Method and apparatus for channel management for point-to-multipoint services in a communication system.

(54) Title: METHOD AND APPARATUS FOR MANAGING CHANNELS FOR SERVICE FROM ONE POINT TO MULTIPLE POINTS IN A COMMUNICATION SYSTEM.

(54) Title: METHOD AND APPARATUS FOR CHANNEL MANAGEMENT FOR POINT-TO-MULTIPOINT SERVICES IN A COMMUNICATION SYSTEM.

(57) Summary

To enable both point-to-point and point-to-point communication services in an existing cellular communication system infrastructure, an apparatus and a system for managing channels and air functions associated with the use of them is described. Channels assigned for point-to-multi-point services in the cellular communication system infrastructure.

(57) Abstract

To enable both point-to-multipoint and point-to-point communication Services in an existing cellular communication system infrastructure, a apparatus and system for channel management and overhead functions associated with use of the assigned channels for point-to-multipoint Services in the cellular communication system infrastructure are described.

(12) INTERNATIONAL APPLICATION PUBLISHED UNDER THE PATENT COOPERATION TREATY (PCT) (19) World IntellectualProperty Organized

International Burean (43) International Publication Date

October 2002 (10.10.2002)

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PCT

IN (10) International Publication Number

WO 02/080609 Al (51) International Patent Classification⁷: H04Q 7/38 (21) International Application Number: PCT / US02 / 09827 (22) International Filing Date: 28 March 2002 (28.03.2002) (25) Filing Language: English (26) Publication Language: English (30) Priority Data:

60 / 279,970 March 28, 2001 (03/28/2001) US (71) Applicant: QUALCOMMINCORPORATED [US / US];

5775 Morehouse Drive, San Diego, CA 92121-1714 (US).

(72) Inventors: CHEN, Tao; 5415 Harvest Run Drive, San Diego, CA 92130 (US). HEDEMANN, Edward, G., ΠΙ; 656 Barretts Mill Road, Concord, MA 01742 (US). WANG, Jun; 13203 Winstanley Way, San Diego, CA 92130 (US), (74) Agents: WADSWORTH, Philip, R. et al .; Qualcomm Incorporated, 5775 Morehouse Drive, San Diego, CA 921211714 (US).

(81) Designated States (national): AE, AG, AL, AM, AT, AU, AZ, ΒΑ, ΒΒ, BG, BR, BY, BZ, CA, CH, CN, CO, CR, CU, CZ, DE , DK, DM, DZ, EC, EE, ES, El, GB, GD, GE, GH, GM, HR, HU, ID, IL, IN, IS, JP, KE, KG, KP, KR, KZ, LC , LK, LR, LS, LT, LU, LV, MA, MD, MG, MK, MN, MW, MX, MZ, NO, NZ, OM, PH, PL, PT, RO, RU, SD, SE, SG , SI, SK, SL, TJ, TM, TN, TR, ΊΤ, TZ, UA, UG, UZ, VN, YU, ZA, ZM, ZW.

(84) Designated States (regional): NBIPO patent (GH, GM, KE, LS, MW, MZ, SD, SL, SZ, TZ, UG, ZM, ZW), Eurasian patent (AM, AZ, BY, KG, KZ, MD, RU, TJ, TM), European patent (AT, BE, CH, CY, DE, DK, ES, El, FR, GB, GR, IE, IT, LU, MC, NL, PT, SE, TR), OAPI patent (BF, BJ, CF, CG, CI, CM, GA, GN, GQ, GW, ML, MR, NE, SN, TD, TG).

Published:

- with international search mport - befare the expiration of the time limtt for amending the claims and to be republished in the event of receipt of amendments

[Continued on nextpage] (54) Title: METHOD AND APPARATUS FOR CHANNEL MANAGEMENT FORPOINT-TO-MULTIPOINT SERVICES IN A COMMUNICATION SYSTEM

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WO 02/080609 Al IIIIIHM (57) Abstract: To enable both point-to-multipoint and point-to-point communication Services in an existing cellular communication system infrastructure, a apparatus and system for channel management and overhead functions associated with use of the assigned channels for point-to-multipoint Services in the cellular communication system infrastructure are described.

METHOD AND APPARATUS FOR THE MANAGEMENT OF CHANNELS FOR SERVICES FROM ONE POINT TO MULTIPLE POINTS IN A COMMUNICATION SYSTEM

BACKGROUND OF THE INVENTION

Field of the invention

The present invention relates to point-to-multi-point services in a wireless or wire communication system. More specifically, the present invention relates to a method and apparatus for managing channels in these point-to-multiple-point services in a communication system.

Background of the Invention

Communication systems have been developed to allow the transmission of information signals from a source station to a physically different destination station. In the transmission of an information signal from the originating station through a communication channel, the information signal is first converted into a form suitable for efficient transmission through the communication channel. Conversion, or modulation, of the information signal involves varying a parameter of a carrier wave in accordance with the information signal in such a way that the spectrum of the resulting modulated carrier wave is confirmed within bandwidth 5 of the communication channel. . At the destination station, the original information signal is duplicated from the modulated carrier wave that was received through the communication channel. This duplication is generally achieved by using a reverse modulation process employed by the originating station.

Modulation also facilitates multiple access, that is, the simultaneous transmission and / or reception, of several signals through a common communication channel. Multiple access communication systems frequently include a plurality of remote subscriber terminals. requiring intermittent service of relatively short duration preferably than continuous access to the common communication channel. Various multiple access techniques are known in the field, such as time division multiple access (TDMA), frequency division multiple access (FDMA), and radio multiple access. modulation of

I amplitude (AM). Another type of a multiple access technique is a code division multiple access (CDMA) spread spectrum system that conforms to the Mobile Station-Base Station Compatibility Standard for the Cellular Spectrum System. TIA / EIA / IS-95 Dual Mode Wideband Extended, later referred to as the IS-95 standard. The use of CDMA techniques in a multiple access communication system is described in US Patent No. 4,901,307, entitled SPREAD SPECTRUM MULTIPLE-ACCESS COMMUNICATION SYSTEM USING SATELLITE OR TERRESTRIAL REPEATERS, and US Patent No. .

