WO2008093208A1

WO2008093208A1 - Method and system for providing multicast-broadcast data service

Info

Publication number: WO2008093208A1
Application number: PCT/IB2008/000193
Authority: WO
Inventors: Roman Pichna; Zexian Li; Ravi Pandei; Alexander Bachmutsky
Original assignee: Nokia Corporation; Nokia Inc.
Priority date: 2007-01-29
Filing date: 2008-01-29
Publication date: 2008-08-07

Abstract

An approach is provided for deploying multicast-broadcast data service. A multicast flow is received at a gateway that is configured to directly join a multicast tree. The multicast flow is forwarded to a base station of an access network to provide a datacast service to a terminal served by the base station.

Description

METHOD AND SYSTEM FOR PROVIDING MULTICAST-BROADCAST DATA SERVICE

RELATED APPLICATIONS

(000 f I This application claims the benefit of the earlier filing date under 35 U.S.C. §119(e) of U.S. Provisional Application Serial No. 60/887,074 filed January 29, 2007, entitled "Method and System For Providing Multicast-Broadcast Data Service," the entirety of which is incorporated by reference.

BACKGROUND

[0002] Radio communication systems, such as wireless data networks (e.g., WiMAX (Worldwide Interoperability for Microwave Access) systems, DVB (Digital Video Broadcasting)-!! (Handheld) systems, and spread spectrum systems (such as Code Division Multiple Access (CDMA) networks), Time Division Multiple Access (TDMA) networks, etc.), provide users with the convenience of mobility along with a rich set of services and features. This convenience has spawned significant adoption by an ever growing number of consumers as an accepted mode of communication for business and personal uses. To promote greater adoption, the telecommunication industry, from manufacturers to service providers, has agreed at great expense and effort to develop standards for communication protocols that underlie the various services and features. One area of effort involves multicast services in support of bandwidth intensive applications, such as audio and video streaming.

SOME EXEMPLARY EMBODIMENTS

{ 00031 There is therefore a need for an approach for providing efficient multicast, which can co-exist with already developed standards (e.g. WiMAX) and protocols (e.g., multicast Internet Protocol (MIP)) while conserving valuable bandwidth. 1001)4 j According to one embodiment of the invention, a method comprises receiving a multicast flow at a gateway that is configured to directly join a multicast tree. The method also comprises forwarding the multicast flow to a base station of an access network to provide a datacast service to a terminal served by the base station.

I CM⁾OS J According to another embodiment of the invention, a system comprises a gateway, within an access network, configured to directly join a multicast tree and to receive a multicast flow. The gateway is further configured to forward the multicast flow to a base station of the access network to provide a datacast service to a terminal served by the base station.

[0006 J According to another embodiment of the invention, a method comprises generating a request to either join or leave a channel associated with a packet-based television service. The method also comprises receiving a multicast flow from an access network that includes a base station coupled to a gateway, the gateway being configured to directly join a multicast tree.

[0007J According to yet an exemplary embodiment, an apparatus comprises a processor configured to generate a request to either join or leave a channel associated with a packet-based television service. The apparatus also includes a transceiver configured to receive a multicast flow from an access network that includes a base station coupled to a. gateway. The gateway is configured to directly join a multicast tree.

100081 Still other aspects, features, and advantages of the invention are readily apparent from the following detailed description, simply by illustrating a number of particular embodiments and implementations, including the best mode contemplated for carrying out the invention. The invention is also capable of other and different embodiments, and its several details can be modified in various obvious respects, all without departing from the spirit and scope of the invention. Accordingly, the drawings and description are to be regarded as illustrative in nature, and not as restrictive. BRIEF DESCRIPTION OF THE DRAWINGS

{00091 The invention is illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings in which like reference numerals refer to similar elements and in which:

[001Oj FIG. 1 is a diagram of a communication system capable of providing multicast- broadcast service, according to an exemplary embodiment of the invention;

10011 J FIGs. 2 A and 2B are diagrams, respectively, of a communication system with an MCBCS architecture in support of datacast services (e.g., Internet Protocol Television (IPTV)) and of a communication system with a MCBCS architecture with an active R4 interface, in accordance with an embodiment of the invention;

[00121 FIG. 3 is a functional diagram of the processes for MCBCS service provisioning, in accordance with an embodiment of the invention;

10013] FIG. 4 is a flowchart of process for joining a channel by a mobile station (MS), in accordance with an embodiment of the invention;

[ 0014] FIG. 5 is a flowchart of process for leaving a channel by a mobile station, in accordance with an embodiment of the invention;

[0015J FIG. 6 is a flowchart of process for providing MS mobility, in accordance with an embodiment of the invention;

[0016] FIG. 7 is a flowchart of process for providing MCBCS bearer optimization, in accordance with an embodiment of the invention;

10017] FIGs. 8 A and 8B are diagrams illustrating, respectively, a traditional approach for multicast transport and an approach for multicast transport according to an exemplary embodiment;

[0018] FIG. 9 is a diagram of a protocol stack for supporting multicast, in accordance with an embodiment of the invention; [00191 FIG. 10 is a diagram of hardware that can be used to implement an embodiment of the invention;

[002(IJ FIGs. HA and HB are diagrams of different cellular mobile phone systems capable of supporting various embodiments of the invention;

[1)02 IJ FIG. 12 is a diagram of exemplary components of a mobile station capable of operating in the systems of FIGs. HA and HB, according to an embodiment of the invention; and

J 0022 J FIG. 13 is a diagram of an enterprise network capable of supporting the processes described herein, according to an embodiment of the invention.

DESCRIPTION OF PREFERRED EMBODIMENT

[0023 J An apparatus, method, and software for providing an efficient multicast mechanism are disclosed. In the following description, for the purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the embodiments of the invention. It is apparent, however, to one skilled in the art that the embodiments of the invention may be practiced without these specific details or with an equivalent arrangement. In other instances, well-known structures and devices are shown in block diagram form in order to avoid unnecessarily obscuring the embodiments of the invention.

[0024J Although the embodiments of the invention are discussed with respect to IPTV-based services using a WiMAX technology, it is recognized by one of ordinary skill in the art that the embodiments of the inventions have applicability to any type of communication services and equivalent technologies.

[0025] FIG. 1 is a diagram of a communication system 100 capable of providing multicast- broadcast service, according to an exemplary embodiment of the invention. According to an exemplary embodiment, one or more mobile stations (MS) 101 (e.g., mobile terminal, unit, or device), such as a WiMAX user equipment (UE), is in the coverage area of an ASN 103 such as a WiMAX access network. Although only a single ASN is depicted, it is recognized that multiple ASNs can exist. The access network 103, which includes one or more base stations (BS) 105 configured to communicate with the MS 101, provides the WIMAX access services, which can include datacast services (e.g., packet-based television service).

(00261 One such packet-based television service is that of Internet Protocol Television (IPTV). This technology relies on the Internet Protocol for providing consumers with access to television programming. With the growing focus towards convergence and mobility in the IT industry, equipment manufacturers are motivated to produce devices that may be used for a variety of functions. One such device that is considered at the pinnacle of convergence and mobility is the cellular telephone, which supports a wide range of features a part from telephony functions including text messaging, web surfing, word processing, image capture, etc. In addition to these features, accessing radio and television broadcasts via converged technologies such as cellular telephones, laptops, and handhelds, etc. are also proving to be highly attractive to consumers.

