JP2009212777A - Group communication server, communication terminal, and communication system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a group communication server, a communication terminal, and a communication system capable of suppressing processing load of the group communication server, in a large-scale group communication with a large number of users in the group. <P>SOLUTION: In the communication system, a group communication session is established by a Session Initiating Protocol (SIP). In the communication system, a PoC server 41 being the group communication server for controlling a group communication session between communication terminals existing in the communication system generates an SIP message for initiating the group communication session including a media description which is information described by a session description protocol (SDP) and is used for multicasting from own server to the communication terminal, and transmits the SIP message to the communication terminal which is a member of the group communication. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a group communication server, a communication terminal, and a communication system used for group communication.

  In recent years, one-to-one or one-to-many half-duplex communication (two-way communication in which only one person can transmit data such as voice at a time) is performed in a communication terminal such as a mobile phone. It has become possible. This is a group communication service called PoC (Push-To-Talk over Cellular), which is standardized by OMA (Open Mobile Alliance) which is an international mobile application standardization organization (see Non-Patent Document 1). .

  When performing group communication, the member list is managed by an XDM server (XML Document Management Server) in cooperation with other servers such as a presence server. Then, when a user in the member list requests the start of a group communication session (hereinafter referred to as a PoC session), a PoC session is established using a session initiation protocol (SIP). Specifically, when a PoC session start is requested by a user, the PoC server (PoC Server) refers to the group communication member list of the XDM server and sends an INVITE message to each user, thereby communicating the group communication. Form a road and invite participation in group communications. Thereafter, media such as audio and video called media burst are transmitted from the communication terminal of the user who has acquired the right to speak using RTP (Real-time Transport Protocol), and the PoC server becomes a member of the group communication. Transferred. In general, the user can request the right to speak by pressing a predetermined button or key of the communication terminal, and MBCP (Media Burst Control Protocol) so that one communication terminal permitted by the PoC server can transmit data. The right to speak is controlled (for example, Non-Patent Document 2).

  In general, the SIP protocol uses a session description protocol (SDP) for negotiation of a unicast session, and the SIP message body contains information such as the type of media used in the session by SDP. Described. Since RTP supports not only unicast sessions but also multicast sessions, it is also possible to start multicast sessions using the SIP protocol. That is, when a participant transmits media to the multicast address and port number, the media reaches all participants. In such a multicast session, the participants have an equal relationship and do not have a function provided by the group communication service such as control of the floor. RTP sessions have the concept of a mixer and a translator. The mixer is used when a speech received from a plurality of speakers is collected into one stream in a conference control server or the like (for example, Non-Patent Document 3).

Masayoshi Fujioka, Yasushi Oda, Kazuhiko Nakata “Introduction to the Latest Technology IMS” Impress Inc., July 1, 2007 “Push to talk over Cellular (PoC)-Architecture, Candidate Version 2.0”-11 Dec 2007, Open Mobile Alliance Ltd. Takuya Sawada, et al. “Practical SIP Detailed Text”, Rick Telecom, November 11, 2005

  However, the conventional group communication apparatus uses communication (unicast session) between two parties between the group communication server and the user communication terminal. For this reason, when the number of users in the group becomes large, there is a problem that the number of media bursts transmitted by unicast increases and the processing load on the group communication server increases.

  On the other hand, when a user simply uses a multicast session on an equal basis without going through a group communication server, there is a problem that it is impossible to provide advanced functions such as control of speaking right and media aggregation.

  The present invention has been made in view of the above, and has a centralized management function possessed by a conventional group communication server, while reducing the processing load of the group communication server even in large-scale group communication with a large number of users in the group. It is an object to obtain a group communication server, a communication terminal, and a communication system that can be suppressed.

  In order to solve the above-described problems and achieve the object, the present invention provides a group communication session between communication terminals existing in the communication system in a communication system that establishes a group communication session using a session initiation protocol (SIP). Managing and generating a SIP message for starting a group communication session including a media description used for multicast in the direction from the local server to the communication terminal, which is information described by a session description protocol (SDP) The SIP message is transmitted to a communication terminal that is a member of group communication.

