JP2008245060A - Communication method and communication system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a communication method that enables load sharing of a subscriber node related to multicast service distribution. <P>SOLUTION: A communication system includes mobile units, a wireless base station, and a subscriber node that makes control of the mobile units via the wireless base station. The communication system is configured so that a pool is constituted of one or more subscriber nodes and the wireless base station is connected to the subscriber nodes. The communication method is for executing multicast service distribution to the mobile units in the communication system. The method includes a step of making the subscriber nodes correspond to each other for each multicast service in the same pool; a step (S4) of transferring a request message for participation in a multicast group or a request message for secession from a multicast group to all the subscriber nodes in the same pool by multicast, when the wireless base station receives the message; and a step (S5) in which the subscriber node, corresponding to the multicast service executes processing for participation in a group or for secession from a group on the basis of the message, when the message is received. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a communication method in a cellular system, and more particularly to a communication method in a communication system that distributes a multicast service.

  A multicast communication method in a conventional cellular system will be described. Various services provided by the cellular system are used by a large number of people because of their high convenience. Further, international standardization work on technical specifications for further increasing the third-generation (3G) cellular system, which has become mainstream today, and realizing high speed / high capacity is now underway.

  For example, in the standard technical specifications of the third generation cellular system established in The 3rd Generation Partnership Project (3GPP), there are a plurality of Mobile Switching Centers (MSCs) or Serving GPRS Support Nodes (SGSNs) each called a pool 1 Configure one control unit. Furthermore, Base Station Controller (BSC) or Radio Network Controller (RNC), which is a control device of the wireless network system, and MSC or SGSN, which is a subscriber node of the core network, are connected by N: M (N and M are natural numbers). It becomes the composition which is done.

  As a result, load distribution or risk distribution of subscriber nodes in the pool is achieved, and a multi-operator core network (MOCN) is realized in which one wireless network is shared and controlled by a plurality of operator core networks. In addition, among a plurality of radio base stations, some radio base stations can be connected to a plurality of subscriber nodes by overlapping between the plurality of pools, thereby enabling load distribution or risk distribution across the pools. (For example, refer to the following non-patent document 1).

  On the other hand, when a mobile device participates in a desired multicast service, multicast group management such as IGMP (Internet Group Management Protocol) and MLD (Multicast Listener Discovery) established as a standard recommendation draft in IETF (Internet Engineering Task Force) Send group join request message (Join Message) by protocol. Then, this group participation request message is directly transmitted to the gateway node (GGSN) through the wireless network and the subscriber node through the IP (Internet Protocol) packet transfer path set by default.

  When the gateway node receives the group participation request message, the gateway node performs authentication processing of the mobile device that is the transmission source of the message with the broadcast / multicast center (BM-SC). Then, in order to activate the multicast service of the mobile station, the gateway node notifies the subscriber node through which the message has passed. The subscriber node that has received the service notification generates a context for multicast communication with the message transmission source mobile device (for example, see Non-Patent Document 2 below).

3GPP, “Intra-domain connection of Radio Access Network (RAN) nodes to multiple Core Network (CN) nodes”, TS 23.236, v6.3.0, June 2006 3GPP, “Multimedia Broadcast / Multicast Service (MBMS); Architecture and functional description”, TS 23.246, v6.10.0, June 2006 3GPP, “Feasibility study for evolved Universal Terrestrial Radio Access (UTRA) and Universal Terrestrial Radio Access Network (UTRAN)”, TR 25.912, v7.0.0, June 2006

  However, according to the above-described conventional technique, when a mobile device participates in a multicast service, a group participation request is directly transmitted to the gateway node through the IP packet transfer path set by default. The gateway node then distributes the multicast service via the subscriber node that transferred the IP packet. Therefore, in the above-described conventional technology, although a plurality of subscriber nodes configure a pool to achieve load distribution, with regard to multicast service distribution, the mobile device is fixed via the subscriber node that has requested group participation. End up. For this reason, there has been a problem that load distribution of subscriber nodes involved in multicast service distribution cannot be achieved.

  The present invention has been made in view of the above, and an object of the present invention is to provide a communication method that enables load distribution of subscriber nodes involved in multicast service distribution.

  In order to solve the above-described problems and achieve the object, the present invention includes a mobile device, a radio base station, and a subscriber node that controls the mobile device via the radio base station, and includes at least one subscriber node. A communication method for distributing a multicast service to the mobile station in a communication system in which a pool as a control unit is configured and the wireless base station is connected to a subscriber node. A subscriber node association step for associating a subscriber node for each service, and a request to join a multicast group or a request to leave the multicast group for the wireless base station to receive a multicast service distribution from the mobile station When a message is received, the message is sent to the same pool by multicast. A message transfer step for transferring to all subscriber nodes, and a message processing step for receiving, when the subscriber node corresponding to the multicast service receives the message, a process for joining or leaving the group based on the message; It is characterized by including.

  According to the present invention, a subscriber node is recessed for each multicast service in the pool, and the radio base station sends a participation or request message to the multicast service transmitted by the mobile station to all subscriber nodes in the pool. Since the transfer is performed by multicast, the load of subscriber nodes involved in multicast service distribution can be distributed.