(0027J Traditionally, IPTV services are mainly supported through wired broadband connections, such as digital subscriber line (DSL) and cable modems. Wirelessly broadcasting bandwidth intensive packetized TV signals, which contain both audio and video data, to a large group of subscribers has received significant attention in the telecommunications industry, largely because of the developments in high-speed, wireless network as well as sophisticated transmission technologies (e.g., multicast technology).

[0028| Multicast technology permit IPTV providers to selectively transmit packetized IPTV data wirelessly to targeted groups of subscribers rather than broadcasting (which can unnecessarily consume network resources). That is, multicasting is especially attractive from the point of view of the service provider precious bandwidth can be conserved. By way of example, the system of FIG. 1 is described with respect to multicasting using IP - i.e., IP multicast (IP-M) — to provide wireless multicast-broadcast services (MCBCS), such as IPTV, over the access service network (ASN) 103.

[0029J Traditionally, multicasting, however, would require directly interfacing a multicast IP home agent (MIP HA) of a connectivity service network (CSN) to an ASN as specified by the Internet Engineering Task Force (IETF) within various request for comments (RFC). This approach unfortunately consumes precious resources, as it is based on using the MIP HA to replicate packets and to unicasting the packets towards the mobile terminals. This approach, in fact, does not take advantage of the bandwidth preserving feature of multicasting. [0030] As shown, the ASN 103 serves mobile stations 101 and can include one or more ASN-Gateways (ASN-GW) 107 to provide an interface between the ASN 103 and the CSN 109. The ASN-GW 107, according to certain embodiments, may be a computing device (e.g., a server, a router, etc.) capable of handling packets that contain IPTV content from the CSN 109 and one or more MS 101. f 0031 J The CSN 109 can include one or more multicast routers (MC-Router) 111, which is responsible for routing IP packets carrying data such as audio, video, etc. between the CSN 109 and the ASN 107. Because IPTV services may be offered to wireless users who subscribe to services for a monthly or yearly fee (rather than for free), a mechanism is needed to authenticate, authorize and keep track of customer activity. Accordingly, the CSN 109 also contains one or more Authentication, Authorization and Accounting (AAA) units 113, which are responsible for authenticating users to determine whether they are authorized to use the datacast services of the provider's CSN 109. The AAA unit 113 can further keep track of user activities for billing purposes. The AAA 113 dynamically determines customer status and activity as numerous mobile stations 101 may continually be in motion — wherein new stations may arrive within the coverage area of ASN 103 while others may leave the coverage area.

[0032] Furthermore, the CSN 109 employs a MIP HA 115, which may be a device or platform used to manage traffic within the CSN 109.

[ 00331 The system 100 can be implemented using various architectures to provide Internet Protocol Television (IPTV) MCBCS services, as depicted in FIGs. 2A and 2B. [0034].. FIG. 2A is a diagram of a communication system with, an MCBCS architecture in support of datacast services (e.g., Internet Protocol Television (IPTV)), in accordance with an embodiment of the invention, hi an exemplary embodiment, the architecture employs multicasting via the IP-multicast (IP-M) protocol, wherein the feeds of multicast flows are delivered from an MC-Router 111 located within the ASN 103 as described previously. IP-M together with other protocols - e.g., IGMP (Internet Group Management Protocol) /MLD (Multicast Listener Discovery) ~ is utilized, in one embodiment, for joining, leaving and routing MS traffic between the MS 101 and the CSN 109. As seen, the MC-Router 111 connects directly to Access Service Network gateways (ASN-GWs) 107, thus, bypassing any MIP HA functionality. Alternatively, the MC-Router 111 and the ASG-GWs 107 can utilize a unicast tunnel or a multicast tunnel over R3mc. The ASN-GW 107 utilizes an R3mc interface to connect with the MC-Router 111. The R3 interface supports communication between the ASN-GW 107 and the AAA unit 113. [CMBSj The R6 interfaces are associated with communications between the base stations 103 and the gateways 107. The R4 interface provides communication between the gateways 107. These interfaces are described in Table 1, as follows:

Table 1 {00361 The architecture of FIG. 2A can be built on top of the regular WiMAX (Worldwide Interoperability for Microwave Access) NWG (Network Working Group) architecture. The existing Rl, R4 and R6 are reused and extended with MCBCS (Multicast Broadcast Service) functionality. User plane of R4 is not part of the MCBCS, but rather the serving ASN-GW 107 joins the multicast tree. In this exemplary embodiment, the architecture can be simplifier because multicast routing, and its optimization do not have to be duplicated for the R4 tunnel layer (an MCBCS variant is described below in FIG. 2B). As for the R3, the part interfacing AAA (Authentication, Authorization and Accounting) 113 is being reused and extended with MCBCS functionality. The addition, from the WiMAX architecture point of view, is the R3mc interface for interconnection between ASN-GW 107 and the IPv4/IPv6 multicast (MC) router 111.

[0037| With the IPTV service, R4 need not be used, as the ASN-GW 107 can join the multicast tree directly. R4 can be used temporarily or permanently to layer multicast (MC) procedures on top of existing WiMAX signaling procedures. This approach may alter IP- multicast (IP-M) functionality at the WMF (WiMAX Forum) layer, e.g., optimal MC routing or MC tree pruning.

|0038| hi one embodiment, the mapping between user and transport IP-M addresses in R6 is rule-based or fixed. Multicast is performed in R6, even if multicast is unicasted across Rl.

[0039] With respect to Rl MCBCS bearer optimization, from the Radio Resource Management (RRM) perspective, for limited number of users, multicast streams are unicasted across Rl. This optimization is performed by the Radio Resource Controller (RRC) either in the ASN-GW 107 or in the BS 105. In an exemplary embodiment, unicast-to-multicast change can be performed quite rapidly compared to previous schemes, while multicast-to-unicast change can be slow to accommodate users flipping channels as well as handoffs (HOs) across sector boundaries.

[004Oj According to an alternative embodiment, procedures similar to those performed by the ASN-GW 107 for multicasting can be implemented in the MIP HA 115. This embodiment can utilize extensions to the R3 User Plane (UP) and Control Plane (CP). One approach for supporting this functionality would be to modify the protocol (e.g., MIP) to enable multicast or designing a new dedicated MC proxy MIP to be incorporated within the system.

[0(141] Under the above scenario, the MS 101 can indicate a change of channel using an IGMP or layer 2 (L2) medium access control (MAC) messages. The L2 MAC message in turn triggers IGMP from BS 105 or L2 signal in R6 towards ASN-GW 107. Fixed broadcast (BC) unicasted radio connections (i.e., connection identifiers (CIDs)) can be utilized in the BC area to avoid the necessity of the hand-off (HO) procedure for MS 101 (which only receives BC streams from ASN 103).