5,103,459, entitled SYSTEM AND METHOD FOR GENERATING

WAVEFORMS IN A CDMA CELLULAR TELEPHONE SYSTEM, both assigned to the assignee of the present invention.

A multiple access communication system can be a wireless or wire system and can carry voice and / or data. An example of a communication system that carries both voice and data is a system in accordance with the IS-95 standard, which specifies the transmission of voice and data through the communication channel. A method of transmitting 25 data in s code channel frames or frames

Fixed size is described in detail in United States Patent No. 5,504,773, entitled METHOD AND APPARATUS FOR THE FORMATTING OF DATA FOR TRANSMISSION, assigned to the assignee of the present invention. According to the IS-95 standard, data or voice is divided into code channel frames that are 20 milliseconds wide with data transfer rates as high as 14.4 Kbps. Additional examples of communication systems that carry both voice and data include the communication systems that conform to the 3-Generation Partnership Project (3GPP), incorporated into a set of documents that include the Documents

Nos. 3G TS 25.211, 3G TS 25.212, 3G TS 25.213 and 3G

TS 25.214 (the W-CDMA standard), or the CDMA2000 TR-45.5 Physical Layer Standard for Spread Spectrum Systems (the IS-2000 standard).

In a multiple access communication system, communications between users are conducted through one or more base stations. A first user at a subscriber station communicates with a second user at a second subscriber station by transmitting data on a link back to a base station. The base station receives the data and can direct the data to another base station. The data is transmitted on a forward link from the same base station, or the other base station, to the second subscriber station. Similarly, communication can be conducted between a first user at a mobile subscriber station and a second user at a land line station. A base station receives user data on a return link and routes the data through a public switched telephone network (PSNT) to the second user.

The wireless communication service described above is an example of a point-to-point communication service. In contrast, a point-to-multiple-point service is a service where the information provided by one source of the information is proposed to a plurality of users. The basic model of a one-point-to-multiple-point communication system comprises a set of users at subscriber stations, a group of which receives information from one or more information sources via a wireless or wire network. In a one-point-to-multiple-point service, in which the source determines the content of the information in a fixed manner, eg news, movies, sporting events, and the like, users generally do not communicate back. In order to save resources, in general, each user subscriber station participating in the point-to-multi-point service (at a subscriber station, member) monitors a shared channel that is modulated by the information. This one-point-to-multiple-point service is also referred to as broadcast or multicast, examples of common use of which include TV broadcast, radio broadcast, and the like. Alternatively, the information source is a user, a group member, who transmits proposed information for the remaining 15 members of the group. If the user wishes to speak, a push-to-talk (PTT) button is pressed. Typically, the speaking user's voice is routed from the subscriber station to the network on a dedicated, backhaul channel. The network then transmits the voice of the speaking user over a shared forward link channel. As in the case of the point-to-point communication system, this communication system allows both the land line and wireless subscriber station 25 to access the system. This one point to multiple point service is also referred to as a group service. Examples of the use of the group service communication system are in dispatch services, 5 such as local police radio systems, taxi dispatch systems, federal intelligence agency operations and secret service, and military communication systems. , general.

The aforementioned point-to-multipoint service communication systems are generally highly specialized, purpose-built communication systems. With recent advances in wireless cellular telephone systems, there has been an interest in utilizing the existing infrastructure of primarily point-to-point cellular telephone systems for point-to-multipoint services. As used in this text, the term "cellular system" includes a system that operates on both the personal and cellular communication system (PCS) frequencies.

As described, to save resources, in general, point-to-multipoint services rely on the allocation of a shared forward link channel to be monitored by all member users. In contrast, wireless cellular telephone systems allocate dedicated, round-trip link channels between a base station or a sector whose coverage area contains users who wish to communicate. Due to the limited number of these dedicated, roundtrip link channels that can be supported by a 10 wireless cellular phone system, the number of members who could participate in a one-point-to-multiple-point service provided through the Dedicated roundtrip link channels is limited. Furthermore, both group services and telephony services are required to be enabled in wireless cellular telephone systems. Therefore, there is a need in the field for a method and apparatus for this channel management that makes both group services and telephony services possible using an existing infrastructure of a wireless cellular telephone system.

SUMMARY OF THE INVENTION

In one aspect of the invention, the needs established above are addressed by channel management in a communication system, which comprises the assignment to each subscriber station, belonging to a group, of a shared forward channel during an active period. ; and assigning to each subscriber station, belonging to a group, a forward channel during a period of silence.

In another aspect of the invention, the needs set forth above are addressed by channel management a communication system, which comprises assigning to each subscriber station, belonging to a group, a return channel, dedicated during an active period; modulating 15 by means of an active subscriber station belonging to the group, the dedicated return channel by user data and control data; and modulate by means of the passive subscriber station belonging to the group, the return channel dedicated by 20 control data.

In yet another aspect of the invention, the needs set forth above are addressed by modulating a backhaul channel by a request to transmit by a subscriber station, belonging to a group; and receiving via a forward link channel, monitored by the subscriber station, a response to the request to transmit. The return link channel used and the forward link channel monitored by the subscriber station depend on a state of the activity of the service from one point to multiple points, for example a period of silence and active. The response may comprise a backhaul link channel assignment and explicit permission to transmit.

