De-registering a multicast group member from a multicast group within a wireless communications network

Aspects of de-registering a multicast group member from a multicast group within a wireless communications network are disclosed. An access terminal sends a first multicast registration message to an access network, with the first multicast registration message identifying a first set of multicast groups. The access network receives the first multicast registration message and registers the access terminal for each of the first set of multicast groups. The access terminal sends a second multicast registration message, the second multicast registration message omitting at least one multicast group from among the first set of multicast groups, the second multicast registration message being sent to request de-registration, for the access terminal, from at least one multicast group. The access network receives the second multicast registration message and interprets the second multicast registration message as a request to de-register the access terminal from the omitted at least one multicast group.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to communications in a wireless telecommunication system and, more particularly to methods of de-registering a multicast group member from a multicast group within a wireless communications network.

2. Description of the Related Art

Wireless communication systems have developed through various generations, including a first-generation analog wireless phone service (1G), a second-generation (2G) digital wireless phone service (including interim 2.5 G and 2.75 G networks) and a third-generation (3G) high speed data/Internet-capable wireless service. There are presently many different types of wireless communication systems in use, including Cellular and Personal Communications Service (PCS) systems. Examples of known cellular systems include the cellular Analog Advanced Mobile Phone System (AMPS), and digital cellular systems based on Code Division Multiple Access (CDMA), Frequency Division Multiple Access (FDMA), Time Division Multiple Access (TDMA), the Global System for Mobile access (GSM) variation of TDMA, and newer hybrid digital communication systems using both TDMA and CDMA technologies.

The method for providing CDMA mobile communications was standardized in the United States by the Telecommunications Industry Association/Electronic Industries Association in TIA/EIA/IS-95-A entitled “Mobile Station-Base Station Compatibility Standard for Dual-Mode Wideband Spread Spectrum Cellular System,” referred to herein as IS-95. Combined AMPS & CDMA systems are described in TIA/EIA Standard IS-98. Other communications systems are described in the IMT-2000/UM, or International Mobile Telecommunications System 2000/Universal Mobile Telecommunications System, standards covering what are referred to as wideband CDMA (WCDMA), CDMA2000 (such as CDMA2000 1xEV-DO standards, for example) or TD-SCDMA.

In wireless communication systems, mobile stations, handsets, or access terminals (AT) receive signals from fixed position base stations (also referred to as cell sites or cells) that support communication links or service within particular geographic regions adjacent to or surrounding the base stations. Base stations provide entry points to an access network (AN)/radio access network (RAN), which is generally a packet data network using standard Internet Engineering Task Force (IETF) based protocols that support methods for differentiating traffic based on Quality of Service (QoS) requirements. Therefore, the base stations generally interact with ATs through an over the air interface and with the AN through Internet Protocol (IP) network data packets.

In wireless telecommunication systems, Push-to-talk (PTT) capabilities are becoming popular with service sectors and consumers. PTT can support a “dispatch” voice service that operates over standard commercial wireless infrastructures, such as CDMA, FDMA, TDMA, GSM, etc. In a dispatch model, communication between endpoints (ATs) occurs within virtual groups, wherein the voice of one “talker” is transmitted to one or more “listeners.” A single instance of this type of communication is commonly referred to as a dispatch call, or simply a PTT call. A PTT call is an instantiation of a group, which defines the characteristics of a call. A group in essence is defined by a member list and associated information, such as group name or group identification.

Conventionally, data packets within a wireless communication network have been configured to be sent to a single destination or access terminal. A transmission of data to a single destination is referred to as “unicast”. As mobile communications have increased, the ability to transmit given data concurrently to multiple access terminals has become more important. Accordingly, protocols have been adopted to support concurrent data transmissions of the same packet or message to multiple destinations or target access terminals. A “broadcast” refers to a transmission of data packets to all destinations or access terminals (e.g., within a given cell, served by a given service provider, etc.), while a “multicast” refers to a transmission of data packets to a given group of destinations or access terminals. In an example, the given group of destinations or “multicast group” may include more than one and less than all of possible destinations or access terminals (e.g., within a given group, served by a given service provider, etc.). However, it is at least possible in certain situations that the multicast group comprises only one access terminal, similar to a unicast, or alternatively that the multicast group comprises all access terminals (e.g., within a given cell, etc.), similar to a broadcast.

Broadcasts and/or multicasts may be performed within wireless communication systems in a number of ways, such as performing a plurality of sequential unicast operations to accommodate the multicast group, allocating a unique broadcast/multicast channel (BCH) for handling multiple data transmissions at the same time and the like. A conventional system using a broadcast channel for push-to-talk communications is described in United States Patent Application Publication No. 2007/0049314 dated Mar. 1, 2007 and entitled “Push-To-Talk Group Call System Using CDMA 1x-EVDO Cellular Network”, the contents of which are incorporated herein by reference in its entirety. As described in Publication No. 2007/0049314, a broadcast channel can be used for push-to-talk calls using conventional signaling techniques. Although the use of a broadcast channel may improve bandwidth requirements over conventional unicast techniques, the conventional signaling of the broadcast channel can still result in additional overhead and/or delay and may degrade system performance.

The 3rdGeneration Partnership Project 2 (“3GPP2”) defines a broadcast-multicast service (BCMCS) specification for supporting multicast communications in CDMA2000 networks. Accordingly, a version of 3GPP2's BCMCS specification, entitled “CDMA2000 High Rate Broadcast-Multicast Packet Data Air Interface Specification”, dated Feb. 14, 2006, Version 1.0 C.S0054-A, is hereby incorporated by reference in its entirety.