10042 j In one embodiment (shown in FIG. 2B), an MC- Anchor ASN-GW 201 is deployed in the ASN 103, resulting in the forking of UC and multicast (MC) U- and C-planes (different anchors for each of the respective planes).

|0043| Thus, the system of FIG. 2A, in one embodiment, adopts a relatively mature technology, IPTV, that is used in fixed wired broadband access networks (e.g., DSL) for WiMAX MCBCS. The architecture of FIG. 2 A adapts existing technology for multicast services, with minimal changes to the WiMAX architecture and protocols. Additionally, this approach, in certain embodiments, minimizes channel switching latency. Furthermore, security can be provided at the application-level (if available) with the approach depicted in FIG. 2A. [0044j One aspect of the MCBCS architecture of FIG. 2A, according to one embodiment, is the absence of the MIP HA interface of the CSN towards ASN 103. This approach may appear counter-intuitive, as IP-Multicast (IP-M) does not support any mobility. To reuse the mobility functionality designed in the WiMAX architecture, the IPM is interfaced to the topologically- highest WiMAX node that serves as mobility anchor, i.e., MIP HA 115. However, it is observed that neither MIPv4 (Mobile IP version 4) (RFC 3344) nor MIPv6 (Mobile IP version 6) (RFC 3775) support IP multicast in a way that could be acceptable for sensible multicast system architectures. Multicast across MIP as specified by the IETF (Internet Engineering Task Force) RFCs (Request for Comments) is supported in such a way that MIP HA 115 replicates packets and unicasts them towards the mobile terminals. As noted previously, this removes the benefits of multicasting in the first place - saving radio resources in Rl and last hop transport resources in R6.

|0045] To attach to the multicast tree from MIP HA 115 of FIG. 2A (and hence, derive the benefit of multicasting in Rl and R6), it is necessary either to modify MIP RFCs or to develop parallel MC-MIP functionality between ASN-GW 107. The node hosting HA including mobility, security, etc. Although possible, this approach would put additional WiMAX-specific requirements on the HA, thus increasing the cost of implementation. As a result, the overall architecture will be more GPRS (General Packet Radio Service)-like.

10046 j Since ASN-GW 107 is the next topologically-highest element and the network protocols topologically below it are in WMF control, ASN-GW 107 is the optimal boundary between IP-M and WiMAX MCBCS. In addition, ASN-GW 107 also terminates L2 for C-MIP terminals and serves as an access router, thereby interacting with the terminal at the L3 layer.

(0047) FIG. 2B is a diagram of a communication system with a MCBCS architecture with an active R4 interface, in accordance with an embodiment of the invention. This architecture provides a variant of the architecture of FIG. 2A, wherein the user plane of R4 participates in the MCBCS functionality. Under this scenario, there is a multicast anchor functionality within, the, ASN 103, which is depicted by the MC-anchor ASN-GW 201 attached to MC-Router 111. The R4 is therefore stretched over to the serving ASN-GWs 107. It is noted that in general the MC- Anchor and the anchor ASN-GW hosting FA (Foreign Agent) or AR (Access Router) can be two physically separate elements rather than one entity as depicted in FIG. 2B.

|0048| It should also be noted that because R3 is positioned between AAA 113 and MC- Anchor ASN-GW 201, the authenticator and MC- Anchor can be co-located. Under circumstances where they cannot be co-located, then the R4 or R3 procedures can be defined for fetching MCBCS information into MC-anchor ASN-GW 201. Also, the channel joining procedure can include Data Path (DP) setup between the serving ASN-GW 107 and the MC- anchor ASN-GW 201, as further described in FIG. 4. [0049] FIG. 3 is a functional diagram of the processes for MCBCS service provisioning, in accordance with an embodiment of the invention. Firstly, the user subscribes, as in step 301, to the datacast service, which consequently requires retrieval of relevant information about the user who is requesting the service. This information may include name and address of the user, the account profile, types of service requested, etc. Next, in step 303, the provisioning process involves obtaining IP connectivity through the access network (e.g., ASN 103) by the user.

10050 J The service announcement process is initiated, as in step 305, and once the user gains access to the resources, the MS 101 of the user can start consuming IPTV/datacast services. The consumption process (denoted as step 307), however, can involve the MS 101 selecting and joining a channel, and thus, be provided with multicast flows via WiMAX MCBCS, per steps 309 and 311. The MS lOl can also leave a channel, as in step 313, and subsequently j oin another channel. The MS 101 can join several channels at the same time (if the operator policy permits), and may have the ability to support multiple displays/screens, e.g., with PiP (Picture-in-Picture) feature.

(0051 j During datacast (step 311), the system 100 can perform MCBCS bearer optimization (step 315) as well as handoff procedures to provide MS mobility (step 317). That is, when the MS 101 is receiving the IPTV/datacast, MS 101 can move among cells and regions within a geographical area, resulting in handovers between base stations of the WiMAX network 103. Also, from the RRM point of view, there can be cases where it is best for the network if multicast flows are unicast via radio waves from the base stations to a small number of terminals. Therefore, the radio bearer optimization process is provided (step 315) in order to perform switching between multicasted and unicasted multicast flows via the radio interface depicted as Rl of FIG. 2A and 2B, for example. Details of these processes are provided with respect to FIGs. 4-7.

J0052] FIG. 4 is a flowchart outlining step 309 for selecting and joining a channel by a mobile station. It is noted that depending on the implementation, the steps for FIGs. 4-7 can performed in parallel or be consolidated or performed in the alternative, hi step 401, the mobile station 101 seeks to join a channel, wherein IP bearers are setup and used for IP signaling, and program channel information are available to MS 101. At this point, the MS 101 has three options (respectively 403, 405, and 407) available for joining a channel.

[00531 In step 403, the MS 101 joins a channel using the IGMP/MLD protocols. In this process, the MS 101 sends an IGMP/MLD join request for joining the multicast channel (e.g. a request containing an identifier such as Channel ID = IP-M@), as in step 409. Once this request is received by ASN 103 via BS 105, it is sent to ASN-GW 107. In step 411, the ASN-GW 107 receives the request and performs a subscription and policy check for MS 101 for authentication purposes. The process then continues with the channel selection and joining procedure, assuming the subscriber is authorized to use the service (as later described).

[0054] Alternatives 2 and 3 are now explained. Assuming alternative 2 (step 405) is executed, the MS 101 can join a channel using an IGMP/MLD proxy in the BS 105. In step 413, the MS 101 sends a service addition request through an L2 message to the BS 105. This request is received by BS 105, which subsequently maps the request to the channel ID (e.g. IP-M@). The BS 105 then sends IGMP/MLD join request on behalf of MS 101 (via a dedicated R6 or any/MS IP bearer) to ASN-GW 107, in step 415. After this request is received by ASN-GW 107, the ASN-GW 107 implements a subscription and policy check for MS 101 (step 417).

[0055| In this third alternative (step 407), the MS 101 joins a channel with IGMP/MLD proxy in ASN-GW 107. hi step 419, the MS 101 then sends a service addition request through an L2 message to BS 105. Upon reception of this message, BS 105, in step 421, sends an R4 control message on behalf of MS 101 to ASN-GW 107. This message is received by ASN-GW 107, which consequently performs subscription and policy check for MS 101 (in step 423).