In still another aspect of the invention, the needs established above are addressed by assigning different go links to be monitored and return links to be used by mobile stations, members according to the activity of the service from one point to multiple points. , for example a period of silence and active.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 illustrates a conceptual diagram of a point to multiple point service communication system.

DETAILED DESCRIPTION OF THE INVENTION

Definitions

The word exemplary is used exclusively in this text to imply that 5 serves as an example, instance or illustration. Although the best mode is contained in this text, one mode described as exemplary should not necessarily be construed as preferred or advantageous over other modes.

The term point-to-point communication is used in this text to mean a communication between two subscriber stations via a dedicated go communication channel and a dedicated return communication channel.

I

The term "point-to-multipoint communication service" is used in this text to mean a communication wherein a plurality of subscriber stations are receiving communication from - typically - one source. These 20 services may comprise, for example, group service, in which the source is a subscriber station; a broadcast service, in which the source is a central station; or a multicast service, in which the receivers comprise a subset of the plurality of stations from

I subscriber.

The term access network is used in this text to mean a collection of base stations and one or more base station controllers. The access network carries data between multiple subscriber stations. The access network can further be connected to additional networks outside the access network, such as a constituted intranet or the Internet, and can carry data 10 between each access terminal and these outside networks.

The term base station is used in this text to mean the physical components (hardware) with which the subscriber stations 15 communicate. Cell refers to the physical components or a geographic coverage area, depending on the context in which the term is used. A sector is a division of a cell. Because a sector has the attributes of a cell, the teachings described in terms of base stations / cells are easily extended to sectors.

The term subscriber station is used in this text to mean the physical components with which an access network communicates.

A subscriber station can be mobile or stationary. A subscriber station can be any data device that communicates over a wireless channel or through a wired channel, for example using fiber optics or coaxial cables. A subscriber station can further be any of a variety of device types including, but not limited to, PC card, compact flash, internal or external demodulator modulator, or cordless or wireline telephone.

A subscriber station that is in the process of establishing an active traffic channel connection with a base station is said to be in a connection setup state.

The term physical channel is used in this text to mean a communication path over which a signal is propagated, described in terms of modulation and coding characteristics.

The term logical channel is used in this text to mean a communication path within the protocol layers of either the base station or the subscriber station.

The term communication channel / link is used in this text to mean a physical channel or a logical channel according to context.

The term return channel / link is used in this text to mean a communication channel / link through which the subscriber station sends signals to the base station.

The forward link / channel is used in this text to mean a communication channel / link through which a base station sends signals to a subscriber station.

The term soft handoff is used in this text to mean a communication between a subscriber station and two or more sectors, where each sector belongs to a different cell. The back link communication is received by₍ Both sectors and the forward link communication is carried simultaneously on the two or more forward links of the sectors.

The term "softer handoff" is used in this text to mean a communication between a subscriber station and two or more sectors, where each sector belongs to the same cell. The return link communication is received by both sectors and the forward link communication is carried simultaneously on one of the two or more forward links of the sectors.

The term puncture is used in this text to mean the replacement of a first information content of a first size with a second information content of a first size.

The term dedicated channel is used in this text to mean an information modulated channel specific to an individual subscriber station.

The term common channel is used in this text to mean a channel modulated by information shared between all subscriber stations.

The term user data or payload is used in this text to mean data other than control data.

The term control data is used in this text to mean the data that make possible the operation of entities in a communication system. The control data comprises, for example, call maintenance signaling, diagnostic and reporting information, and the like.

Description

Figure 1 illustrates a conceptual diagram of a communication system 100 capable of providing point to multiple point services in accordance with embodiments of the present invention. For didactic purposes, the following description illustrates a group service; however, a person of ordinary experience in the field understands how to apply the concepts described to other services from one point to multiple points. A (calling) group is defined by the membership of the group, which comprises subscriber station users who talk to each other frequently enough to establish the calling group. The calling group is said to be in a sleep state when no member is either idle or active, eg, all members either do not participate in the calling group or have deactivated their subscriber stations. The calling group is in the idle state when at least one member participates in the group. The calling group is in the active state when one of at least two members 20 initiates a group call. A group call is divided into active and silent periods. The group call is in the active period when there are transmissions between the members without long idle periods. In the group call it is in a period of silence when there is no member that transmits any traffic during a period that extends the long idle period.

In an active period, a group user at a subscriber station, for example subscriber station 102 (1), communicates user information (voice or data) to other group users at subscriber stations 102 (2) through 102 (5) by means of an access network comprising base stations 104 and a controller 110. For short, the term subscriber station, member is used later to mean a user of the group at a subscriber station unless stated otherwise. Base stations 104 are connected to controller 110 by reverse ranges 112. The term reverse range is used to mean a communication link between a controller and a base station. Reverse scope 112 can be implemented in a variety of connection types including, for example, microwave or El or Ti wireline, fiber optic, and other types of connection known to a person skilled in the field. Controller 110 is connected to an interface unit 114, which interfaces communication system 100 with other services (not shown), for example a public switched telephone network (PSTN), a packet data service node (PDSN, for its acronym in English) and other services known to ordinary experts in the field.

