. The DS1 card 1530 notifies the class 5 switch 1528 of off-hook via in-band notification as in step 1610 (Fig. 16). The ATU-R1514 provides silence to the telephone 1510 while the Class 5 switch 1528 is processing the off-hook signal (step 1718). Also, in step 1720, Litespan TCP1516 allocates a TSI time slot for this call and sends this allocation to gateway 1520. When the time slot allocation message is received by the gateway 1520, the gateway 1520 notifies the ATU-R via an AAL2 notification (step 1722) and an AAL2 voice packet between the ATU-R1514 and the gateway 1520 can be initiated. ..

【0048】

Eventually, at step 1724, the Class 5 switch 1528 sends a connection message back to the Litespan TCP 1516 via the DS1 card 1530, sending an in-band dial tone from the Class 5 switch 1528 to the telephone 1510 (step 1726). AB notification monitoring is then performed between the Class 5 switch 1528 and the telephone 1510 (step 1728). Dial numerals and voice data are then transmitted between the telephone 1510 and the Class 5 switch 1528 as described above (step 1730).

【0049】

FIG. 18 is a simplified ladder diagram showing a conventional call in the configuration of FIG. 14 with the GR-303 interface to the Class 5 switch 1420. At time 1810, phone 1410 goes off-hook. The POTS line card 1412 detects this condition and sends an off-hook SBDL message to the Litespan TCP 1414, which then sends a channel configuration request message to the Class 5 switch 1420 via the Interface Group (IG) Timeslot Management Channel (TMC). Send. At time 1812, the Class 5 switch 1420 sends an IG TMC configuration confirmation message back to TCP 1414 via the DS1 card 1426, indicating the DS0 allocation for the new call. Class 5 switch at time 1814 Litespan Send a connection message to TCP1414. TCP 1414 cross-connects DS0 on POTS card 1412 to a Class 5 DS1 time slot assigned by a Class 5 switch. At time 1816, the Class 5 switch sends a dial tone. A TCP connection is established and ABCD route monitoring is performed between the DS1 card 1426 and the POTS line connector card 1412. Phone 1410 sends dialed numbers to a Class 5 switch in band, an end-to-end call is established, and finally at time 1822, the customer returns the handset on phone 1410 to on-hook. The POTS line connector 1412 sends an on-hook display to TCP 1414 via the SBDL time slot of the POTS card 1412. TCP1414 then releases the communication path to free the POTS line. TCP 1414 also instructs the DS1 card 1426 to notify the class 5 switch 1420 of the on-hook status.

【0050】

FIG. 19 is a simplified ladder diagram showing a call in the free incoming line configuration of FIG. 15 where the interface between Litespan and the Class 5 switch 1528 is the GR-303 interface. At step 1910, the customer unhooks phone 1510. At step 1912, the ATU-R1514 detects an off-hook condition and notifies the gateway 1520 via an A / B notification on the AAL2 cell as described above. At step 1914, the gateway 1520 further sends off-hooks to the Litespan TCP 1516 via the ABCU's SBDL, as shown in Figure 17. Meanwhile, the ATU-R1514 sends silence to the telephone 1510 (step 1916). At step 1918, Litespan TCP 1516 sends a channel configuration request to DS1 card 1530 via SBDL, and DS1 card 1530 sends this request to class 5 exchange 1528 via TMC messaging DS0 (steps 1918 and 1920). Class 5 switch 1528 responds with a TMC configuration confirmation message and a connection message (steps 1922 and 1924). However, Litespan The TCP1516 provides the gateway 1520 with its own time slot allocation without waiting for these messages (step 1926). At step 1928, a time slot connection message is sent from gateway 1520 to ATU-R1524, and transmission of AAL2 voice packets between ATU-R1514 and gateway 1520 begins. When the connection message is received by Litespan TCP 1516 (step 1924), an in-band dial tone is sent from the class 5 switch 1528 to phone 1510 (step 1930), AB notification monitoring is performed (step 1932), and phone 1510 and class. 5 Dialed numbers and voice data are transmitted to and from the exchange 1528 (step 1934). Finally, the customer puts the handset back on-hook (step 1936).

【0051】

The hardware and software used by the Litespan terminal described in the present specification to perform the gateway function will be described below. Most of the applicable functions and hardware devices are detailed in Nattkemper et al., US Pat. No. 5,953,318, which is incorporated above, and will not be repeated here. Instead, this specification only describes certain changes in the system.