[0056] The join process, in step 425, determines that the subscriber is allowed to engage in the service, and thus, the ASN-GW 107 requests the necessary resources from the BS 105. In response to this request, BS 105 decides to either unicast IP the multicast stream to the MS 101 (if there are too few multicast users) or to add MS 101 to an existing multicast radio bearer (step 427). Following this, the multicast data path setup/update occurs between ASN-GW 107 and BS 105, per step 429. If the ASN-GW 107 is not a member of the IP multicast tree, the ASN-GW 107 joins the IP-Multicast tree (multicast router connects to ASN-GW 107, hence bypassing MIP and HA), per step 431. Thereafter, the IP multicast data flow is provided to the subscriber (step 433).

[0057 J After joining the channel, the user can decide to change a channel or simply turn off the TV service, whereby the system 100 need to perform a process for leaving the channel.

|0058J FIG. 5 is a flowchart of process for leaving a channel by a mobile station, in accordance with an embodiment of the invention. As with the join process, the MS 101 can leave a channel using various approaches. In this example, the user is experiencing an ongoing datacast (as in step 501). In the first alternative, the MS 101 leaves a channel using IGMP/MLD (step 503). Next, the MS 101 sends an IGMP/MLD leave for the subject multicast channel, specifying an identifier of the channel (e.g. Channel ID = IP-M@) to the ASN-GW 107, as in step 509. The ASN-GW 107 intercepts IGMP/MLD leave request from MS 101 in step 511. The process then continues to step 525.

(0059) Alternatively, the second approach (step 505), involves using an IGMP/MLD proxy in the BS 105. Under this scenario, the MS 101, in step 513, sends a service deletion request through an L2 message to the base station 105. The BS 105 intercepts, as in step 515, the L2 deletion request message from MS 101 and maps request to Channel ID (e.g. IP-M@). Next, BS 105 also sends IGMP/MLD leave request on behalf of MS 101 (via dedicated R6 or any MS IP bearer) in step 515. The leave request is received by the ASN-GW 107, per step 517.

|006fl| Under the third alternative (step 507), the MS 101 leaves a channel using an IGMP/MLD proxy in the ASN-GW 107. In step 519, the MS 101 sends a service deletion request through an L2 message. Thereafter, the BS 105 then sends a control message on behalf of the MS 101 to the ASN-GW 107, per step 521. The ASN-GW 107 receives the control message from the BS 105, in step 5523.

[006I J After performing one of the three alternative approaches, the process, in step 525, involves removing the mobile station 101 from the multicast data path, which exists between the ASN-GW 107 and the BS 105. In step 5527, the BS 105 deletes the MS 101 from the multicast radio bearer, which can be either unicast or multicast. If the deleted user is the last user in the multicast group, the ASN-GW 107 sends an IGMP/MLD leave message to the multicast router 111 (step 529). Finally, in step 531 , the IP multicast data flow is halted for the subscriber.

10062 J FIG. 6 is a flowchart of process for providing MS mobility, according to an exemplary embodiment. It is noted that during the handover execution phase stemming from mobility of the MS 101, the target BS (e.g., BS 105) adds the newly arrived MS 101 to either the unicast IP multicast stream (in the case of few multicast users) or adds the MS 101 to an existing multicast radio bearer.

10063 J In this example, the MS 101 is engaged in an IP multicast session, per step 601. As the user crosses coverage area boundaries, the handover preparation and execution procedure is realized, as in step 603. This procedure may be performed according to WiMAX specifications, according to one embodiment. At this stage, the target BS 105 has two options based on whether R4 is used for the multicast user plane. If R4 is indeed used, then the process branches to step 605. If, however, it is not used, then the process branches over to step 607. In the case that R4 is utilized, the target BS initiates, as in step 609, multicast data path setup with an anchor ASN-GW 201.

[0064} Jn the case that R4 is not utilized,. the target BS initiates, as in. step 611, multicast data path setup with target ASN-GW 107. Furthermore, if it is determined that the target ASN-GW 107 is not a member of the BP multicast tree (step 613), the target ASN-GW 107 joins the IP- Multicast tree (i.e., multicast router 111 connects to target ASN-GW 107, hence bypassing MIP and HA).

[0065] In steps 615 and 617, the process tears down the unused reference points (RPs) and conducts radio bearer optimization. The mobility phase is completed in step 619, where the IP multicast data flow starts for the subscriber at the new location.

[0066| FIG. 7 is a flowchart of process for providing MCBCS bearer optimization, in accordance with an embodiment of the invention. The bearer optimization process can be based, for example, on cumulative event or be fixed-time based. According to one embodiment, this procedure uses MAC (L2) signaling with each MS concerned. This can entail significant overhead, especially considering the possibility that some mobile stations may be in the idle state and some may be receiving MCBCS service at any given time. For this reason and because the expected behavior of mobile users is to frequently change channels and to undergo handoffs, there is a need to minimize the optimization signaling overhead while saving radio resources. This lends itself to a procedure that is quick to change unicasted multicast flows into multicast flows across the radio channel and to split multicast flows over the radio channels into unicasted radio connections (i.e., CIDs).

[00671 In step 701, a choice is made between unicast or multicast bearer for Rl (for instance). If no change is made, as in step 703, the procedure is terminated and optimization is not necessary, per step 705. If the choice is made to switch from multicast to unicast (corresponding to step 707), a delay is introduced in step 709. Following this delay, the choice to switch from multicast to unicast is evaluated again for Rl (step 711). If the decision is still valid, then the multicast is changed to unicasted multicast, per steps 713 and 715. However, if the choice is changed, then the procedure is terminated and optimization is not necessary.

[0068] The bearer change can be from unicast to multicast (step 717). As such, the process modifies the unicasted multicast to multicast in step 719

[0069] As described previously, multicast flows are transported to the BS 105 across ASN 103 using multicast bearers in R6 and R4. These are subsequently mapped to multicast radio bearers across Rl. However, from the RRM perspective, it is not always advantageous to multicast across the radio interface, especially if the number of listening terminals is small, e.g., less than 5. In this case, the ASN 103 can optimize the use of radio bearers and the multicast stream can be replicated and unicast across the radio interface to each terminal separately.

[0070J To maximize the benefits of the multicast in R6 (and R4), it would be beneficial if one site, such as the base transceiver station (BTS) 801, would be fed only one copy of a stream shared by all sectors. The approach is described in FIG. 8B. All base stations 105 part of the BTS 801 receive the same copy of the stream shared by all sectors. This is in contrast to the approach depicted in FIG. 8A, whereby multiple copies of the stream are conveyed to each BS 105 respectively by ASN-GW 107.

[0071 ] FIG. 9 is a diagram of a protocol stack for supporting multicast, in accordance with an embodiment of the invention. The protocol stack relates to the R6 interface and includes the following layers: user IP-M layer 901, a GRE (Generic Routing Encapsulation) layer 903, transport IP-M layer 905, and a Transport layer 907. The IP transport layer 907 can support IP- M; and the GRE flow tags (keys) allocated to a particular flow to different BSs from the same ASN-GW are identical. In an exemplary embodiment, mapping of IP-M addresses at user IP level 901 and GRE keys to transport IP level 905 can be rule based or fixed and implemented in the respective elements.

(0072 J The above processes provide an efficient deployment of multicast-broadcast data service. A multicast flow is received at a gateway (e.g., gateway 107) that is configured to directly join a multicast tree. This approach advantageously assists a base station (e.g., BS 105) of an access network to provide a datacast service to a terminal (e.g., bandwidth intensive applications) served by the base station 105, thus resulting in better system performance.