SUMMARY

Embodiments of the present invention are directed to aspects of de-registering a multicast group member from a multicast group within a wireless communications network. An access terminal sends a first multicast registration message to an access network, with the first multicast registration message identifying a first set of multicast groups. The access network receives the first multicast registration message and registers the access terminal for each of the first set of multicast groups. The access terminal sends a second multicast registration message, the second multicast registration message omitting at least one multicast group from among the first set of multicast groups, the second multicast registration message being sent to request de-registration, for the access terminal, from at least one multicast group. The access network receives the second multicast registration message and interprets the second multicast registration message as a request to de-register the access terminal from the omitted at least one multicast group.

DETAILED DESCRIPTION

The words “exemplary” and/or “example” are used herein to mean “serving as an example, instance, or illustration.” Any embodiment described herein as “exemplary” and/or “example” is not necessarily to be construed as preferred or advantageous over other embodiments. Likewise, the term “embodiments of the invention” does not require that all embodiments of the invention include the discussed feature, advantage or mode of operation.

A High Data Rate (HDR) subscriber station, referred to herein as an access terminal (AT), may be mobile or stationary, and may communicate with one or more HDR base stations, referred to herein as modem pool transceivers (MPTs) or base stations (BS). An access terminal transmits and receives data packets through one or more modem pool transceivers to an HDR base station controller, referred to as a modem pool controller (MPC), base station controller (BSC) and/or packet control function (PCF). Modem pool transceivers and modem pool controllers are parts of a network called an access network. An access network transports data packets between multiple access terminals.

The access network may be further connected to additional networks outside the access network, such as a corporate intranet or the Internet, and may transport data packets between each access terminal and such outside networks. An access terminal that has established an active traffic channel connection with one or more modem pool transceivers is called an active access terminal, and is said to be in a traffic state. An access terminal that is in the process of establishing an active traffic channel connection with one or more modem pool transceivers is said to be in a connection setup state. An access terminal may be any data device that communicates through a wireless channel or through a wired channel, for example using fiber optic or coaxial cables. An access terminal may further be any of a number of types of devices including but not limited to PC card, compact flash, external or internal modem, or wireless or wireline phone. The communication link through which the access terminal sends signals to the modem pool transceiver is called a reverse link or traffic channel. The communication link through which a modem pool transceiver sends signals to an access terminal is called a forward link or traffic channel. As used herein the term traffic channel can refer to either a forward or reverse traffic channel.

FIG. 1illustrates a block diagram of one exemplary embodiment of a wireless system100in accordance with at least one embodiment of the invention. System100can contain access terminals, such as cellular telephone102, in communication across an air interface104with an access network or radio access network (RAN)120that can connect the access terminal102to network equipment providing data connectivity between a packet switched data network (e.g., an intranet, the Internet, and/or carrier network126) and the access terminals102,108,110,112. As shown here, the access terminal can be a cellular telephone102, a personal digital assistant108, a pager110, which is shown here as a two-way text pager, or even a separate computer platform112that has a wireless communication portal. Embodiments of the invention can thus be realized on any form of access terminal including a wireless communication portal or having wireless communication capabilities, including without limitation, wireless modems, PCMCIA cards, personal computers, telephones, or any combination or sub-combination thereof. Further, as used herein, the terms “access terminal”, “wireless device”, “client device”, “mobile terminal” and variations thereof may be used interchangeably.

Referring back toFIG. 1, the components of the wireless network100and interrelation of the elements of the exemplary embodiments of the invention are not limited to the configuration illustrated. System100is merely exemplary and can include any system that allows remote access terminals, such as wireless client computing devices102,108,110,112to communicate over-the-air between and among each other and/or between and among components connected via the air interface104and RAN120, including, without limitation, carrier network126, the Internet, and/or other remote servers.

The RAN120controls messages (typically sent as data packets) sent to a base station controller/packet control function (BSC/PCF)122. The BSC/PCF122is responsible for signaling, establishing, and tearing down bearer channels (i.e., data channels) between a packet data service node100(“PDSN”) and the access terminals102/108/110/112. If link layer encryption is enabled, the BSC/PCF122also encrypts the content before forwarding it over the air interface104. The function of the BSC/PCF122is well-known in the art and will not be discussed further for the sake of brevity. The carrier network126may communicate with the BSC/PCF122by a network, the Internet and/or a public switched telephone network (PSTN). Alternatively, the BSC/PCF122may connect directly to the Internet or external network. Typically, the network or Internet connection between the carrier network126and the BSC/PCF122transfers data, and the PSTN transfers voice information. The BSC/PCF122can be connected to multiple base stations (BS) or modem pool transceivers (MPT)124. In a similar manner to the carrier network, the BSC/PCF122is typically connected to the MPT/BS124by a network, the Internet and/or PSTN for data transfer and/or voice information. The MPT/BS124can broadcast data messages wirelessly to the access terminals, such as cellular telephone102. The MPT/BS124, BSC/PCF122and other components may form the RAN120, as is known in the art. However, alternate configurations may also be used and the invention is not limited to the configuration illustrated. For example, in another embodiment the functionality of the BSC/PCF122and one or more of the MPT/BS124may be collapsed into a single “hybrid” module having the functionality of both the BSC/PCF122and the MPT/BS124.