【0052】

FIG. 2 is a block diagram of the corresponding aspect of Litespan CBA 2010. Figure 2 includes one ATM bank controller (ABCU) card 22 and multiple asynchronous digital subscriber line (ADSL) line cards 24. Although the ADSL line card 24 is described herein with respect to an asynchronous digital subscriber line protocol, the ADSL line card 24 may be implemented in other suitable transmission protocols instead. In general downlink operation, Litespan CBA2010 receives ATM cells at ATM switch fabric 25. The ATM switch fabric 25 routes ATM cells between loop (ADSL) ports, network ports, and up-chain imports and down-chain imports. The ADSL port is located on the ADSL line card 24. Each such card includes a bus interface 27 that is provided to the transmitter / receiver 28 that takes out the ATM cell and converts the ATM cell into a suitable ADSL transmission format and sends it to a remote device (not shown in FIG. 2). The remote device processes the ADSL transmission data received from the ADSL line card 24 via the transmitter / receiver, physical layer device, segmentation and resegmentation device or other suitable device and user interface, and transmits it to the end user. ..

【0053】

The ABCU card 22 can also receive TDM downlink traffic from the TDM switch 13 over the TSI cable 34 via a switch such as the DLC system 15. The ABCU card 22 includes a time slot allocation device (TSA) 35 (also referred to herein as a TSI mapping device) that converts TDM traffic into SBI format. SBI-formatted TDM traffic is provided to the SBI selector 36, sent to the appropriate ADSL line card 24, and then sent to the end user.

【0054】

In the uplink direction, the ADSL line card 24 receives ADSL or narrowband transmission data from a remote device and puts this transmission data on a suitable ATM or TDM traffic stream at the bus interface 27. The ATM and TDM traffic streams are sent to the appropriate SBI selector 36 to provide TDM traffic to the time slot allocation device 35 and ATM traffic to the ATM switch fabric 25.

【0055】

ABCU22 also includes gateway function 2014. Gateway 2014 has ATM interface 2016, TDM interface 2018, and interface 2020 to gateway controller 2022. The ATM interface 2016 of the gateway 2014 interfaces with the ATM switch fabric 25 in the same way that any bus interface 26 and SBI selector 36 interface with the ATM switch fabric 25. Gateway 2014 TDM Interface 2018 interfaces with the narrowband TSA35 in the same way that the narrowband TSA35 interfaces with any SBI selector 36. Gateway 2014 sets a VC-matched toll-free line service mapping between gateway ATM interface 2016 and any ATU-R (not shown in Figure 2), on the one hand, to the TSA35's TDM switch assignment. On the other hand, it is set to the TDM switch 13. The software running in gateway controller 2022 establishes such a mapping in response to exchange / call offer commands from the Litespan common controller. For the GR-303 interface to TDM switch 13, the Litespan common controller software assigns the GR-303 CRV to the SBI channel.

【0056】

The ABCU Gateway 2014 in the firmware in Figure 2 supports AAL2 encapsulation and voice processing with several (eg 256) DSP chips for simultaneous connectivity to the gateway based on a standard profile. ABCU Gateway 2014 also provides exchange access to network echo cancellation and compression and echo cancellation for all toll-free line connections. ABCU Gateway 2014 and ATU-R also support dynamic switching to 64kbps in the CPE direction, which reserves fax sound recognition and ongoing access reversal of calls. Silence compression in both directions is also supported. Gateway 2014 also recognizes dial pulse and touchtone CPE notification uplink CAS numeric messages and GR-303 / TR-08 in-band audible sound reproduction.

【0057】

ATM Interface 2016 is split in half for each direction. Each half of the interface conforms to the Utopia interface specification described in the Utopia specification incorporated above. This Utopia interface specification has the following characteristics. Utopia Level 2, 16-bit data exchange (16-bit input, 16-bit output), 32.768MHz clock, MultiPHY (Physical Layer Multiprotocol), 1 address assigned to Gateway 2014, with polling-1 transmit cell and 1 receive cell Available, two transfer clocks (one internal, one external). This Utopia interface specification also uses cell-level handshakes, with a load of 4PHY (Physical Layer Protocol) and 1 ATM layer.