[0073 J One of ordinary skill in the art would recognize that the processes for providing a multicast-broadcast service may be implemented via software, hardware (e.g., general processor, Digital Signal Processing (DSP) chip, an Application Specific Integrated Circuit (ASIC), Field Programmable Gate Arrays (FPGAs), etc.), firmware, or a combination thereof. Such exemplary hardware for performing the described functions is detailed below with respect to FIG. 10.

[0074] FIG. 10 illustrates exemplary hardware upon which various embodiments of the invention can be implemented. A computing system 1000 includes a bus 1001 or other communication mechanism for communicating information and a processor 1003 coupled to the bus 1001 for processing information. The computing system 1000 also includes main memory 1005, such as a random access memory (RAM) or other dynamic storage device, coupled to the bus 1001 for storing information and instructions to be executed by the processor 1003. Main memory 1005 can also be used for storing temporary variables or other intermediate information during execution of instructions by the processor 1003. The computing system 1000 may further include a read only' memory (ROM) 1007 or other static storage device coupled to the bus 1001 for storing static information and instructions for the processor 1003. A storage device 1009, such as a magnetic disk or optical disk, is coupled to the bus 1001 for persistently storing information and instructions.

[0075] The computing system 1000 may be coupled via the bus 1001 to a display 1011, such as a liquid crystal display, or active matrix display, for displaying information to a user. An input device 1013, such as a keyboard including alphanumeric and other keys, may be coupled to the bus 1001 for communicating information and command selections to the processor 1003. The input device 1013 can include a cursor control, such as a mouse, a trackball, or cursor direction keys, for communicating direction information and command selections to the processor 1003 and for controlling cursor movement on the display 1011.

[0076] According to various embodiments of the invention, the processes described herein can be provided by the computing system 1000 in response to the processor 1003 executing an arrangement of instructions contained in main memory 1005. Such instructions can be read into main memory 1005 from another computer-readable medium, such as the storage device 1009. Execution of the arrangement of instructions contained in main memory 1005 causes the processor 1003 to perform the process steps described herein. One or more processors in a multiprocessing arrangement may also be employed to execute the instructions contained in main memory 1005. In alternative embodiments, hard- wired circuitry may be used in place of or in combination with software instructions to implement the embodiment of the invention. In another example, reconfigurable hardware such as Field Programmable Gate Arrays (FPGAs) can be used, in which the functionality and connection topology of its logic gates are customizable at run-time, typically by programming memory look up tables. Thus, embodiments of the invention are not limited to any specific combination of hardware circuitry and software.

10077 ] The computing system 1000 also includes at least one communication interface 1015 coupled to bus 1001. The communication interface 1015 provides a two-way data communication coupling to a network link (not shown). The communication interface 1015 sends and receives electrical, electromagnetic, or optical signals that carry digital data streams representing various types of information. Further, the communication interface 1015 can include peripheral interface devices, such as a Universal Serial Bus (USB) interface, a PCMCIA (Personal Computer Memory Card International Association) interface, etc.

|00781 The processor 1003 may execute the transmitted code while being received and/or store the code in the storage device 1009, or other non- volatile storage for later execution, hi this manner, the computing system 1000 may obtain application code in the form of a carrier wave.

[00791 The term "computer-readable medium" as used herein refers to any medium that participates in providing instructions to the processor 1003 for execution. Such a medium may take many forms, including but not limited to non-volatile media, volatile media, and transmission media. Non-volatile media include, for example, optical or magnetic disks, such as the storage device 1009. Volatile media include dynamic memory, such as main memory 1005. Transmission media include coaxial cables, copper wire and fiber optics, including the wires that comprise the bus 1001. Transmission media can also take the form of acoustic, optical, or electromagnetic waves, such as those generated during radio frequency (RF) and infrared (IR) data communications. Common forms of computer-readable media include, for example, a floppy disk, a flexible disk, hard disk, magnetic tape, any other magnetic medium, a CD-ROM, CDRW, DVD, any other optical medium, punch cards, paper tape, optical mark sheets, any other physical medium with patterns of holes or other optically recognizable indicia, a RAM, a PROM, and EPROM, a FLASH-EPROM, any other memory chip or cartridge, a carrier wave, or any other medium from which a computer can read.

10080 J Various forms of computer-readable media may be involved in providing instructions to a processor for execution. For example, the instructions for carrying out at least part of the invention may initially be borne on a magnetic disk of a remote computer. In such a scenario, the remote computer loads the instructions into main memory and sends the instructions over a telephone line using a modem. A modem of a local system receives the data on the telephone line and uses an infrared transmitter to convert the data to an infrared signal and transmit the infrared signal to a portable computing device, such as a personal digital assistant (PDA) or a laptop. An infrared detector on the portable computing device receives the information and instructions borne by the infrared signal and places the data on a bus. The bus conveys the data to main memory, from which a processor retrieves and executes the instructions. The instructions received by main memory can optionally be stored on storage device either before or after execution by processor.

[008Ij FIGs. HA and HB are diagrams of different cellular mobile phone systems capable of supporting various embodiments of the invention. FIGs. HA and HB show exemplary cellular mobile phone systems each with both mobile station (e.g., handset) and base station having a transceiver installed (as part of a Digital Signal Processor (DSP)), hardware, software, an integrated circuit, and/or a semiconductor device in the base station and mobile station). By way of example, the radio network supports Second and Third Generation (2G and 3G) services as defined by the International Telecommunications Union (ITU) for International Mobile Telecommunications 2000 (IMT-2000). For the purposes of explanation, the carrier and channel selection capability of the radio network is explained with respect to a cdma2000 architecture. As the third-generation version of IS -95, cdma2000 is being standardized in the Third Generation Partnership Project 2 (3GPP2).

J 0082 j A radio network 1100 includes mobile stations 1101 (e.g., handsets, terminals, stations, units, devices, or any type of interface to the user (such as "wearable" circuitry, etc.)) in communication with a Base Station Subsystem (BSS) 1103 through a relay station (RS) 1104. According to one embodiment of the invention, the radio network supports Third Generation (3G) services as defined by the International Telecommunications Union (ITU) for International Mobile Telecommunications 2000 (IMT-2000).

[0083 J In this example, the BSS 1103 includes a Base Transceiver Station (BTS) 1105 and Base Station Controller (BSC) 1107. Although a single BTS is shown, it is recognized that multiple BTSs are typically connected to the BSC through, for example, point-to-point links. Each BSS 1103 is linked to a Packet Data Serving Node (PDSN) 1109 through a transmission control entity, or a Packet Control Function (PCF) 1111. Since the PDSN 1109 serves as a gateway to external networks, e.g., the Internet 1113 or other private consumer networks 1115, the PDSN 1109 can include an Access, Authorization and Accounting system (AAA) 1117 to securely determine the identity and privileges of a user and to track each user's activities. The network 1115 comprises a Network Management System (NMS) 1131 linked to one or more databases 1133 that are accessed through a Home Agent (HA) 1135 secured by a Home AAA 1137.

