Method For Controlling Communication Route of Wireless Multi-Hop Network System and Communication Terminal

• US 20080186907A1
• Filed: 11/30/2005
• Published: 08/07/2008
• Est. Priority Date: 11/30/2004
• Status: Active Grant

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Jibiki, Masahiro, Yagyuu, Tomohiko
• Granted Patent: US 7,860,049 B2
• Time in Patent Office: Days
• US Class Current: 370/328
• CPC Class Codes: H04B 7/155 Ground-based stations H04B7/204 takes precedence
• CPC Class Codes: H04B 7/2606 Arrangements for base station coverage control, e.g. by using relays in tunnels
• CPC Class Codes: H04L 45/028 Dynamic adaptation of the update intervals, e.g. event-triggered updates
• CPC Class Codes: H04W 40/248 Connectivity information update
• CPC Class Codes: H04W 40/30 for proactive routing

Abstract

A wireless multi-hop network is formed by exchanging a control message including a HELLO message and a topology message between a plurality of communication terminals. A communication terminal adjusts a control message transmission interval so as to reduce the control load according to its movement state and transmits a control message at a longer transmission interval as the movement becomes smaller. Moreover, when link information is updated, the communication terminal includes the sequence number of the HELLO message in the topology message transmitted. Thus, it is possible to realize stable communication in accordance with a movement characteristic with a small message transmission frequency.

Claims

1. A communication route control method for a wireless multi-hop network which forms a multi-hop network in which control packets are exchanged by wireless signals between a plurality of communication terminals serving as nodes of the network, retains topology information of the multi-hop network, and controls communication routes of the packets exchanged between the communication terminals based on the topology information, said communication route control method comprising:

a step in which each of the communication terminals detects its own movement information including at least a movement speed;

a step in which each of the communication terminals controls the exchange frequency of the control packet to be exchanged with other communication terminals on the multi-hop network based on the detected movement information so as to reduce a control load in accordance with its movement state;

a step in which each of the communication terminals updates the topology information of the multi-hop network that each itself retains based on the control packets from the other communication terminals.

a step in which each of the communication terminals exchanges neighbor detection messages with neighboring communication terminals on the wireless multi-hop network as the control packets;

a step in which, when a link with each of the neighboring communication has been established by the exchange of the neighor detection message, each of the communication terminals retains, in addition to terminal identification information of each of the neighboring communication terminals, identification attribute information of the neighbor detection message received from each of the neighboring communication terminals at the time point when the link has been established as link information included in the topology message; and

a step in which each of the communication terminals broadcasts, as the control packet, a network topology message including the link information composed of the terminal identification information of each of the neighboring communication terminals and identification attribute information of the neighor detection message on the multi-hop network.

2. The communication route control method for a wireless multi-hop network according to claim 1, further comprising:

a step in which each of the communication terminals receives instruction information from a user; and

a step in which each of the communication terminals controls the exchange frequency of the control packet according to the instruction information.

3. The communication route control method for a wireless multi-hop network according to claim 1, further comprising:

a step in which each of the communication terminals receives instruction information from a network management apparatus on the multi-hop network; and

a step in which each of the communication terminals controls the exchange frequency of the control packet according to the instruction information.

4. The communication route control method for a wireless multi-hop network according to claim 1, further comprising:

a step in which each of the communication terminals detects its own communication state including the transmission frequency of data packet; and

a step in which each of the communication terminals controls the exchange frequency of the control packet according to the communication state such that the higher the transmission frequency of the data packet, the lower the exchange frequency of the control packet becomes.

6. The communication route control method for a wireless multi-hop network according to claim 1,further comprising:

a step in which, when receiving the network topology message including the link information from each of the other communication terminals, each of the communication terminals compares the identification attribute information of the neighbor detection message included in the network topology message and identification attribute information of the neighbor detection message included in the link information that each of the communication terminals itself retains for each neighboring communication terminal; and

a step in which, in the case where the identification attribute information of the neighbor detection message included in the network topology message is newer than the identification attribute information of the neighbor detection message included in the link information that each of the communication terminals itself retains, each of the communication terminals updates the link information that each itself retains.

7. The communication route control method for a wireless multi-hop network according to claim 1, further comprising:

a step in which, when broadcasting the network topology message, each of the communication terminals selects a broadcast method of the network topology message in accordance with a state of a neighboring communication terminal that causes the link information included in the topology information to be changed.

8. The communication route control method for a wireless multi-hop network according to claim 1, characterized by further comprising:

a step in which, when receiving a topology message having a newer link information than the link information that each of the communication terminals itself retains, each of the communication terminals transmits a neighbor detection message transmission request to a neighboring communication terminal corresponding to the link information and confirms a connection with the neighboring communication terminal depending on presence/absence of a reply from the neighboring communication terminal.

