Relay device, wireless communication system and multicast relay method

• US 20080107060A1
• Filed: 10/01/2007
• Published: 05/08/2008
• Est. Priority Date: 11/07/2006
• Status: Active Grant

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: ANDOU, Tadanao, ASADA, Takeshi
• Granted Patent: US 8,023,433 B2
• Time in Patent Office: Days
• US Class Current: 370/312
• CPC Class Codes: H04L 12/185 with management of multicast group membership
• CPC Class Codes: H04L 12/1886 with traffic restrictions for efficiency improvement, e.g. involving subnets or subdomains
• CPC Class Codes: H04L 12/189 in combination with wireless systems selective distribution or broadcast in wireless communication networks H04W4/06

Abstract

The present invention relates to a relay device realizing multicast communications efficient and effective in mobile communications. The relay device transmitting a multicast user data packet containing a content to a plurality of base stations comprises a storing unit storing, in a storing unit, information about a multicast group, information about the base station and information about the zone in a way that associates these items of information with each other, a determining unit determining, when receiving a LEAVE packet via the base station, whether or not it is required to transmit a query packet about a leave target multicast group by comparing the base station stored in the way being associated with the leave target multicast group and with the zone to which the via-base-station belongs with the base station relaying the received LEAVE packet, and a transmitting unit transmitting the user data packet containing the query packet to each of the base stations belonging to the zone on the basis of a result of the determination by the determining unit.

Claims

1. A relay device transmitting a user data packet, containing a content to be distributed to a mobile terminal, in which to set information about a multicast group associated with the content, to a plurality of base stations managed in the way of being grouped into zones, the relay device comprising:

a storing unit storing information about a multicast group in which the mobile terminal participates, information about the base station performing wireless communications with the mobile terminal and information about the zone to which the base station belongs in a way that associates these items of information with each other;

a extracting unit extracting, when receiving a LEAVE packet of a request for leaving the multicast group from the mobile terminal via any one of the plurality pf base stations, the information about the base station, which is stored in the way of being associated with the leave target multicast group and with the zone to which the via-base-station belongs, from the storing unit;

a determining unit determining whether or not it is required to transmit a query packet for checking existence of the mobile terminal continuing the participation in the leave target multicast group by comparing the base station extracted by the extracting unit with the base station that relays the received LEAVE packet; and

a transmitting unit transmitting the user data packet containing the query packet to each of the base stations belonging to the zone whose information is stored together with the information about the leave target multicast group in the storing unit on the basis of a result of the determination made by the determining unit.

2. A relay device according to claim 1, further comprising an updating unit updating, when receiving a JOIN packet of a request for participating in the multicast group from the mobile terminal via any one of the plurality of base stations, the information about the base station that is stored in the storing unit in the way of being associated with the zone to which the via-base-station belongs and with the participation target multicast group, with the information about the base station that relays the JOIN packet.

3. A relay device according to claim 1, further comprising a deleting unit deleting, if a response packet is not received when the transmitting unit has transmitted the user data packet containing the query packet, a record containing the leave target multicast group, the base station that relays the LEAVE packet and the zone to which the base station belongs in the way of their being associated with each other from the storing unit.

4. A relay device according to claim 3, further comprising a transferring unit checking, when the record is deleted by the deleting unit, existence of other records stored in the storing unit in the way of being associated with the multicast group contained in the deleted record, transferring the received LEAVE packet to a high-order device if no other records exist, and transferring none of the received LEAVE packet if other records exist.

5. A wireless communication system comprising:

a plurality of base stations managed in the way being grouped into zones; and

a relay device transmitting a user data packet, containing a content to be distributed to a mobile terminal, in which to set information about a multicast group associated with the content, to any of the plurality of base stations,

the relay device comprising;

a storing unit storing information about a multicast group in which the mobile terminal participates, information about the base station performing wireless communications with the mobile terminal and information about the zone to which the base station belongs in a way that associates these items of information with each other;

a extracting unit extracting, when receiving a LEAVE packet of a request for leaving the multicast group from the mobile terminal via any one of the plurality pf base stations, the information about the base station, which is stored in the way of being associated with the leave target multicast group and with the zone to which the via-base-station belongs, from the storing unit;

a determining unit determining whether or not it is required to transmit a query packet for checking existence of the mobile terminal continuing the participation in the leave target multicast group by comparing the base station extracted by the extracting unit with the base station that relays the received LEAVE packet; and

a transmitting unit transmitting the user data packet containing the query packet to each of the base stations belonging to the zone whose information is stored together with the information about the leave target multicast group in the storing unit on the basis of a result of the determination made by the determining unit,

wherein in the plurality of base stations, each of the base stations belonging to the same zone receives the user data packet transmitted from the transmitting unit of the relay device, and wirelessly transmits the query packet contained in the user data packet substantially simultaneously with the other base stations belonging to the same zone.

6. A wireless communication system according to claim 5, wherein the relay device further comprises an updating unit updating, when receiving a JOIN packet of a request for participating in the multicast group from the mobile terminal via any one of the plurality of base stations, the information about the base station that is stored in the storing unit in the way of being associated with the zone to which the via-base-station belongs and with the participation target multicast group, with the information about the base station that relays the JOIN packet.

7. A wireless communication system according to claim 5, wherein the relay device further comprises a deleting unit deleting, if a response packet is not received when the transmitting unit has transmitted the user data packet containing the query packet, a record containing the leave target multicast group, the base station that relays the LEAVE packet and the zone to which the base station belongs in the way of their being associated with each other from the storing unit.

8. A wireless communication system according to claim 7, wherein the relay device further comprises a transferring unit checking, when the record is deleted by the deleting unit, existence of other records stored in the storing unit in the way of being associated with the multicast group contained in the deleted record, transferring the received LEAVE packet to a high-order device if no other records exist, and transferring none of the received LEAVE packet if other records exist.

9. A multicast relay method of transmitting a user data packet, containing a content to be distributed to a mobile terminal, in which to set information about a multicast group associated with the content, to a plurality of base stations managed in the way of being grouped into zones, the multicast relay method comprising:

a storing step of storing, in a storing unit, information about a multicast group in which the mobile terminal participates, information about the base station performing wireless communications with the mobile terminal and information about the zone to which the base station belongs in a way that associates these items of information with each other;

an extracting step of extracting, when receiving a LEAVE packet of a request for leaving the multicast group from the mobile terminal via any one of the plurality pf base stations, the information about the base station, which is stored in the way of being associated with the leave target multicast group and with the zone to which the via-base-station belongs, from the storing unit;

a determining step of determining whether or not it is required to transmit a query packet for checking existence of the mobile terminal continuing the participation in the leave target multicast group by comparing the base station extracted in the extracting step with the base station that relays the received LEAVE packet; and

a transmitting step of transmitting the user data packet containing the query packet to each of the base stations belonging to the zone whose information is stored together with the information about the leave target multicast group in the storing unit on the basis of a result of the determination made in the determining step.