[0084J Although a single BSS 1103 is shown, it is recognized that multiple BSSs 1103 are typically connected to a Mobile Switching Center (MSC) 1119. The MSC 1119 provides connectivity to a circuit-switched telephone network, such as the Public Switched Telephone Network (PSTN) 1121. Similarly, it is also recognized that the MSC 1119 may be connected to other MSCs 1119 on the same network 1100 and/or to other radio networks. The MSC 1119 is generally collocated with a Visitor Location Register (VLR) 1123 database that holds temporary information about active subscribers to that MSC 1119. The data within the VLR 1123 database is to a large extent a copy of the Home Location Register (HLR) 1125 database, which stores detailed subscriber service subscription information, hi some implementations, the HLR 1125 and VLR 1123 are the same physical database; however, the HLR 1125 can be located at a remote location accessed through, for example, a Signaling System Number 7 (S S 7) network. An Authentication Center (AuC) 1127 containing subscriber-specific authentication data, such as a secret authentication key, is associated with the HLR 1125 for authenticating users. Furthermore, the MSC 1119 is connected to a Short Message Service Center (SMSC) 1129 that stores and forwards short messages to and from the radio network 1100.

[0085| During typical operation of the cellular telephone system, BTSs 1105 receive and demodulate sets of reverse-link signals from sets of mobile units 1101 conducting telephone calls or other communications. Each reverse-link signal received by a given BTS 1105 is processed within that station. The resulting data is forwarded to the BSC 1107. The BSC 1107 provides call resource allocation and mobility management functionality including the orchestration of soft handoffs between BTSs 1105. The BSC 1107 also routes the received data to the MSC 1119, which in turn provides additional routing and/or switching for interface with the PSTN 1121. The MSC 1119 is also responsible for call setup, call termination, management of inter- MSC handover and supplementary services, and collecting, charging and accounting information. Similarly, the radio network 1100 sends forward-link messages. The PSTN 1121 interfaces with the MSC 1119. The MSC 1119 additionally interfaces with the BSC 1107, which in turn communicates with the BTSs 1105, which modulate and transmit sets of forward-link signals to the sets of mobile units 1101.

10086] As shown in FIG. HB, the two key elements of the General Packet Radio Service (GPRS) infrastructure 1150 are the Serving GPRS Supporting Node (SGSN) 1132 and the Gateway GPRS Support Node (GGSN) 1134. In addition, the GPRS infrastructure includes a Packet Control Unit PCU (836) and a Charging Gateway Function (CGF) 1138 linked to a Billing System 1139. A GPRS the Mobile Station (MS) 1141 employs a Subscriber Identity Module (SIM) 1143. Under this scenario, a relay station (RS) 1144 provides extended coverage for the MS 1141.

J0087) The PCU 1136 is a logical network element responsible for GPRS-related functions such as air interface access control, packet scheduling on the air interface, and packet assembly and re-assembly. Generally the PCU 1136 is physically integrated with the BSC 1145; however, it can be collocated with a BTS 1147 or a SGSN 1132. The SGSN 1132 provides equivalent functions as the MSC 1149 including mobility management, security, and access control functions but in the packet-switched domain. Furthermore, the SGSN 1132 has connectivity with the PCU 1136 through, for example, a Fame Relay-based interface using the BSS GPRS protocol (BSSGP). Although only one SGSN is shown, it is recognized that that multiple SGSNs 1131 can be employed and can divide the service area into corresponding routing areas (RAs). A SGSN/SGSN interface allows packet tunneling from old SGSNs to new SGSNs when an RA update takes place during an ongoing Personal Development Planning (PDP) context. While a given SGSN may serve multiple BSCs 1145, any given BSC 1145 generally interfaces with one SGSN 1132. Also, the SGSN 1132 is optionally connected with the HLR 1151 through an SS7- based interface using GPRS enhanced Mobile Application Part (MAP) or with the MSC 1149 through an SS7-based interface using Signaling Connection Control Part (SCCP). The SGSN/HLR interface allows the SGSN 1132 to provide location updates to the HLR 1151 and to retrieve GPRS-related subscription information within the SGSN service area. The SGSN/MSC interface enables coordination between circuit-switched services and packet data services such as paging a subscriber for a voice call. Finally, the SGSN 1132 interfaces with a SMSC 1153 to enable short messaging functionality over the network 1150.

10088 j The GGSN 1134 is the gateway to external packet data networks, such as the Internet 1113 or other private customer networks 1155. The network 1155 comprises a Network Management System (NMS) 1157 linked to one or more databases 1159 accessed through a PDSN 1161. The GGSN 1134 assigns Internet Protocol (IP) addresses and can also authenticate users acting as a Remote Authentication Dial-In User Service host. Firewalls located at the GGSN 1134 also perform a firewall function to restrict unauthorized traffic. Although only one GGSN 1134 is shown, it is recognized that a given SGSN 1132 may interface with one or more GGSNs 1133 to allow user data to be tunneled between the two entities as well as to and from the network 1150. When external data networks initialize sessions over the GPRS network 1150, the GGSN 1134 queries the HLR 1151 for the SGSN 1132 currently serving a MS 1141.

[0089] The BTS 1147 and BSC 1145 manage the radio interface, including controlling which Mobile Station (MS) 1141 has access to the radio channel at what time. These elements essentially relay messages between the MS 1141 and SGSN 1132. The SGSN 1132 manages communications with an MS 1141, sending and receiving data and keeping track of its location. The SGSN 1132 also registers the MS 1141 , authenticates the MS 1141 , and encrypts data sent to the MS 1141.

|0090| FIG. 12 is a diagram of exemplary components of a mobile station (e.g., handset) capable of operating in the systems of FIGs. HA and HB, according to an embodiment of the invention. Generally, a radio receiver is often defined in terms of front-end and back-end characteristics. The front-end of the receiver encompasses all of the Radio Frequency (RF) circuitry whereas the back-end encompasses all of the base-band processing circuitry. Pertinent internal components of the telephone include a Main Control Unit (MCU) 1203, a Digital Signal Processor (DSP) 1205, and a receiver/transmitter unit including a microphone gain control unit and a speaker gain control unit. A main display unit 1207 provides a display to the user in support of various applications and mobile station functions. An audio function circuitry 1209 includes a microphone 1211 and microphone amplifier that amplifies the speech signal output from the microphone 1211. The amplified speech signal output from the microphone 1211 is fed to a coder/decoder (CODEC) 1213. f0091 | A radio section 1215 amplifies power and converts frequency in order to communicate with a base station, which is included in a mobile communication system (e.g., systems of FIG. HA or HB), via antenna 1217. The power amplifier (PA) 1219 and the transmitter/modulation circuitry are operationally responsive to the MCU 1203, with an output from the PA 1219 coupled to the duplexer 1221 or circulator or antenna switch, as known in the art. The PA 1219 also couples to a battery interface and power control unit 1220.

[0092] Ln use, a user of mobile station 1201 speaks into the microphone 1211 and his or her voice along with any detected background noise is converted into an analog voltage. The analog voltage is then converted into a digital signal through the Analog to Digital Converter (ADC) 1223. The control unit 1203 routes the digital signal into the DSP 1205 for processing therein, such as speech encoding, channel encoding, encrypting, and interleaving. In the exemplary embodiment, the processed voice signals are encoded, by units not separately shown, using the cellular transmission protocol of Code Division Multiple Access (CDMA), as described in detail in the Telecommunication Industry Association's TIA/EIA/IS-95-A Mobile Station-Base Station Compatibility Standard for Dual-Mode Wideband Spread Spectrum Cellular System; which is incorporated herein by reference in its entirety.