5. (canceled)

9. A communication terminal for use in a wireless multi-hop network which forms a multi-hop network in which control packets are exchanged by wireless signals between a plurality of communication terminals serving as nodes of the network, retains topology information of the multi-hop network, and controls communication routes of the packets exchanged between the communication terminals based on the topology information, said communication terminal comprising:

means for detecting own movement information including at least a movement speed;

means for controlling the exchange frequency of the control packet to be exchanged with other communication terminals on the multi-hop network based on the detected movement information so as to reduce a control load in accordance with its movement state;

means for updating the topology information of the multi-hop network that the communication terminal itself retains based on the control packets from the other communication terminals.

means for exchanging neighbor detection messages with neighboring communication terminals on the multi-hop network as the control packets;

means for, when a link with each of the neighboring communication terminals has been established by the exchange of the neighbor detection message, retaining, in addition to terminal identification information of each of the neighboring communication terminals, identification attribute information of the neighboring detection message received from each of the neighboring communication terminals at the time point when the link has been established as link information included in the topology message; and

means for broadcasting, as the control packet, a network topology message including the link information compsoed of the terminal identification information of each of the neighboring communication terminals and identification attribute information of the neighbor detection message on the wireless multi-hop network.

10. The communication terminal for use in a wireless multi-hop network according to claim 9, further comprising:

means for receiving instruction information from a user; and

means for controlling the exchange frequency of the control packet according to the instruction information.

11. The communication terminal for use in a wireless multi-hop network according to claim 9, further comprising:

means for receiving instruction information from a network management apparatus on the multi-hop network; and

means for controlling the exchange frequency of the control packet according to the instruction information.

12. The communication terminal for use in a wireless multi-hop network according to claim 9, further comprising:

means for detecting its own communication state including the transmission frequency of data packet; and

means for controlling the exchange frequency of the control packet according to the communication state such that the higher the transmission frequency of the data packet, the lower the exchange frequency of the control packet becomes.

14. The communication terminal for use in a wireless multi-hop network according to claim 9, further comprising:

means for, when receiving the network topology message including the link information from each of the other communication terminals, comparing the identification attribute information of the neighbor detection message included in the network topology message and identification attribute information of the neighbor detection message included in the link information that the communication terminal itself retains for each neighboring communication terminal; and

means for, in the case where the identification attribute information of the neighbor detection message included in the network topology message is newer than the identification attribute information of the neighbor detection message included in the link information that the communication terminal itself retains, updating the link information that the communication terminal itself retains.

15. The communication terminal for use in a wireless multi-hop network according to claim 9, further comprising:

means for, when broadcasting the network topology message, selecting a broadcast method of the network topology message in accordance with a state of a neighboring communication terminal that causes the link information included in the topology information to be changed.

16. The communication terminal for use in a wireless multi-hop network according to claim 14, further comprising:

means for, when receiving a topology message having a newer link information than the link information that the communication terminal itself retains, for transmitting a neighbor detection message transmission request to a neighboring communication terminal corresponding to the link information and confirms a connection with the neighboring communication terminal depending on presence/absence of a reply from the neighboring communication terminal.

13. (canceled)

17. A wireless multi-hop network which includes a plurality of communication terminals, forms a multi-hop network in which control packets are exchanged by wireless signals between the communication terminals serving as nodes of the network, retains topology information of the multi-hop network, and controls communication routes of the packets exchanged between the communication terminals based on the topology information, wherein

each of the communication terminals comprises:

means for detecting own movement information including at least a movement speed;

means for controlling the exchange frequency of the control packet to be exchanged with other communication terminals on the multi-hop network based on the detected movement information so as to reduce a control load in accordance with its movement state;

means for updating the topology information of the multi-hop network that the communication terminal itself retains based on the control packets from the other communication terminals,

a step in which each of the communications terminals exchanges neighbor detection messages with neighboring communications terminals on the multi-hop network as the control packets;

a step in which, when a link with each of the neighboring communication terminals has been established by the exchange of the neighbor detection message, each of the communication terminals retains, in addition to terminal identification information of each of the neighboring communication terminals, identification attribute information of the neighbor detection message received from each of the neighboring communication terminals at the time point when the link has been established as link information included in the topology message; and

a step in which each of the communications terminals broadcasts, as the control packet, a network topology message inlcuding the link information composed of the terminal identification information of each of the neighboring communication terminals and identification attribute information of the neighbor detection message on the multi-hop network

18. An operation program of a communication terminal for use in a wireless multi-hop network system which forms a multi-hop network in which control packets are exchanged by wireless signals between a plurality of communication terminals serving as nodes of the network, retains topology information of the multi-hop network, and controls communication routes of the packets exchanged between the communication terminals based on the topology information, characterized by allowing a computer to execute the steps of:

detecting movement information of each of the communication terminals itself, including at least a movement speed;

controlling the exchange frequency of the control packet to be exchanged with other communication terminals on the multi-hop network based on the detected movement information so as to reduce a control load in accordance with the movement state of each of the communication terminals itself;

updating the topology information of the multi-hop network that each of the communication terminals itself retains based on the control packets from the other communication terminals,

means for eschanging neighbor detection messages with neighboring communication terminals on the multi-hop network as the control packets;

means for, when a link with each of the neighboring communication terminals has been established by the exchange of the neighbor detection message, retaining, in addition to terminal identification information of each of the neighboring communication terminals, identification attribute information of the neighbor detection message received from each of the neighboring communication terminals at the time point when the link has been established as link information included in the topology message; and

means for broadcasting, as the control packet, a network topology message including the link information composed of the terminal identification information of each of the neighboring communication terminals and identification attribute information of the neighbor detection message on the multi-hop network.

19. (canceled)

20. (canceled)