HK1079945A - Method and apparatus for supporting application-layer media multicasting - Google Patents

Description

Method and apparatus for supporting application layer media multicast

Technical Field

The present invention relates to point-to-multipoint communication systems, and more particularly, to a method and apparatus for supporting application layer multicast for delivering media streams to a group of target communication devices within a wireless communication network.

Background

In a group call service, a large number of group participants are typically gathered in a small geographic area, such as a construction site. It is not feasible to set up a point-to-point communication link for such group participants, who would be located in a single sector. The group participant will "arch" all resources available to the sector. This results in a very high call barring rate experienced by other users. Furthermore, if the density of group participants is high in a given sector, the network may not have sufficient resources to allocate a dedicated channel to each group participant. Thus, users are denied access to the group call not because of having group membership issues, but because of a lack of available network resources. This problem negatively affects group call users.

Existing group calls require the group call server to replicate the media and send only one copy to each group participant on a separate point-to-point communication link. Having the group call server duplicate media for transmission to all participants of the target group is a processor intensive task and burdensome on the server when the number of group participants is large. Having the group call server send one copy of the media to each group participant improves network traffic on both the wireless access network (RAN) of the wireless infrastructure and the Wide Area Network (WAN) of the service provider.

For example, one class of wireless services is directed to fast, efficient, one-to-one or one-to-many (group) communications. Typically, these services are half-duplex, where a user presses a "push-to-talk" (PTT) button on the phone/radio to start a group call. If the floor is granted, the speaker will typically speak for a few seconds. After the speaker releases the PTT button, the other group members can request the floor. These services are traditionally used in applications where: one of the people, the "dispatcher," needs to communicate with a group of people, such as field service personnel or taxi drivers, where the "dispatch" name of the service comes from. Similar services are provided on the internet, which are referred to as "voice chat".

Therefore, mechanisms are needed for conserving radio resources, reducing the processing load of the server, and reducing network traffic for both the RAN of the wireless infrastructure and the WAN of the service provider.

Disclosure of Invention

The disclosed embodiments provide a novel and improved method and apparatus for delivering media to a group of target communication devices that uses a media multicast mechanism at the application layer to conserve network resources. In one aspect, a method and apparatus are used for multicasting media to a set of target communication devices within a wireless communication network that includes a wireless infrastructure and a Group Call Server (GCS). The method multicasts one copy of the media from the GCS to the wireless infrastructure for transmission to the set of target communication devices. The method also transmits a copy of the media from the wireless infrastructure to each of the first plurality of target communication devices within the first cell or sector and multicasts a copy of the media from the wireless infrastructure to the second plurality of target communication devices within the second cell or sector.

In one aspect, a method and apparatus for determining whether to multicast media to a set of target communication devices on a multicast path includes determining a count of participants in the set of target communication devices and multicasting media to a wireless infrastructure for transmission to the set of target communication devices if the determined count exceeds a predetermined threshold.

In one aspect, an apparatus for communicating information to a set of target communication devices in a wireless communication system comprises: a memory unit, a receiver, a transmitter, and a processor communicatively coupled to the memory unit, the receiver, and the transmitter. The processor is capable of implementing the above-described method.

Drawings

The features, nature, and advantages of the present invention will become more apparent from the detailed description set forth below when taken in conjunction with the drawings in which like elements have like numerals wherein:

FIG. 1 illustrates a set of communication systems;

fig. 2 illustrates an embodiment of the base station and mobile station of fig. 1;

fig. 3 illustrates how several communication devices interact with a group call server;

FIG. 4 illustrates one embodiment of a group call server operating in FIG. 1;

fig. 5 illustrates a call setup procedure according to the first embodiment; and

fig. 6 illustrates a call setup procedure according to the second embodiment.

Detailed Description

Before explaining several embodiments in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting.