  According to the present invention, since the number of media bursts transmitted by unicast can be suppressed even in large-scale group communication with a large number of users in the group, the processing load of the PoC server is reduced compared to the conventional case. There is an effect that it can be suppressed.

  Embodiments of a group communication system according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment 1 FIG.
FIG. 1 is a diagram illustrating a configuration example of a first embodiment of a group communication system according to the present invention. This group communication system includes a group communication terminal (hereinafter also referred to as a communication terminal (MS)) 10-J (J = 1, 2,...) Owned by a user and an access that provides a radio access service to the communication terminal 10-J. A network 20-K (K = 1, 2,...), A network 30 connected to the access network 20-K and providing IP (Internet Protocol) connectivity to the communication terminal 10-J, and a service providing platform 40. ing.

  The access network 20-K is a network that provides an access service to a communication terminal, and includes a base station 21-L (L = 1, 2,...) And a gateway router 22-M (M = 1, 2,...). The In the present embodiment, an example in which a communication terminal is connected by a wireless access line is shown, but it may be connected by a wired access line.

  The network 30 is a network that provides IP connectivity to communication terminals centered on the SIP / IP core 31, and includes, for example, a SIP / IP core 31 that performs forwarding and routing of IP packets and SIP messages, a broadcast service, and multicast. A multicast server 32 that provides services, a location server 33 that manages location information of communication terminals, an authentication server 34 that performs communication service authentication processing, and a QoS policy charging server 35 that manages QoS (Quality of Service) policies and charges The home agent 36 for managing the association between the home address of the communication terminal and the destination address is provided.

  The service providing platform 40 includes a PoC server (group communication server) 41 that centrally manages a PoC session in which a group of communication terminals participates, a presence server 43 that distributes presence information of communication terminals, and a member that registers members that perform group communication. An XDM server 42 that manages the list in an XML (eXtensible Markup Language) format is provided, and an application service is provided to the communication terminal.

  Here, the operation of the group communication system configured as described above will be described. The PoC session in FIG. 1 is a session showing the operation of the present embodiment. The PoC session includes a unicast media burst in the direction from the communication terminal to the PoC server 41 and a multicast media burst in the direction from the PoC server 41 to the communication terminal. The PoC server 41 controls the right to speak media bursts, and grants transmission permission to communication terminals having the right to speak. In FIG. 1, for example, the communication terminal 10-1 has the right to speak. The media burst (sound or video) transmitted by the communication terminal 10-1 is converted into a multicast media burst by the PoC server 41. For example, a multicast of a session in which the communication terminals 10-1 to 3 which are members of the group communication participate. Sent to an address.

  FIG. 2 is a diagram showing an outline of the session description used for defining the PoC session in FIG. 2 includes a first media description unit 62 used for unicast and a second media description unit 63 used for multicast.

  In general, in the SIP protocol, SDP is used to describe a session to be controlled. Descriptions regarding the PoC session, unicast media burst, and multicast media burst in FIG. 1 correspond to the session description unit 61, the first media description unit 62, and the second media description unit 63 in FIG. 2, respectively. Although omitted in FIG. 2, the session description of the actual PoC session includes a media description used for the floor control protocol (MBCP). It may also contain a media description for use in text message transfer protocol (MSRP).

  FIG. 3 is a diagram for explaining an interface protocol in group communication. Each communication terminal includes, for example, a PoC client 15, an XDM client 16, a presence source / watcher 17, and the like. The communication terminal is also called a PoC client or PoC user equipment (UE: User Equipment) in the PoC technology and a user agent (UA: User Agent) in the SIP technology. The SIP / IP core 31 is composed of a SIP proxy and a SIP registrar and has a function of transferring a SIP signaling message to a destination.

