Relay device, wireless communication system and multicast relay method
9 claims: 4 independent, 5 dependent
- 1移動端末へ配信するためのコンテンツを含みこのコンテンツに対応するマルチキャストグループに関する情報の設定されたユーザデータパケットを、ゾーンに区分け管理される複数の基地局へ送信する中継装置であって、 前記移動端末により参加されるマルチキャストグループに関する情報を該移動端末が無線通信する基地局に関する情報及びその基地局の属するゾーンに関する情報と関連付けて記憶部に格納する格納手段と、 前記マルチキャストグループからの脱退依頼のLEAVEパケットを前記移動端末から前記複数の基地局のいずれか1つを経由して受信した場合に、脱退対象のマルチキャストグループ及びこの中継基地局の属するゾーンに関連付けられて格納されている基地局に関する情報を前記記憶部から抽出する抽出手段と、 前記抽出手段により抽出された基地局と受信されたLEAVEパケットを中継した基地局との比較により、前記脱退対象のマルチキャストグループに関し参加を継続している移動端末の存在を確認するためのクエリパケットの送信の要否を決定する決定手段と、 前記決定手段による決定結果に基づいて、前記クエリパケットを含むユーザデータパケットを前記記憶部に前記脱退対象のマルチキャストグループに関する情報と共に格納されるゾーンに属する各基地局に対してそれぞれ送信する送信手段と、 を備える中継装置。
- 2前記マルチキャストグループへの参加依頼のJOINパケットを前記移動端末から前記複数の基地局のいずれか1つを経由して受信した場合に、この中継基地局の属するゾーン及び参加対象のマルチキャストグループに関連付けられて前記記憶部に格納されている基地局に関する情報をこのJOINパケットを中継した基地局に関する情報で更新する更新手段を更に備える請求項1に記載の中継装置。
- 3前記送信手段により前記クエリパケットを含むユーザデータパケットが送信されその応答パケットが受信されなかった場合に、前記脱退対象のマルチキャストグループ、前記LEAVEパケットを中継した基地局及びその基地局の属するゾーンが関連付けられたレコードを前記記憶部から削除する削除手段を更に備える請求項1又は2に記載の中継装置。
- 4前記削除手段によりレコードが削除された場合に、前記記憶部にその削除されたマルチキャストグループと関連付けられ格納されている他のレコードの存在を確認し、該他のレコードが存在しない場合には、前記受信されたLEAVEパケットを上位装置へ転送し、該他のレコードが存在する場合には、前記受信されたLEAVEパケットの転送を行わない転送手段を更に備える請求項3に記載の中継装置。
- 5ゾーンに区分け管理される複数の基地局と、移動端末へ配信するためのコンテンツを含みこのコンテンツに対応するマルチキャストグループに関する情報の設定されたユーザデータパケットを前記複数の基地局のいずれか複数へ送信する中継装置と、を有する無線通信システムであって、 前記中継装置は、 前記移動端末により参加されるマルチキャストグループに関する情報を該移動端末が無線通信する基地局に関する情報及びその基地局の属するゾーンに関する情報と関連付けて記憶部に格納する格納手段と、 前記マルチキャストグループからの脱退依頼のLEAVEパケットを前記移動端末から前記複数の基地局のいずれか1つを経由して受信した場合に、脱退対象のマルチキャストグループ及びこの中継基地局の属するゾーンに関連付けられて格納されている基地局に関する情報を前記記憶部から抽出する抽出手段と、 前記抽出手段により抽出された基地局と受信されたLEAVEパケットを中継した基地局との比較により、前記脱退対象のマルチキャストグループに関し参加を継続している移動端末の存在を確認するためのクエリパケットの送信の要否を決定する決定手段と、 前記決定手段による決定結果に基づいて、前記クエリパケットを含むユーザデータパケットを前記記憶部に前記脱退対象のマルチキャストグループに関する情報と共に格納されるゾーンに属する各基地局に対してそれぞれ送信する送信手段と、 を備え、 前記複数の基地局のうち同一ゾーンに属する各基地局は、 前記中継装置の送信手段から送信されたユーザデータパケットをそれぞれ受信し、そのユーザデータパケットに含まれるクエリパケットを同一ゾーンに属する他の基地局と略同時にそれぞれ無線送信する、 無線通信システム。
- 6前記中継装置は、 前記マルチキャストグループへの参加依頼のJOINパケットを前記移動端末から前記複数の基地局のいずれか1つを経由して受信した場合に、この中継基地局の属するゾーン及び参加対象のマルチキャストグループに関連付けられて前記記憶部に格納されている基地局に関する情報をこのJOINパケットを中継した基地局に関する情報で更新する更新手段、 を更に備える請求項5に記載の無線通信システム。
- 7前記中継装置は、 前記送信手段により前記クエリパケットを含むユーザデータパケットが送信されその応答パケットが受信されなかった場合に、前記脱退対象のマルチキャストグループ、前記LEAVEパケットを中継した基地局及びその基地局の属するゾーンが関連付けられたレコードを前記記憶部から削除する削除手段、 を更に備える請求項5又は6に記載の無線通信システム。
- 8前記中継装置は、 前記削除手段によりレコードが削除された場合に、前記記憶部にその削除されたマルチキャストグループと関連付けられ格納されている他のレコードの存在を確認し、該他のレコードが存在しない場合には、前記受信されたLEAVEパケットを上位装置へ転送し、該他のレコードが存在する場合には、前記受信されたLEAVEパケットの転送を行わない転送手段、 を更に備える請求項7に記載の無線通信システム。
- 9移動端末へ配信するためのコンテンツを含みこのコンテンツに対応するマルチキャストグループに関する情報の設定されたユーザデータパケットを、ゾーンに区分け管理される複数の基地局へ送信するマルチキャスト中継方法であって、 前記移動端末により参加されるマルチキャストグループに関する情報を該移動端末が無線通信する基地局に関する情報及びその基地局の属するゾーンに関する情報と関連付けて記憶部に格納する格納ステップと、 前記マルチキャストグループからの脱退依頼のLEAVEパケットを前記移動端末から前記複数の基地局のいずれか1つを経由して受信した場合に、脱退対象のマルチキャストグループ及びこの中継基地局の属するゾーンに関連付けられて格納されている基地局に関する情報を前記記憶部から抽出する抽出ステップと、 前記抽出ステップにより抽出された基地局と受信されたLEAVEパケットを中継した基地局との比較により、前記脱退対象のマルチキャストグループに関し参加を継続している移動端末の存在を確認するためのクエリパケットの送信の要否を決定する決定ステップと、 前記決定ステップによる決定結果に基づいて、前記クエリパケットを含むユーザデータパケットを前記記憶部に前記脱退対象のマルチキャストグループに関する情報と共に格納されるゾーンに属する各基地局に対してそれぞれ送信する送信ステップと、 を備えるマルチキャスト中継方法。
Independent claims9
121 paragraphs, as filed
The present invention relates to a relay device, a wireless communication system, and a multicast relay method that realize efficient and effective multicast communication in mobile communication.
WiMAX (Worldwide Interoperability for Microwave Access) is IEEE80 2.16 Fixed wireless communication technology based on the standard. This WiMAX technology is standardized to provide high-speed wireless communication services in the field of wireless MAN (Metropolitan Area Network). Is underway. The WiMAX Forum is an industry group established as a promotion organization for this WiMAX technology. Non-Patent Document 1 below is a document published by this WiMAX Forum as a technical overview on WiMAX technology.
The following Non-Patent Document 1 describes that WiMAX technology supports MultiBS (Base Station) -MBS (Multicast Broadcast Service). That is, In a wireless communication system using WiMAX technology, it is required to provide various contents such as news programs, sports programs, weather forecasts, and traffic information by using multicast communication.