Fig. 1 illustrates a functional block diagram of a group communication system 100 according to an embodiment. The group communication system 100 is also referred to as a push-to-talk (PTT) system, internet broadcast service (NBS), dispatch system, or point-to-multipoint communication system. In one embodiment, group communication system 100 includes a group call server 102, which may be deployed in a centralized or a regionalized arrangement, such as the copending patent application filed on month 2 and 14, 2002: described in U.S. patent application serial No. 10/076,726, which is assigned to the assignee of the present invention and is incorporated herein by reference in its entirety.

The group communication device 104 may be deployed as the cdma2000 family of handsets, for example, the group communication device 104 may request a packet data session using a data service option. Each communication device may register the IP address of the communication device with group call server 102 using the session to perform group call origination. In one embodiment, communication devices 104 may have an Internet Protocol (IP) connection to group call server 102 through PDSN 106 and IP network 108 when requesting packet data sessions from the wireless infrastructure. The PDSN provides an interface between data transmission within the fixed network and data transmission over the air. Each PDSN may interface with a Base Station Controller (BSC)110 through a Packet Control Function (PCF)112, which PCF 112 may be co-located with the BSC.

After power up, CD 104 may request a packet data session using a data service option. Each CD may be assigned an IP address as part of establishing a packet data session. Each CD may perform a registration procedure to inform GCS 102 about the CD's IP address. Registration may be performed using an IP protocol, such as session initiation protocol over User Datagram Protocol (UDP). The IP address of the CD may be used to contact the CD when inviting the corresponding user to a group call. Once the group call is established, CD 104 and GCS 102 can exchange media and signaling messages. In one embodiment, media may be sent between the call participants and GCS 102 using Real Time Protocol (RTP) over UDP. The signaling message may also be a signaling protocol over UDP.

Group communication system 100 performs several different functions in order to operate a group service. The functions on the user side include user registration, group call origination, group call termination, sending alerts to group members, late join to group call, talker arbitration, adding users to a group, removing members from a group, revoking members, and authentication. Functions related to system preparation and operation include management, provisioning, scalability, and reliability. These functions are described in detail in the aforementioned application No. 10/076,726.

Fig. 2 is a simplified block diagram of an embodiment of base station 204 and mobile station 206, base station 204 and mobile station 206 being capable of implementing various disclosed embodiments. For particular communications, voice data, packet data, and/or messages may be exchanged between base station 204 and mobile station 206, via an air interface 208. Various types of messages may be transmitted, such as messages used to establish a communication session between a base station and a mobile station, registration and paging messages, and messages used to control data transmission (e.g., power control, data rate information, acknowledgment, and so on). Some of these message types are described in detail below.

For the reverse link, at mobile station 206, voice and/or packet data (e.g., from a data source 210) is provided to a Transmit (TX) data processor 212, which formats and encodes the data and messages with one or more coding schemes to generate coded data. Each coding scheme may include any combination of Cyclic Redundancy Check (CRC), convolutional, turbo, block, and other codes, or no coding at all. Voice data, packet data, and messages may be encoded using different schemes, and different types of messages may be encoded differently.

The coded data is then provided to a Modulator (MOD)214 and further processed (e.g., covered, spread with short PN sequences, and scrambled with a long PN sequence assigned to the user terminal). The modulated data is then provided to a transmitter unit (TMTR)216 and conditioned (e.g., converted to one or more analog signals, amplified, tabulated, and quadrature modulated) to generate a reverse link signal. The reverse link signal is routed through a duplexer (D)218 and transmitted via an antenna 220 to base station 204.