  For the interface between the PoC client 15 and the PoC server 41, RTP, RTCP (Real Time Control Protocol), and MBCP are used. RTP is a protocol used to transfer media such as audio and video. RTCP is a protocol used for exchanging statistical information related to media transfer and also for transferring MBCP messages. MBCP is a protocol used for controlling the right to speak a PoC session. The PoC client 15 has an interface via the SIP / IP core 31 with the PoC server 41. In this interface, a PoC session is established and managed using messages such as SIP INVITE, re-INVITE, REFER, UPDATE, BYE, Trying, OK, ACK, and Accepted.

  As an interface between the XDM client 16 and the XDM server 42, XCAP (XML Configuration Access Protocol) is used. As a result, the XDM client 16 can access the XDM server 42 to register and edit the member list. The presence source / watcher 17 has an interface via the SIP / IP core 31 with the presence server 43. In this interface, the presence function is realized by using messages such as SIP REGISTER, SUBSCRIBE, NOTIFY, PUBLISH, and the like.

  Next, a specific procedure for starting a PoC session will be described in detail. FIG. 4 is a sequence diagram illustrating an example of a PoC session setup process. Here, a processing procedure when the communication terminal 10-1 starts a PoC session is shown. First, the communication terminals 10-1 to 10-3 register location information and presence information of their own communication terminals in advance (step S11). Specifically, each communication terminal 10-1 to 10-3 registers the location information and presence information of its own communication terminal in the XDM server 42 via the presence server 43 using the SIP protocol REGISTER and SUBSCRIBE messages. To do.

  The presence server 43 notifies the location information and presence information to the communication terminals 10-1 to 10-3 that have performed the registration process (step S12). Specifically, the presence server 43 refers to the information managed by the XDM server 42, and uses the SIP protocol NOTIFY and PUBLISH messages to register the information of the communication terminals 10-1 to 10-3. Notify the communication terminal that performed.

  With the information of the communication terminals 10-1 to 10-3 registered in this way, for example, the communication terminal 10-1 arranges a group communication member list with the XDM server 42 (step S13). Thus, PoC group information including a group communication member list is set in the XDM server 42. As an example, the communication terminal 10-1 registers the communication terminals 10-2 and 10-3 in the member list.

  Next, the communication terminal 10-1 requests the PoC server 41 to start a PoC session using an SIP protocol invitation (INVITE) message (step S14). This INVITE message includes the PoC group information set in step S13.

  When the PoC server 41 receives the INVITE message from the communication terminal 10-1, the PoC server 41 returns a provisional response (Trying) indicating that the message is being processed to the communication terminal 10-1 (step S15), and the designated PoC A group member list is acquired from the XDM server 42 (step S16).

  In addition, the PoC server 41 transmits an invitation (INVITE) message to the PoC session to the communication terminals 10-2 and 10-3 that are members of the group communication designated by the communication terminal 10-1 (step S17). ). The body of this INVITE message includes a session description protocol (SDP) including a first media description unit 62 used for unicast and a second media description unit 63 used for multicast as described in FIG. ing.

  When receiving the INVITE message from the PoC server 41, the communication terminals 10-2 and 10-3 each return a provisional response (Trying) indicating that the message is being processed to the PoC server 41 (step S18). The SDP of the INVITE message received by the communication terminals 10-2 and 10-3 includes a media description used for multicast.

  Next, the communication terminals 10-2 and 10-3 send a message requesting the multicast distribution tree path change to the PoC server 41 via the access network 20 and the SIP / IP core 31, thereby multicasting. Is requested (step S21). As a message for requesting multicast distribution by a communication terminal, a Join message that complies with IGMP (Internet Group Management Protocol) in IPv4 and MLD (Multicast Listener Discovery) protocol in IPv6 is used. The access network 20 that has received the Join message transmitted from the communication terminal uses a Join message that conforms to the PIM (Protocol Independent Multicast) protocol as a message for requesting multicast distribution to a device upstream from itself. . Further, the access network 20 performs path setting for performing multicast distribution to the communication terminals 10-1 to 3 (step S22).