【0058】

The TDM interface connects Gateway 2014 to Litespan's TSI cable. These cables transmit TDM voice, phone notifications and SBDL communication channels from the line connector slot in the CBA to the TSI card in the CCA. Each TSI cable carries 60 SBI streams, one cable for transmission to each line-connector slot and the other cable for reception from each line-connector slot. Normally, the 24 TDM voice data time slots carried on each SBI carry TDM voice samples from the assigned line-connecting device slots. These SBIs are synchronized to the Litespan master clock and use a frame sync pulse to indicate the start of a frame. VoDSL uses these unused time slots in SBI to exchange voice samples for free incoming lines with CCA.

【0059】

In the uplink direction, Gateway 2014 provides the FPGA / ASIC with a digitized voice sample of the free incoming call line (64KHz, μ rule PCM), which puts the voice sample on the SBI stream. In the downlink direction, Gateway 2014 receives a digitized audio sample (64KHz, μ-law PCM) from the FPGA / ASIC that extracted the audio sample from the SBI stream.

【0060】

The uplink TDM interface consists of a large number of serial outputs controlled by an externally supplied synchronized clock. The serial stream is synchronized to an externally provided 125 microsecond frame sync signal. The downlink TDM interface consists of a large number of serial inputs controlled by an externally supplied synchronized clock. The serial stream is synchronized to an externally provided 125 microsecond frame sync signal. The interface is symmetric. That is, transmission and reception use the same time slot on the same audio channel.

【0061】

The microprocessor physical interface between Gateway 2014 and Gateway Controller 2022 is a means by which the microprocessor of ABCU configures, tests, checks the status, and exchanges messages with Gateway 2014. The program code can be downloaded and executed in the memory of Gateway 2014.

【0062】

Provide, configure, enable, and disable voice connection and request status The ABCU microprocessor sends call offer and configuration messages to gateway 2014 during normal operation. Messages that are more relevant than this are described below. Greek letters indicate values that are variables. -A specific VVC (Virtual Voice Connection) is configured using the call offer message.

【0063】

Number of bits used for VPI, VCI and CID of call reference β The call reference β uses VCI = ρ, VCI = σ, and CID = τ.

【0064】

Set the voice profile for call β to 1 or 7 or hybrid.

【0065】

Set the CODEC of call β to PCM or ADPCM.

【0066】

Set the echo canceller of call β to on or off.

【0067】

Set the initial reception (uplink) ABCD notification state of call β to Ψ.

【0068】

Set the initial reception (downlink) ABCD notification state of call β to Ψ.

【0069】

Enables or disables fax / modem tone detection and automatic CODEC switching for call beta.

【0070】

Enables or disables automatic CODEC switching to match the received CODEC of call β.

【0071】

Enables or disables the downlink SID (silence insert descriptor) of the call reference β.

【0072】

When available, it sends the SID cell of the call reference β every γ milliseconds.

【0073】

The call reference β uses the SID value ω. -Set the call of the call reference β (the notification bit indicates that this call is active). -Discard the call reference β (notification bit indicates that this call has ended). Enables or disables the sending of status messages from the call reference β to the ABCU microprocessor.

【0074】

During normal operation, a message providing status and reporting a failure is also sent from Gateway 2014 to the microprocessor of the ABCU in response to the above message. More relevant messages sent from Gateway 2014 to the microprocessor of the ABCU include the call status messages listed below. -Call reference β is assigned to TDM time slot γ (instructs the microprocessor of ABCU how to assign calls from SBI to gateway 2014 and in the opposite direction). -The voice profile of call reference β is set to 1 or 7 or hybrid. -The CODEC of the call reference β is set to PCM or ADPCM. -The echo canceller of call β is on or off. -No fax or modem tone has been detected for the call. -The current reception (uplink) ABCD notification state of the call reference β is Ψ. -The current transmission (downlink) ABCD notification status of the call reference β is Ψ.