At base station 204, the reverse link signal is received by an antenna 250, routed through a duplexer 252, and provided to a receiver unit (RCVR) 254. Base station 204 may receive registration information and status information, such as mobile station mobility rate, from mobile station 206. Receiver unit 254 conditions (e.g., filters, amplifies, frequency downconverts, and digitizes) the received signal and provides samples. A demodulator (DEMOD)256 receives and processes (e.g., despreads, decovers, and pilot demodulates) the samples to provide recovered symbols. Demodulator 256 may implement a rake receiver that processes multiple instances of the received signal and generates combined symbols. A Receive (RX) data processor 258 then decodes the symbols to recover the data and messages transmitted on the reverse link. The recovered voice/packet data is provided to a data sink 260 and the recovered messages are provided to a controller 270. Controller 270 may include instructions for: paging a group of mobile stations, sending radio parameters to the mobile stations, and binding the mobile stations to a multicast group. The processing by demodulator 256 and RX data processor 258 are complementary to that performed at mobile station 206. Demodulator 256 and RX data processor 258 may further be operated to process multiple transmissions received via multiple channels, e.g., a reverse fundamental channel (R-FCH) and a reverse supplemental channel (R-SCH). Likewise, transmissions may be simultaneously from multiple mobile stations, each transmitting on a reverse fundamental channel, a reverse supplemental channel, or both.

On the forward link, at base station 204, voice and/or packet data (e.g., from a data source 262) and messages (e.g., from controller 270) are processed (e.g., formatted and encoded) by a Transmit (TX) data processor 264, further processed (e.g., covered and spread) by a Modulator (MOD)266, and conditioned (e.g., converted to analog signals, amplified, filtered, and quadrature modulated) by a transmitter unit (TMTR)268 to generate a forward link signal. The forward link signal is routed through a duplexer 252 and transmitted via an antenna 250 to mobile station 206. The forward link signals include paging signals.

At mobile station 206, the forward link signal is received by an antenna 220, routed through a duplexer 218, and provided to a receiver unit 222. Receiver unit 222 conditions (e.g., downconverts, ratios, amplifies, quadrature modulates, and digitizes) the received signal and provides samples. The samples are processed (e.g., despreaded, decovered, and pilot demodulated) by a demodulator 224 to provide symbols, and the symbols are further processed (e.g., decoded and checked) by a receive data processor 226 to recover the data and messages transmitted on the forward link. The recovered data is provided to a data sink 228 and the recovered messages are provided to a controller 230. Controller 230 may include instructions for: registering the mobile station 206, requesting a group call, and sending media to the base station 204.

The Group Call Service (GCS) may allow a user to speak to a group of users in a half-duplex mode or a full-duplex mode. In the former case, the permission to talk may be mitigated by the infrastructure, since only one person is allowed to talk at a time. In such systems, a user may request permission to speak by pressing, for example, a "push-to-talk" button (PTT). The system may arbitrate requests received from multiple users, and through a contention-resolution process, the system may select a requester according to a predetermined algorithm. The system will then notify the selected users that the user has permission to speak. The system distributes the user's traffic information, such as voice and/or data, from an authorized speaker to the rest of the group members, the rest being considered "listeners". Voice and/or data traffic in the GCS may require prioritization over some sessions, unlike traditional one-to-one telephone calls.

Fig. 3 illustrates a group call layout showing how CDs 302, 304, and 306 interact with a group call server 308. Multiple group call servers may be employed for large-scale groups as needed. In fig. 3, when CD 302 is permitted to send media to other members of the group, CD 302 is considered the talker and will send the media over the established channel. When CD 302 is designated as the speaker, the remaining participants, CD 304 and CD 306, may not have permission to send media to the group. Thus, CD 304 and CD 306 are designated as listeners. As described above, CDs 302, 304, and 306 connect to group call server 308 using at least one channel. In one embodiment, the channels include a Session Initiation Protocol (SIP) channel, a media signaling channel, and a media traffic channel.

FIG. 4 illustrates one embodiment of a group call server 102 operating in the system of FIG. 1. The group call server includes antennas 402, 404 for transmitting and receiving data. Antenna 402 is coupled to receiver circuitry 406 and antenna 404 is coupled to transmit circuitry 408. Communication bus 410 provides a common connection among the other modules of fig. 4. The communication bus 410 is also coupled to a storage unit 412. Memory 412 stores computer readable instructions for various operations and functions performed by the group call server. The processor 414 executes instructions stored in the memory 412.