  When the media burst to be multicast is encrypted, the PoC server 41 distributes the encryption key for the group communication session to the access network 20 using the location information of the communication terminal or the information related to the multicast distribution tree (step S23). Thereafter, when the communication terminal requests an encryption key for group communication (step S24), the access network 20 uses an encryption method set for each communication terminal to use an encryption key (KEK) for key distribution related to the group communication session. : Key Encryption Key) and a traffic encryption key (TEK) are distributed (step S25).

  In this way, when the process for the INVITE message (step S17) received from the PoC server 41 is completed, each communication terminal returns a response (OK) message to the PoC server 41 (step S41). When the PoC server 41 receives the OK message from the communication terminals 10-2 and 10-3 that are members of the group communication, the PoC server 41 transmits an OK message notifying the start of the PoC session to the communication terminal 10-1 (step S42). ). With the above operation, a PoC session using multicast is established between the communication terminals 10-1 to 10-3.

  As described above, in this embodiment, media bursts in the direction from the communication terminal to the PoC server are transmitted by unicast according to the control of the floor of the PoC server, and media bursts in the direction from the PoC server to the communication terminal are multicast. It is transmitted by. As a result, even in a large-scale group communication with a large number of users in the group, the number of media bursts transmitted by unicast can be suppressed, so that the processing load of the PoC server can be suppressed compared to the conventional case. it can.

Embodiment 2. FIG.
In the first embodiment, the case where there is one media burst in the direction from the communication terminal to the PoC server has been described as an example. In the present embodiment, a case where there are a plurality of media bursts in the direction from the communication terminal to the PoC server will be described.

  FIG. 5 is a diagram showing a configuration example of the second embodiment of the group communication system according to the present invention. Compared with the group communication system of FIG. 1, the group communication system of FIG. 5 includes a PoC server 41 </ b> B instead of the PoC server 41 in the service providing platform 40. In addition to the function of the PoC server 41, the PoC server 41B has a mixer function for mixing a plurality of media bursts. In the present embodiment, a configuration and operation different from those of the above-described first embodiment will be described.

  Subsequently, the operation of the group communication system configured as described above will be described. The PoC session in FIG. 5 is a session showing the operation according to the present embodiment. The PoC session includes a plurality of unicast media bursts in the direction from the communication terminal to the PoC server 41B, and a multicast media burst in the direction from the PoC server 41B to the communication terminal. In FIG. 5, the communication terminal 10-1 and the communication terminal 10-3 obtain the floor and transmit media. The PoC server 41B mixes media bursts from the communication terminal 10-1 and the communication terminal 10-3 by a mixer function, converts the media burst into multicast media, and the communication terminals 10-1 to 10-3, which are members of group communication, participate. Send to a multicast address.

  FIG. 6 is a diagram showing an outline of the session description used for defining the PoC session in FIG. The session description unit 65 shown in FIG. 5 includes a first media description unit 66 and a second media description unit 67 used for unicast, and a third media description unit 68 used for multicast. The descriptions regarding the PoC session, unicast media burst, and multicast media burst in FIG. 5 are the session description unit 65, the first media description unit 66, the second media description unit 67, and the third media in FIG. This corresponds to the description unit 68.

  As described above, in the present embodiment, a configuration is adopted in which media transmitted from a plurality of communication terminals by unicast are mixed and multicast distributed to group communication participants. As a result, the same effects as in the first embodiment can be obtained, and moreover, since a plurality of group communication participants can simultaneously transmit media without waiting for the right to speak, group communication with a rich sense of reality Is possible.

Embodiment 3 FIG.
In the first and second embodiments, the multicast function is realized by a single PoC server. In the present embodiment, a case will be described in which a PoC server realizes a PoC session in cooperation with a multicast server that provides a broadcast or multicast service. In the present embodiment, a configuration and operation different from those of the first and second embodiments will be described.

  FIG. 7 is a diagram showing a configuration example of a third embodiment of the group communication system according to the present invention. Compared with the group communication system of FIG. 1, the group communication system of FIG. 7 includes a PoC server 41 </ b> C instead of the PoC server 41 in the service providing platform 40. In addition to the function of the PoC server 41, the PoC server 41C has a mixer function for mixing a plurality of media bursts and a function for transmitting media bursts to be multicast using a dedicated path to the multicast server 32.