  Embodiments of a communication method and a 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 showing a configuration example of a first embodiment of a communication system according to the present invention. As shown in FIG. 1, the communication system according to the present embodiment includes mobile stations 11 and 1 that are mobile bodies that perform wireless communication, and radio base stations 21 and 22 that perform wireless communication between the mobile apparatuses 11 and 12. , 23, 24, and a plurality of radio base stations, and location registration control for simultaneously calling the mobile devices 11 and 12 via the connected radio base stations, and user packet transfer between the mobile devices 11 and 12 Subscriber nodes 41, 42, 43, and 44 that perform session control, etc., a gateway node 6 that accommodates a plurality of subscriber nodes and serves as a gateway to the external network 9, and a mobile device (user) A multicast service center 7 that performs management for providing various multicast services, and a multicast source 8 that is a source node of multicast packets corresponding to the services If, in is configured.

  In FIG. 1, service areas 31, 32, 33, and 34 are service area ranges each composed of one or a plurality of cells for each radio base station. Here, the service areas 31, 32, 33, and 34 are service areas constituted by the radio base stations 21, 22, 23, and 24, respectively. The pools 51 and 52 are control units composed of a plurality of subscriber nodes for load distribution and ensuring redundancy. Further, the gateway node 6 of the present embodiment is connected to the external network 9. The multicast source 82 and multicast source 83 are multicast packet transmission source nodes existing in the external network 9.

  In the present embodiment, a subscriber node that forwards the packet of the service for each multicast service is assigned in advance in one pool, and each subscriber node performs processing related to the multicast packet of the multicast service to which the node is assigned. I do. The multicast service center 7 accommodates a multicast source 81 in the same network and multicast sources 82 and 83 existing in an external network, and performs authentication / billing for mobile devices (users) 11 and 12 participating in various multicast services, multicast groups Management and notification of multicast services to mobile devices.

  FIG. 2 is a sequence diagram showing an example of the overall operation in the present embodiment. FIG. 3 is a diagram illustrating an example of a protocol configuration between the mobile device, the radio base station, and the subscriber node according to the present embodiment. FIG. 4 is a flowchart showing an example of the RRC message reception process of the radio base station 21 according to the present embodiment. Hereinafter, the operation in this embodiment will be described with reference to these drawings.

  First, as shown in FIG. 2, the mobile device 11 is assumed to exist in the service area 31, and carries user packets and control messages with the radio base station 21 by the “RRC (Radio Resource Control) Connection Setup” procedure. A wireless line is set for this (step S1). Next, the mobile device 11 executes a “Context Activation” procedure with the subscriber node via the radio base station 21 (step S2). In the “Context Activation” procedure, user authentication, location registration, etc. are performed, and a session is established. As a result, the mobile device 11 can transmit and receive user packets in this communication system.

  Next, the mobile station 11 wirelessly transmits a group join request message (Join Message) using a multicast group management protocol such as IGMP (Internet Group Management Protocol) or MLD (Multicast Listener Discovery) in order to receive a desired multicast service. Transmit to the base station 21 (step S3). At this time, the specific loop participation request message includes an identifier of the multicast service desired to participate. The group join request message is transmitted as an RRC Direct Transfer message for transparent transfer. In the following description, the multicast group management protocol is described as being an IGMP or MLD message. However, the present invention is not limited to this, and other multicast group management protocols supported by the communication system may be used.

  Here, the protocol configuration shown in FIG. 3 will be described. As shown in FIG. 3, the protocols of the mobile stations 11 and 12 of this embodiment are Physical (physical), MAC (Media Access Control), RLC (Radio Link Control), RRC, NAS (Non Access Stratum), IGMP. / MLD. The protocols of the radio base stations 31 to 34 according to the present embodiment are configured by Physical, MAC, RLC, RRC, RANAP (Radio Access Network Application Part), SCTP, and IP. In addition, the protocol of the subscriber nodes 41 to 44 of the present embodiment is composed of RANAP, SCTP (Stream Control Transmission Protocol), IP (Internet Protocol), and Physical. The NAS (Non Access Stratum) is transmitted as an RRC Direct Transfer message from the mobile devices 11 and 12, converted into a RANAP Direct Transfer message in the radio base stations 31 to 34, and reaches the subscriber nodes 41 to 44. The IGMP / MLD is transmitted from the mobile devices 11 and 12 as an RRC Direct Transfer message, is assigned an IP multicast address in the radio base stations 31 to 34, and is transferred to the subscriber nodes 41 to 44.

  In addition, when receiving the RRC message, the radio base station 21 performs reception processing based on the content of the RRC message. Here, the RRC message reception process of the radio base station 21 will be described with reference to FIG. The radio base station 21 receives the RRC message (step S22) while waiting for the RRC message (step S21). Next, the radio base station 21 determines whether or not the received message type is a Direct Transfer message (step S23). If it is determined that the message type is not a Direct Transfer message (No in step S23), processing corresponding to the RRC message is performed (step S24).

  If it is determined that the message type is a Direct Transfer message (Yes in step S23), it is further determined whether it is a NAS message (step S25). If it is determined that the received message is a NAS message (Yes in step S25), it is re-mapped to a direct transfer message of RANAP, which is a control protocol with the subscriber node, and the subscriber node 41 controlling the mobile station 11 ( Transfer to the subscriber node that established the session in step S2 (step S26). If it is determined that the message is not a NAS message (No in step S25), it is further determined whether the message is an IGMP or MLD message (step S27).