FIG. 2illustrates the carrier network126according to an embodiment of the present invention. In the embodiment ofFIG. 2, the carrier network126includes a packet data serving node (PDSN)160, a broadcast serving node (BSN)165, an application server170and an Internet175. However, application server170and other components may be located outside the carrier network in alternative embodiments. The PDSN160provides access to the Internet175, intranets and/or remote servers (e.g., application server170) for mobile stations (e.g., access terminals, such as102,108,110,112fromFIG. 1) utilizing, for example, a cdma2000 Radio Access Network (RAN) (e.g., RAN120ofFIG. 1). Acting as an access gateway, the PDSN160may provide simple IP and mobile IP access, foreign agent support, and packet transport. The PDSN160can act as a client for Authentication, Authorization, and Accounting (AAA) servers and other supporting infrastructure and provides mobile stations with a gateway to the IP network as is known in the art. As shown inFIG. 2, the PDSN160may communicate with the RAN120(e.g., the BSC/PCF122) via a conventional A10 connection. The A10 connection is well-known in the art and will not be described further for the sake of brevity.

Referring toFIG. 2, the broadcast serving node (BSN)165may be configured to support multicast and broadcast services. The BSN165will be described in greater detail below. The BSN165communicates with the RAN120(e.g., the BSC/PCF122) via a broadcast (BC) A10 connection, and with the application server170via the Internet175. The BCA10 connection is used to transfer multicast and/or broadcast messaging. Accordingly, the application server170sends unicast messaging to the PDSN160via the Internet175, and sends multicast messaging to the BSN165via the Internet175.

Generally, as will be described in greater detail below, the RAN120transmits multicast messages, received from the BSN165via the BCA10 connection, over a broadcast channel (BCH) of the air interface104to one or more access terminals200.

Referring toFIG. 3, an access terminal200, (here a wireless device), such as a cellular telephone, has a platform202that can receive and execute software applications, data and/or commands transmitted from the RAN120that may ultimately come from the carrier network126, the Internet and/or other remote servers and networks. The platform202can include a transceiver206operably coupled to an application specific integrated circuit (“ASIC”208), or other processor, microprocessor, logic circuit, or other data processing device. The ASIC208or other processor executes the application programming interface (“API”)210layer that interfaces with any resident programs in the memory212of the wireless device. The memory212can be comprised of read-only or random-access memory (RAM and ROM), EEPROM, flash cards, or any memory common to computer platforms. The platform202also can include a local database214that can hold applications not actively used in memory212. The local database214is typically a flash memory cell, but can be any secondary storage device as known in the art, such as magnetic media, EEPROM, optical media, tape, soft or hard disk, or the like. The internal platform202components can also be operably coupled to external devices such as antenna222, display224, push-to-talk button228and keypad226among other components, as is known in the art.

Accordingly, an embodiment of the invention can include an access terminal including the ability to perform the functions described herein. As will be appreciated by those skilled in the art, the various logic elements can be embodied in discrete elements, software modules executed on a processor or any combination of software and hardware to achieve the functionality disclosed herein. For example, ASIC208, memory212, API210and local database214may all be used cooperatively to load, store and execute the various functions disclosed herein and thus the logic to perform these functions may be distributed over various elements. Alternatively, the functionality could be incorporated into one discrete component. Therefore, the features of the access terminal inFIG. 3are to be considered merely illustrative and the invention is not limited to the illustrated features or arrangement.

The wireless communication between the access terminal102and the RAN120can be based on different technologies, such as code division multiple access (CDMA), WCDMA, time division multiple access (TDMA), frequency division multiple access (FDMA), Orthogonal Frequency Division Multiplexing (OFDM), the Global System for Mobile Communications (GSM), or other protocols that may be used in a wireless communications network or a data communications network. The data communication is typically between the client device102, MPT/BS124, and BSC/PCF122. The BSC/PCF122can be connected to multiple data networks such as the carrier network126, PSTN, the Internet, a virtual private network, and the like, thus allowing the access terminal102access to a broader communication network. As discussed in the foregoing and known in the art, voice transmission and/or data can be transmitted to the access terminals from the RAN using a variety of networks and configurations. Accordingly, the illustrations provided herein are not intended to limit the embodiments of the invention and are merely to aid in the description of aspects of embodiments of the invention.

As discussed in the Background section, multicast messaging may be performed in a number of ways. In order to better understand embodiments of the present invention, a conventional multicast messaging process will be described with respect toFIGS. 4 and 5, respectively. Then, a multicast messaging process wherein a set of prospective sectors which are likely to include one or more multicast members is established before multicast session initiation will be described according to an embodiment of the present invention.

FIG. 4illustrates a conventional multicast messaging process using a broadcast multicast server (BCMCS) framework. The multicast messaging process ofFIG. 4is described below as performed within the wireless system100ofFIGS. 1 and 2. Referring toFIG. 4, in400, the application server170(or other initiator) requests a multicast message be sent to a multicast group including ATs (e.g., A, B and C). The multicast message from400is routed to the BSN165. In405, the BSN165forwards the multicast message over the BCA10 connection to the RAN120. For example, the multicast message is first forwarded to the BSC/PCF122, and the BSC/PCF122analyzes the multicast group members for the multicast message and forwards the multicast message to each MPT/BS124serving one or more multicast group members.