  The multicast server 32 is a server that provides broadcast and multicast services as described in the first embodiment. Specifically, assuming a server that provides multicast services such as 3GPP MBMS (Multimedia Broadcast Multicast Service), 3GPP2 BCMCS (Broadcast Multicast Services), OMA BCAST Enabler, and WiMAX MBS (Multicast and Broadcast Service). Yes.

  Subsequently, the operation of the group communication system configured as described above will be described. The operation of the group communication system in the present embodiment is different from that in the first embodiment in that multicast media bursts are multicast through the multicast server 32. The PoC session in FIG. 7 is a session showing the operation according to the present invention. The PoC session includes a unicast media burst in the direction from the communication terminal 10-1 to the PoC server 41C, and a multicast media burst in the direction from the PoC server 41C to the communication terminal.

  Moreover, in this Embodiment, the communication terminal 10-1 has obtained the right to speak as an example. The media burst transmitted by the communication terminal 10-1 is converted into a multicast media burst by the PoC server 41C, and is sent to the multicast address through which the communication terminals 10-1 to 10-3, which are members of the group communication, participate via the multicast server 32. Sent to.

  Next, a specific procedure for starting a PoC session will be described in detail focusing on differences from the first and second embodiments. FIG. 8 is a sequence diagram illustrating an example of a PoC session setup process. Here, as in the first embodiment, a processing procedure when the communication terminal 10-1 starts a PoC session is shown.

  For example, after the processing of step S11 to step S16 is performed as described above, the PoC server 41C requests the multicast server 32 to set the multicast service, and sets information such as a multicast address to be used (step S31). . Also, a dedicated path for transmitting the multicast media to the multicast server 32 is set (step S32).

  Next, the PoC server 41C transmits an INVITE message to the PoC session to the communication terminals 10-2 and 10-3 that are members of the group communication designated by the communication terminal 10-1 (step S17). The body of this INVITE message includes a session description protocol similar to that described in FIG.

  When receiving the INVITE message from the PoC server 41C, the communication terminals 10-2 and 10-3 each return Trying to the PoC server 41 (step S18).

  The multicast server 32 commands the access network 20 to set a multicast distribution tree (Join command: step S33). Receiving this Join command, the access network 20 sets a path for distributing multicast to the communication terminals 10-1 to 3 (step S34). Further, the access network 20 requests multicast distribution from a device upstream of itself (multicast server 32) (Join: step S35).

  Further, when encrypting the media to be multicast, the multicast server 32 distributes the multicast key for the multicast group to the access network 20 using the location information of the communication terminal or the information related to the multicast distribution tree (step S36). Thereafter, the access network 20 distributes a key distribution encryption key (KEK) and a traffic encryption key (TEK) for the group communication session using an encryption method set for each communication terminal (step S37).

  The sequence of steps S33 to S37 in the present embodiment is an example in which multicast distribution tree setting and encryption key distribution are led by the multicast server 32, but the PoC server 41C takes the initiative instead of the multicast server 32. It is also possible to adopt a sequence led by a communication terminal, such as a sequence to be performed or S21 to S25 in FIG.

  In this way, when the processing for the INVITE message (step S17) received from the PoC server 41C is completed, each communication terminal returns an OK message to the PoC server 41C (step S41). When the PoC server 41C receives an OK message from the communication terminals 10-2 and 10-3 that are members of the group communication, the PoC server 41C transmits an OK message notifying the start of the PoC session to the communication terminal 10-1 (step S42). ). With the above operation, a PoC session using multicast is established between the communication terminals 10-1 to 10-3.

  As described above, in this embodiment, media bursts in the direction from the PoC server to the communication terminal are transmitted using the function of the multicast server. Thereby, since it is not necessary to add a control function related to multicast to the PoC server, it is possible to increase the number of communication terminals participating in group communication without increasing the load on the PoC server.