【0075】

Gateway 2014 performs AAL2 SAR (segmentation and reassembly) functions for both downlink and uplink messages. For downlink messages, the ABCU microprocessor sends the message to Gateway 2014, which formats the message into AAL2 PDUs (protocol data units) and inserts them into the ATM cell stream. The ABCU microprocessor keeps track of time and initiates messages that should be sent at specific time intervals, such as CAS keep alive messages. More relevant messages are described below. AAL2 CAS message to be sent When the downlink ABCD notification changes, the ABCU microprocessor prompts the gateway 2014 to send a CAS notification cell. These cells are transmitted three times at 5 millisecond intervals. Gateway 2014 automatically generates second and third messages and sends them at 5ms intervals. Gateway 2014 automatically generates a 5-second CAS keep alive message for each of up to 1024 offered channels. AAL2 alarm message to send -AAL2 status message to be sent (including CO-IWF <-> CP-IWF built-in operating channel (EOC)) For uplink messages, Gateway 2014 validates the ATM header via HEC, validates the AAL2 header via HEC, validates the AAL2 type 3 PDU via CRC, and reports CAS. Except for the case of, it sends to the microprocessor of ABCU in addition to the VVC to which the gateway belongs. ABCU's microprocessor reserves enough queue space to buffer the maximum number of messages that should be received from gateway 2014 at any one time. More relevant messages are described below. · Received AAL2CAS message Gateway 2014 maintains a table of all current notification status for 1024 uplink channels. The initial state of each table item is provided. Gateway 2014 informs the ABCU microprocessor only when the CAS message indicates a state change. Gateway 2014 informs the ABCU microprocessor if three redundant messages are not received, if the ABCD bits of the three redundant messages do not match, and if the CASkeep alive message is not received every 5 seconds.

【0076】

Whenever gateway 2014 changes the state of a channel that is notifying bits, gateway 2014 sends a new notification bit to the microprocessor to ensure that it is not out of sync with it.

【0077】

Gateway 2014 does not need to perform this function because CP-IWF (Customer Home Network Connection Function, eg IAD) debounces the change in notification state before sending it to CO-IWF. Instead, Gateway 2014 sends all incoming notification state changes to the ABCU microprocessor. The notification state changes relatively slowly (up to 20 pulses / sec), so the notification state does not change during the 15 ms when the three redundant CAS notification cells are transmitted. Gateway 2014 operates according to the following algorithm.

【0078】

Receives the first of the three CAS notification PDUs (shown in the redundancy field).

【0079】

-Resets the three notification states that have changed due to the first, second, or third PDU flags.

【0080】

-If the CRC result of a type 3 message is bad, discard the message and count up the error counter.

【0081】

Alternatively, if the ABCD notification bit is different from the current state, send a new ABCD bit to the ABCU microprocessor and store the new ABCD bit in the gateway 2014.

【0082】

Flags notifications that have changed due to the first CAS PDU.

【0083】

-Alternatively, the notification status has not changed, so do nothing.

【0084】

End Receives the second of the three CAS notification PDUs (shown in the redundancy field).

【0085】

-If the CRC result of a type 3 message is bad, discard the message and count up the error counter.

【0086】

Alternatively, if the ABCD notification bit is different from the current state, flag it to indicate a notification that has changed due to the second CAS PDU.

【0087】

Send the new ABCD bits to the ABCU microprocessor and store the new ABCD bits in the gateway 2014.

【0088】

-Alternatively, the notification status has not changed, so do nothing.

【0089】

End Receives the third of the three CAS notification PDUs (shown in the redundancy field).

【0090】

-If the CRC result of a type 3 message is bad, discard the message and count up the error counter.

【0091】

Alternatively, if the ABCD notification bit is different from the current state, flag it for notification that has changed due to a third CAS PDU.

【0092】

Send the new ABCD bits to the ABCU microprocessor and store the new ABCD bits in the gateway 2014.

【0093】

-If the notification status flag changes because multiple CAS PDUs are set, an error message is sent to the ABCU microprocessor and the "signaling changing too often" error counter is counted up.

【0094】

End Received AAL2 alarm message Received AAL2 status message Because the gateway is an endpoint of ATM connectivity, it detects OAM (operation and maintenance) F4 and F5 loopback cells and sends them to the microprocessor. The gateway also sends OAM cells received from the microprocessor (from the ATM Utopia interface to the ABCU's switch fabric).