Multicast communication using IP (Internet Protocol) protocol There are IGMP (Internet Group Management Protocol) and MLD (Multicast Listener Discovery) as protocols for managing multicast groups such as joining and leaving hosts in cast groups. IGMP is a multicast group management protocol that supports IPv4, and MLD is a multicast group management protocol that supports IPv6.
The following documents are available as prior art documents that disclose systems and the like that support such multicast communication. The following Patent Document 1 discloses a wireless multicast system and the like. In this wireless multicast system, a router that stores correspondence information between information indicating a wireless access point device sending a packet to a multicast group and information indicating the multicast group transmits the correspondence information to a wireless terminal. , The access point device to be connected to the wireless terminal is specified.
Further, Patent Document 2 below discloses an IP packet multicast method. In this method, in each relay node having a hierarchical structure, the upper node stores the information of the lower node in response to the participation request from the lower node, and deletes the information in response to the cancellation request.<patcit num="1"><text>Japanese Unexamined Patent Publication No. 2004-15435</text></patcit><patcit num="2"><text>Japanese Unexamined Patent Publication No. 2002-94562</text></patcit><nplcit num="1"><text>WiMAX Forum, A Technical Overview and Performance Evaluation, Mobile WiMAX-Part 1, February 16, 2006</text></nplcit>
<p> However, in the wireless multicast system disclosed in Patent Document 1 described above, in order to select a wireless access point device to be connected to a wireless terminal that wants to receive packets of a predetermined multicast group, a system that supports mobile communication is used. Not suitable.</p><p> Further, in the multicast communication method disclosed in Patent Document 2 described above, in order to manage the information of the multicast group to which each base station (RNC) is connected to each mobile terminal, the information of the multicast group is managed by each base station. There is a problem that the system configuration becomes complicated because the amount of information increases and it is necessary to synchronize the information between each base station.</p><p> Further, even in Non-Patent Document 1 described above, a specific method for supporting multi-BS-MBS in WiMAX technology is not disclosed.</p><p> An object of the present invention is to provide a relay device, a wireless communication system, and a multicast relay method that realize efficient and effective multicast communication in mobile communication.</p>
<p> The present invention adopts the following configuration in order to solve the above-mentioned problems. That is, the present invention is a relay device that transmits a user data packet including content for distribution to a mobile terminal and in which information about a multicast group corresponding to this content is set, to a plurality of base stations that are divided into zones and managed. A storage means for storing information about a multicast group joined by a mobile terminal in a storage unit in association with information about a base station to which the mobile terminal wirelessly communicates and information about a zone to which the base station belongs, and a storage means from the multicast group. When a withdrawal request LEAVE packet is received from a mobile terminal via any one of multiple base stations, the base station stored in association with the multicast group to be withdrawn and the zone to which this relay base station belongs. By comparing the extraction means for extracting information about the above from the storage unit with the base station extracted by this extraction means and the base station that relayed the received LEAVE packet, the participation in the multicast group to be withdrawn is continued. A decision means for determining whether or not to send a query packet for confirming the existence of a mobile terminal, and a user data packet including the query packet are stored in the storage unit as a withdrawal target based on the determination result by the determination means. It relates to a relay device provided with a transmission means for transmitting to each base station belonging to the zone, which is stored together with information about the multicast group of the above.</p><p> In the relay device according to the present invention, information about the multicast group in which the mobile terminal participates is managed together with the base station to which the mobile terminal wirelessly communicates and the zone to which the base station belongs. When a LEAVE message is received from a mobile terminal, the LEAVE message is relayed to the base station stored in the storage unit for the multicast group to be withdrawn and the zone to which the base station that relayed the received LEAVE message belongs. The base station is compared with the base station, and based on the comparison result, whether or not to send a query packet to the target zone regarding the multicast group to be withdrawn is determined.</p><p> As a result, according to the present invention, if it is determined that the comparison results are different, for example, it is determined that another mobile terminal participating in the withdrawal target multicast group still exists in the zone, and the withdrawal target multicast is determined. It is possible to prevent the query packet about the group from being sent to each base station belonging to the zone.</p><p> Therefore, according to the present invention, it is possible to reduce the exchange of messages for managing a useless multicast group such as a query packet in such a situation, and in a system for a mobile terminal on the premise of moving. , Efficient and effective multicast communication can be performed.</p><p> Further, when the relay device according to the present invention receives a JOIN packet requesting participation in a multicast group from a mobile terminal via any one of a plurality of base stations, the zone to which the relay base station belongs and participation The above storage associated with the target multicast group An update means for updating the information about the base station stored in the above with the information about the base station that relayed this JOIN packet may be further provided.</p><p> That is, in the present invention, the participation status of the mobile terminal in the multicast group is managed by sequentially updating the information about the relay base station of the JOIN message for each zone to which the base station belongs each time the JOIN message is relayed. Will be done.</p><p> As a result, according to the present invention, if the base station that relays the received LEAVE message is different from the base station stored in the storage unit for the multicast group to be withdrawn and the zone, the zone is set. It can be determined that there is another base station that is wirelessly connected to another mobile terminal that has recently joined the multicast group. In such a case, it is not necessary to send a query packet to the zone, so that useless messages can be reduced.</p><p> Further, in the relay device according to the present invention, when a user data packet including a query packet is transmitted by the transmission means and the response packet is not received, the multicast group to be withdrawn, the base station that relays the LEAVE packet, and the relay device A deletion means for deleting the record associated with the zone to which the base station belongs from the storage unit may be further provided.</p><p> Further, when a record is deleted by the deletion means, the relay device according to the present invention confirms the existence of another record associated with the deleted multicast group in the storage unit, and confirms the existence of the other record. If the record of is not present, the received LEAVE packet is forwarded to the host device, and if the other record is present, a forwarding means that does not forward the received LEAVE packet is further provided. May be good.</p><p> In the present invention, based on the information stored in the storage unit, it is possible to confirm the existence of mobile terminals under the control of other zones participating in the multicast group to be withdrawn in the received LEAVE packet, and thus all zones. The LEAVE packet can be forwarded to the host device only when there are no more mobile terminals participating in the multicast group.</p><p> Therefore, according to the present invention, it is possible to eliminate unnecessary messages between the relay device and the host device, so that efficient multicast communication can be realized.</p><p> The present invention is also an invention relating to a wireless communication system having the relay device and the base station device, and is also an invention relating to a multicast relay method for realizing any function of the relay device in a computer or the like. Further, the present invention may be a program that realizes any of the above functions, or such a program may be recorded on a computer-readable storage medium.</p>
<p> According to the present invention, it is possible to provide a relay device, a wireless communication system, and a multicast relay method that realize efficient and effective multicast communication in mobile communication.</p>
[Embodiment] Hereinafter, the multi-BS-MBS system (hereinafter, simply referred to as MBS system) according to the embodiment of the present invention will be described with reference to the drawings. The configuration of the embodiment described below is an example, and the present invention is not limited to the configuration of the following embodiment. Also, in the following explanation Although only the multicast communication service of the MBS system in the present embodiment will be described, the MBS system may have other functions.
[System configuration and device configuration] The system configuration of the MBS system in this embodiment will be described with reference to FIG. FIG. 1 is a diagram showing a system configuration of the MBS system according to the present embodiment.
The MBS system in the present embodiment is configured by connecting the CSN (Connectivity Service Network) 10 and the ASN (Access Service Network) 15 via the edge router 20. The MBS system in the present embodiment may be configured so that a plurality of CSN10s and ASN15s are present, or each network may be connected without going through the edge router 20.