  As described above, the group communication server, the communication terminal, and the communication system according to the present invention are useful for group communication, and are particularly suitable when it is desired to suppress the processing load of the system in large-scale group communication.

It is a figure which shows the structural example of Embodiment 1 of the group communication system concerning this invention. It is a figure which shows the outline of the session description used for the definition of the PoC session in FIG. It is a figure for demonstrating the interface protocol in group communication. It is a sequence diagram which shows an example of the setup process of a PoC session. It is a figure which shows the structural example of Embodiment 2 of the group communication system concerning this invention. It is a figure which shows the outline of the session description used for the definition of the PoC session in FIG. It is a figure which shows the structural example of Embodiment 3 of the group communication system concerning this invention. It is a sequence diagram which shows an example of the setup process of a PoC session.

Explanation of symbols

10-J group communication terminal 15 PoC client 16 XDM client 17 presence source / watcher 20-K access network 21-L base station 22-M gateway router 30 network 31 SIP / IP core 32 multicast server 33 location server 34 authentication server 35 QoS Policy charging server 36 Home agent 40 Service providing platform 41, 41B, 41C PoC server 42 XDM server 43 Presence server 61, 65 Session description section 62, 66 First media description section 63, 67 Second media description section 68 Third Media predicates of

Claims (11)

In a communication system that establishes a group communication session using a session initiation protocol (SIP), a group communication server that manages a group communication session between communication terminals existing in the communication system,
Generate a SIP message for starting a group communication session, including a media description used for multicasting in the direction from the local server to the communication terminal, which is information described by a session description protocol (SDP). A group communication server which transmits to a communication terminal which is a member of group communication.   When a unicast media burst is received from a communication terminal having a floor, the unicast media burst is converted into a multicast media burst, and the converted media burst is a member of a group communication in which the communication terminal participates. The group communication server according to claim 1, wherein the group communication server is distributed to a communication terminal.   When unicast media bursts are received from multiple communication terminals that have the right to speak, the unicast media bursts are mixed and converted to multicast media bursts, and the multiple communication terminals participate in the converted media bursts The group communication server according to claim 1, wherein the group communication server is distributed to a communication terminal that is a member of the group communication.   The group communication server according to claim 2 or 3, wherein the group communication server manages a right to speak about a media burst.   5. The group communication server according to claim 2, wherein an encryption key related to the group communication session is distributed to a communication terminal that is a member of the group communication. Set up a dedicated path to distribute media bursts with the multicast server that provides the multicast service,
When a unicast media burst is received from a communication terminal having the floor, the unicast media burst is converted to a multicast media burst, and the converted media burst is converted into a member of a group communication in which the communication terminal participates. 2. The group communication server according to claim 1, wherein the group communication server is distributed to a certain communication terminal via the multicast server. Set up a dedicated path to distribute media bursts with the multicast server that provides the multicast service,
When a unicast media burst is received from a plurality of communication terminals having the floor, the unicast media burst is mixed and converted into a multicast media burst. The group communication server according to claim 1, wherein the group communication server distributes to a communication terminal that is a member of group communication to participate through the multicast server. In a communication system that establishes a group communication session using a session initiation protocol (SIP), a communication terminal that participates in the group communication session,
When the SIP message including the media description used for multicasting in the direction from the server to the terminal is transmitted from the group communication server according to any one of claims 1 to 5, the group communication server participates in the group communication. Therefore, a communication terminal that requests multicast distribution to its own terminal. In a communication system that establishes a group communication session using a session initiation protocol (SIP), a communication terminal that participates in the group communication session,
8. When receiving a SIP message including a media description used for multicasting in the direction from the server to the own terminal, transmitted by the group communication server according to claim 6 or 7, to the own terminal to participate in the group communication A communication terminal characterized by requesting multicast distribution. A group communication server according to any one of claims 1 to 5;
A plurality of communication terminals according to claim 8;
A communication system comprising: A group communication server according to claim 6 or 7,
A multicast server providing a multicast service;
A plurality of communication terminals according to claim 9;
A communication system comprising:

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