[0093 J The encoded signals are then routed to an equalizer 1225 for compensation of any frequency-dependent impairments that occur during transmission though the air such as phase and amplitude distortion. After equalizing the bit stream, the modulator 1227 combines the signal with a RF signal generated in the RF interface 1229. The modulator 1227 generates a sine wave by way of frequency or phase modulation. In order to prepare the signal for transmission, an up-converter 1231 combines the sine wave output from the modulator 1227 with another sine wave generated by a synthesizer 1233 to achieve the desired frequency of transmission. The signal is then sent through a PA 1219 to increase the signal to an appropriate power level. In practical systems, the PA 1219 acts as a variable gain amplifier whose gain is controlled by the DSP 1205 from information received from a network base station. The signal is then filtered within the duplexer 1221 and optionally sent to an antenna coupler 1235 to match impedances to provide maximum power transfer. Finally, the signal is transmitted via antenna 1217 to a local base station. An automatic gain control (AGC) can be supplied to control the gain of the final stages of the receiver. The signals may be forwarded from there to a remote telephone which may be another cellular telephone, other mobile phone or a land-line connected to a Public Switched Telephone Network (PSTN), or other telephony networks.

100941 Voice signals transmitted to the mobile station 1201 are received via antenna 1217 and immediately amplified by a low noise amplifier (LNA) 1237. A down-converter 1239 lowers the carrier frequency while the demodulator 1241 strips away the RF leaving only a digital bit stream. The signal then goes through the equalizer 1225 and is processed by the DSP 1205. A Digital to Analog Converter (DAC) 1243 converts the signal and the resulting output is transmitted to the user through the speaker 1245, all under control of a Main Control Unit (MCU) 1203-which can be implemented as a Central Processing Unit (CPU) (not shown).

|0095| The MCU 1203 receives various signals including input signals from the keyboard 1247. The MCU 1203 delivers a display command and a switch command to the display 1207 and to the speech output switching controller, respectively. Further, the MCU 1203 exchanges information with the DSP 1205 and can access an optionally incorporated SIM card 1249 and a memory 1251. In addition, the MCU 1203 executes various control functions required of the station. The DSP 1205 may, depending upon the implementation, perform any of a variety of conventional digital processing functions on the voice signals. Additionally, DSP 1205 determines the background noise level of the local environment from the signals detected by microphone 1211 and sets the gain of microphone 1211 to a level selected to compensate for the natural tendency of the user of the mobile station 1201.

100961 The CODEC 1213 includes the ADC 1223 and DAC 1243. The memory 1251 stores various data including call incoming tone data and is capable of storing other data including music data received via, e.g., the global Internet. The software module could reside in RAM memory, flash memory, registers, or any other form of writable storage medium known in the art. The memory device 1251 may be, but not limited to, a single memory, CD, DVD, ROM, RAM, EEPROM, optical storage, or any other non-volatile storage medium capable of storing digital data.

10097 J An optionally incorporated SIM card 1249 carries, for instance, important information, such as the cellular phone number, the carrier supplying service, subscription details, and security information. The SIM card 1249 serves primarily to identify the mobile station 1201 on a radio network. The card 1249 also contains a memory for storing a personal telephone number registry, text messages, and user specific mobile station settings.

J 00981 FIG. 13 shows an exemplary enterprise network, which can be any type of data communication network utilizing packet-based and/or cell-based technologies (e.g., Asynchronous Transfer Mode (ATM), Ethernet, IP-based, etc.). The enterprise network 1301 provides connectivity for wired nodes 1303 as well as wireless nodes 1305-1309 (fixed or mobile), which are each configured to perform the processes described above. The enterprise network 1301 can communicate with a variety of other networks, such as a WLAN network 1311 (e.g., IEEE 802.11), a cdma2000 cellular network 1313, a telephony network 1316 (e.g., PSTN), or a public data network 1317 (e.g., Internet).

10099 J While the invention has been described in connection with a number of embodiments and implementations, the invention is not so limited but covers various obvious modifications and equivalent arrangements, which fall within the purview of the appended claims. Although features of the invention are expressed in certain combinations among the claims, it is contemplated that these features can be arranged in any combination and order.

Claims

CLAIMSWHAT IS CLAIMED IS:

1. A method comprising: receiving a multicast flow at a gateway that is configured to directly join a multicast tree or to receive the multicast flow via a unicast tunnel or a multicast tunnel; and forwarding the multicast flow to a base station of an access network to provide a datacast service to a terminal served by the base station.

2. A method according to claim 1, wherein the datacast service includes an Internet Protocol Television (IPTV) service.

3. A method according to claim 2, further comprising: intercepting, by the gateway, a request from the terminal to join a channel of the IPTV service; and requesting resources from the base station for establishing a multicast stream or unicast stream, corresponding to the channel, to the terminal.

4. A method according to claim 2, further comprising: intercepting a request, by the base station configured to act as a proxy for the terminal, from the terminal to join a channel of the IPTV service, wherein the base station is configured to map the request to an identifier of the channel, and to send a join request on behalf of the terminal; and requesting resources from the base station for establishing a multicast stream or unicast stream, corresponding to the channel, to the terminal.

5. A method according to claim 2, further comprising: receiving, by the gateway configured to act as a proxy for the terminal, a control message from the base station on behalf of the terminal to join a channel of the IPTV service; and requesting resources from the base station for establishing a multicast stream or unicast stream, corresponding to the channel, to the terminal.

6. A method according to claim 2, further comprising: intercepting, by the gateway, a request from the terminal to leave a channel of the IPTV service; removing the terminal from a multicast data path between the gateway and the base station; and sending a leave message to the multicast router if the terminal is a last member in a multicast group, wherein the multicast flow is halted for the terminal.

7. A method according to claim 2, further comprising: intercepting a request, by the base station configured to act as a proxy for the terminal, from the terminal to leave a channel of the IPTV service, wherein the base station is configured to send a leave request on behalf of the terminal; removing the terminal from a multicast data path between the gateway and the base station; and sending a leave message to the multicast router if the terminal is a last member in a multicast group, wherein the multicast flow is halted for the terminal.

8. A method according to claim 2, further comprising: receiving, by the gateway configured to act as a proxy for the terminal, a control message from the base station on behalf of the terminal to leave a channel of the IPTV service; removing the terminal from a multicast data path between the gateway and the base station; and sending a leave message to the multicast router if the terminal is a last member in a multicast group, wherein the multicast flow is halted for the terminal.

9. A method according to claim 1, further comprising: performing a handover procedure for the terminal; and establishing a multicast data path with the base station that is configured to initiate set-up of the multicast data path, wherein the multicast flow is transmitted to the terminal over the multicast data path.

10. A method according to claim 9, further comprising: determining whether to change a radio bearer choice from a multicast service to a unicast service or from a unicast service to a multicast service to support the multicast flow.

11. A method according to claim 1, wherein the access network is compliant with a Worldwide Interoperability for Microwave Access (WiMAX) network.