When a subscriber station, member, for example subscriber station 102 (1), wishes to transmit user data to the group via the return link, the subscriber station, member, needs to request an assignment of a return link and permission to transmit. A control unit located in the individual sector, in a base station that comprises the sector, in the controller, or in any other element that comprises the access network, is responsible for channel assignment. The subscriber station member is then provided with the assignment by means of a forward link channel monitored by the subscriber station. The return link is divided into return link channels. Once the subscriber station, member 102 (1) is assigned a return link channel 108 (1), the subscriber station 102 (1) can transmit information to a base station 104 (1). This subscriber, member, transmitter station is referred to as an active member or speaking element. The base station 104 (1) directs the received information to the base stations

I

104 (2) and 104 (3) and transmits the received information on a shared forward link channel 106 (1) to the subscriber station 102 (2). Base stations 104 (2) and 104 (3) transmit the directed information on shared forward link channels 106 (2) and 106 (3). To receive the information of the active member subscriber station 102 (1), all the subscriber stations, members of an active group, i.e. the subscriber stations 102 (1) through 102 (5) are assigned to monitor the Forward link shared channel (s) 106 of your individual base stations 104 during active group calls. In general, the shared forward link channels 106 (1), 106 (2) and 106 (3) allocated by the respective base stations or 104 (1), 104 (2) and 104 (3) are different from each other. However, to allow for improved reception of subscriber stations, members 102 located in overlapping coverage areas, the shared forward link channel 106 can be transmitted synchronously by more than one sector or base station 104. The method of improved reception of the shared, common, forward link channel in the overlapping coverage areas is described in co-pending application serial number 09 / 933,607, entitled

METHOD AND SYSTEM FOR A HANDOFF IN A BROADCAST COMMUNICATION SYSTEM, filed August 20, 2001, assigned to the assignee of the present invention. An ordinary skilled person in the field 5 recognizes that a base station serving an area can be divided into sectors. Consequently, the terms sector or base station are used interchangeably, unless expressly specified otherwise.

In one embodiment, the shared forward link channel 106 is modulated by proposed user information for subscriber stations, members, and control data, eg, signaling information, power control information, and other types of necessary information. for the operation of the entities of the communication system known to the person skilled in the field. However, the limited capacity of a shared forward link channel can prevent modulation by both call information and call maintenance information. Consequently, in another embodiment, only user information is transmitted on shared forward link channel 106 and control data may be modulated on an additional forward link channel, later referred to as a forward link channel. control / signaling. In that case, each subscriber station member 102 must monitor, in addition to the shared forward link channel, the control / signaling forward link channels. This control / signaling channel can be a dedicated channel or a common channel.

When the active period ends, ie the subscriber station, member 102 (1) terminates communication and no other subscriber station, member 102 initiates communication for a first determined time interval, a period of silence begins. To reduce wasted capacity, subscriber stations, members 102 stop monitoring the shared forward link channel 106 and the control / signaling forward link channels if they are monitored, and start monitoring a forward link channel determined, thus transiting in a latent state. In one embodiment, transmission of the shared forward link channel 106 may cease. The term latency is used in this text to mean a state of which the subscriber stations, members 102 transition to monitoring the shared forward link channel according to a predetermined procedure. This default procedure can be implemented as a state machine. After a determined second time interval of lack of group communication activity, the subscriber stations, members 102 transition from the dormant state to an idle state. In the idle state, the subscriber stations, members 102 monitor a given forward link channel, but a transition to the forward link shared channel monitoring is carried out according to a predetermined procedure different from the predetermined procedure for the transition to latency forward link shared channel monitoring. Additionally, if the subscriber stations, members 102 knew that the end group call, the subscriber stations, members 102 can transition directly to the idle state.

In another embodiment, the subscriber stations, members 102 are instructed by a control entity via the base stations 104 to transition to an appropriate state.

When the silence period ends and an active period begins, the subscriber stations, members 102 transition from the dormant or idle state back to the shared forward link channel 106. Subscriber stations, members 102 are notified about the start of the active period by means of signaling messages transmitted via base stations 104 on the forward link channels monitored by subscriber stations, members 102 in the dormant state or at rest.

An application of the concepts described above is explained in further detail below for a communication system according to the IS-2000 standard. Although specific channels for the communication system according to the IS-2000 standard are used in the following answer for didactic purposes, a person skilled in the field will be able to extend the concepts described above to communication system channels according to other standards.

Ida Link Channel Assignment

To maximize capacity and minimize power while allowing multiple users to receive user communication (voice or data), members of an active group are assigned to a shared forward link channel of their individual sectors during group calls. Active, ie, member subscriber stations are provided with information that enables the member subscriber station to receive modulated data on the shared forward link channel. In one embodiment, in a communication system in accordance with the IS-2000 standard, the forward link shared channel comprises a Forward Complementary Channel (F-SCH), which is modulated by both the user data as control data and is shared by subscriber stations, members in a sector coverage area. When a subscriber station member joins an active group, a control entity by means of an appropriate sector assigns the subscriber station member to supervise (demodulate) the F-SCH (s) shared by a finite or infinite duration. This assignment is done by sending an assignment message on the channel, which the subscriber station monitors while it is in an idle or dormant state. The shared F-SCH (s) can operate in a fixed speed mode for simplicity or a variable speed mode for more flexibility. The term variable mode is used in this text to mean that a data transfer rate can change within an agreed set of data transfer rates without notification.

Once the subscriber station, member is monitoring the F-SCH (s), the control data necessary to maintain the call, for example, a pilot resistance measurement message, transfer direction message, handover completion message and other messages known to a person skilled in the field and group call related control data can also be sent to the F-SCHs. Messages related to the group call may comprise, for example, the start and end of the group call, request and grant of a right to transmit and other messages known to a person of ordinary skill in the field. Because the F-SCH is a shared channel, appropriate addressing information from the subscriber station member must be used so that the subscriber station member can discern the shared information that is directed to all subscriber stations. , members from dedicated information that is directed to a particular subscriber, member, station. The control data messages and the addressing header of the subscriber stations, members negatively affect the user data portability of the F-SCHs. Therefore, alternatively, the control data messages are carried on the forward control / signaling link channel (s).