【0095】

Figure 10 shows the functions performed by various components of Gateway 2014 with respect to the conversion between ATM and TDM formats. The gateway contains a DSP device 2110 that contains n DSP cores in a DSP (digital signal processor) array 2112. When converting from ATM to TDM format, incoming AAL2 cells are routed by ATM interface logic 2111 based on UUI fields. The voice cell is routed to the appropriate one of the DSP cores in the DSP array 2112. The DSP core processes the cell as described herein, extracts the PCM audio band sample and sends it from the TDM interface 2018 to the SBI multiplexer 2113 via TDM interface logic 2017. ATM interface logic 2111 routes notification states, statuses, alarms (for AAL2 type 3) and OAM cells from DSP unit 2110 to gateway controller 2022. The gateway controller 2022 retrieves the ABCD notification bit for each channel and sends it to the microprocessor interface of the SBI multiplexer 2113. The SBI multiplexer 2113 multiplexes DS0 on the SBI towards the individual line connection device 24 (Fig. 2) and inserts a notification state from the gateway controller 2022. The gateway controller 2022 also programs the ATM VC / CID (call ID) to DSP mapping in the DSP device 2110 and also the DSP to SBI mapping in the SBI multiplexer 2113.

【0096】

In the TDM to ATM format conversion, the TDM data from the TSI cable 34 is provided to the SBI multiplexer 2113, which extracts the notification state and maps each input DS0 to the appropriate DSP core in the DSP device 2110. .. The voice band data is transmitted to the TDM interface 2018 of the DSP device 2110. The TDM interface logic 2017 in the DSP device 2110 provides voice band data to any one of the DSP cores in the DSP array 2112, which processes the TDM data as described herein. The output of the DSP core is provided to ATM interface logic 2111, which assembles the data into AAL2 cells. ATM interface logic 2111 maintains a DSP-to-VC / CID mapping to fill in cell headers. The SBI multiplexer 2113 routes the notification information from the TSI cable to the gateway controller 2022, which sends any ABCD notification bits from the common controller to the AAL2 cell assembly function in the DSP device 2110. Gateway controller 2022 programs the DSP-to-VC / CID mapping in DSP device 2110. The AAL2 ATM cell that carries in-band data is multiplexed with the ATM cell that carries out-of-band data and is transmitted out of the gateway ATM interface 2016.

【0097】

FIG. 12 is a diagram showing certain functions of Gateway 2014 regarding transmission of incoming and outgoing free lines. Voice-over-AAL2 cells from ADLU24 (Figure 2) are provided to ATM switch fabric 25, which routes those cells to the ATM interface of gateway 2014. Gateway 2014 performs AAL2 segmentation and reassembly (SAR) of voice band data. The output data is converted from ADPCM to PCM (if not yet in PCM format) within the transcoder 2310 and then provided to the appropriate one of the q SBI queues 2314. Gateway 2014 then performs near-end echo cancellation within Echo Canceller 2316 and provides its output to Gateway 2014's TDM interface 2018.

【0098】

FIG. 13 is a diagram showing voice processing executed for downlink transmission of a free incoming call line in gateway 2014. PCM data from SBI will be provided to Gateway 2014 via TDM Interface 2018. The near-end echo is erased in the echo canceller 2316. The output is provided to the transcoder 2314, which optionally converts the PCM data to ADPCM data. This data is then provided to the appropriate one of the q SBI queues 2312 (one for each free incoming line supported by ABCU22) and its output is provided to the AAL2 segmentation and reassembly unit 2312. .. The AAL2 SAR device provides an ATM voice cell to the ATM switch 25 via ATM interface 2016. The ATM switch 25 routes the voice-over-AAL2 cell to the appropriate ADLU24 (Figure 2).

【0099】

Figures 3, 4 and 11 show the Access Management System (AMS) 98. The AMS98 is a single-element management system that manages POTS integrated DLC / DSLAM / gateway 114 gateways and TDM and ATM routing capabilities, data and free incoming voice services. The AMS98 is particularly relevant to the information needed to manage each network element in the Litespan system. It contains the information needed to manage the network element functions within the Litespan system and the physical aspects of each network element. AMS98 also keeps track of information that physically and logically represents the access network. In particular, AMS98 recognizes how each of the network element entities is related, interconnected from a topographical point of view, and configured to provide and maintain end-to-end connectivity. To manage connectivity, AMS98 allows users to provide PVC and PVP via the Litespan system from the ATU-R to the gateway on one of the ABCUs in the Litespan system. As mentioned above, the gateway running the service for a given toll-free line does not have to be in the CBA containing the ADLU physically connected to the customer's home. The gateway may be on an ABCU in another CBA within the same Litespan terminal, or on a CBA in a central station terminal. The AMS98 also performs a number of additional element management and network management functions that are not important to the understanding of the present invention.