After receiving the forwarded multicast message, the RAN120waits for a next available control channel capsule in410. The control channel referred to herein is a downlink control channel which is assigned a different frequency, coding and/or bandwidth than the broadcast channel (BCH). Generally, less bandwidth is allocated to the control channel, which is conventionally intended to include control messaging only, while more bandwidth is allocated to the broadcast channel (BCH) which is conventionally intended to include data.

Referring toFIG. 5, each control channel cycle includes a total of 256 slots. Each control channel cycle includes a synchronous control channel capsule (SC), an asynchronous control channel capsule (AC), and a number of sub-synchronous control channels (SSCs). One SC is regularly or periodically transmitted at a given timeslot for each control channel cycle having a period of 256 slots, whereas the AC is transmitted at “random”, or at non-synchronous timeslots, within the control channel cycle. The SC is first transmitted at a timeslot corresponding to “T mod 256=Offset”, and then retransmitted at a timeslot corresponding to “T mod 4=Offset”, where T denotes a system time and an Offset denotes a time value delayed from a fixed time, which are included in the control channel header. Each SC may include a plurality of control channel MAC layer packets, whereas each AC includes only one control channel MAC layer packet. As each MPT/BS124periodically transmits one or more control channel MAC layer packets, interference (e.g., inter-cell interference) may occur if each MPT/BS124transmits at the same time. Accordingly, a different offset is applied to the SC for each MPT/BS124to avoid collisions. The MPT/BS may transmit as many as three SSC capsules within one control channel period or 256 slot cycle. Each SSC typically transmits only one control channel MAC layer packet. Assuming an offset value of 2, the SSCs are transmitted at time slots66,130and194. Control channel capsules (e.g., SCs, ACs, SSCs, etc.) are generally well-known in the art within BCMCS systems, and as such a further description thereof has been omitted for the sake of brevity.

Returning back toFIG. 4, in410, the RAN120may wait for either a synchronous control channel capsule (SC) (e.g., timeslot 2 in a next control channel cycle assuming an offset of 2) or, alternatively, a sub-synchronous control channel capsule (SSC) (e.g., one of timeslots66,130,194of the control channel cycle assuming an offset of 2), where the periodic BOM message is scheduled. For example, one particular control channel capsule within each control channel cycle may be reserved for a particular BOM since other applications may be attempting to access the control channel and other messages may be scheduled a delay of multiple cycles may be incurred.

In415, after waiting for the next available SC or SSC, the RAN120transmits a broadcast overhead message (BOM) over the air interface to one or more multicast group members (e.g., ATs A, B, C) over a large number of sectors of the wireless communication system100because the locations of the multicast group members for the multicast session are not precisely known at the RAN120. The BOM is a forward link control message defined by EV-DO standards. The BOM is used to notify each multicast group member of the BCMCS flows which are currently being carried in a sector. The BOM also provides Interlaced Multiplexed Pair (IM-Pair) information which is information regarding the forward link physical layer timeslots that should be decoded to receive the desired packet flows, and information on the number of physical layer slots per broadcast physical layer packet and physical layer rate used to transmit the flow. In420, the RAN120waits a predetermined number of slots (e.g., 8 to 16 slots) for the BOM to be decoded at the target ATs. After the delay420, the RAN120waits for the BCH slot designated by the decoded BOM,425. This creates another delay, which may be further exacerbated based on the traffic on the broadcast channel (BCH). In430, the RAN120transmits the announce message to each multicast group member or target AT which it is serving over the broadcast channel (BCH) on the designated BCH slot in all possible sectors. Next, in435, each of ATs A, B and C that wish to monitor the multicast session responds to the RAN120with a BCMCSFlowRegistration message, as defined by 1x EV-DO standards.

As described above with respect toFIG. 4, conventional BCMCS multicast messaging typically requires each target AT or multicast group member to decode a broadcast overhead message (BOM) before a multicast message is transmitted over a broadcast channel (BCH) to the respective members of the multicast group. This creates delays both for the scheduling of the BOM, delays for the decoding, and potential subsequent delays for the scheduling the announce message. Also, the BOMs and announce messages are transmitted in all possible sectors within the wireless communication system100. It will be appreciated, however, that multicast group members are not necessarily present within each sector. Thus, a certain number of transmissions are wasted each time a multicast session is initiated.

Embodiments of the present invention will hereinafter be described wherein access terminals “pre-register” with the RAN120for future multicast sessions. Thereafter, the access terminals periodically update their location and/or their group membership information such that, upon initiation of a given multicast session, the RAN120has at least some knowledge regarding where the multicast group members for the given multicast session are located. Thus, the RAN120may reduce the number of transmissions required to establish and/or maintain the given multicast session.

FIG. 6illustrates group membership reporting and location update process according to an embodiment of the present invention. In the embodiment ofFIG. 6, in600, a given AT desiring to belong to one or more multicast groups powers on. After the given AT powers up, the given AT sends a Group Membership Notification (GMN) message to the RAN120in605(e.g., after locating a pilot signal sent by one or more base stations within the RAN120, and/or performing any other initial power-up procedures). The GMN message includes a list of the multicast groups to which the given AT is a current or prospective multicast group member.