  If it is determined that the message is not an IGMP or MLD message (not an IGMP message or an MLD message) (No in step S27), error processing such as discarding the message is performed (step S28). If it is determined that the message is an IGMP or MLD message (step S27 Yes), an IP multicast address destined for all subscriber nodes in the pool 51 is assigned and transferred to the subscriber node (step S29). Then, the RRC message is waited again (step S30).

  Returning to the description of FIG. 2, in step S4, the radio base station 21 transfers the group join request message to all subscriber nodes in the pool 51 by IP multicast (step S4). Specifically, the radio base station 21 performs the processing described with reference to FIG. 4, and in this case, since the IGMP or MLD message is received, the processing in step S29 is performed.

  As described above, a subscriber node in charge of each multicast service in the pool is assigned. Here, it is assumed that the subscriber node 41 is assigned to the multicast service specified by the group participation request message transmitted in step S3 (desired to be distributed by the mobile device 11).

  The subscriber node 41 determines that the multicast service specified by the group join request message transferred in step 4 is a service assigned to the own node. Then, a group participation request message by a multicast routing management protocol such as PIM (Protocol Independent Multicast) is transmitted to the gateway node 6 (step S5). On the other hand, the subscriber node 42 determines that the multicast service specified by the group participation request message transferred in step 4 is not a service assigned to the own node, and discards the transferred group participation request message. .

  When the gateway node 6 receives the group participation request message, the gateway node 6 transmits an authentication request message (Authorization Request) to the multicast service center 7 to request authentication of the mobile device 11 for participation in the multicast service (step S6). The multicast service center 7 transmits an authentication response message (Authorization Response) message to the gateway node 6 and returns an authentication result of the mobile device 11 (step S7). Here, it is assumed that the participation of the mobile device 11 in the multicast service is authenticated in the multicast service center 7.

  When the gateway node 7 receives the authentication response message, the gateway node 7 notifies the subscriber node 41 of the multicast notification (MBMS (Multimedia Broadcast / Multicast) in order to inform the mobile station 11 that distribution of the multicast service requested to participate is started. Service) Notification) message is transmitted (step S8).

  Next, the subscriber node 41 transmits a response (MBMS Notification Response) message to the multicast notification to the gateway node 6 (step S9). Further, the subscriber node 41 transmits a “Request MBMS Context Activation” message for requesting activation of a context for managing multicast distribution to the mobile device 11 (step S10). Upon receiving the “Request MBMS Context Activation” message, the mobile device 11 transmits an “Activate MBMS Context Request” message for requesting the creation of a context to the subscriber node 41 (step S11). The subscriber node 41 generates a context for managing the multicast distribution of the mobile device 11 and transmits a “Create MBMS Context Request” message for instructing the context for managing the multicast distribution to the gateway node. (Step S12).

  The gateway node 6 also generates a context for managing the multicast distribution of the mobile device 11 and transmits “Create MBMS Context Response” that is a response to the “Create MBMS Context Request” message to the subscriber node 41. (Step S13). Then, the subscriber node 41 transmits an “Activate MBMS Create Context Accept” message that is a response to the “Activate MBMS Context Request” message to the mobile device 11 (S14). Here, the case of requesting to join the multicast service has been described, but even when leaving from the multicast service, the radio base station 21 similarly sends a leave request message to all subscriber nodes in the pool by IP multicast. Then, the subscriber node may perform the withdrawal process for the multicast service.

  Thus, in the present embodiment, subscriber nodes are allocated for each multicast service in the pool 51, and the radio base station 21 sends a participation request message to the multicast service transmitted from the mobile device 11 in the pool. Multicast to all subscriber control nodes. Then, the subscriber node corresponding to the requested multicast service performs processing up to the start of multicast service distribution. For this reason, it is possible to divide subscriber nodes that perform control for each multicast service, and to perform load distribution of the subscriber nodes.

Embodiment 2. FIG.
FIG. 5 is a sequence diagram showing an example of the operation in the second embodiment of the communication system according to the present invention. The configuration example of the communication system in the present embodiment is the same as that in FIG. 1 of the first embodiment. Hereinafter, description of the same parts as those of the first embodiment will be omitted, and parts different from those of the first embodiment will be described.

  Also in the present embodiment, as in the first embodiment, a subscriber node that performs packet transfer of the service for each multicast service is assigned in advance within one pool, and each subscriber node is assigned by that node. The process related to the multicast packet of the given multicast service is performed.

  In recent years, technical reference specifications for next-generation radio access schemes / radio access networks using multi-carrier schemes such as Orthogonal Frequency Division Multiplexing (OFDM) have been studied to further increase the speed and bandwidth of the radio access portion. . In this technical reference specification, a system called SFN (Single Frequency Network) in which a plurality of stations transmit signals having the same content at the same frequency (channel) is shown. In this system, for example, as described in “3GPP,“ Feasibility study for evolved Universal Terrestrial Radio Access (UTRA) and Universal Terrestrial Radio Access Network (UTRAN) ”, TR 25.912, v7.0.0, June 2006”. In addition, the cell edge throughput in multicast service distribution is improved by multi-cell transmission in which the same contents are transmitted by synchronizing the transmission timing between the cells.

  When multicast service distribution is performed by multi-cell transmission, it is necessary to share timing synchronization, radio block resource block allocation, transmission schedule, and the like between base stations that perform multi-cell transmission. As for timing, synchronization is achieved by using GPS (Global Positioning System) or the like, but a method for sharing resource block allocation information and transmission schedule in a wireless section has not been established between wireless base stations. For this reason, there arises a problem that even if multi-cell transmission is performed between radio base stations, the mobile device cannot correctly receive content information and packets. In this embodiment, in order to solve this problem, a communication method for sharing the resource blocks in these wireless sections and sharing the transmission schedule is realized.