In a group communication system, as shown in fig. 1, for example, a large number of group participants are typically clustered in a small geographic area, such as a building site. It is not feasible to set up multiple point-to-point communication links for all participants located within a single sector. The group participant will "arch" all available resources within the sector. This can cause other users not belonging to the group to experience a very high call barring rate. Furthermore, if the density of group participants is high in a given sector, the network may not have sufficient resources to allocate a dedicated channel to each group participant. Thus, users are denied access to the group call not because of having group membership issues, but because of a lack of available network resources. This problem has a negative impact on the group call users.

According to one embodiment, the media multicast mechanism reduces network traffic because the media multiplexing mechanism eliminates the need to establish a separate traffic channel between the group call server and each member of the group of target communication devices. This mechanism also eliminates the need for media replication by the group call server in order to send to all members of the target group. In one embodiment, one copy of the media may be sent to the group address, and the underlying wireless infrastructure may replicate the media at the wireless infrastructure hops where paths to different group members diverge. Since the group call server sends one copy of the media, the media is replicated at network hops as needed, thereby significantly reducing network traffic over both the wireless infrastructure RAN and the service provider's WAN.

In an embodiment, the activation of application layer media multicasting depends on whether the communication is one-to-one or one-to-many (group). In another embodiment, in a group communication service, activation of application-layer media multicasting is dependent on the number of participants in the target group. Fig. 5 illustrates a call setup procedure according to the first embodiment, where there are only two participants in a group, e.g. a one-to-one call, or the number of participants in the target group is below a predetermined threshold required to activate the application layer media multicast mechanism.

A user who wishes to originate a group call may select one or more target users, one or more predefined groups, or a combination of both, and may press a push-to-talk (PTT) button to originate the group call. When a caller initiates a group call, the participants in the target group may be in a dormant packet data session. Participating CDs establish packet data sessions 502 and perform the necessary registrations, such as described in the above-mentioned co-pending patent application. The caller's CD may send a group call request 504 to the group call server using the established packet data session to set up the group call. The group call request may be sent to the group call server regardless of whether the caller's CD has a dedicated traffic channel, as described in U.S. patent application serial No. 10/006,037 filed on 12, 4, 2002, which is assigned to the assignee of the present invention and is incorporated herein by reference.

In one embodiment, the caller's CD may send the group call request to the group call server on an available channel without waiting for a dedicated channel to be established for the caller's CD. In one embodiment, the group call request may be sent to the group call server as a Short Data Burst (SDB). After sending the request, if the caller's CD is in a dormant packet data session, the caller's CD may begin the following process: the dedicated traffic channel is re-established and the packet data session is prepared for media activity.

When the group call server receives a group call request, the server extends the predefined groups into the target member list if any are specified in the request. The group call server may retrieve location information, such as an IP address, for the target member. The group call server may also determine whether the desired group is already running in the system.

The group call server responds with a group call request acknowledgement 506 using the established packet data session. In one embodiment, the group call server determines 508 whether the number of participants in the target group meets a threshold required to activate the application layer multicast mechanism. If the number of participants in the target group does not meet the required threshold, the group call server may send group call announcements 510 to the caller's CD and to the listener's CD over the established packet data session.

Group call announcement 510 may include information indicating that a unicast delivery mechanism may be used by a group call server, where the group call service may use the established packet data session to communicate media to the group members. This requires the group call server to replicate and send one copy of the media to each individual group member, but saves time in establishing multicast trees for a one-to-one call or a group call with a small number of participants. The group call server may retrieve media 512 from the caller's CD on the established packet data session and forward the received media 514 to the listener's CD.

Fig. 6 illustrates a call setup procedure in which the number of group participants exceeds a predetermined threshold required to activate the application-layer media multicast mechanism, according to an embodiment. As discussed in connection with fig. 5, after establishing the packet data session 602, the caller's CD may send a group call request 604 to the group call server to establish the group call. When the group call server receives the group call request 604, the group call server may respond with a set of call request confirmations 606.