In an example, the GMN message may be included within a standard BCMCSFlowRegistration message. The BCMCSFlowRegistration message is well-known in the art, and is defined within 1x EV-DO standards. Typically, an AT sends a BCMCSFlowRegistration message after receiving a BOM with a register set to prompt a BCMCSFlowRegistration message (e.g., a register for dynamic broadcast (RFDB) field or register for paging (RFP) field equal to 1). The BCMCSFlowRegistration message includes a list of BCMCSFlowIDs that an AT wishes to monitor. The BCMCSFlowIDs can be either dynamically assigned (e.g., by a BCMCS Controller (not shown)) or can be pre-configured. If the BCMCSFlowIDs are dynamically assigned by the BCMCS Controller, the AT can acquire the BCMCSFlowIDs via a BCMCS flow discovery process before sending the BCMCSFlowRegistration message. On the other hand, in another embodiment of the present invention, a certain block of BCMCSFlowIDs may be pre-configured to be reserved irrespective of whether a multicast session is actually active. In this example, each “reserved” BCMCSFlowID may be mapped to a respective IP Group ID (i.e., a multicast IP address and port number pair). In an example, the mapping of the “reserved” BCMCSFlowIDs is pre-configured at each multicast group member and at the RAN120and/or BSN165, as discussed in greater detail within U.S. Provisional Application No. 60/974,827, entitled “METHODS OF GENERATING MULTICAST FLOW IDENTIFIERS”, filed Sep. 24, 2007, which is assigned to the assignee hereof and hereby expressly incorporated by reference herein in its entirety. Accordingly, in this example, the BCMCSFlowIDs included within the GMN message of605may correspond to one or more of the “reserved” BCMCSFlowIDs.

In an alternative example, the GMN message may be included within a proprietary or non-standard message, such as, for example, in a StorageBLOBNotification message on the uplink. In this example, the GMN message may include a list of BCMCSFlowIDs. Alternatively, the GMN message may include a list of multicast IP addresses and port numbers for the multicast sessions being requested.

While600and605ofFIG. 6are directed to AT “power-up”, in an alternative embodiment, a supplemental GMN message may be sent to the RAN120each time the given AT hands off (e.g., to a new base station, a new sub-net, etc.).

The RAN120receives the GMN message,605, and populates a group member list in610. Each group member list entry includes (i) a list of ATs having sent GMN messages to the RAN120(“AT List Field”), (ii) the associated multicast groups for each AT within the group member list (“Multicast Group Field”) (e.g., stored as a BCMCS flow ID entry of a BCMCSFlowID is reported in605, stored as a multicast IP address and port number pair if a proprietary message is reported in605, etc.), (iii) a last-known location for each AT (“Location Field”) (e.g., indicating a sector identification, a base station identification, etc.) and (iv) a time-stamp indicating a time at which the last-known location of the AT was reported (“Time-Stamp Field”). An example of a group member list entry is provided below as Table 1:

Thus, as shown in the example of Table 1, the given AT is labeled as “AT 1” and the given AT is a member of multicast groups T_Flow, U_Flow and V_Flow. The last-known location of the given AT is within Sector Y of the wireless communication system100, and the last-known location was reported at 7:06 PM Eastern Standard Time (EST).

In another example, the group member list entries may be grouped based on the multicast group field, as provided below as Table 2:

Thus, as shown in the example of Table 2, ATs 1 through 4 are registered for multicast group T_Flow. The location field and time-stamp field have not been included within Table 2 for convenience of illustration, as these fields are specific to each of ATs 1 through 4.

It will be appreciated that the group member list entries provided above have been given for example purposes only, and other embodiments of the present invention may configure the group member list entry in any well-known fashion. For example, the Location Field may alternatively store a base station identifier, and not a sector identifier. In another example, the Location Field may store an identifier identifying a plurality of sectors, such as a location area (LA) identifier, where each LA corresponds to a portion of a subnet or PCF area (e.g., as defined by the RAN120), or a multicast area (MA) identifier, where each MA corresponds to a portion of a subnet or PCF area identified by the RAN120solely for a multicasting purpose.

In615, after updating the group member list based on the GMN message in610, the RAN120determines whether to dynamically set a location update rule or protocol for the AT. The location update rule corresponds to the manner in which the AT schedules the transmission of RouteUpdate messages to the RAN120. A RouteUpdate message updates Location Field and Time-Stamp Field (see above) for a particular AT. Generally, if the RAN120wishes to keep closer track of the locations of multicast group members for a particular multicast group, the RAN120may set a relatively aggressive location update rule in615. Otherwise, if the RAN120wishes to reduce reverse link traffic, the RAN120may set a relatively conservative location update rule in615. In another alternative example, the RAN120may set no location update rule, and may rely upon a default or manually entered location update rule at the given AT. Examples of location update rules are provided below.

In620, the given AT establishes the location update rule. For example, if the RAN120determines not to dynamically set the location update rule in615, a default location update rule may be established in620. Alternatively, if the RAN120determines to dynamically set the location update rule in615, the dynamically set location update rule is activated in620. In another alternative example, the user of the given AT may manually select and enter a custom location update rule.

In an example, the location update rule may be a distance-based registration (DBR) protocol, such that the given AT sends a RouteUpdate message after traversing a given distance (e.g., based on which sector(s) the given AT has traversed, etc.). The given distance may be based on which base stations the given AT has been handed off to, which base stations the given AT has been monitoring while in an idle state, etc. In another example, the location update rule may be to transmit a RouteUpdate message each time the given AT enters a new location area (LA), where each LA corresponds to a portion of a subnet or PCF area (e.g., as defined by the RAN120).