  As shown in FIG. 5, in the present embodiment, when the multicast service center 7 is ready to distribute the multicast service, it notifies the multicast service to be distributed and the attributes, service area, service quality, etc. of the multicast service. Then, a Session Start Request is transmitted to the gateway node 6 (step S31). The gateway node 6 transmits a Session Start Response to the multicast service center 7 (step S32), and further MBMS Session Start Request to a plurality of subscriber nodes corresponding to the service area specified by the Session Start Request. Is transmitted (step S33). Here, one of the subscriber nodes corresponding to the designated service area is assumed to be the subscriber node 41, and the following explanation will be given by taking the subscriber node 41 as an example.

  Upon receiving the MBMS Session Start Request, the subscriber node 41 transmits an MBMS Session Start Response to the gateway node 6 (Step S34). Then, the subscriber node 41 determines and stores a radio block resource block and a transmission schedule according to the multicast service attribute specified by the MBMS Session Start Request, for example, the maximum bit rate (step S35). Then, the subscriber node 41 transmits an MBMS Session Start Request including a resource block and a transmission schedule of the determined radio section to a plurality of radio base stations corresponding to the service area specified by the MBMS Session Start Request ( Step S36). Here, it is assumed that one of the radio base stations corresponding to the designated service area is the radio base station 21, and the radio base station 21 is taken as an example for the following description.

  When receiving the MBMS Session Start Request, the radio base station 21 transmits an MBMS Session Start Response to the subscriber node 41 (Step S37). Based on the resource block included in the MBMS Session Start Request and the transmission schedule, the radio base station 21 secures radio resources with the mobile station 11 for delivering the multicast service packet (step S38: Radio Resource Setup). ).

  Further, the subscriber node 41 notifies the other subscriber nodes in the pool 51 (subscriber node 42 in this case) of the resource block and transmission schedule in the wireless section by broadcast using multicast ( Step S39). The other subscriber nodes that have received the notification store the notified resource block and transmission schedule of the radio section (step S40). Then, when the other subscriber node receives the MBMS Session Start Request from the gateway node 6 in the same manner and determines the resource block and the transmission schedule of the wireless section, Decide not to overlap. The determination result is similarly notified to other subscriber nodes by multicast.

  The processing in the case where there is a multicast service distribution request from the mobile device 11 is the same as in the first embodiment.

  As described above, in the present embodiment, when the subscriber node 41 determines the resource block and the transmission schedule of the radio section related to the multicast group assigned to itself, the subscriber node 41 notifies the radio base station connected to the subscriber node 41, The subscriber node is notified by multicast. Further, the subscriber node that has been notified determines that the resource block and the transmission schedule related to the multicast group assigned to itself are not duplicated with the notified resource block and the transmission schedule, and further, the determination result is stored in the pool 51. The subscriber node is notified by multicast.

  For this reason, in addition to the effects of the first embodiment, all the subscriber nodes and the radio base stations in the pool 51 can share the resource block and the transmission schedule of the radio section related to the multicast service. Therefore, even when performing multi-cell transmission, the mobile device 11 can correctly receive packets from a plurality of radio base stations.

Embodiment 3 FIG.
FIG. 6 is a sequence diagram showing an example of operation in the third embodiment of the communication system according to the present invention. The configuration example of the communication system in the present embodiment is the same as that in FIG. 1 of the first embodiment. Hereinafter, description of the same parts as those of the first embodiment or the second embodiment will be omitted, and parts different from the first embodiment or the second embodiment will be described.

  Also in the present embodiment, as in the first embodiment, a subscriber node that performs packet transfer of the service for each multicast service is assigned in advance within one pool, and each subscriber node is assigned by that node. The process related to the multicast packet of the given multicast service is performed.

  In FIG. 6, from when the multicast service center 7 transmits a Session Start Request to when the subscriber node 41 determines a resource block and a transmission schedule in the wireless section (steps S31 to S35), Since it is the same, the same step number is attached | subjected and description is abbreviate | omitted.

  Next, the subscriber node 41 sends the determined resource block and transmission schedule of the wireless section to the other subscriber nodes in the pool 51 (subscriber node 42 in this case) by broadcast using multicast. The monitoring timer is started (step S41). Then, the response message from the other subscriber node to be notified is monitored. The other subscriber nodes confirm whether or not the resource block and transmission schedule of the notified wireless section are in conflict with the resource block and transmission schedule stored in itself (step S42). Here, it is assumed that there is a competition. The subscriber node 42 notifies the subscriber node 41 that it is competing (step S43).

  The subscriber node 41 notified of the contention again determines the resource block and transmission schedule in the wireless section (step S44), and notifies the other subscriber nodes again by broadcast using multicast (step S44). S45). The other subscriber nodes confirm again whether or not the resource block and transmission schedule of the notified wireless section are in conflict with the resource block and transmission schedule stored in itself (step S46). Here, it is assumed that no conflict has occurred and the other subscriber nodes have not notified the conflict.