In one embodiment, the group call server may send the response using the established packet data session. The group call server may determine 608 the number of participants in the target group. If the number of participants in the target group exceeds the desired threshold, the group call server uses an IP media multicast mechanism to deliver the media it receives from the caller's CD to the target listener's CD. The group call server may send the group call announcement 610 to the caller's CD as well as the listeners' CDs on the established packet data session. The group call announcement 610 sent from the group call server to the group participants may include information indicating that the group call server can use IP media multicast mechanisms to conserve network resources.

The group call declaration may also contain information indicating that the target group members may need to bind to the requested group call. Such information may include an IP multicast address and/or some multicast service identifier. In one embodiment, the group call server may query another network component to obtain the IP multicast address to be used for the target group call. In one embodiment, the group call server may be assigned to a pool of IP multicast addresses for group communications. At the end of the group call, the IP multicast address may be returned to the pool.

After receiving the group call announcement, each participating CD may perform a registration process 612 with the wireless infrastructure. The registration procedure 612 may be performed on a dedicated channel, such as a reverse fundamental channel (R-FCH), or a common channel, such as a reverse enhanced access channel (R-EACH), or a reverse access channel (R-ACH). The registration message may inform the BSC: participating CDs wish to participate in the group call. The registration message also includes information identifying the cell and/or sector in which each participating CD is located. The registration message may also include an IP multicast address, a multicast service identifier, and other network parameters that the participating CDs may receive from the group call server.

The BSC may bind 614 the registered participating CDs with the multicast IP-multicast address of the target group. In one embodiment, the BSC binds each registered participating CD with the IP multicast address via a separate dedicated channel. This may occur if the count of registered participating CDs in one cell and/or sector is less than a predetermined number, or if the registered participating CDs are sparsely located in more than one cell and/or sector. For example, if the target listeners' CDs are arranged as CDs 104B or 104C shown in fig. 1, the corresponding BSC may bind these CDs with the IP multicast address via a dedicated channel.

In one embodiment, the BSC maps the registered participating CDs to IP multicast addresses over a shared channel. This may occur if the count of registered participating CDs in a cell and/or sector is greater than a predetermined number or if the registered participating CDs are located in a cell and/or sector. For example, if the target listeners' CDs are arranged as CDs 104A or 104D shown in fig. 1, the respective BSCs would map these CDs to IP multicast addresses via a shared channel. In one embodiment, the BSC has shared forward channel capabilities if there are physical layer channels, such as a forward broadcast control channel (F-BCCH), a forward common control channel (F-CCCH), a forward paging channel (F-PCH), or a forward supplemental channel (F-SCH), for conveying the group call medium to a group of targeted listeners.

For some time, the BSC may broadcast certain radio parameters 616 to the participating CDs, or send them separately to the participating CDs as overhead messages. The BSC may forward these parameters to each cell or sector separately. The radio parameters may include information indicating whether the target CD is bound to the IP multicast address via a dedicated channel or a shared channel. In one embodiment, the BSC may transmit the radio parameters on a forward broadcast control channel (F-BCCH), a forward paging channel (F-PCH), or a forward common control channel (F-CCCH). Alternatively, the BSC may send the radio parameters directly to the participating CDs on the existing packet data session.

In one embodiment, a participating CD that has received the wireless parameters but has not yet registered with the corresponding BSC need not register with the BSC if the BSC has indicated in the wireless parameters that the BSC has mapped shared channels to the cell and/or sector in which the unregistered participating CD is located. However, if the BSC has indicated in the radio parameters that the BSC has mapped dedicated channels to the cells and/or sectors in which such unregistered CDs are located, the unregistered participating CDs must register with the respective BSC.

The BSC may then establish a multicast path 618 between the BSC and the group call server, as described in the following co-pending patent applications: U.S. patent application serial No. 10/011,526, filed 11/5/2001, assigned to the assignee of the present invention and incorporated herein by reference in its entirety.