In another example, the location update rule may correspond to any of a number of possible of location update strategies. For example, the location update rule may be timer-based, wherein the given AT maintains a timer with a predetermined or custom period and transmits a RouteUpdate message once for each timer period. In this example, lower timer periods corresponds to a more aggressive location update rule for maintaining more up-to-date location entries for the group member list. However, lower timer periods are also associated with higher levels of traffic on the reverse link.

After setting the location update rule in620, the given AT resumes normal operation (e.g., enters idle mode, makes voice calls, etc.),625. In630, the given AT determines whether to update its location information with a RouteUpdate message based on the location update rule established in620. If the location update rule requires a RouteUpdate message, the RouteUpdate message is sent to the RAN120in635. In640, the RAN120updates the group member list parameters based on the RouteUpdate message. For example, the RAN120updates the Location Field and Time-Stamp Field of the group member list for the given AT based on the RouteUpdate message. Otherwise, if the location update rule indicates that a RouteUpdate message need not be sent, the process advances to645.

In645, the given AT determines whether to update its group membership information with a supplemental GMN message. For example, if the given AT wishes to join a new multicast group, the given AT may determine to send a supplemental GMN message (i.e., including the BCMCSFlowID and/or multicast IP address and port number pair for the new multicast group). In another example, if the given AT wishes to cancel its membership to a multicast group that it has already registered for, the given AT may determine to send a supplemental GMN message (i.e., omitting the BCMCSFlowID and/or multicast IP address and port number pair for the canceled multicast group). Each supplemental GMN message supersedes any previously send GMN message. If the given AT determines not to update its group membership information, the process returns to625and the given AT resumes normal operation. Otherwise, if the given AT determines to update its group membership information, the given AT sends the supplemental GMN message in650.

Examples of configurations of the supplemental GMN message will now be described in greater detail. In an example, the supplemental GMN message may correspond to a BCMCSFlowRegistration message.

Conventionally, BCMCSFlowRegistration messages include a listing of BCMCSFlowIDs to which a given AT is presently requesting to register, and does not necessarily include a “regurgitation” or re-listing of BCMCSFlowIDs to which the given AT has already monitoring. However, according to an embodiment of the present invention, the ATs and RAN120are configured to interpret “omitted” BCMCSFlowIDs within a supplemental GMN message as an implicit request to de-register the given AT from the multicast group associated with the omitted BCMCS flow.

Accordingly, in an example, in645, assume that the given AT determines to de-register from one multicast group initially registered for in605re-sends the same BCMCSFlowRegistration message initially sent in605, except that the BCMCSFlowID for the multicast group for de-registration, which was included in the BCMCSFlowRegistration message of605, is omitted from the new registration message. Further examples of de-registration messages are provided below.

In655, the RAN120updates the group member list parameters based on the supplemental GMN message. If the supplemental GMN message requests different multicast groups than the previously sent GMN message, the Multicast Group Field, which maintains a list of multicast groups to which the given AT belongs, is updated to add the multicast groups listed in the supplemental GMN message. Alternatively, the Multicast Group Field is updated to remove multicast groups based on the supplemental GMN message if group removal is indicated within the GMN message. As will be appreciated, this may necessitate removing previously listed multicast groups, adding new multicast groups and/or both adding and removing certain multicast groups from the associated multicast group field for the given AT. Further, the RAN120updates the Location Field and Time-Stamp Field of the group member list for the given AT sending the supplemental GMN message.

For example, in655, assume the RAN120receives the GMN message, or BCMCSFlowRegistration message, having an omitted BCMCS flow (i.e., the “de-registration” message). The RAN120interprets the BCMCSFlowRegistration received at640as a request from the given AT to withdraw from the multicast group associated with the BCMCSFlowID, and accordingly removes or de-registers the given AT from that multicast group.

Additional examples of supplemental GMN messages will now be described in greater detail.

In a first example, assume that the given AT is currently a member of multicast groups with BCMCSFlowIDs of FLOW_1, FLOW_2, FLOW_3and FLOW_4(e.g., based on an initial GMN message, or BCMCSFlowRegistration message sent in605), and that the given AT has determines, in645, to register for FLOW_5. In this example, the supplemental GMN message sent in650may be configured as follows:

Example Supplemental GMN Message 1

Thus, as shown above in Example Supplemental GMN Message 1, the supplemental GMN message sent in650includes (i) each multicast group to which the given AT is currently registered (i.e., FLOW_1, FLOW_2, FLOW_3and FLOW_4) and (ii) each multicast group that the given AT has not yet registered for and which the given AT wishes to register to (i.e., FLOW_5). The RAN120receives the supplemental GMN message in655, and the RAN120(i) maintains the given AT's registration to BCMCS flows FLOW_1, FLOW_2, FLOW_3and FLOW_4, and (ii) registers the given AT to BCMCS flow FLOW_5.