  The subscriber node 41 determines that the resource block and the transmission schedule in the wireless section have been secured when no conflict is notified from another subscriber node even when the monitoring timer expires. Then, the subscriber node 41 transmits an MBMS Session Start Request to a plurality of radio base stations corresponding to the service area specified by the MBMS Session Start Request (Step S47). Here, it is assumed that one of the radio base stations corresponding to the designated service area is the radio base station 21, and the radio base station 21 is taken as an example for the following description.

  Next, the radio base station 21 transmits an MBMS Session Start Response to the subscriber node 41 (step S48). Then, the radio base station 21 secures radio resources between the mobile station 11 for delivering the multicast service packet based on the resource block included in the MBMS Session Start Request and the transmission schedule (step S49: Radio). Resource Setup).

  The processing in the case where there is a multicast service distribution request from the mobile device 11 is the same as in the first embodiment.

  As described above, in the present embodiment, when the subscriber node 41 determines the resource block and transmission schedule of the wireless section related to the multicast group assigned to itself, the subscriber node 41 notifies the subscriber node in the pool 51 by multicast and monitors it. A notification of contention from other subscriber nodes is monitored by a timer. When there is no notification of contention from another subscriber node by the expiration of the monitoring timer, it is determined that there is no contention, and the resource block and the transmission schedule in the wireless section are determined. For this reason, in addition to the effects of the second embodiment, the resource block and the transmission schedule can be determined so as not to cause a conflict with other subscriber nodes, and the deterioration of the communication state due to the conflict can be prevented. .

Embodiment 4 FIG.
FIG. 7 is a sequence diagram showing an example of the operation in the fourth embodiment of the communication system according to the present invention. The configuration example of the communication system in the present embodiment is the same as that in FIG. 1 of the first embodiment. Hereinafter, description of the same parts as those of the first to third embodiments will be omitted, and parts different from those of the first to third embodiments will be described.

  Also in the present embodiment, as in the first embodiment, a subscriber node that performs packet transfer of the service for each multicast service is assigned in advance within one pool, and each subscriber node is assigned by that node. The process related to the multicast packet of the given multicast service is performed.

  First, it is assumed that the mobile device 11 receives the multicast service distribution after performing the processing related to the multicast service distribution request shown in the first embodiment (step S51). The multicast at this time is distributed from the multicast source 81 to the mobile device 11 via the multicast service center 7, the gateway node 6, the subscriber node 41, and the radio base station 21 in order. The packet flow of the multicast service is called a multicast flow. Further, it is assumed that the multicast flow is not distributed in the service area adjacent to the service area 31 at the time of step S51.

  Then, the mobile device 11 moves to a place where the service area 31 of the radio base station 21 and the service area 32 of the radio base station 22 overlap. As a result of this movement, the reception level of the signal from the connected radio base station 21 becomes weaker than a predetermined threshold in the mobile station 11, and it can also be received from a cell controlled by the radio base station 22 by a neighboring cell search. Suppose that The mobile device 11 measures the reception level of the signal from the radio base station 21 periodically or as necessary. The mobile device 11 notifies the radio base station 21 by the Measurement Report message that the reception level of the signal from the radio base station 21 has become weaker than a predetermined threshold (step S52). At this time, the reception level (measurement value) of the signal from the radio base station 21 and the cell ID determined to be receivable by the neighboring cell search are also included in the Measurement Report message and notified.

  Upon receiving the Measurement Report message, the radio base station 21 controls the radio base station 22 based on the notified reception level of the signal from the radio base station 21 in the mobile device 11 and the notified cell ID. Cell (part of the service area 32). Then, it is determined to perform multicell transmission with the radio base station 22 (step S53). Then, the mobile station 11 is notified of an MBMS Transmission Request message, which is a message requesting that the mobile station 11 transmit the multicast service being distributed (step S54). At this time, the MBMS Transmission Request message is notified including the resource block and the transmission timing information of the radio section related to the multicast service.

  When receiving the MBMS Transmission Request message, the radio base station 22 performs admission control according to the resource block and the transmission timing of the radio section included in the message (step S55). And the radio | wireless resource between the mobile devices 11 for distributing the multicast flow which the mobile device 11 is receiving is ensured (step S56: Radio Resource Setup).

  Next, the radio base station 22 designates the multicast service notified by the MBMS Transmission Request, and transmits a group participation request message (Join Message) using a multicast group management protocol such as IGMP or MLD toward the subscriber node. (Step S57). Then, the radio base station 22 transmits an MBMS Transmission Response message that is a response to the MBMS Transmission Request to the radio base station 21 (step S58).

  The subscriber node 41 that has received the group participation request message from the radio base station 21 adds the transfer path addressed to the radio base station 22 to the path table corresponding to the multicast service requested to participate (step S59). Thereafter, the subscriber node 41 also transfers the multicast flow to the radio base station 22 (step S60).

  The processing in the case where there is a multicast service distribution request from the mobile device 11 is the same as in the first embodiment. Further, by performing the same operation as in the second embodiment or the third embodiment, each subscriber node and each radio base station share the resource block and the transmission schedule of the radio section related to the multicast service. Also good. In this case, in the MBMS Transmission Request in step S54, it is only necessary to specify the multicast service, and it is not necessary to transmit the resource block and the transmission schedule in the wireless section.