<CSN> CSN10 is a router, AAA (Authentication Authorization Accounting) Proki The server, user database, Interworking gateway, etc. are connected and configured (not shown). CSN10 provides IP (Internet Protocol) connection service and the like to WiMAX subscribers (for example, mobile terminal 60) who receive WiMAX service. In addition, CSN10 provides various contents such as news programs, sports programs, weather forecasts, and traffic information as WiMAX services using multicast communication. Each content provided is given a different multicast address, and CSN10 manages a relative table of each content and the multicast address. This relative table may be held in the memory of the CSN 10 or the like so as to be adjustable in advance. Hereinafter, the service using multicast communication will be described as the communication service provided by CSN10, but it is also possible to provide other communication services in this MBS system.
The CSN10 is connected to the ASN15 via the edge router 20. For example, IP is used for this connection. The CSN 10 transmits the content to be provided to the edge router 20 as a multicast packet set with the multicast address given for the content.
<Edge router> The edge router 20 is connected to a plurality of ASN gateways 30 under management, and manages information related to multicast communication for delivering the content transmitted from the CSN 10. The edge router 20 treats each ASN gateway 30 under management as a host that participates in the multicast group. The edge router 20 controls the procedure for each ASN gateway 30 to join or leave a predetermined multicast group by processing the multicast group management message independently.
<ASN> The ASN15 is configured by connecting the ASN gateway 30, the base station 50, and the like. The mobile terminal 60 connects to the MBS system according to the present embodiment by wirelessly communicating with the base station 50 whose position is the communicable area, and receives the WiMAX service. Hereinafter, each device constituting the ASN 15 will be described.
<< ASN Gateway >> The ASN gateway 30 includes a CPU (Central Processing Unit), memory, and input / output. It is a gateway device equipped with an interface and the like. The ASN gateway 30 is connected to a plurality of base stations 50 under management. In the example of FIG. 1, the ASN gateway 30 is the base station B. It is connected to S1, BS2, BS3, BS4 and BS5 respectively. The ASN gateway 30 divides the base station 50 under management into predetermined MBS zones and controls multicast communication for each MBS zone. In the example of FIG. 1, base stations BS1, BS2 and BS3 are managed as MBS zone # 1, and base stations BS4 and BS5 are managed as MBS zone # 2, respectively.
Hereinafter, the device configuration of the ASN gateway 30 will be described with reference to FIG. FIG. 2 is a block diagram showing the functional configuration of the ASN gateway 30. The ASN gateway 30 includes an upper communication unit 201, a multicast control unit 202, an MBS zone management unit 203, a multicast group management unit 204, a tunneling control unit 208, an MBS zone management database 205, a multicast group management database 206, a tunnel information database 209, and the like. Have.
The upper communication unit 201 controls multicast communication with the edge router 20. Specifically, the host communication unit 201 receives the multicast packet including the content information transmitted from the edge router 20, and passes the received multicast packet to the multicast control unit 202. Further, the upper communication unit 201 transmits a multicast packet to the edge router 20. The upper communication unit 201 may also process data other than the multicast packet.
The multicast control unit 202 cooperates with the upper communication unit 201, the MBS zone management unit 203, the multicast group management unit 204, and the tunneling control unit 208 to distribute the content information transmitted from the CSN 10 to the mobile terminal 60. Control communication. Each mobile terminal 60 needs to join a predetermined multicast group in order to receive the desired content distribution. The multicast control unit 202 controls the procedure for each mobile terminal 60 to join or leave a predetermined multicast group. For example, the multicast control unit 202 controls IGMP (Internet Group Management Protocol) or MLD (Multicast Listener Discovery) used as such a procedure. The multicast control unit 202 is a multicast group management message used in such a protocol, such as a JOIN message (membership report message), a LEAVE message, and a membership query (Group). Process Specific) messages (hereinafter referred to as GS-query messages), membership query (General) messages (hereinafter referred to as G-query messages), etc. ..
Further, the multicast control unit 202 processes the multicast data including the content information transmitted from the CSN 10. Of these multicast group management messages and multicast data, the multicast control unit 202 passes the multicast packet to be transmitted to the edge router 20 to the upper communication unit 201, and the multicast packet to be transmitted to the mobile terminal 60 is the destination MBS zone. It is passed to the tunneling control unit 208 together with the information about. Details of the multicast group management message and the multicast data processed by the multicast control unit 202 will be described later.
The MBS zone management unit 203 manages information about the zone to which each base station 50 belongs by referring to the MBS zone management database 205. The MBS zone management unit 203 refers to the MBS zone information table in the MBS zone management database 205. FIG. 3 is a diagram showing an example of the MBS zone information table in the MBS zone management database 205. This MBS zone information table holds information on the MBS zone to which each base station belongs. This MBS zone information table may be preset or dynamically updated by communication.
The multicast group management unit 204 manages, for each MBS zone, information about the multicast group in which the mobile terminal 60 in the MBS zone participates, based on the multicast group management message processed by the multicast control unit 202. The multicast group management database 206 is used for this management.
FIG. 4 is a diagram showing a multicast group information table in the multicast group management database 206. The multicast group management unit 204 holds the multicast address, MBS zone information, and last-responder information in this multicast group information table for each multicast group and MBS zone. As the last stress ponder information, information about the base station that was in the same MBS zone and last relayed the participation request (JOIN message) to the same multicast group is held.
The tunneling control unit 208 is a GRE (Generic Routing Encapsulation) tunnel. It controls generation and release, etc., and processes multicast communication with base station 50 using this GRE tunnel. Specifically, the tunneling control unit 208 transmits a multicast packet sent from the multicast control unit 202 to a predetermined base station 50 using a GRE tunnel. At this time, the tunneling control unit 208 similarly transmits to a predetermined base station 50 using the GRE tunnel regardless of whether the multicast packet is a multicast group management message or multicast data. Further, the tunneling control unit 208 receives a frame transmitted from the base station 50 using the GRE tunnel, and passes the received data to the multicast control unit 202. In this MBS system, a GRE tunnel is used for communication between the base station 50 and the ASN gateway 30 when the multicast group management message and the multicast data are exchanged between the CSN 10 and the mobile terminal 60. The details of the GRE tunneling protocol are as specified in RFC2784 and RFC2890, and the description thereof will be omitted here.
At the time of initial operation, the tunneling control unit 208 generates a downlink GRE tunnel to be used for the multicast communication with each base station 50 based on the information in the tunnel information database 209. The downlink GRE tunnel used for communication from the ASN gateway 30 to the base station 50 is generated by, for example, the number of base stations 50 connected to the ASN gateway 30 multiplied by the number of contents provided.
FIG. 5 is a diagram showing an example of a tunnel information table in the tunnel information database 209. This tunnel information table stores information about the GRE tunnel to be generated. In this tunnel information table, for each GRE tunnel, the GRE key that is an identifier, the multicast address that uses the GRE tunnel, and the MBS zone information to be generated (ZONE # 1, ZONE # 2, ZONE # 3 in Fig. 5) ) Are stored respectively.
When the tunneling control unit 208 receives information about the multicast packet to be transmitted from the multicast control unit 202 and the MBS zone of the destination, the tunneling control unit 208 requests the MBS zone management unit 203 to request a base belonging to the MBS zone of the destination. Get information about station 50. The tunneling control unit 208 replicates the multicast packet according to the number of acquired base stations 50. The tunneling control unit 208 adds a predetermined header such as a GRE header to the duplicated multicast packet, and then transmits the generated frame using the GRE tunnel established between each base station 50.