【0100】

As used herein, a given signal, event or value is a preceding signal, event or value if the signal, event or value preceding it affects a given signal, event or value. A value "reacts" to a given signal. A given signal, event or value may also "react" to a preceding signal, event or value if there is an intervening processing element, step or time interval. If the intervening processing element or step combines multiple signals, events or values, the signal output of the processing element or step is considered to "react" to each of the signal, event or value inputs. If a given signal, event or value is the same as the signal, event or value that precedes it, then this is a corruption that is considered to "react" to the signal, event or value that the given signal, event or value still precedes. It's just a case. A "dependency" on a given signal, event or value on another signal, event or value is defined as well.

【0101】

The above description of preferred embodiments of the present invention is for illustration and description purposes only and is not exhaustive and does not limit the invention to the disclosed form. It will be apparent to those skilled in the art that numerous modifications and modifications can be made to the present invention. In particular, for example, the loop emulation services described herein are provided on an ATM interface, but such services include IP, IP-over-ATM, and Frame Relay (FR), but this. It is understood that it can be provided otherwise or additionally via other types of packet / cell transport, but not limited to. In one embodiment, the integrated gateway described herein only requires software / firmware reprogramming to change its function from conversion between TDM and ATM transport to conversion between packet / cell transport different from TDM. In addition to, but not limited to, any, but not limited to, any, but not limited to, any modification of the invention described, proposed or incorporated as a reference in the background section of this patent application. It is specifically incorporated as a reference in the description of the embodiment. The embodiments described herein are selected and described to best illustrate the principles of the invention and its practical application, whereby other skilled artisans may also think of the invention with respect to various embodiments. It makes it possible to understand with various changes suitable for a particular usage. The scope of the present invention is described in the above-mentioned claims and claims for equivalent effect.

[Simple explanation of drawings]

[Figure 1]

It is a figure which shows the conventional network architecture symbolically.

[Figure 2]

It is a block diagram of the corresponding part of Litespan CBA in FIG.

[Fig. 3]

It is a figure which shows each part of the Litespan system which incorporated the function of this invention.

[Fig. 4]

It is a figure which shows each part of the Litespan system which incorporated the function of this invention.

[Fig. 5]

It is a figure which shows each part of the Litespan system which incorporated the function of this invention.

[Fig. 6]

It is a figure which shows each part of the Litespan system which incorporated the function of this invention.

[Fig. 7]

It is a figure which shows each part of the Litespan system which incorporated the function of this invention.

[Fig. 8]

It is a figure which shows each part of the Litespan system which incorporated the function of this invention.

[Fig. 9]

It is a figure which shows the communication protocol symbolically.

[Fig. 10]

It is a figure which shows the function performed by the gateway of FIG.

[Fig. 11]

It is a figure which symbolically shows the network architecture of FIG. 1 modified to incorporate the function of this invention.

[Fig. 12]

It is a figure which shows the function performed by the gateway of FIG.

[Fig. 13]

It is a figure which shows the function performed by the gateway of FIG.

[Fig. 14]

It is a figure which symbolically shows the flow of message transmission and reception via a conventional Litespan terminal.

[Fig. 15]

It is a figure which symbolically shows the flow of message transmission and reception through a Litespan terminal modified according to one aspect of this invention.

[Fig. 16]

It is a ladder diagram which shows the call flow using the configuration of FIG. 14 in the case of TR-8 connection.

[Fig. 17]

It is a ladder diagram which shows the modified form of the ladder diagram of FIG. 16 for carrying out the aspect of this invention.

[Fig. 18]

It is a ladder diagram which shows the call flow using the configuration of FIG. 14 in the case of GR-303 connection.

[Fig. 19]

It is a ladder diagram which shows the modified form of the ladder diagram of FIG. 18 for carrying out the aspect of this invention.

[Explanation of symbols]

98 AMS 110 data network 112 ATU-R 116, 119 splitter 120 ATM network 128 TDM port 133 Local Service Provider Central Office 310 Litespan Central Station Terminal (COT) 312 Central station (provider) 318 DSLAM 320, 322, 324 gateway function