Upon receiving the group call announcement and successfully registering with the BSC, the caller's CD may send media 620 to the group call server on a reverse dedicated channel, such as a reverse supplemental channel (R-SCH), a reverse dedicated control channel (R-DCCH), or a reverse fundamental channel (R-FCH). Alternatively, the caller's CD may communicate with the BSC using a reverse common channel, such as a reverse enhanced access channel (R-EACH) or a reverse access channel (R-ACH). In either case, the existing packet data session may be placed in dormant mode. The BSC may send media 622 that the BSC has received from the caller's CD to the group call server using the established packet data session or multicast path.

The group call server may use the IP multicast address and multicast a copy of the media to the associated BSC over the established IP multicast path 624. The media proceeds along multicast path 624 and reaches those BSCs that have established a multicast path for the same IP-multicast address. In one embodiment, the BSC may need to copy the media it receives from the group call server for transmission to the target listeners' CDs. This may occur where the IP multicast address is mapped to a target CD via a dedicated traffic channel, such as in the case of CD 104B or 104C described in fig. 1.

The BSC may send a copy 626 of the media to each target listener's CD mapped to an IP multicast address via a dedicated channel on such an established dedicated channel. The BSC may also send one copy of the media 626 to the target listener's CD mapped to the IP multicast address via a shared channel.

In one embodiment, the BSC may set up the forward traffic channel as a shared forward channel regardless of the number of participants in the group call. In the message to the participating CD, the BSC may indicate that the BSC broadcasts the radio parameters to the participating CD. Participating CDs that receive messages but have not performed registration need not register any more. Such CDs can tune to the radio parameters specified in the message for receiving group call media, which advantageously prevents flooding of registration messages sent on the common reverse link, thus reducing the number of unnecessary registration messages processed by the BSC.

In one embodiment, the BSC may set up the forward traffic channel as the shared forward channel if the number of registration messages the BSC receives from a given cell or sector exceeds a given threshold. If the number of registration messages the BSC receives from a cell or sector is below the threshold, the BSC may send the media to each participating CD on a dedicated channel. The BSC may send a message to each or some of the participating CDs indicating that the BSC is either using a shared channel or a dedicated forward channel.

In one embodiment, the group communication system 100 supports both a chat-room mode and an ad-hoc (ad-hoc) mode for group call services. In the chat-room model, groups are predefined and they may be stored on the group call distribution server. The predefined group or network may be public, meaning that the group has an open member list, i.e., any CD may join the group. In this case, each group member distribution user is a potential participant in a group call. In the chat-room model, the group call is started when the first group member chooses to start joining the group call. The call remains active regardless of the speech activity for a predetermined period of time, which may be configurable by the service provider, and server resources are allocated to the call. During a group call, group members specifically request to join and/or leave such a call. During periods of talk inactivity, each group call may be brought into a group dormant state, discussed below, until a group member requests permission to talk. When operating in a chat-room mode, a group of communication device users, also referred to as net members, communicate with each other using communication devices assigned to each net member. The term "net" denotes a group of communication device users that are authorized to communicate with each other.

However, in the ad hoc mode of the group call service, groups may be defined in real time and have a closed member list associated with each group. The closed member list may specify which members are allowed to participate in the group call. The member list is not available to other users outside the closed member list and only exists for the duration of the call. The ad hoc group definition may not be stored in the group call server. The definitions may be used to establish a group call and release the call after the call is completed. An ad hoc group may be formed when an originating speaker selects one or more target members and generates a group call request that is sent to a group call server to start the call. The group call server may send a notification to the target group members that they have been included in the group. The group call server may automatically join the target member into the group call, i.e. without any user action by the target member.

When an ad hoc call becomes inactive, the group communication server will "tear down" (tear down) the call and release the resources allocated to the group, including the group definition used to start the call. In one embodiment, after a period of inactivity, the BSC may release the traffic channel, e.g., shared and/or dedicated traffic channel, but still keep the multicast path active. However, after an extended period of inactivity, the BSC and/or wireless network infrastructure may trigger a multicast group leave, such as Internet Group Management Protocol (IGMP), to tear down the multicast tree. This may prevent the RAN of the wireless network infrastructure and/or the WAN of the service provider from remaining connected to the group call session that ended due to network or group call server failure.