At this time, the tunneling control unit 208 sets the timing information corresponding to the destination MBS zone in the GRE header. This timing information is used to simultaneously wirelessly transmit the same message sent from the ASN gateway 30 at each base station 50 belonging to the same MBS zone. Further, this timing information is, for example, the maximum delay time in each MBS zone calculated based on the processing delay time, communication delay time, etc. collected from each base station 50 belonging to each MBS zone by a functional unit (not shown). Is generated by. The present invention does not limit the method for generating the timing information, etc., as long as the timing information is information for transmitting the same multicast data substantially simultaneously from base stations belonging to the same MBS zone by wireless communication. Good.
Hereinafter, each message processed by the multicast control unit 202 will be described with reference to FIGS. 6 to 12, respectively.
FIG. 6 is a diagram showing a JOIN message transmitted from the base station 50 to the ASN gateway 30. The JOIN message is a message sent from the mobile terminal 60 by specifying the multicast address to be joined when joining the multicast group, and the message type is the same as the membership report message. FIG. 6 shows the frame configuration when the base station 50, which has received the JOIN message from the mobile terminal 60, transmits the JOIN message using the GRE tunnel. This frame is configured by adding a predetermined header 302 (GRE header, IP header, and L2 (layer 2) header) to the membership report packet 301 transmitted from the mobile terminal 60. The multicast address (multicast group) that you want to join is set in the group address field of the membership report 301.
Upon receiving this JOIN message, the multicast control unit 202 identifies the source base station by referring to the SA (Sender Address) field of the IP header. The multicast control unit 202 acquires the MBS zone to which the specified base station belongs from the MBS zone management unit 203. The multicast control unit 202 extracts the multicast address from the group address field of the IGMP unit of the received membership report packet 301. The multicast control unit 202 requests the multicast group management unit 204 to check whether or not the extracted multicast address is already stored in the multicast group information table.
If the multicast address is already stored in the multicast group information table for the MBS zone, the multicast control unit 202 sends information about the source base station 50 and the MBS zone to which the base station 50 belongs to the multicast group, respectively. Pass it to the management department 204. Based on this information, the multicast group management unit 204 updates the last stress ponder information with respect to the information regarding the base station 50 of the source concerned regarding the records related to the target multicast address and the target MBS zone in the multicast group information table.
Even if the target multicast address is stored, if only records related to different MBS zones exist, the multicast group management unit 204 adds a new record to the multicast group information table and registers the information. ..
On the other hand, if the multicast address is not yet set in the multicast group information table, the multicast control unit 202 extracts the membership report packet 301 from the frame and puts it in the SA field of the IP header part of the extracted packet. The IP address of the own device (ASN gateway 30) is set, and this packet is passed to the upper communication unit 201 so as to be transmitted to the edge router 20. Figure 7 shows the ASN gateway 30 It is a figure which shows the JOIN message sent to the edge router 20. As shown in FIG. 7, the membership report packet whose source is set to the ASN gateway 30 is sent to the edge router 20 with the L2 header added.
Next, FIG. 8 is a diagram showing a membership query (Group Specific) message transmitted from the ASN gateway 30 to the base station 50. The GS-query message is a message sent to confirm the existence of a mobile terminal 60 that joins a specific multicast group (receives a multicast message to which a specific multicast address is specified). The ASN gateway 30 sends a GS-query message about each multicast group set in the multicast group information table to each MBS zone set in the table.
At this time, the multicast control unit 202 generates the GS-query packet 701 as shown in FIG. In the GS-query packet 701, the multicast address to be confirmed for existence is set in the group address field of the IGMP part and the DA (Destination Address) field of the IP header part. Multicast control unit 202 is generated Pass the GS-query packet 701 to the tunneling control unit 208. The tunneling control unit 208 duplicates this GS-query packet 701 according to the number of base stations belonging to the destination MBS zone, adds a predetermined header 702 to each duplicated GS-query packet 701, and generates it. Each frame is transmitted to each of the base stations 50 using the GRE tunnel. At this time, the tunneling control unit 208 sets the timing information corresponding to the MBS zone to be the transmission destination in the GRE header unit of the header 702.
FIG. 9 is a diagram showing a membership report message transmitted from the base station 50 to the ASN gateway 30 as a response to the GS-query message. The membership report message is a message transmitted from the mobile terminal 60 when the mobile station 60 that has received the above GS-query message continuously participates in the multicast group set in the mobile station 60. FIG. 9 shows the frame configuration when the base station 50, which receives the membership report message from the mobile terminal 60, transmits the message using the GRE tunnel. This frame is configured by adding a predetermined header 802 (GRE header, IP header, L2 header) to the membership report packet 801 transmitted from the mobile terminal 60. The multicast address that continues to participate is set in the DA field and group address field of the membership report packet 801.
When the multicast control unit 202 receives this membership report message, the mobile terminal 60 that continues to participate in the multicast address set in the group address field of the IGMP unit of the membership report packet 801 exists. Recognize. After that, the multicast control unit 202 passes the membership report packet 801 to the tunneling control unit 208. The tunneling control unit 208 adds a predetermined header to this membership report packet 801 and transmits the generated frame to each base station 50 belonging to the MBS zone registered for the multicast group using the GRE tunnel. To do. As a result, it is recognized that the mobile terminal 60 existing in the MBS zone and participating in the multicast group does not need to send the membership report message any more.
On the other hand, if the multicast control unit 202 does not receive this membership report for a predetermined time, it recognizes that the mobile terminal 60 participating in the multicast group does not exist in the MBS zone. Then, the multicast group management unit 204 is notified to that effect. Multicast group management unit 204 connects to the MBS zone. Delete the record related to the multicast group. The multicast control unit 202 may retransmit the GS-query message a plurality of times when recognizing that the mobile terminal 60 participating in the multicast group does not exist.
Next, FIG. 10 is a diagram showing a LEAVE message transmitted from the base station 50 to the ASN gateway 30. The LEAVE message is a message transmitted from the mobile terminal 60 when leaving the participating multicast group. FIG. 10 shows a frame configuration when the base station 50, which has received the LEAVE message from the mobile terminal 60, transmits the LEAVE message using the GRE tunnel. This frame is configured by adding a predetermined header 902 (GRE header, IP header, L2 header) to the LEAVE packet 901 transmitted from the mobile terminal 60. The multicast address you want to leave is set in the group address field of LEAVE packet 901.
Upon receiving this LEAVE message, the multicast control unit 202 identifies the source base station by referring to the SA field of the IP header. The multicast control unit 202 acquires the MBS zone to which the specified base station belongs from the MBS zone management unit 203. The multicast control unit 202 extracts the multicast address from the group address field of the IGMP unit of the received LEAVE packet 901. The multicast control unit 202 requests the multicast group management unit 204 to inspect whether or not the last stress ponder of the MBS zone of the extracted multicast address matches the base station of the source.
When the base station of the transmission source is other than the last stress ponder, the multicast control unit 202 terminates the process as it is, assuming that there is another mobile station 60 participating in the multicast group. On the other hand, when the base station of the transmission source is the last stress ponder, the multicast control unit 202 determines whether or not there is another mobile station 60 participating in the multicast group in the MBS zone in which the base station exists. Send a GS-query message to that MBS zone to see if. The processing related to the transmission of this GS-query message is the same as described above. As a result, it is confirmed that there is no other mobile terminal 60 participating in the multicast group that was the target of the LEAVE message, and the record related to the multicast group is deleted from the multicast group information table.
When the multicast control unit 202 deletes the record related to the multicast group from the multicast group information table by the LEAVE message, in other words, the mobile terminal 60 participating in the multicast group for the MBS zone no longer exists. When it is recognized, the LEAVE packet 901 is extracted from the frame, the IP address of the own device is set in the SA field of the IP header part of the extracted packet, and the upper communication unit 201 is sent to the edge router 20. Pass to. FIG. 11 is a diagram showing a LEAVE message transmitted from the ASN gateway 30 to the edge router 20. As shown in FIG. 11, the LEAVE packet whose source is set to the ASN gateway 30 is sent to the edge router 20 with the L2 header added.