In one embodiment, the control / signaling forward link channel, which the control entity by means of a sector assigns to each individual, member, subscriber station in a communication system according to the IS-2000 standard, comprises a channel of Dedicated Control of Ida (F-

DCCH, for its acronym in English). In addition to other control data messages, the F-DCCH can also be modulated by backlink power control commands that control the transmit power level of a subscriber station, transmitting member on a link channel of Return. Power control commands comprise an Outbound Power Control Subchannel (F-PCSCH), which is tapped on the FDCCH. The term punctured is used in this text to mean the sending of a link power control command back instead of an F-DCCH command. When there is no signaling load on the F-DCCH, only FPCSCH is transmitted, thus little power and capacity is consumed. However, other power control methods are contemplated for a one-point-to-multiple-point service communication system as described in co-pending application serial number XX / XX, XXX, entitled POWER CONTROL FOR POINT-TO-MULTIPOINT SERVICES. PROVIDED IN COMMUNICATION SYSTEMS, filed March 28, 2002, assigned to the assignee of the present invention.

Alternatively, the control / signaling forward link channel, which the control entity by means of a sector assigns to each individual subscriber station, member, in a communication system according to the IS-2000 standard, comprises a Ida Common Control Channel (F-CCCH), an Ida Broadcast Channel (F-BCCH), or a combination of F-CCCH and F-BCCH. Consequently, the signaling messages for the subscriber station, member are modulated on the F-CCCH / F-BCCH. Additionally, the return link power control commands that control the transmit power level of a subscriber station, transmitting member of a return link channel can be modulated into a 5-Channel Common Outgoing Power Control Channel. (F-CPCCH, for its acronym in English). When there is no signaling load on the F-CCCH / F-BCCH, only the F-CPCCH is transmitted, thus little power and capacity is consumed. The use of the F-CPCCH is described in the co-pending application, mentioned above, serial number XX / XX, XXX, entitled POWER CONTROL FOR POINT-TO-MULTIPOINT SERVICES PROVIDED IN COMMUNICATION SYSTEMS, filed March 28, 2002, assigned to the assignee of the present invention.

The subscriber station member can inform the broadcast sector about the quality of service (QoS). In this way, in one embodiment, when the common information modulating the forward link shared channel is received in error, the subscriber station member can inform the transmitting sector about the error and the information can be retransmitted. In a communication system in accordance with the IS-2000 standard, the Access Channel

Return Enhanced (R-EACH) can be used to report QoS. In one embodiment, retransmissions take place on the shared forward link channel. In another embodiment, retransmissions take place on the forward control / signaling link channel assigned to the subscriber station, member, eg, F-DCCH, F-CCCH, F-BCCH. This is feasible when the time lag or lag variation caused by the transmission is tolerable for the application. Details on retransmission are described in copending application serial number 09 / 989,347, filed July 2, 2001 entitled SYSTEM AND METHOD FOR FRAME RE-TRANSMISSION IN A BROADCAST COMMUNICATION SYSTEM, assigned to the assignee of the present invention.

In another embodiment, the forward link shared channel comprises an F-CCCH, an F-BCCH, or the combination of the F-CCCH and the F-BCCH. Member subscriber stations can share the F-CCCHs and F-BCCHs for group calls, while non-member subscriber stations monitor the F-CCCHs and F-BCCHs for paging. The FCCCH (s) and F-CCCH (s) assigned for group calls can operate in a fixed rate mode for simplicity or a variable rate mode for more flexibility. Because F-CCCH and F-BCCH are common channels, appropriate subscriber station addressing information must be used so that a subscriber station can discern the shared information that is proposed for subscriber stations. , members from that of information directed to an individual subscriber station.

To avoid the addressing header, in one embodiment, the F-CCCHs and F-BCCHs can be divided so that the F-CCCHs and F-BCCHs in a sector are designated as 15 shared forward link channels for the subscriber stations, members for one point to multiple point services and the remaining F-CCCHs and F-BCCHs are designated exclusively for paging of non-member subscriber stations.

As described, the signaling messages and the subscriber station addressing header negatively affect the traffic capacity of the forward link shared channel (s), therefore, alternatively, the 25 Signaling messages are carried on a forward control / signaling link channel.

Consequently, when some of the F-CCCHs and F-BCCHs in a sector or base station are assigned as shared forward link channels for point-to-multipoint services, an F-CCCH and a Fast Paging Channel of go (F-QPCH) associated with the additional F-CCCH can be added for paging and an additional F-BCCH can be used for signaling the service from one point to multiple points. Member subscriber stations continuously monitor the F-CCCH (s) and F-BCCH (s) assigned to the group as shared forward link channels and the signaling F-BCCH. In addition, each subscriber-member station is assigned to monitor a slot on the F-QPCH to decide whether there is a need to monitor the F-CCCH associated with the F-QPCH for paging information. This use of the F-QPCH and the associated F-CCCH is fully described in the IS-2000 standard, thus known to a person of ordinary skill in the field.

When an active member subscriber station communicates with the base station, in one mode the return link power commands are transmitted on the shared forward link channels, ie, F-CCCH / F-BCCH. In another embodiment, the backlink power commands for both the 5-member subscriber stations and the non-member subscriber stations are modulated on an F-PCSCH. To properly interpret the backlink power commands, each individual subscriber station monitors a different understream of the power control commands 10 on the F-PCSCH assigned to the subscriber station. Alternatively, some of the F-PCSCHs in a sector or base station are assigned to subscriber stations, members only, while other F-CPCCHs are assigned to subscriber stations, non-members.

Again, each individual subscriber station is assigned to monitor a different understream of power control commands on the assigned F-PCSCHs. The use of F-CPCCHs is described in the co-pending application, mentioned above, serial number XX / XX, XXX, entitled METHOD AND APPARATUS FOR A POWER CONTROL IN A POINT-TOMULTIPOINT SERVICES IN A COMMUNICATION SYSTEM, filed on 28 March 2002, assigned to the assignee of the present invention.