12. A system comprising: a gateway, within an access network, configured to receive a multicast flow by directly joining a multicast tree or via a unicast tunnel or a multicast tunnel, the gateway being further configured to forward the multicast flow to a base station of the access network to provide a datacast service to a terminal served by the base station.

13. A system according to claim 12, wherein the datacast service includes an Internet Protocol Television (IPTV) service.

14. A system according to claim 13, wherein the gateway is further configured to intercept request from the terminal to join a channel of the IPTV service, and to request resources from the base station for establishing a multicast stream or unicast stream, corresponding to the channel, to the terminal.

15. A system according to claim 13, wherein the base station is configured to act as a proxy for the terminal by intercepting a request from the terminal to join a channel of the IPTV service, wherein the base station is further configured to map the request to an identifier of the channel, and to send a join request on behalf of the terminal, the gateway being further configured to request resources from the base station for establishing a multicast stream or unicast stream, corresponding to the channel, to the terminal.

16. A system according to claim 13, wherein the gateway is further configured to act as a proxy for the terminal by receiving a control message from the base station on behalf of the terminal to join a channel of the IPTV service, the gateway being further configured to request resources from the base station for establishing a multicast stream or unicast stream, corresponding to the channel, to the terminal.

17. A system according to claim 13, wherein the gateway is further configured to intercept a request from the terminal to leave a channel of the DPTV service and to remove the terminal from a multicast data path between the gateway and the base station, the gateway being further configured to send a leave message to the multicast router if the terminal is a last member in a multicast group, wherein the multicast flow is halted for the terminal.

18. A system according to claim 13, wherein the base station configured to act as a proxy for the terminal by intercepting a request from the terminal to leave a channel of the IPTV service, and to send a leave request on behalf of the terminal, wherein the gateway is further configured to remove the terminal from a multicast data path between the gateway and the base station, the gateway being further configured to send a leave message to the multicast router if the terminal is a last member in a multicast group, wherein the multicast flow is halted for the terminal.

19. A system according to claim 13, wherein the gateway is further configured to act as a proxy for the terminal by receiving a control message from the base station on behalf of the terminal to leave a channel of the IPTV service, and to remove the terminal from a multicast data path between the gateway and the base station, the gateway being further configured to send a leave message to the multicast router if the terminal is a last member in a multicast group, wherein the multicast flow is halted for the terminal.

20. A system according to claim 12, wherein a handover procedure is performed for the terminal, and the gateway is further configured to establish a multicast data path with the base station that is configured to initiate set-up of the multicast data path, the multicast flow being transmitted to the terminal over the multicast data path.

21. A system according to claim 20, wherein a determination is made whether to change a radio bearer choice from a multicast service to a unicast service or from a unicast service to a multicast service to support the multicast flow.

22. A system according to claim 12, wherein the access network is compliant with a Worldwide Interoperability for Microwave Access (WiMAX) network.

23. A method comprising: generating a request to either join or leave a channel associated with a packet-based television service; and receiving a multicast flow from an access network that includes a base station coupled to a gateway, the gateway being configured to directly join a multicast tree.

24. A method according to claim 23, wherein the gateway is further configured to intercept the request from the terminal to join a channel of the packet-based television service, and to request resources from the base station for establishing a multicast stream or unicast stream corresponding to the channel, the method further comprising: receiving either the multicast stream or the unicast stream.

25. A method according to claim 23, wherein the base station is configured to act as a proxy by intercepting the request to join a channel of the packet-based television service, the base station being further configured to map the request to an identifier of the channel, and to send a join request on behalf of the terminal, wherein the gateway is further configured to request resources from the base station for establishing a multicast stream or unicast stream corresponding to the channel, the method further comprising: receiving either the multicast stream or the unicast stream.

26. A method according to claim 23, wherein the gateway is configured to act as a proxy by receiving a control message from the base station for joining a channel of the packet-based television service in response to the request, wherein the gateway is further configured to request resources from the base station for establishing a multicast stream or unicast stream corresponding to the channel, the method further comprising: receiving either the multicast stream or the unicast stream.

27. A method according to claim 23, wherein the gateway is configured to intercept the request to leave a channel of the packet-based television service and to send a leave message to the multicast router, wherein the multicast flow is halted.

28. A method according to claim 23, wherein the base station is configured to act as a proxy by intercepting the request to leave a channel of the packet-based television service in response to the request, wherein the base station is configured to send a leave request to the gateway, wherein the gateway is further configured to send a leave message to the multicast router, wherein the multicast flow is halted.

29. A method according to claim 23, wherein the gateway is further configured to act as a proxy by receiving a control message from the base station to leave a channel of the packet-based television service in response to the request, wherein the multicast flow is halted.

30. A method according to claim 23, further comprising: executing a handover procedure, wherein the gateway is. further configured to establish a multicast data path with the base station that is configured to initiate set-up of the multicast data path, wherein the multicast flow is received over the multicast data path.

31. A method according to claim 30, wherein a determination is made whether to change a radio bearer choice from a multicast service to a unicast service or from a unicast service to a multicast service to support the multicast flow.

32. An apparatus comprising: a processor configured to generate a request to either join or leave a channel associated with a packet-based television service; and a transceiver configured to receive a multicast flow from an access network that includes a base station coupled to a gateway, the gateway being configured to directly join a multicast tree.

33. An apparatus according to claim 32, wherein the gateway is further configured to intercept the request from the terminal to join a channel of the packet-based television service, and to request resources from the base station for establishing a multicast stream or unicast stream corresponding to the channel, the transceiver being further configured .to receive either the multicast stream or the unicast stream.

34. An apparatus according to claim 32, wherein the base station is configured to act as a proxy by intercepting the request to join a channel of the packet-based television service, the base station being further configured to map the request to an identifier of the channel, and to send a join request on behalf of the terminal, wherein the gateway is further configured to request resources from the base station for establishing a multicast stream or unicast stream corresponding to the channel, the transceiver being further configured to receive either the multicast stream or the unicast stream.

35. An apparatus according to claim 32, wherein the gateway is configured to act as a proxy by receiving a control message from the base station for joining a channel of the packet-based television service in response to the request, wherein the gateway is further configured to request resources from the base station for establishing a multicast stream or unicast stream corresponding to the channel, the transceiver being further configured to receive either the multicast stream or the unicast stream.

36. An apparatus according to claim 32, wherein the gateway is configured to intercept the request to leave a channel of the packet-based television service and to send a leave message to the multicast router, wherein the multicast flow is halted.

37. An apparatus according to claim 32, wherein the base station is configured to act as a proxy by intercepting the request to leave a channel of the packet-based television service in response to the request, wherein the base station is configured to send a leave request to the gateway, wherein the gateway is further configured to send a leave message to the multicast router, wherein the multicast flow is halted.

38. An apparatus according to claim 32, wherein the gateway is further configured to act as a proxy by receiving a control message from the base station to leave a channel of the packet-based television service in response to the request, wherein the multicast flow is halted.

39. An apparatus according to claim 32, wherein the processor is further configured to execute a handover procedure, the gateway being further configured to establish a multicast data path with the base station that is configured to initiate set-up of the multicast data path, wherein the multicast flow is received over the multicast data path.

40. An apparatus according to claim 39, wherein a determination is made whether to change a radio bearer choice from a multicast service to a unicast service or from a unicast service to a multicast service to support the multicast flow.