FIG. 12 is a diagram showing multicast data transmitted from the CSN 10 and distributed to the mobile terminal 60 via the edge router 20, the ASN gateway 30, and the base station 50. The multicast data 1201 transmitted from the CSN 10 has a multicast address set corresponding to the content information included in the multicast data 1201, and is sent to the ASN gateway 30 via the edge router 20. The upper communication unit 201 of the ASN gateway 30 is When the multicast data of is received, this data is passed to the multicast control unit 202.
The multicast control unit 202 extracts the multicast address set in the DA field of this data, and requests the multicast group management unit 204 for information on the MBS zone in which the mobile terminal 60 participating in this multicast address exists. The multicast control unit 202 sends information about the MBS zone notified from the multicast group management unit 204 to the tunneling control unit 208 together with the multicast data 1201.
The tunneling control unit 208 replicates this multicast data 1201 according to the number of notified MBS zones and the number of base stations belonging to each MBS zone, and adds a predetermined header 1202 to each replicated multicast data 1201. , Each generated frame is transmitted to each of the base stations 50 using the GRE tunnel. At this time, the tunneling control unit 208 sets the timing information corresponding to the MBS zone to be the transmission destination in the GRE header unit of the header 1202. Upon receiving this frame, each base station 50 in the same MBS zone wirelessly transmits the multicast data 1201 in the frame at the same time according to the timing information. In the MBS system of the present embodiment, the same header is added and transmitted both when the multicast data is transmitted to the base station and when the previous multicast group management message is transmitted to the base station.
<<base station>> Base station 50 includes CPU (Central Processing Unit), memory, and input / output interface. Etc., and connect the mobile terminal 60 in the communication area to this MBS system by wireless communication. Further, the base station 50 is connected to a predetermined ASN gateway 30 by wire, transfers a signal (multicast packet) transmitted from the mobile terminal 60 to the ASN gateway 30 using a GRE tunnel, and transfers the signal (multicast packet) from the ASN gateway 30 to the GRE. The multicast packet transmitted using the tunnel is wirelessly transmitted to the mobile terminal 60. The processing of establishing and releasing the wireless link between the base station 50 and the mobile terminal 60, IP address assignment, and the like is the same as the well-known technology, and thus the description thereof will be omitted.
The base station 50 holds information (for example, an IP address, etc.) about the ASN gateway 30 that manages its own device. The base station 50 uses the GRE tunneling protocol specified in RFC 2784 and RFC 2890 to generate an upstream GRE tunnel for multicast communication with the ASN gateway 30 during initial operation.
When the base station 50 receives the membership report packet 301 (see FIG. 6) (response message of JOIN message and GS-query message) and the LEAVE packet 901 (see FIG. 10) transmitted from the mobile terminal 60, the base station 50 determines the membership report packet 301 (see FIG. 6). Generates a frame with header 302 (L2 header, IP header, GRE header) added, and sends this frame to the ASN gateway 30. At this time, the base station 50 sets the SA field of the IP header to the IP address of its own device and sets the DA field to the IP address of the ASN gateway 30.
When the base station 50 receives a frame transmitted from the ASN gateway 30 using the GRE tunnel, the multicast packet (GS-query packet 701 (see FIG. 8) and the multicast data 1201 (see FIG. 12)) in the frame are received. )) Is extracted. Subsequently, the base station 50 transmits the extracted multicast packet by a predetermined radio channel at the time corresponding to the timing information set in the GRE header of the same frame. Multicast packet sent from ASN gateway 30 using GRE tunnel The same timing information is set for each MBS zone. As a result, the base stations 50 belonging to the same MBS zone transmit the same multicast packet substantially at the same time.
<Mobile terminal> The mobile terminal 60 has a CPU (Central Processing Unit), memory, and an input / output interface. It is a terminal device provided with a device, for example, a mobile phone , a PDA (Personal Digital Assistant), a personal computer, or the like. The mobile terminal 60 has a multicast communication function and a wireless communication function. The mobile terminal 60 wirelessly communicates with the base station 50 that covers the position as a communication area according to its existence position. The mobile terminal 60 receives various contents multicast-distributed from the CSN 10 via the base station 50 having an established wireless link. Each mobile terminal 60 receives each content by joining a multicast group of desired content.
In order to join a desired multicast group, the mobile terminal 60 may hold the relative table of each content held by the CSN 10 and the multicast address by downloading or the like in advance. Further, the mobile terminal 60 may acquire an IP address for connecting to the MBS system in advance. Since the present invention does not limit the method of knowing the multicast address of the content in the mobile terminal 60, the method of acquiring the IP address, and the like, the description thereof will be omitted here.
[Operation example] An operation example of the MBS system in this embodiment will be described below with reference to FIGS. 13 and 14.
First, the operation when a JOIN message is transmitted from the mobile terminal 60 will be described with reference to FIG. FIG. 13 is a sequence diagram showing processing when a JOIN message is received, and is shown by taking the system configuration shown in FIG. 1 as an example. BS1, BS2 and BS3 of base station 50 are defined as belonging to MBS zone # 1, BS4 and BS5 of base station 50 are defined as belonging to MBS zone # 2, and MS1 of mobile terminal 60 is within the communication area of BS2. The case where the mobile terminal 60 exists and MS3 and MS4 of the mobile terminal 60 exist in the communication area of BS5 is taken as an example.
MS1 wishes to join the multicast group (224.22.3.45) and wirelessly sends a JOIN message with its multicast address (224.22.3.45) set (S1301).
When BS2 receives this JOIN message signal, it extracts the membership query report packet from this signal. BS2 sends a frame with a predetermined header added to this membership query report packet to the ASN gateway 30 using the GRE tunnel (S1302). At this time, BS2 sets its own IP address in the SA field in the predetermined header, and sets the IP address of the ASN gateway 30 in the DA field.
When the ASN gateway 30 receives the frame from this GRE tunnel, it extracts the membership query report packet in the frame. Furthermore, the ASN gateway 30 identifies the source BS2 based on the IP address set in the SA field of the header of the frame, and the MBS zone to which the BS2 belongs is the MBS based on the MBS zone information table (Fig. 3). Recognize that it is zone # 1. Next, the ASN gateway 30 is set in the group address field of the IGMP part in the frame. Check if the pair of Lucicast address (224.22.3.45) and MBS zone # 1 is registered in the multicast group information table (Fig. 4) (S1303).
When the ASN gateway 30 confirms that the pair of the multicast address (224.22.3.45) and MBS zone # 1 is not registered, it adds a new record to the multicast group information table and registers this information (S1304). ). Specifically, in the multicast group information table, "224.22.3.45" is set in the multicast address field, "MBS zone # 1" is set in the MBS zone field, and "BS2" is set in the last stress ponder field. Record is added.
The ASN gateway 30 then sends the extracted membership query report packet to the edge router 20 with an L2 header (S1305). At this time, the ASN gateway 30 sets its own IP address in the SA field of the IP header in the packet. As a result, the edge router 20 that receives this packet recognizes that the ASN gateway 30 joins the multicast group (224.22.3.45) by the IP address set in the SA field.
Next, the processing when a plurality of mobile terminals MS3 and MS4 in the same MBS zone send a JOIN message will be described.
First, it is assumed that MS3 wishes to join the multicast group (224.0.10.15) and wirelessly transmits a JOIN message set with the multicast address (224.0.10.15) (S1310).