The subscriber station member can inform the broadcast sector about the quality of service (QoS). In this way, -in one embodiment, when the common information modulating the shared forward link channel F-CCCH (s) or FBCCH (s), is received in error by a subscriber station, member, the subscriber station , member can use a return enhanced access channel (R-EACH) to inform the transmitting sector about the error and the information can be retransmitted. Retransmissions can take place on the F-CCCH or F-BCCH of the group call. Retransmission is feasible when the time lag or delay variation caused by retransmission is tolerable for the application. Details on retransmission are described in copending application, cited above, serial number 09 / 898,347, filed July 2, 2001, entitled SYSTEM AND METHOD FOR FRAME RETRANSMISSION IN A BROADCAST COMMUNICATION SYSTEM, assigned to the assignee of the present invention. .

Return Link Channel Assignment

As described above, generally only one subscriber station member transmits on a return link at a time. Consequently, although passive member subscriber stations do not transmit user data over the link back to either sector, passive member subscriber stations may need to use a return link to communicate with the sectors necessary information. for call maintenance, eg handoff messages, power control, or other information known to a person of ordinary skill in the field. The term passive is used in this text to mean a subscriber station, member that monitors a shared forward link channel and any control / signaling forward link channel required for the group call, but does not transmit data user on a backhaul channel. In addition, the passive member subscriber station may wish to communicate some data; therefore, the passive member subscriber station needs means to request a return traffic channel assignment. Consequently, passive, member, subscriber stations need to be assigned back link channels.

According to one embodiment, the control entity by means of a sector assigns to each individual subscriber station, member, a dedicated return channel, which, in a communication system according to the IS-2000 standard, comprises a Return Dedicated Control Channel 5 (R-DCCH), with the binding of an active group. Passive, member, subscriber stations use the R-DCCH to transmit control data for regular calls (e.g. forward link pilot report), and to transmit control data related to group call (e.g. , forward link broadcast channel quality metric report, request for a return link traffic channel assignment). The active member station 15 further uses the R-DCCH to transmit user data. When transmitting the R-DCCH, the subscriber station member also transmits a Return Pilot Channel (R-PICH) and a Return Power Control Subchannel (R-PCSCH). The R-PCSCH carries feedback on a forward link shared channel quality metric.

Because the R-DCCH is modulated by control data only, there are periods in which there is no need to transmit this information. Consequently, the passive member subscriber station may stop transmitting the R-DCCH and may transmit only the R-PICH multiplexed with the R-PCSCH. This mode of operation is described in the IS-2000 standard.

If the idle periods exceed a predetermined interval, a further reduction in power and capacity consumption can be achieved by unlocking the R-PICH / R-PCSCH. The term "unlock" used in this text means to activate the transmission of the R-PICH / R-PCSCH only in predetermined power control groups (PCGs). Additionally, as the frequency of the power measurement in the sectors decreases because the need for precise control of the return link power becomes less important, the data transfer rate in the corresponding substream in the F decreases. -CPCCH that carries the control power commands back. Rate reduction on the F-CPCCH is achieved by assigning the unlocked member subscriber station to a lower rate substream of the F-CPCCH or by sharing a higher rate substream by multiple unlocked member subscriber stations.

Furthermore, if there is no need to transmit the power control commands, the R-PCSCH transmission may be discontinued because, according to the IS-2000 standard, the only transmission required from the subscriber station is the R -PICH, that is, the R-PICH is sent continuously without the multiplexed R-PCSCH. Additionally, the transmission on the R-PICH / R-PCSCH can be stopped together. This results in the stopping of the undercurrent at the corresponding F-CPCCH.

Also, a combination of the two methods can be used. In this method, the subscriber-station member initiates the transmission of R-PICH / RPCSCH unlocked after a first interval of inactivity and stops the transmission of R-PICH / RPCSCH after a second interval of inactivity. Consequently, the data transfer rate of the corresponding F-CPCCH is reduced.

If the subscriber station, member needs to transmit control data signaling messages to a sector during the unlocked or stopped mode on the R-DCCH, a transmission of a first signaling message ends the unlock, that is, the R-PICH , R-PCSCH and R-DCCH are activated continuously during the signaling message. Once the signaling messages have been sent, the subscriber station reverts to the unlocked or stopped mode as previously described. Furthermore, to assist the industry in acquiring the subscriber station signal, the RPICH may be activated in advance of the RDCCH message, possibly at a high power level, as a preamble.

In an alternative embodiment, only the active member subscriber station is assigned a dedicated backhaul link channel, eg RDCCH. Passive member subscriber stations are not assigned dedicated backhaul link channels. Instead, passive, member, subscriber stations use an enhanced R-EACH return access channel to signal the return link when needed, using basic access, reservation access, and power control access. Basic access, reservation access and power control access are defined in the IS-2000 standard, therefore they are well known to an ordinary skilled person in the field.

According to the basic mode of access, the subscriber station, member randomly selects an R-EACH and transmits a preamble with the increased power on the R-PICH, followed by the message on the R-EACH. The subscriber-station member then monitors the shared forward link channel for acknowledgment and initiates transmission on the R-EACH upon receipt of the acknowledgment.

According to the reservation access, the subscriber station, member randomly selects an R-EACH and transmits a short header to a sector in the R-EACH to reduce the probability of collision with other access attempts in the R-EACH, which could result in the loss of the access attempt. The sector sends an Early Recognition Channel Assignment (EACAM) message on an Outbound Common Assignment Channel (F-CACH) to sign a return common control channel (R-CCCH) to the subscriber station, member. The subscriber-station-member then monitors the shared forward link channel for the EACAM and initiates transmission on the R-CCCH upon receipt of the EACAM.

In another embodiment, a member subscriber station transmits on an R-EACH in a Power Controlled Access Mode (PCAM). In PCAM, the access procedure is similar to reservation access and the transmission in the R-EACH is controlled by its power by the designated power control bits that are sent by the base station with the acquisition of the R-EACH in the Ida Common Power Control Channel (FCPCCH).