Thus, the disclosed embodiments provide for a significant reduction in network traffic and media processing time by sending media in an IP multicast mode, where a single copy of the media directed to a group of intended recipients is sent to the wireless infrastructure over a single multicast path. The wireless infrastructure replicates and sends one copy of the received media to each target recipient that is assigned to a dedicated channel. However, the wireless infrastructure only sends one copy of the received media to those target recipients that are assigned to the shared channel.

Those of skill in the art would understand that information and signals may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referenced throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

Those of skill would further appreciate that the various illustrative logical blocks, modules, and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.

The implementation or execution of the various illustrative logical blocks, modules, and algorithm steps described in connection with the embodiments described herein may be implemented or performed with: a general purpose processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination designed to perform the functions described herein. A general purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

The steps of a method or algorithm described in connection with the embodiments disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. A software module may reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. An exemplary storage medium is coupled to the processor such the processor can read information from, and write information to, the storage medium. In the alternative, the storage medium may be integral to the processor. The processor and the storage medium may reside in an ASIC. The ASIC may reside in a user terminal. In the alternative, the processor and the storage medium may reside as discrete components in a user terminal.

The previous description of the preferred embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without the use of the inventive faculty. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (32)

1. A method for multicasting media to a set of target communication devices in a wireless communication network, the wireless communication network comprising a wireless infrastructure and a group call server, GCS, the method comprising:

multicasting a copy of the media from the GCS to the wireless infrastructure for transmission to the set of target communication devices;

transmitting a copy of the media from the wireless infrastructure to each of a first plurality of target communication devices within a first area; and

multicasting a copy of the media from the wireless infrastructure to a second plurality of target communication devices within a second area.

2. The method of claim 1, wherein multicasting one copy of the media from the GCS comprises: a copy of the media is sent to a single multicast group address.

3. The method of claim 1, further comprising: replicating, by the wireless infrastructure, the media for transmission to each of the first plurality of target communication devices.

4. The method of claim 3, wherein the sending to each of the first plurality of target communication devices comprises: transmitting a copy of the media on a forward dedicated channel of the wireless infrastructure.

5. The method of claim 1, wherein the multicasting to the second plurality of target communication devices comprises: transmitting a copy of the media on a forward shared channel of the wireless infrastructure.

6. The method of claim 1, wherein the second area comprises a cell coverage area.

7. The method of claim 1, wherein the second area comprises a sector coverage area.

8. A method for determining whether to multicast media to a group of target communication devices over a shared path, the method comprising:

determining a participant count in the set of target communication devices that are within a coverage area; and

multicasting a copy of the media to the set of target communication devices over the shared channel if the count exceeds a predetermined threshold.

9. The method of claim 8, further comprising:

if the count is below the predetermined threshold, a copy of the media is sent to each member of the set of target communication devices on a dedicated channel.

10. The method of claim 8, wherein the coverage area comprises a cell coverage area.

11. The method of claim 8, wherein the coverage area comprises a sector coverage area.

12. A computer readable medium comprising a method of multicasting media to a set of target communication devices within a wireless communication network, the wireless communication network comprising a wireless infrastructure and a group call server, GCS, the method comprising:

multicasting a copy of the media from the GCS to the wireless infrastructure for transmission to the set of target communication devices;

transmitting a copy of the media from the wireless infrastructure to each of a first plurality of target communication devices within a first area; and

multicasting a copy of the media from the wireless infrastructure to a second plurality of target communication devices within a second area.

13. The computer-readable medium of claim 12, wherein multicasting one copy of the media from the GCS comprises: a copy of the media is sent to a single multicast group address.

14. The computer-readable medium of claim 12, wherein the method further comprises: replicating, by the wireless infrastructure, the media for transmission to each of the first plurality of target communication devices.

15. The computer-readable media of claim 14, wherein the sending to the first plurality of target communication devices comprises: transmitting a copy of the media on a forward dedicated channel of the wireless infrastructure.