When BS5 receives this JOIN message signal, it extracts the membership query report packet from this signal. BS5 sends a frame with a predetermined header added to this membership query report packet to the ASN gateway 30 using the GRE tunnel (S1311). At this time, BS5 sets its own IP address in the SA field of the predetermined header, and sets the IP address of the ASN gateway 30 in the DA field.
When the ASN gateway 30 receives the frame from this GRE tunnel, it extracts the membership query report packet in the frame. Furthermore, the ASN gateway 30 identifies the source BS5 based on the IP address set in the SA field of the header of the frame, and the MBS zone to which the BS5 belongs is MBS zone # 2 based on the MBS zone information table. Recognize that there is. Next, the ASN gateway 30 determines whether or not the multicast address (224.0.10.15) and MBS zone # 2 pair set in the group address field of the IGMP part in the frame are registered in the multicast group information table. Check (S1312).
When the ASN gateway 30 confirms that the pair of the multicast address (224.0.10.15) and MBS zone # 2 is not registered, it adds a new record to the multicast group information table and registers this information (S1313). ). Specifically, in the multicast group information table, "224.0.10.15" is set in the multicast address field, "MBS zone # 2" is set in the MBS zone field, and "BS5" is set in the last stress ponder field. Record is added.
The ASN gateway 30 then sends the extracted membership query report packet to the edge router 20 with an L2 header (S1314).
Next, it is assumed that MS4 wishes to join a multicast group (224.0.10.15) similar to MS3 and wirelessly transmits a JOIN message set with the multicast address (224.0.10.15) (S1320).
When BS4 receives this JOIN message signal, it extracts the membership query report packet from this signal. BS4 sends a frame with a predetermined header added to this membership query report packet to the ASN gateway 30 using the GRE tunnel (S1321).
When the ASN gateway 30 receives the frame from this GRE tunnel, it extracts the membership query report packet in the frame. Further, the ASN gateway 30 identifies the BS4 that is the source of the frame, and recognizes that the MBS zone to which the BS4 belongs is the MBS zone # 2, as in the case of the MS3. Next, the ASN gateway 30 determines whether or not the multicast address (224.0.10.15) and MBS zone # 2 pair set in the group address field of the IGMP part in the frame are registered in the multicast group information table. Check (S1322).
When the ASN gateway 30 recognizes that the pair of the multicast address (224.0.10.15) and MBS zone # 2 has already been registered, it updates the last stress ponder field of the target record in the multicast group information table to "BS4" (S1323). ), Finish the process. As a result, when the ASN gateway 30 receives a JOIN message about a multicast group already registered in the same MBS zone, it does not send it to the edge router 20.
Next, the operation when the ASN gateway 30 confirms the existence of the mobile terminal 60 participating in the multicast group set in the multicast group information table will be described with reference to FIG. FIG. 14 is a sequence diagram showing processing at the time of transmitting a GS-query message, and is shown by taking the system configuration shown in FIG. 1 as an example.
It is assumed that the multicast group information table of the ASN gateway 30 is in the state shown in FIG. The ASN gateway 30 confirms the existence of each multicast group set in the multicast group information table at a predetermined cycle.
Specifically, the ASN gateway 30 is a GS-query in which the multicast address (224.0.10.15) is set in the group address field of the IGMP part and the DA field of the IP header part as a survival confirmation of the multicast group (224.0.10.15). Generate a packet. The ASN gateway 30 recognizes that the MBS zone registered for the multicast address is MBS zone # 2, and identifies BS4 and BS5 as base stations belonging to the MBS zone # 2. The ASN gateway 30 identifies the GRE tunnel generated for the multicast address (224.0.10.15) to and from this identified BS4 and BS5.
The ASN gateway 30 duplicates the previously generated GS-query packet and adds a predetermined header set for the destination base station to each GS-query packet. The ASN gateway 30 transmits each frame thus generated to BS4 and BS5 by using each GRE tunnel (S1401). Each frame sent The same information is set in the timing information set in the GRE header part of the software.
Upon receiving this frame, BS4 and BS5 simultaneously transmit the GS-query packet in this frame using a predetermined radio channel at the timing corresponding to the timing information set in the GRE header section (S1402).
The MS3 and MS4 receive a GS-query packet transmitted from either BS4 or BS5 depending on their location. Since the same data is transmitted from BS4 and BS5 at substantially the same time even when moving, MS3 and MS4 receive only the data transmitted from any one of the base stations. Here, both MS3 and MS4 continue to participate in the multicast group (224.0.10.15), and the case where MS3 first sends the membership query report packet in response to the GS-query is taken as an example.
MS3 wirelessly sends a query response message with its multicast address (224.0.10.15) to indicate that it continues to join the multicast group (224.0.10.15) (S1403).
Upon receiving this query response message signal, BS5 extracts the membership query report packet from this signal. BS5 sends a frame with a predetermined header added to this membership query report packet to the ASN gateway 30 using the GRE tunnel (S1404). At this time, BS5 sets its own IP address in the SA field in the predetermined header, and sets the IP address of the ASN gateway 30 in the DA field.
When the ASN gateway 30 receives the frame from this GRE tunnel, it extracts the membership query report packet in the frame. The ASN gateway 30 refers to the multicast address (224.0.10.15) set in the group address field of the IGMP part in the frame. Further, the ASN gateway 30 identifies the BS5 that is the source of the frame, and recognizes that the MBS zone to which the BS5 belongs is the MBS zone # 2 based on the MBS zone information table. As a result, the ASN gateway 30 confirms that the mobile terminal 60 that continues to participate in MBS zone # 2 for the multicast address (224.0.10.15) exists in response to the previously sent GS-query message.
After the above confirmation, the ASN gateway 30 identifies BS4 and BS5 as base stations belonging to its MBS zone # 2, and the GRE generated for the multicast address (224.0.10.15) between the identified BS4 and BS5. Identify the tunnel. The ASN gateway 30 duplicates the extracted membership query report packet as it is, adds a predetermined header to each duplicated packet, and then uses each GRE tunnel specified for each generated frame to perform BS4 and Send to BS5 (S1405). The same information is set in the timing information set in the GRE header part of each transmitted frame.
Upon receiving this frame, BS4 and BS5 simultaneously transmit the membership query report packet in this frame using a predetermined wireless channel at the timing corresponding to the timing information set in the GRE header section (S1406).
MS3 and MS4 receive the membership query report packet transmitted from either BS4 or BS5 depending on their location. This allows the MS4 to recognize that it does not need to respond to the previously received GS-query packet and issues a query response message. Do not transmit wirelessly. This is because the ASN gateway 30 participates in each multicast group for each MBS zone, and the participation continuation information is notified by another mobile terminal MS3 that already exists in the same MBS zone.
Next, the case where the ASN gateway 30 confirms the existence of the multicast group (224.22.3.45) for MBS zone # 1 will be described based on the multicast group information table. Here, the case where MS1 existing in MBS zone # 1 withdraws from the multicast group (224.22.3.45) is taken as an example.
The ASN gateway 30 generates a GS-query packet in which the multicast address (224.22.3.45) is set in the group address field of the IGMP part and the DA field of the IP header part as confirmation of the existence of the multicast group (224.22.3.45). The ASN gateway 30 recognizes that the MBS zone registered for the multicast address is MBS zone # 1, and identifies BS1, BS2, and BS3 as base stations belonging to the MBS zone # 1. The ASN gateway 30 identifies the GRE tunnel generated for the multicast address (224.22.3.45) to and from this identified BS1, BS2 and BS3.
The ASN gateway 30 duplicates the previously generated GS-query packet and adds a predetermined header set for the destination base station to each GS-query packet. The ASN gateway 30 transmits each frame thus generated to BS1, BS2, and BS3 by using each GRE tunnel (S1410). The same information is set in the timing information set in the GRE header part of each transmitted frame.