  As described above, in this embodiment, the radio base station 21 that distributes the multicast service performs multi-cell communication with the adjacent radio base stations based on the Measurement Report notified from the connected mobile station 11. When it is determined that transmission is necessary, the radio base station 22 that performs multi-cell transmission is selected based on the measurement report. Then, it notifies the adjacent radio base station 21 of the resource block and transmission timing used in the delivery of the multicast service, and requests the radio base station 21 to set up a radio channel for delivering the multicast service. I did it. The adjacent radio base station 22 can distribute the multicast service based on the notified resource block and transmission timing, and transmits a participation request to the subscriber node that distributes the multicast service. For this reason, resource blocks and transmission timing can be shared, and multi-cell transmission can be performed correctly.

Embodiment 5. FIG.
FIG. 8 is a sequence diagram showing an example of operation in the fifth embodiment of the communication system according to the present invention. The configuration example of the communication system in the present embodiment is the same as that in FIG. 1 of the first embodiment. Hereinafter, description of the same parts as those of the first to fourth embodiments will be omitted, and parts different from those of the first to fourth embodiments will be described.

  Also in the present embodiment, as in the first embodiment, a subscriber node that performs packet transfer of the service for each multicast service is assigned in advance within one pool, and each subscriber node is assigned by that node. The process related to the multicast packet of the given multicast service is performed.

  First, it is assumed that the multi-cell transmission by the radio base station 21 and the radio base station 22 is performed to the mobile device 11 by the operation described in the fourth embodiment as shown in FIG. 8 (step S60). Next, it is assumed that the mobile device 11 further moves to the radio base station 22 side, and the reception level of the signal from the radio base station 21 in the mobile device 11 further decreases. The mobile device 11 notifies the base station 21 by the Measurement Report message that the reception level of the signal from the radio base station 21 has further decreased (step S61). At this time, the reception level (measurement value) of the signal from the radio base station 21 is included in the Measurement Report message and notified.

  The radio base station 21 receives the Measurement Report message, determines that the reception level in the mobile device 11 has further decreased, decides to hand over to the radio base station 22, and sends a Handover Request to the radio base station 22. A message is transmitted (step S62). The radio base station 22 that has received the Handover Request message secures radio resources for communication individually used by the mobile device 11 and transmits a Handover Request Acknowledgment message to the radio base station 21 (step S63).

  The radio base station 21 that has received the Handover Request Acknowledgment message transmits a Handover Command message to the mobile device 11 (step S64), and requests the mobile device 11 to perform handover to the radio base station 22 by this message. When the mobile device 11 receives the Handover Command message and completes the handover, the mobile device 11 transmits a Handover Confirm message to the radio base station 22 (step S65).

  Upon receiving the Handover Confirm message, the radio base station 22 is a subscriber node 42 in charge of communication control of the mobile device 11 (in this case, the subscriber node 42 was in charge of communication control of the mobile device 11. In order to switch the transfer path, a Handover Complete message is transmitted (step S66). After switching the transfer path from the direction of the radio base station 21 to the direction of the radio base station 22, the subscriber node 42 transmits a Handover Complete Acknowledge message to the radio base station 22 (step S67).

  When receiving the Handover Complete Acknowledge message, the radio base station 22 transmits a Release Resource message to the radio base station 21 (step S68). The radio base station 21 releases the radio resource that has been transferred for communication that is individually used by the mobile device 11 (step S69). Then, the radio base station 21 confirms whether or not other mobile devices (other than the mobile device 11) in its service area 31 have received the distribution of the multicast flow that the mobile device 11 has been distributed (step). S70). When there is no other mobile device that receives the multicast flow distribution, a group leave request message (Leave Message) by a multicast group management protocol such as IGMP or MLD is transmitted toward the subscriber node ( Step S71).

  When receiving the group leave request message, the subscriber node 41 corresponding to the multicast service deletes the transfer route addressed to the radio base station 21 from the route table (step S72). Then, the subscriber node 41 does not transfer the multicast flow to the radio base station 22 thereafter. Since subscriber nodes other than the subscriber node 41 do not support the multicast service, they are discarded even if a group leave request message (Leave Message) is received.

  The processing in the case where there is a multicast service distribution request from the mobile device 11 is the same as in the first embodiment.

  Thus, in the present embodiment, when the mobile station 11 is handed over to an adjacent base station, the radio base station 21 receives the multicast service that the mobile station 11 has received in its service area. Check if there are other mobile devices. When there is no other mobile station receiving the multicast service, the subscriber node leaves the subscriber node in order to stop the delivery of the multicast service from the subscriber node delivering the multicast service. Made a request. For this reason, the resources of the radio base station 21 can be efficiently released after the handover.

Embodiment 6 FIG.
FIG. 9 is a sequence diagram showing an example of operation in the sixth embodiment of the communication system according to the present invention. The configuration example of the communication system in the present embodiment is the same as that in FIG. 1 of the first embodiment. Hereinafter, description of the same parts as those of the first to fifth embodiments will be omitted, and parts different from those of the first to fifth embodiments will be described.

  Also in the present embodiment, as in the first embodiment, a subscriber node that performs packet transfer of the service for each multicast service is assigned in advance within one pool, and each subscriber node is assigned by that node. The process related to the multicast packet of the given multicast service is performed.

  In FIG. 9, steps S51 to S57 are the same as those in the fourth embodiment, and thus the same step numbers are given and description thereof is omitted. When receiving the MBMS Transmission Response in step 57, the radio base station 21 determines to transfer the multicast flow distributed to the mobile device 11 to the radio base station 22 (step S81). Then, the wireless base station 21 transfers the data to the wireless base station 22 while distributing it to the service area 31 (step S82). The radio base station 22 transmits the forwarded multicast flow to the service area 32 with the resource block and the transmission timing of the radio section notified by the MBMS Transmission Request message in step S54 (step S83). In this way, the multi-cell transmission by the radio base station 21 and the radio base station 22 of the multicast flow that the mobile device 11 is receiving can be performed.

