Packet transmission method and communication system
First Claim
1. A packet transmission method adapted for a communication system comprising a mobile terminal, a plurality of access routers, each access router forming a cell and configured to perform radio communication with a mobile terminal located in the cell, and a plurality of relay routers connected to a hierarchical structure above the access routers, said packet transmission method being applied when a packet from a packet source is transmitted from an upper layer in the communication system toward a target mobile terminal, said packet transmission method comprising:
- letting the relay router engaged in relaying the packet from the packet source, multicast a router advertisement with said packet to all access routers forming cells into which said target mobile terminal may move;
letting said mobile terminal receive multicast router advertisements from a plurality of neighbor access routers;
letting said mobile terminal calculate a difference between reception times of packets from respective access routers, based on information about reception from the plurality of access routers, and specify a relay router that should perform multicasting;
letting said mobile terminal transmit to said specified relay router a multicast message containing delay information of a delay to be added to each path in the multicasting by the relay router; and
letting said relay router receive the multicast message from the mobile terminal and add the delay to each path in the multicasting on the basis of the delay information.
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Accused Products
Abstract
The object is to prevent occurrence of packet loss in Cellular IP and a drop of TCP throughput due to duplication of packets. On the occasion of relaying a packet from correspondent, a relay router multicasts a router advertisement to access routers forming respective cells into which a target mobile terminal might move. The mobile terminal receives the router advertisements from the neighbor access routers, calculates a difference between reception times of the packets from the respective access routers, and specifies a relay router to perform multicasting. Then the mobile terminal transmits delay information of a delay to be added to each path in multicasting by the relay router, to the relay router thus specified. The relay router adds the delay to each path in multicasting on the basis of the delay information.
103 Citations
6 Claims
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1. A packet transmission method adapted for a communication system comprising a mobile terminal, a plurality of access routers, each access router forming a cell and configured to perform radio communication with a mobile terminal located in the cell, and a plurality of relay routers connected to a hierarchical structure above the access routers, said packet transmission method being applied when a packet from a packet source is transmitted from an upper layer in the communication system toward a target mobile terminal, said packet transmission method comprising:
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letting the relay router engaged in relaying the packet from the packet source, multicast a router advertisement with said packet to all access routers forming cells into which said target mobile terminal may move;
letting said mobile terminal receive multicast router advertisements from a plurality of neighbor access routers;
letting said mobile terminal calculate a difference between reception times of packets from respective access routers, based on information about reception from the plurality of access routers, and specify a relay router that should perform multicasting;
letting said mobile terminal transmit to said specified relay router a multicast message containing delay information of a delay to be added to each path in the multicasting by the relay router; and
letting said relay router receive the multicast message from the mobile terminal and add the delay to each path in the multicasting on the basis of the delay information. - View Dependent Claims (2, 3)
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4. A communication system comprising a mobile terminal, a plurality of access routers, each access router forming a cell and configured to perform radio communication with a mobile terminal located in the cell, and a plurality of relay routers connected to a hierarchical structure above the access routers,
wherein each of the relay routers comprises: -
multicasting means for, during relaying performed when a packet from a packet source is transmitted from an upper layer in the communication system toward a target mobile terminal, multicasting a router advertisement with said packet to all access routers forming cells into which the target mobile terminal may move; and
delay adding means for receiving a multicast message containing delay information of a delay that the relay router should add to each path in multicasting, from the mobile terminal and adding the delay to each path in the multicasting on the basis of the delay information; and
wherein the mobile terminal comprises;
receiving means for receiving the multicast router advertisements from a plurality of neighbor access routers;
calculating-specifying means for calculating a difference between reception times of packets from respective access routers, based on information about reception from the plurality of access routers, and specifying a relay router that should perform multicasting; and
message transmitting means for transmitting a multicast message containing delay information of a delay that the relay router should add to each path in the multicasting, to the specified relay router. - View Dependent Claims (5, 6)
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Specification