In a second example, assume that the given AT is currently a member of multicast groups with BCMCSFlowIDs of FLOW_1, FLOW_2, FLOW_3and FLOW_4(e.g., based on an initial GMN message, or BCMCSFlowRegistration message sent in605), and that the given AT has determines, in645, to de-register from multicast groups associated with flows FLOW_3and FLOW_4. In this example, the supplemental GMN message sent in650may be configured as follows:

Example Supplemental GMN Message 2

Thus, as shown above in Example Supplemental GMN Message 2, the supplemental GMN message sent in650(i) includes each multicast group to which the given AT is currently registered and is interested in maintaining registration (i.e., FLOW_1and FLOW_2), and (ii) omits each multicast group that the given AT is no longer interested in (i.e., FLOW_3and FLOW_4). The RAN120receives the supplemental GMN message in655, and the RAN120(i) maintains the given AT's registration to BCMCS flows FLOW_1and FLOW_2and (ii) de-registers the given AT from BCMCS flows FLOW_3and FLOW_4.

In a third example, assume that the given AT is currently a member of multicast groups with BCMCSFlowIDs of FLOW_1, FLOW_2, FLOW_3and FLOW_4(e.g., based on an initial GMN message, or BCMCSFlowRegistration message sent in605), and that the given AT has determines, in645, to de-register from multicast groups associated with flows FLOW_2, FLOW_3and FLOW_4, and to register to FLOW_5. In this example, the supplemental GMN message sent in650may be configured as follows:

Example Supplemental GMN Message 3

Thus, as shown above in Example Supplemental GMN Message 3, the supplemental GMN message sent in650(i) includes each multicast group to which the given AT is currently registered and is interested in maintaining registration (i.e., FLOW_1), and each multicast group to which the given AT is not yet registered for and is requesting registration (i.e., FLOW_5) and (ii) omits each multicast group that the given AT is no longer interested in (i.e., FLOW_2, FLOW_3, and FLOW_4). The RAN120receives the supplemental GMN message in655, and the RAN120(i) maintains the given AT's registration to BCMCS flow FLOW_1(ii) de-registers the given AT from BCMCS flows FLOW_2, FLOW_3and FLOW_4and (iii) registers the given AT to BCMCS flow FLOW_5.

In yet another example, if the supplemental GMN message includes no listed multicast groups, the supplemental GMN message is interpreted as a request to drop or cancel the given AT from the group member list entirely. This type of GMN message can be referred to as a “NULL” GMN message. Accordingly, if the supplemental GMN message includes no multicast groups in650, the RAN120removes each of the AT List Field, the Multicast Group Field, the Location Field and the Time-Stamp Field for the given AT in655. In another example, the NULL GMN message can contain a special multicast group ID (or a BCMCSFlowID) that is reserved for implying deregistration from all groups. In another example, the NULL GMN message can be a separate, proprietary message, and not merely an “empty” GMN message or BCMCSFlowRegistration message.

As will be appreciated in view of the above-description ofFIG. 6, at any given time, the group member list includes information regarding where multicast group members are “potentially” located before an active multicast session for the multicast group is actually initiated (e.g., “potentially” because the group member list may not necessarily be perfectly accurate).

Further, while not illustrated inFIG. 6explicitly, the RAN120may periodically update the group member list on its own initiative (i.e., not in response to RouteUpdate messages and/or GMN messages received from one or more ATs). For example, if a Location Field for a particular AT becomes “stale”, or exceeds an age threshold, the RAN120may interpret the stale Location Field as not being up-to-date, and may remove the associated AT from the group member list entirely.

FIG. 7illustrates a multicast messaging process according to an embodiment of the present invention. With regard toFIG. 7, assume that the group member list maintained by the RAN120includes a plurality of ATs that have registered for multicast group T_Flow. Accordingly, as an example, the group member list for ATs having registered for T_Flow may include the following entries in Table 3 (below):

Referring toFIG. 7, in700, the application server170issues a request to initiate a multicast flow for a given multicast group. For purposes of example, assume the multicast flow corresponds to T_Flow, as in the Multicast Group Field for each of ATs A through G as in Table 3 (above). For example, the multicast flow T_Flow generated in700ofFIG. 7may be responsive to a given access terminal's request to speak to the given multicast group (not shown). After the application server170decides to accept the AT's request, the server170can generate a multicast flow announcement message to be sent to the group members via IP multicasting. The application server170forwards the multicast flow to the BSN165in705, and the BSN165forwards the BCMCS flow over the BCA10 connection to the RAN120, which is responsible for transmitting the multicast messages of the BCMCS flow to the multicast group members via the air interface104in one or more sectors, in710.

In710ofFIG. 7, the RAN120determines an initial set of target sectors for an initial “cluster”. As used herein, a target sector is any sector within a wireless communication system having or “potentially” having at least one multicast group member. As used herein, a “cluster” corresponds to a set of sectors (e.g., one or more sectors) upon which the BCH carries the BCMCS flow for a particular multicast group. As will be described below in greater detail, the cluster includes both target sectors and supporting sectors for a particular multicast group or BCMCS flow.

Still referring to710ofFIG. 7, the RAN120determines the initial set of target sectors based on the group member list maintained at the RAN120(e.g., see Table 3). Accordingly, in the example of Table 3, the initial set of target sectors may correspond to sectors T1through T4. More generally, the initial set of target sectors may correspond to all sectors that satisfy a certain proximity metric with respect to any of sectors T1through T4(e.g., because the last-known location for an AT maintained at the RAN120within a group member list entry is not necessarily correct, but is likely to be proximate to the AT's actual current location if the time-stamp field is relatively recent).