  The processing in the case where there is a multicast service distribution request from the mobile device 11 is the same as in the first embodiment.

  As described above, in this embodiment, the radio base station 21 that distributes the multicast service performs multi-cell communication with the adjacent radio base stations based on the Measurement Report notified from the connected mobile station 11. When it is determined that transmission is necessary, the radio base station 22 that performs multi-cell transmission is selected based on the measurement report. Then, it notifies the adjacent radio base station 21 of the resource block and transmission timing used in the delivery of the multicast service, and requests the radio base station 21 to set up a radio channel for delivering the multicast service. I did it. The radio base station 21 transfers the multicast flow to the adjacent radio base station 22 while continuing to distribute the multicast flow to its service area. For this reason, resource blocks and transmission timing can be shared, and multi-cell transmission can be performed correctly.

Embodiment 7 FIG.
FIG. 10 is a sequence diagram showing an example of operation in the seventh embodiment of the communication system according to the present invention. The configuration example of the communication system in the present embodiment is the same as that in FIG. 1 of the first embodiment. Hereinafter, description of the same parts as those of the first to sixth embodiments will be omitted, and parts different from those of the first to sixth embodiments will be described.

  Also in the present embodiment, as in the first embodiment, a subscriber node that performs packet transfer of the service for each multicast service is assigned in advance within one pool, and each subscriber node is assigned by that node. The process related to the multicast packet of the given multicast service is performed.

  In the present embodiment, first, it is assumed that a multicast flow is distributed to the mobile device 11 by multi-cell transmission by the radio base station 21 and the radio base station 22 by the operation described in the sixth embodiment. Steps S84, S85, S86, S87, S88, S89, and S90 shown in FIG. 10 are the same as steps S61, S62, S63, S64, S65, S66, and S67 shown in FIG. Description is omitted.

  Next, the radio base station 22 designates the multicast service designated by the Handover Request of Step S85 or notified by the Handover Confirm of Step S88, and sends a group join request message based on the multicast group management protocol toward the subscriber node. Transmit (step S91). The subscriber node 41 that has received the group join request message adds the transfer route addressed to the radio base station 22 to the route table related to the requested multicast group (step S92).

  Steps S68 to S73 are the same as the steps with the same numbers in FIG. Through the above operation, the route addressed to the radio base station 21 in the subscriber node 41 is deleted, and the multicast flow is transferred to the mobile device 11 via the radio base station 22.

  Thus, in the present embodiment, when the mobile station 11 is handed over to an adjacent base station, the radio base station 21 receives the multicast service that the mobile station 11 has received in its service area. Check if there are other mobile devices. Then, when there is no other mobile station receiving the multicast service, a group is assigned to the subscriber node in order to stop the delivery of the multicast service from the subscriber node delivering the multicast service. Request to leave. For this reason, the resources of the radio base station 21 can be efficiently released after the handover.

  In addition, when receiving the Handover Complete Acknowledge message from the subscriber node 41, the radio base station 22 transmits a group join request. Therefore, even when the wireless base station 22 distributes the multicast flow by forwarding from the wireless base station 21 without receiving the multicast flow distribution from the subscriber node 41 at the time of multi-cell transmission, it continues after the handover. Multicast flow can be transferred.

  As described above, the communication method and the communication system according to the present invention are useful for a wireless communication system, and are particularly suitable for a wireless communication system performing a multicast service.

It is a figure which shows the structural example of the communication system of Embodiment 1 concerning this invention. 6 is a sequence diagram illustrating an example of the overall operation of the first embodiment. FIG. FIG. 3 is a diagram illustrating an example of a protocol configuration between a mobile device, a radio base station, and a subscriber node according to the first embodiment. 6 is a flowchart illustrating an example of RRC message reception processing of the radio base station according to the first embodiment. FIG. 10 is a sequence diagram illustrating an example of an operation according to the second embodiment. FIG. 10 is a sequence diagram illustrating an example of operation of the third embodiment. FIG. 20 is a sequence diagram illustrating an example of operation of the fourth embodiment. FIG. 22 is a sequence diagram illustrating an example of operation of the fifth embodiment. FIG. 20 is a sequence diagram illustrating an example of an operation in the sixth embodiment. FIG. 23 is a sequence diagram illustrating an example of operation according to the seventh embodiment.

Explanation of symbols

11, 12 Mobile device 21, 22, 23, 24 Wireless base station 31, 32, 33, 34 Service area 41, 42, 43, 44, 45 Subscriber node 51, 52 Pool 6 Gateway node 7 Multicast service center 81, 82 , 83 Multicast source 9 External network

Claims (8)