Transmission to the Group

When a subscriber station, member wants to transmit voice or data to the group, the subscriber station, member needs to be assigned a return channel and receive permission to transmit.

As described, in one embodiment, each subscriber station member is assigned a backhaul link channel to transmit control data, eg, an R-DCCH with the joining of an active group. When the group activity ends, there is no need for the subscriber stations, members to transmit control data, therefore, after a predetermined period of group call inactivity, the subscriber stations, members release the channel of link back and start monitoring a different back link channel used for a system access of. 41 communication. In one embodiment, the subscriber station, member monitors a return access channel (R-ACH) or a return enhanced access channel (R-EACH). Consequently, when a subscriber station, member in an active group call, with inactivity that does not exceed the period of time necessary to transmit user data, a control data signaling message is sent through the R-DCCH from the subscriber station, 10 member to a sector. If the subscriber station member has released the R-DCCH, the subscriber station member sends a control data signaling message on the R-ACH or R-EACH.

In one embodiment, the control data signaling message is a request for permission to transmit. Upon receipt of the request, the industry issues permission to transmit via a forward link channel monitored by the subscriber station, member. As described above, when the silence period exceeds a predetermined interval, the subscriber stations, members stop monitoring the shared forward link channel and the control / signaling forward link channels, if monitored, and start monitoring. monitor a given forward link channel, thus transiting in a latent state. Therefore, if there are recent group activities that do not exceed the predetermined period of inactivity, the subscriber station, member is monitoring the shared forward link channel or the control / signaling forward link channels; consequently, the permit is issued on the forward link shared channel or the control / signaling forward link channels. If the member subscriber stations released the shared forward link channel and the control / signaling forward link channels, permission is issued on the monitored forward link channel by the member subscriber stations. In this case, all subscriber stations, members must also be sent a signaling message to initiate the forward link shared channel supervision in their sectors and the control / signaling forward channel if this is used. channel.

The return link transmission may proceed on the return link channel, eg the R-DCCH, once the subscriber station member receives permission to use the R25 DCCH. Alternatively, the return link channel assigned for communication may comprise, for example, a Return Common Control Channel (R-CCCH), a Return Fundamental Channel (RFCH) or a Return Complementary Channel (R-SCH) .

The R-SCH allocation can be infinite.

The assignment is revoked when the member subscriber station informs the sector through the RDCCH that the communication is terminated or when the sector detects the termination of transmission of the member subscriber station for a predetermined period of time. The base station can then assign the R-SCH to another subscriber station, member who wishes to transmit to the group. Because there is at least one subscriber station, a member transmitting at any given time, there will be at least one R-SCH in all sectors containing subscriber stations, members, active to support a group call.

As described, in one embodiment, the 20 subscriber stations, members are not assigned individual RDCCHs, but use the R-EACH for backhaul signaling and communication when necessary. Consequently, the request for permission to transmit is sent using the R25 EACH or an R-EACH and R-CCCH. The R-EACH or the R-EACH / R

CCCH are used in the basic access mode, reservation access and power control access as defined in the IS-2000 standard.

Upon receipt of the request, the base station assigns the subscriber station, member, an R-FCH, an R-DCCH, an R-CCCH or an R-SCH and issues permission to initiate transmission through the channels one way monitoring subscriber station, member. Therefore, if there are recent group activities and the subscriber station, member is monitoring the forward link broadcast channel, the permission is issued on the forward link broadcast channel, for example the F-SCH, F-CCCH / F-BCCH or the F-DCCH monitored by the subscriber station, member. If the subscriber stations, members released the forward link shared channel or the F-DCCH, the permission is issued on an F-PCH or F-CCCH. In this case, all subscriber-member stations must also be sent a signaling message to begin monitoring the forward link broadcast channel in their sectors and a control / signaling forward channel if that is used. channel.

If the subscriber station, member wishing to transmit is granted an R-FCH or an R-DCCH, the R-FCH or R-DCCH establishment and release procedures according to the IS-2000 standard apply. Signaling between the active, member, subscriber station and the system takes place on the R-FCH, or assigned R-DCCH or the R-EACH / F-CCCH.

If the subscriber station, member wishing to transmit is granted an R-CCCH, the R-CCCH can be assigned exclusively to the subscriber station, member per sector for a predetermined duration to avoid conflicts with other subscriber stations , member or the R-CCCH can be shared to improve effectiveness.

If the subscriber station member who wishes to transmit is granted an R-SCH, the R-SCH is assigned exclusively to a subscriber station, member by sector for a predetermined duration. For user data transmission, the R-SCH allocation can be infinite. The assignment ends when the member subscriber station 20 informs the sector on the R-EACH that the speech segment ended or when the sector detects no further transmission from the member subscriber station. The sector can then assign another subscriber station, member to transmit on the R25 SCH.

I

Alternatively, group transmissions shorter than a threshold occur at R-EACH without request-permit exchanges. Basic access, reservation access and power control access 5 are three exemplary modes for the use of these channels and are defined in the IS-2000 standard. In this mode, group transmissions longer than the threshold of a subscriber station member need to follow the request-permission exchange.

In the embodiment described above, the subscriber station member must send a request and receive permission before the subscriber station member can initiate transmission on the assigned backhaul link channel. Two separate requests are not required for channel assignment and permission to transmit. The return channel assignment occurs at the lower layer, eg a sector and the permission to transmit to a higher layer, eg a group call manager. Therefore, in one embodiment, the subscriber-station member can initiate transmission with the channel assignment, which implies that a permission to transmit has been given.