Next, in715ofFIG. 7, the RAN120determines an initial set of supporting sectors for the BCMCS flow T_Flow. In an example, the initial set of supporting sectors may be based on the initial set of target sectors. For example, the supporting sectors may correspond to any sector adjacent to one or more target sectors which itself is not a target sector. Alternatively, a supporting sector may correspond to a sector in a given proximity (e.g., a distance proximity, a signal strength proximity, etc.) to a target sector without actually being adjacent to the target sector.

In720ofFIG. 7, the RAN120determines an initial set of non-supporting sectors for the BCMCS flow. The initial set of non-supporting sectors for the BCMCS flow includes any sector within the wireless system100which is neither a target sector as determined in710ofFIG. 4nor a supporting sector as determined in715ofFIG. 7.

In725ofFIG. 4, the RAN120executes target sector and supporting sector processes at the respective target and supporting sectors. Generally, each target sector and each supporting sector carries the BCMCS flow on a downlink broadcast channel BCH, and as such the RAN120forwards the multicast message to base stations serving target sectors T1through T4and the supporting sectors. However, in order to reduce excessive AT feedback, supporting sectors transmit BOMs configured to prompt AT feedback (e.g., with RFDB=1 or RFP=1) at each BOM period (e.g., to prompt feedback from an AT “wandering” into a supporting sector), whereas target sectors send BOMs to prompt AT feedback less frequently, and more frequently send BOMs to suppress AT feedback (e.g., with RFDB=0 or RFP=0) (e.g., to discourage AT registration when the target sector already carries the BCMCS flow). Non-supporting sectors do not carry the BCMCS flow T_Flow, and the RAN120need not forward multicast messages for T_Flow to non-supporting sectors. A more detailed discussion of target sector behavior, supporting sector behavior and non-supporting sector behavior may be found within U.S. Provisional Application No. 60/974,800, entitled “METHODS OF PROVIDING MOBILITY SUPPORT FOR MULTICAST COMMUNICATIONS WITHIN A WIRELESS COMMUNICATIONS NETWORK”, filed Sep. 24, 2007, which is assigned to the assignee hereof and hereby expressly incorporated by reference herein in its entirety.

Next, in730ofFIG. 7, the RAN120updates the sector assignments of the cluster (e.g., adds new target/supporting sectors, removes target/supporting sectors, etc.). Again, a more detailed description of the sector assignment updates is provided within the above-referenced co-pending application. Also, while not explicitly shown inFIG. 7, it will be appreciated that, during the active multicast session, the RAN120continues to maintain/update the group member list based on GMN messages and RouteUpdate messages received from multicast group members.

FIG. 8illustrates a wireless communication system800configured based on the assumptions provided within Table 3 (above) and the process ofFIG. 7. As shown inFIG. 8, the wireless communication system800includes a plurality of sectors805, including target sectors T1through T4, supporting sectors N1through N11and non-supporting sectors X1through X17. As discussed above, the multicast or BCMCS flow T_Flow is announced/carried within target sectors T1through T4and supporting sectors N1through N11, and the RAN120does not announce or send multicast messaging in support of T_Flow to base stations within non-supporting sectors. Accordingly, the level of system-wide multicast communication traffic is reduced as compared to the conventional art wherein the multicast flow T_Flow would be announced at each respective sector.

In an alternative embodiment of the present invention, as discussed above with respect to710ofFIG. 7, the target sectors may be configured to include (i) sectors stored in the last known location field of each AT maintained in Table 3 (i.e., sectors T1through T4) (ii) and sectors satisfying a given proximity metric with respect to (i). For example, if the given proximity metric corresponds to adjacent sectors, then the wireless communication system800would be modified such that the supporting sectors N1through N11would also be target sectors, sectors adjacent to the new set of target sectors would be supporting sectors, and so on. As another example, if the given proximity metric corresponds to all sectors within the distance from the last registered sector for conducting distance-based registration, all sectors within the distance would also be target sectors. Accordingly, it will be appreciated that the initial target sector group is not necessarily limited to the last-known locations of ATs as maintained at the RAN120for a given multicast group.

In another example, the group member list may be used to provide scheduling instructions, from the RAN120to multicast group members, that instruct the multicast group members with regard to how to respond to “interactive” multicast messages, such as announce messages, where an interactive multicast message is a multicast message that requests or requires feedback from one or more multicast group members. For example, if a large number of multicast group members are expected to be present within a particular sector, and an announce message for a multicast session is sent within the sector, a relatively large number of multicast group members may attempt to access the reverse link channel at the same time to respond to the announce message and register for the multicast session. However, with information present within the group member list, the RAN120can schedule a response sequence for the access terminals to respond to the announce message via an “access channel message” (ACM). For example, the RAN120may send the ACM along with the announce message, with the ACM designating a prioritized response order that reserves feedback slots for a number of access terminals based on the group member list. For example, the access terminal with the most recent update to its Location Field (e.g., updated via a GMN message, a RouteUpdate message, etc.) at the group member list maintained by the RAN120may be granted the first response slot by the ACM, the AT having the next most recent updated Location Field may be granted the second response slot by the ACM, and so on. ACMs and scheduling of interactive multicast message feedback on the reverse link are discussed in more detail within U.S. Provisional Application No. 60/974,796, entitled “METHODS OF RESPONDING TO AN INTERACTIVE MULTICAST MESSAGE WITHIN A WIRELESS COMMUNICATION SYSTEM”, filed Sep. 24, 2007, which is assigned to the assignee hereof and hereby expressly incorporated by reference herein in its entirety.