A mobile node, a wireless base station, and a subscriber node that controls the mobile device via the wireless base station, wherein a pool as a control unit is configured by at least one subscriber node, and the wireless base station In a communication system to which a multicast service is distributed to the mobile device,
A subscriber node association step for associating a subscriber node for each multicast service in the same pool;
When the wireless base station receives, from the mobile device, a multicast group join request message for receiving a multicast service distribution or a leave request message for the multicast group, the message is sent to all of the same pool by multicast. A message forwarding step for forwarding to the subscriber node;
When the subscriber node corresponding to the multicast service receives the message, a message processing step of performing a process for joining or leaving the group based on the message;
A communication method comprising: When the subscriber node receives a multicast session start request message notifying that the multicast service corresponding to the subscriber node is ready for distribution, it determines a resource block and a transmission schedule used by the multicast service, and A first schedule notification step of notifying the result to other subscriber nodes in the same pool by multicast;
The subscriber node that has received the notified resource block and transmission schedule determines the resource block and transmission schedule of the multicast service corresponding to itself so that they do not overlap with each other, and the result is transmitted to other members in the same pool by multicast. A second schedule notification step of notifying the subscriber node of
The communication method according to claim 1, further comprising: When the subscriber node receives a multicast session start request message notifying that the multicast service corresponding to the subscriber node is ready for distribution, it determines a resource block and a transmission schedule used by the multicast service, and A schedule notification step of notifying the result to other subscriber nodes in the same pool by multicast as a schedule notification;
When the subscriber node that has received the schedule notification compares the received resource block and transmission schedule with the resource block and transmission schedule of the multicast service corresponding to itself and determines whether or not there is a conflict, Includes a conflict notification step for notifying the subscriber node that has transmitted the schedule notification that there is a conflict.
When the subscriber node that has transmitted the schedule notification receives the contention notification before a predetermined time has elapsed since the transmission of the schedule notification, it again determines a different resource block and transmission schedule, A schedule re-notification step of notifying the result to other subscriber nodes in the same pool by multicast;
On the other hand, when the subscriber node that has transmitted the schedule notification does not receive the notification of contention until the predetermined time has elapsed since the transmission of the schedule notification, the result determined in the schedule notification step A schedule confirmation step for confirming
The communication method according to claim 1, further comprising: When the mobile station is receiving multicast service distribution, if the measured value of the reception level of the signal from the connected radio base station is less than a predetermined threshold, the reception level search of neighboring cells is performed. A measurement result notifying step of acquiring an identifier of a receivable cell according to the step, and notifying the measurement value and the identifier of the cell to the connected radio base station as measurement information;
The connected radio base station (first radio base station) determines that multi-cell transmission using a second radio base station corresponding to the cell identifier is necessary based on the measurement information, and A multi-cell transmission start notification step for transmitting a multi-cell transmission start message including a multicast service to which the mobile station is receiving distribution, a resource block related to the multicast service, and a transmission schedule;
A resource setting step in which the second radio base station sets a radio resource with the mobile device based on a resource block and a transmission schedule included in the received multi-cell transmission start message;
A group participation request message transmission step in which the second wireless base station transmits a participation request message to a multicast group corresponding to a multicast service to which the mobile station receives distribution to all subscriber nodes in the same pool; ,
The communication method according to claim 1, 2, or 3. After the first radio base station performs handover to the second base station in a state where the mobile station is receiving distribution of the multicast service, the first radio base station releases the radio resources for multi-cell transmission and If there is no other mobile device receiving the multicast service distribution in the service area of the mobile station, if there is no other mobile device, a leave request message for the multicast group corresponding to the multicast service is stored in the same pool. Leaving request message sending step to send to all the subscriber nodes in multicast by multicast;
The communication method according to claim 4, further comprising: The mobile device measures the reception level of a signal from the connected radio base station, and if the measured value is less than a predetermined threshold, searches the reception level of the neighboring cells of the mobile device. A measurement result notification step of acquiring an identifier of a receivable cell and notifying the measurement value and the identifier of the cell to the connected radio base station as measurement information;
The connected radio base station (first base station) determines that multi-cell transmission using a second radio base station corresponding to the cell identifier is necessary based on the measurement information, and the movement A multi-cell transmission start notification step for transmitting a multi-cell transmission start message including a multicast service to which the machine is distributed, a resource block related to the multicast service, and a transmission schedule;
A resource setting step in which the second radio base station sets a radio resource with the mobile device based on a resource block and a transmission schedule included in the received multi-cell transmission start message;
A multicast packet forwarding step in which the first radio base station forwards a packet of a multicast service delivered by the mobile station to the second radio base station;
The communication method according to claim 1, 2, or 3. The second wireless base station sends a group join request message to a multicast group corresponding to a multicast service to which the mobile device is distributed after the mobile device has handed over from the first wireless base station to the mobile station. Sending a group join request message to all subscriber nodes in the same pool;
After the first radio base station performs handover to the second base station in a state where the mobile station is receiving multicast service distribution, the first radio base station releases radio resources for multi-cell transmission and The presence / absence of another mobile device receiving the multicast service in the service area of the station is confirmed. If there is no other mobile device, the same leave request message for the multicast group corresponding to the multicast service is used. A leave request message sending step for sending to all subscriber nodes in the pool by multicast;
The communication method according to claim 6, further comprising: A mobile node, a wireless base station, and a subscriber node that controls the mobile device via the wireless base station, wherein a pool as a control unit is configured by at least one subscriber node, and the wireless base station A communication system that distributes a multicast service to the mobile device in a connected state,
When the subscriber node receives a group participation request message for receiving distribution of a multicast service associated with itself, the subscriber node performs processing for group participation or group departure based on the message,
When the wireless base station receives a join request message or a leave request message for receiving a multicast service distribution from the mobile device, the message is forwarded to all subscriber nodes in the same pool by multicast. A communication system characterized by the above.

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