BS1, BS2, and BS3 that received this frame simultaneously transmit GS-query packets in this frame using a predetermined wireless channel at the timing corresponding to the timing information set in the GRE header section (S1411). ..
The MS1 receives a GS-query packet transmitted from any one of BS1, BS2 and BS3 depending on its location. MS1 has withdrawn from joining the multicast group (224.22.3.45) and therefore does not respond to its GS-query message.
The ASN gateway 30 continues to join the multicast group (224.22.3.45) in MBS zone # 1 if the response to the previously sent GS-query message is not sent within the specified timeout period. It is tentatively determined that the mobile terminal 60 is not present (S1412). The ASN gateway 30 resends a GS-query message similar to the one sent earlier to MBS zone # 1 (S1413).
The ASN gateway 30 also determines that there is no mobile terminal 60 in MBS zone # 1 that continues to join the multicast group (224.22.3.45) if there is no response to this resent GS-query message. Then, delete the target record from the multicast group information table. Subsequently, the ASN gateway 30 confirms whether or not a record related to another MBS zone is registered in the multicast group information table for the multicast group (224.22.3.45). When the ASN gateway 30 confirms that no records related to other MBS zones are registered, it sends a LEAVE message about the multicast group (224.22.3.45) to the edge router 20.
Upon receiving this LEAVE message, the edge router 20 recognizes that the ASN gateway 30 has left the multicast group (224.22.3.45). This is synonymous with recognizing that none of the mobile terminals 60 under the ASN gateway 30 continue to join the multicast group.
As a processing sequence when the LEAVE message is transmitted from the mobile terminal 60, when the ASN gateway 30 receives the LEAVE message, the above-mentioned GS-query message is transmitted. Since the subsequent processing is the same as the processing sequence shown in FIG. 14, the description thereof will be omitted.
Next, the operation when the LEAVE message is transmitted from the mobile terminal 60 will be described with reference to FIGS. 15 and 16. FIG. 15 is a sequence diagram showing a first processing pattern when a LEAVE message is received, and FIG. 16 is a sequence diagram showing a second processing pattern when a LEAVE message is received. It is shown as.
First, the first processing pattern when a LEAVE message is received will be described with reference to FIG. At this time, it is assumed that the multicast group information table of the ASN gateway 30 is in the state shown in FIG. 4, and only MS3 and MS4 are requesting the multicast group (224.0.10.15) to join the multicast group (224.0.10.15) from MBS zone # 2. It shall be.
In order to leave the multicast group (224.0.10.15), the MS3 wirelessly transmits a LEAVE message signal with its multicast address (224.0.10.15) set (S1501).
When the BS5 receives this LEAVE message signal, it extracts the LEAVE packet from this signal. BS5 transmits a frame with a predetermined header added to this LEAVE packet to the ASN gateway 30 using the GRE tunnel (S1502). At this time, BS5 sets its own IP address in the SA field in the predetermined header, and sets the IP address of the ASN gateway 30 in the DA field.
When the ASN gateway 30 receives the frame from this GRE tunnel, it extracts the LEAVE packet in the frame. Furthermore, the ASN gateway 30 identifies the source BS5 based on the IP address set in the SA field of the header of the frame, and the MBS zone to which the BS5 belongs is the MBS based on the MBS zone information table (Fig. 3). Recognize that it is in zone # 2. Subsequently, the ASN gateway 30 registers the multicast address (224.0.10.15) and the MBS zone # 2 pair set in the group address field of the IGMP part in the frame from the multicast group information table (Fig. 4). Extract the base station information registered in the multicast ponder field of the record (S1503). Here, the information indicating BS4 is extracted from the last stress ponder field of the record.
After confirming that BS5, the source of the LEAVE message, and this extracted lastless ponder (BS4) are different, ASN gateway 30 still continues to participate in the multicast address (224.0.10.15) in MBS zone # 2. It is determined that the mobile terminal 60 is present, and the process is terminated (S1504).
After that, in order for MS3 to leave the multicast group (224.0.10.15), the LEAVE mail that set the multicast address (224.0.10.15) Wirelessly transmit the message (S1510).
When BS4 receives this LEAVE message signal, it extracts a LEAVE packet from this signal. BS4 transmits a frame with a predetermined header added to this LEAVE packet to the ASN gateway 30 using the GRE tunnel (S1511). At this time, BS4 sets its own IP address in the SA field in the predetermined header, and sets the IP address of the ASN gateway 30 in the DA field.
When the ASN gateway 30 receives the frame from this GRE tunnel, it identifies the BS4 that is the source of the frame, as in the case of MS3, and the MBS zone to which the BS4 belongs based on the MBS zone information table (Fig. 3). Recognize that is MBS zone # 2. Subsequently, the ASN gateway 30 registers the multicast address (224.0.10.15) and the MBS zone # 2 pair set in the group address field of the IGMP part in the frame from the multicast group information table (Fig. 4). Extract the base station information (BS4) registered in the multicast ponder field of the record.
When the ASN gateway 30 confirms that BS4, which is the source of the LEAVE message, matches this extracted last stress ponder (BS4), it already continues to participate in the multicast address (224.0.10.15) in MBS zone # 2. It is determined that the mobile terminal 60 is not present (S1512). As a result, the ASN gateway 30 transmits GS-query packets to BS4 and BS5 belonging to its MBS zone # 2 using each GRE tunnel (S1513).
After that, the process is the same as the case of confirming the existence of the mobile terminal 60 participating in the multicast group shown in FIG. At this time, since there is no mobile terminal 60 that has already joined the multicast group (224.0.10.15) in MBS zone # 2, the query response message for the GS-query packet is not sent.
Therefore, finally, the ASN gateway 30 determines that there are no mobile terminals participating in the multicast group (224.0.10.15) in MBS zone # 2, and from the multicast group information table, MBS zone # 2 and the multicast group (224.0). 10.15) deletes the paired record (S1519). Subsequently, the ASN gateway 30 confirms whether or not a record related to another MBS zone is registered in the multicast group information table for the multicast group (224.0.10.15). When the ASN gateway 30 confirms that no other MBS zone is registered, it sends a LEAVE message about the multicast group (224.0.10.15) to the edge router 20 (S1520).
Next, the second processing pattern when the LEAVE message is received will be described with reference to FIG. At this time, the multicast group information table of the ASN gateway 30 is assumed to be in the state shown in FIG. 4, and only MS3 and MS4 are requesting the multicast group (224.0.10.15) to join the multicast group (224.0.10.15) from MBS zone # 2, respectively. It shall be.
In order to leave the multicast group (224.0.10.15), the MS4 wirelessly transmits a LEAVE message signal with its multicast address (224.0.10.15) set (S1601).
When BS4 receives this LEAVE message signal, it receives the LEAVE package from this signal. Extract. BS4 sends a frame with a predetermined header added to this LEAVE packet to the ASN gateway 30 using the GRE tunnel (S1602). At this time, BS4 sets its own IP address in the SA field in the predetermined header, and sets the IP address of the ASN gateway 30 in the DA field.
When the ASN gateway 30 receives the frame from this GRE tunnel, it identifies the BS4 that is the source of the frame as described above, and the MBS zone to which the BS4 belongs is the MBS based on the MBS zone information table (Fig. 3). Recognize that it is zone # 2. Subsequently, the ASN gateway 30 registers the multicast address (224.0.10.15) and the MBS zone # 2 pair set in the group address field of the IGMP part in the frame from the multicast group information table (Fig. 4). Extract the base station information (BS4) registered in the multicast ponder field of the record.