16. The computer-readable media of claim 12, wherein the multicasting to the second plurality of target communication devices comprises: transmitting a copy of the media on a forward shared channel of the wireless infrastructure.

17. A computer-readable medium embodying a method for determining whether to multicast media to a set of target communication devices over a shared path, the method comprising:

determining a participant count in the set of target communication devices that are within a coverage area; and

multicasting a copy of the media to the set of target communication devices over the shared channel if the count exceeds a predetermined threshold.

18. The computer-readable medium of claim 17, wherein the method further comprises:

if the count exceeds a predetermined threshold, a copy of the media is sent to the set of target communication devices over the shared channel.

19. An apparatus for multicasting media to a set of target communication devices within a wireless communication network, the wireless communication network including a wireless infrastructure and a Group Call Server (GCS), the apparatus comprising:

means for multicasting a copy of the media from the GCS to the wireless infrastructure for transmission to the set of target communication devices;

means for transmitting a copy of the media from the wireless infrastructure to each of a first plurality of target communication devices within a first area; and

means for multicasting a copy of the media from the wireless infrastructure to a second plurality of target communication devices within a second area.

20. The apparatus of claim 19, wherein the means for multicasting one copy of the media from the GCS comprises: means for sending a copy of the media to a single multicast group address.

21. The apparatus of claim 19, further comprising: means for replicating the media within a wireless infrastructure for transmission to each of the first plurality of target communication devices.

22. The apparatus of claim 21, wherein means for transmitting to each of the first plurality of target communication devices comprises: means for transmitting a copy of the media on a forward dedicated channel of the wireless infrastructure.

23. The apparatus of claim 19, wherein the means for multicasting to the second plurality of target communication devices comprises: means for transmitting a copy of the media on a forward shared channel of the wireless infrastructure.

24. An apparatus for determining whether to multicast media to a group of target communication devices on a multicast path, the apparatus comprising:

means for determining a participant count in the set of target communication devices located within the coverage area; and

means for multicasting a copy of the media to the set of target communication devices over the shared channel if the count exceeds a predetermined threshold.

25. The apparatus of claim 24, further comprising:

means for transmitting a copy of the media to each member of the set of target communication devices on a dedicated channel if the count is below the predetermined threshold.

26. An apparatus for multicasting media to a set of target communication devices within a wireless communication network, comprising:

a storage unit;

a receiver;

a transmitter; and

a processor coupled to the memory unit, the receiver, and the transmitter, the processor capable of:

multicasting a copy of the media from the GCS to the wireless infrastructure for transmission to the set of target communication devices;

transmitting a copy of the media from the wireless infrastructure to each of a first plurality of target communication devices within a first area; and

multicasting a copy of the media from the wireless infrastructure to a second plurality of target communication devices within a second area.

27. The apparatus of claim 26, wherein multicasting one copy of the media from the GCS comprises: a copy of the media is sent to a single multicast group address.

28. The apparatus of claim 26, wherein the processor is further capable of: replicating the media within a wireless infrastructure for transmission to each of the first plurality of target communication devices.

29. The apparatus of claim 28, wherein the transmission to each of the first plurality of target communication devices comprises: transmitting a copy of the media on a forward dedicated channel of the wireless infrastructure.

30. The apparatus of claim 26, wherein the multicasting to the second plurality of target communication devices comprises: transmitting a copy of the media on a forward shared channel of the wireless infrastructure.

31. An apparatus for determining whether to multicast media to a group of target communication devices on a multicast path, comprising:

a storage unit;

a receiver;

a transmitter; and

a processor coupled to the memory unit, the receiver, and the transmitter, the processor capable of:

determining a participant count in the set of target communication devices that are within a coverage area; and

multicasting a copy of the media to the set of target communication devices over the shared channel if the count exceeds a predetermined threshold.

32. The apparatus of claim 31, wherein the processor is further capable of:

if the count is below the predetermined threshold, a copy of the media is sent to each member of the set of target communication devices on a dedicated channel.