I

4Ί

Determination of the Period of Silence

To reduce wasted capacity, subscriber stations, members are assigned only for shared forward link channels 5 during active group calls. Therefore, the sectors and the subscriber stations, members must be able to determine the beginning of a period of silence. The term silent period is used in this text to identify the dormant state or the idle state. The silence period starts, for example, because or there are no more requests for transmission to the group for a predetermined interval or because the pre-ordered schedule for the group call expired. In one embodiment, a decision must be made by the access network and communicated to the subscriber stations, members. Alternatively, the subscriber station member determines the start of the silence period from a long period of inactivity 20 and the transition into a dormant / idle mode autonomously, with or without notifying the sector. In another alternative embodiment, the subscriber stations, members as well as the access network transit the silent period based on the 25 individual programs.

Once the start of a quiet period ends, the subscriber station, member transfers to a slotted mode of operation, periodically monitoring only the common channels associated with the group call or the Quick Paging Channels associated with common channels (QPCH optionally provided.

Alternatively, the subscriber station member transitions to the paging channels that the subscriber station member would regularly monitor (the F-PCH or the combination of the F-CCCH and the F-BCCH, each with an optionally associated QPCH).

If the subscriber stations, members are monitoring the F-SCH and the F-DCCH in the active period, the subscriber stations, members monitor the F-DCCH in the silent period.

In a third alternative modality, the control entity by means of a sector assigns the subscriber station, member to monitor the FCCCH and F-BCCH associated with the group call for group activities and another pair of F-CCCH or FCCCH / F-BCCH for paging and regular messaging.

In a fourth alternative modality, the

I control entity by means of a sector allocates the subscriber station, member to supervise a set of F-CCCH (s) and F-BCCH (s) for group activities, one F-CCCH for regular paging 5, a QPCH associated with the F-CCCH for regular paging and an F-BCCH for signaling the service from one point to multiple points. A member subscriber station continuously monitors the group's F-CCCH and F-BCCH, as well as the ΓΙΟ BCCH and assigned positions (called a

Paging in IS-2000) on the QPCH for that subscriber station, member to decide whether there is a need to also monitor its F-CCCH for regular, assigned paging.

¹⁵ .

Active Period Notification

Once an active period begins, the member subscriber station is notified through messages transmitted on the one-way link channels monitored by the member subscriber station in the silent period.

In one embodiment, the forward link channels used for each of the subscriber stations, members in the active state is (are) forward common control channel (s) (F-BCCH), forward broadcast (F-CCCH) or both the F-CCCH and the F-BCCH.

In one embodiment, all the F-CCCH and F-BCCH are shared by the subscriber stations, 5 members for group calls and by non-members for their paging needs in a given sector. This is accomplished by having proper routing information in transmission on these forward link channels.

In another embodiment, some F-CCCH and F-BCCH in a sector are designated exclusively for group calling purposes and the remaining F-CCCH and F-BCCH are designated exclusively for paging of non-member subscriber stations.

Those of ordinary skill in the field will recognize that although various modalities were described in terms of flow charts and methods, it was not for pedagogical purposes only. The methods can be performed by means of an apparatus, which in one embodiment comprises a processor interconnected with a transmitter, a receiver and any other appropriate block of the AT and / or AP.

Those skilled in the field 25 would understand that information and signals can be represented using any of a variety of different technologies and techniques. For example, the data, instructions, commands, information, signals, bits, symbols and fragments 5 that can be referred to throughout the previous description can be represented by voltages, electric currents, electromagnetic waves, magnetic fields or particles, optical fields or particles. or any combination thereof.

Those skilled in the field would further appreciate that the various illustrative logic blocks, modules, circuits, and algorithm steps described in connection with the modalities described in this text can be implemented as electronic hardware, software, and hardware. computer or combinations of both. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blogs, modules, circuits, and steps have been described above generally in terms of their functionality. Whether this functionality is implemented as hardware or software depends on the particular application and the design constraints imposed on the total system. Skilled architects may implement the described functionality in different ways for each particular application, but these implementation decisions should not be construed as causing a departure from the scope of the present invention.

The various illustrative logic blocks, modules and circuits described in connection with the modalities described in this text can be implemented or realized with a general purpose processor, a digital signal processor (DSP), an integrated circuit specific to the application (ASIC), a programmable logic device made up of gate arrays (FPGAs) or other programmable logic devices, a discrete or logic gate of transistors, discrete physical components, or any combination thereof designed to perform the functions described in this text. A general purpose processor may be a microprocessor, but alternatively, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor can also be implemented as a combination of 25 computing devices, for example, a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration. .

The steps of a method or algorithm described in connection with the modalities described in this text can be incorporated directly in the physical components, in a software module executed by a processor, or in a combination of the two. A software module may reside in RAM memory, Flash memory, ROM memory, EPROM memory, EEPROM memory, recorders, hard disk, removable disk, CD-ROM, or any other form of storage medium known in the field. An exemplary storage medium is coupled to the processor in such a way that the processor can read information from, and information written to, the storage medium. Alternatively, the storage medium can be integral to the processor. The processor and storage medium can reside in an ASIC. The ASIC can receive at a user terminal. Alternatively, the processor and storage medium may reside as discrete components on a user terminal.

The previous description of the described modalities is provided to enable any person skilled in the field to make or use the present invention. Various modifications of these embodiments will be readily apparent to those skilled in the field and the generic principles described in this text can be applied to other embodiments without departing from the spirit or scope of the invention. Thus, it is not intended that the present invention be limited to the embodiments shown in this text but should be in accordance with the broadest scope consistent with the principles and novel features described in this text.

A portion of the description in this patent document contains material, which is subject to copyright protection. The copyright owner has no objection to the reproduction by means of facsimile 20 of any of the patent documents or the patent description, as it appears in the patent file or registry of the Patent and Trademark Office , but otherwise any of all copyrights are reserved.