When the ASN gateway 30 confirms that BS4, which is the source of the LEAVE message, matches this extracted last stress ponder (BS4), it already continues to participate in the multicast address (224.0.10.15) in MBS zone # 2. It is determined that the mobile terminal 60 is not present (S1603). As a result, the ASN gateway 30 sends GS-query packets to BS4 and BS5 belonging to its MBS zone # 2 using each GRE tunnel (S1604).
After that, the process is the same as the case of confirming the existence of the mobile terminal 60 participating in the multicast group shown in FIG. At this time, there is a mobile terminal (MS3) that continues to participate in the multicast group (224.0.10.15) in MBS zone # 2. When the MS3 receives this GS-query packet, it sends a query response message (S1606). Based on this response, the ASN gateway 30 determines that there is a mobile terminal 60 in MBS zone # 2 that is still participating in the multicast group (224.0.10.15). The ASN gateway 30 sends the query response message as it is to each BS4 and BS5 of MBS zone # 2 in the same manner as the process shown in FIG. 14 (S1608).
Finally, the ASN gateway 30 updates the last-stress ponder field of the multicast group information table with the information about the base station (BS5) that relayed the query response message (S1610), and ends the process (S1611).
<Action and effect in this embodiment> Here, the operation and effect of the MBS system in the above-described embodiment will be described.
In the MBS system of the present embodiment, when a JOIN message (request for participation in a predetermined multicast group) transmitted from the mobile terminal 60 is transmitted to the ASN gateway 30 via the base station 50, it becomes the target of the JOIN message. Information about the MBS zone to which the base station that relayed the JOIN message belongs for the multicast group and information about the base station that relayed the JOIN message are stored.
Then, when the LEAVE message (request for withdrawal from the predetermined multicast group) transmitted from the mobile terminal 60 is transmitted to the ASN gateway 30 via the base station 50, the base station that relays the LEAVE message is the LEAVE message. It is confirmed whether or not the target multicast group is registered in the multicast group information table as a last-stress ponder. If the registered last stress ponder and the base station that relayed the LEAVE message match, the MBS zone to which the relay station belongs A GS-query message (survival confirmation) is sent to the user. As a result, it is confirmed that there is no other mobile terminal that continues to join the multicast group, and the target record is deleted from the multicast group information table.
On the other hand, if the registered last stress ponder and the base station that relayed the LEAVE message do not match, the processing is terminated. This is because it can be recognized that another mobile terminal exists in the MBS zone to which the base station belongs.
As a result, according to the present embodiment, even if a LEAVE message is received, if there is a high possibility that another mobile terminal that continues to participate in the same MBS zone exists, the existence is confirmed. You don't have to send a GS-query message to do this, so you can reduce unnecessary traffic.
As a result, according to the present embodiment, it is possible to efficiently perform multicast communication in the MBS system for the mobile terminal 60, which is premised on moving.
[Modification example] In the above-mentioned ASN gateway 30, when the JOIN message was received, the last stress ponder field of the multicast group information table was updated by the information about the base station that relayed the message, but the JOIN message was received first for the same MBS zone. Information about the base station that relayed the message may be set in the multicast ponder field only when the message is executed.
Even in this case, the existence of mobile terminals participating in the multicast group can always be confirmed for each MBS zone by periodically confirming the mobile terminals that continue to participate by the GS-query message.
<figref num="1">It is a figure which shows the system configuration of the multi-BS-MBS system in this embodiment.</figref><figref num="2">It is a figure which shows the functional structure of the ASN gateway.</figref><figref num="3">It is a figure which shows the example of the MBS zone information table in the MBS zone management database.</figref><figref num="4">It is a figure which shows the multicast group information table in a multicast group management database.</figref><figref num="5">It is a figure which shows the example of the tunnel information table in the tunnel information database.</figref><figref num="6">It is a figure which shows the JOIN message transmitted from a base station to an ASN gateway.</figref><figref num="7">It is a figure which shows the JOIN message sent from the ASN gateway to the edge router.</figref><figref num="8">It is a figure which shows the membership query (Group Specific) message sent from the ASN gateway to the base station.</figref><figref num="9">GS-Figure shows a membership report message sent from a base station to an ASN gateway in response to a query message.</figref><figref num="10">It is a figure which shows the LEAVE message transmitted from the base station to the ASN gateway.</figref><figref num="11">It is a figure which shows the LEAVE message sent from the ASN gateway to the edge router.</figref><figref num="12">It is a figure which shows the multicast data transmitted from a CSN and distributed to a mobile terminal via an edge router, an ASN gateway and a base station.</figref><figref num="13">It is a figure which shows the process at the time of receiving a JOIN message.</figref><figref num="14">GS-It is a figure which shows the process at the time of sending a query message.</figref><figref num="15">It is a figure which shows the 1st processing pattern at the time of receiving a LEAVE message.</figref><figref num="16">It is a figure which shows the 2nd processing pattern at the time of receiving a LEAVE message.</figref>
Code description
10 CSN (Connectivity Service Network) 15 ASN (Access Service Network) 20 edge router 30 ASN gateway 50 base stations 60 mobile terminal 201 Upper communication department 202 Multicast control unit 203 MBS Zone Management Department 204 Multicast Group Management Department 205 MBS Zone Management Database 206 Multicast group management database 208 Tunneling control unit 209 Tunnel information database 301 Membership Report Packet 302 header 701 Membership query packet, GS (Group Specific)-query packet 702 header 801 Membership report packet 802 header 901 LEAVE packet 902 header 1201 Multicast data
16 sheets
Sheet 1 Sheet 2 Sheet 3 Sheet 4 Sheet 5 Sheet 6 Sheet 7 Sheet 8 Sheet 9 Sheet 10 Sheet 11 Sheet 12 Sheet 13 Sheet 14 Sheet 15 Sheet 16
Every citation, both waysCites: the store holds 3 of 4
| Document | Relation | Office |
|---|---|---|
| WO2006097989A1 | Cites | World Intellectual Property Organization (WIPO) |
| JP2004229117A | Cites | Japan |
| JP200899291A | Cites | Japan |
| 岩松 隆則,移動体向けに省電力機能などを追加 マルチキャスト・サービスも可能に,日経コミュニケーション,2006年 3月15日,第458号,pp.124-129 | Non-patent | – |
12 members in 6 offices
Priority claims2
| Document | Office | Kind | Date |
|---|---|---|---|
| 2006301594 | Japan | A | |
| JP20060301594 | – | – | – |
Members12
| Document | Office | Kind | |
|---|---|---|---|
| US2008107060A1 | United States of America | A1 | |
| KR20080041569A | Republic of Korea | A | |
| CN101179496A | China | A | |
| EP1921794A2 | European Patent Office (EPO) | A2 | |
| EP1921794A3 | European Patent Office (EPO) | A3 | |
| JP2008118525A | Japan | A | |
| KR100933611B1 | Republic of Korea | B1 | |
| EP1921794B1 | European Patent Office (EPO) | B1 | |
| DE602007011026D1 | Germany | D1 | |
| JP4723458B2This record | Japan | B2 | |
| CN101179496B | China | B | |
| US8023433B2 | United States of America | B2 |
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Numbers
- Publication
- 4723458
- Publication, DOCDB
- 4723458
- Publication, EPODOC
- JP4723458B
- Application
- 301594
- Application, DOCDB
- 2006301594
- Application, EPODOC
- JP20060301594
Titles2
- Japanese
- 中継装置、無線通信システム及びマルチキャスト中継方法
- English
- Relay device, wireless communication system and multicast relay method
Classification
- CPC, 5
- H04L12/189
- H04L12/18
- H04L12/185
- H04L12/1886
- H04W4/06
- IPC, 4
- H04L12 56
- H04W4 06
- H04L45 16
- H04W4 08
