Wireless ad-hoc communication system and communication terminal synchronizing method in wireless ad-hoc communication system

• US 20060245440A1
• Filed: 04/25/2006
• Published: 11/02/2006
• Est. Priority Date: 04/28/2005
• Status: Active Grant

• Current Assignee: Renesas Electronics Corporation
• Original Assignee: NEC Electronics Corporation (Renesas Electronics Corporation)
• Inventors: Mizukoshi, Nobuyuki
• Granted Patent: US 7,636,343 B2
• Time in Patent Office: Days
• US Class Current: 370/400
• CPC Class Codes: H04B 7/2678 Time synchronisation
• CPC Class Codes: H04W 16/14 Spectrum sharing arrangements between different networks
• CPC Class Codes: H04W 56/00 Synchronisation arrangements
• CPC Class Codes: H04W 84/18 Self-organising networks, e.g. ad-hoc networks or sensor networks

Abstract

In a wireless ad-hoc communication system according to an embodiment of the invention, a plurality of communication terminals transmit/receive beacons and are synchronized. The wireless ad-hoc communication system includes first and second networks each including one or more communication terminals; and one or more synchronizing terminals. The synchronizing terminals are capable of transmitting/receiving the beacons to/from the communication terminals. In the wireless ad-hoc communication system, at least one of the communication terminals belonging to the first network and at least one of the communication terminals belonging to the second network exist within a reachable range of the beacons from one of the one or more synchronizing terminals to construct one synchronized network with the first network, the second network, and the synchronizing terminals.

Claims

1. A wireless ad-hoc communication system for transmitting/receiving beacons between a plurality of communication terminals to synchronize the communication terminals, comprising:

a first network to which first subset of the plurality of communication terminals belong;

a second network to which second subset of the plurality of communication terminals belong; and

one or more synchronizing terminals capable of transmitting/receiving the beacon to/from the communication terminals,

wherein at least one of the communication terminals belonging to the first network and at least one of the communication terminals belonging to the second network exist within a reachable range of the beacons from one of the one or more synchronizing terminals to construct one synchronized network with the first network, the second network, and the synchronizing terminals.

2. The wireless ad-hoc communication system according to claim 1, wherein the synchronized network is constructed in such a manner that the plural communication terminals commonly use the same common starting position of a transmission frame defined by length.

3. The wireless ad-hoc communication system according to claim 1, wherein the beacon includes information about a priority, and the communication terminals compare the information about the priority in the received beacons to construct the synchronized network based on a beacon of the highest priority.

4. The wireless ad-hoc communication system according to claim 3, wherein the information about the priority in the beacon sent from the synchronizing terminal represents a priority higher than a priority assigned to a beacon sent from the communication terminals.

5. The wireless ad-hoc communication system according to claim 4, wherein the information about the priority represents relay counts of the beacon starting from the synchronizing terminal.

6. The wireless ad-hoc communication system according to claim 3, wherein the communication terminal determines a priority assigned to a beacon to be sent based on the priority assigned to the received beacon.

7. The wireless ad-hoc communication system according to claim 3, wherein if the communication terminal receives a new beacon not synchronous with the synchronized network to which the communication terminal belongs, the communication terminal compares a priority assigned to the new beacon with a priority assigned to the beacon from a terminal in the synchronized network to which the communication terminal belongs, and

if the communication terminal determines that the priority assigned to the new beacon is higher, the communication terminal is synchronized to a synchronized network as a sender of the new beacon.

8. The wireless ad-hoc communication system according to claim 1, wherein the synchronizing terminal transmits/receives synchronization timing information used for constructing the synchronized network to/from the other synchronizing terminal via a communication line other than a wireless line for transmitting/receiving a beacon.

9. The wireless ad-hoc communication system according to claim 1, wherein the synchronizing terminals receive a synchronization signal sent from a synchronization signal generating device, the synchronizing terminals generate a synchronization timing based on the synchronization signal, and the synchronization timing is used for constructing the synchronized network and commonly applied to the synchronizing terminals.

10. The wireless ad-hoc communication system according to claim 1, wherein the synchronizing terminals transmit/receive data as well as the beacons to/from the communication terminals.

11. A communication terminal synchronizing method in a wireless ad-hoc communication system for transmitting/receiving beacons between a plurality of communication terminals to synchronize the communication terminals, comprising:

arranging one or more synchronizing terminals to be able to transmit/receive the beacons to/from at least one of the communication terminals in a first network and at least one of the communication terminals in a second network, and

constructing one synchronized network with the first network, the second network, and the synchronizing terminal even if the first network and the second network cannot directly transmit/receive the beacons to/from each other.

12. The communication terminal synchronizing method according to claim 11, wherein the beacon includes information about a priority, and the communication terminals compare the information about the priority in the received beacons to construct the synchronized network based on a beacon of the highest priority.

13. The communication terminal synchronizing method according to claim 12, wherein the information about the priority in the beacon sent from the synchronizing terminal represents a priority higher than a priority assigned to a beacon sent from the communication terminals.

14. The communication terminal synchronizing method according to claim 12, wherein if the communication terminal receives a new beacon not synchronous with the synchronized network to which the communication terminal belongs, the communication terminal compares a priority assigned to the new beacon with a priority assigned to the beacon from a terminal in the synchronized network to which the communication terminal belongs, and

if the communication terminal determines that the priority assigned to the new beacon is higher, the communication terminal is synchronized to a synchronized network as a sender of the new beacon.

15. A communication terminal synchronizing method executed by a communication terminal in a wireless ad-hoc communication system for transmitting/receiving a beacon to/from other communication terminals, comprising:

receiving beacons including information about a priority;

comparing priorities assigned to the received beacons and

synchronizing the communication terminal with a beacon of the highest priority.

16. The communication terminal synchronizing method according to claim 15, wherein the communication terminal determines a priority assigned to a beacon to be sent based on the priorities assigned to the received beacons.

17. The communication terminal synchronizing method according to claim 15, wherein a synchronizing terminal that sends a beacon of a priority higher than a priority preset for the plurality of communication terminals is provided in the wireless ad-hoc communication system, and

the communication terminal is preferentially synchronized with the beacon sent from the synchronizing terminal.

18. The communication terminal synchronizing method according to claim 17, wherein the information about the priority represents relay counts of the beacon starting from the synchronizing terminal.

19. A wireless ad-hoc communication system, comprising:

a plurality of communication terminals that are synchronized by transmitting/receiving beacons to/from each other,

wherein each of the communication terminals transmits/receives beacons including information about a priority; and

each of the communication terminals compares priorities assigned to the received beacons and is synchronized with a beacon of the highest priority.

20. The wireless ad-hoc communication system according to claim 19, wherein the communication terminals determine a priority assigned to a beacon to be sent based on the priorities assigned to the received beacons.

21. The wireless ad-hoc communication system according to claim 19, further comprising a synchronizing terminal that sends a beacon of a priority higher than a priority preset for the plurality of communication terminals,

wherein the communication terminal is preferentially synchronized with the beacon sent from the synchronizing terminal.

22. The wireless ad-hoc communication system according to claim 19, wherein the information about the priority represents relay counts of the beacon starting from the synchronizing terminal.

23. A communication terminal for constructing a wireless ad-hoc communication system in which a plurality of the communication terminals transmit/receive beacons to/from each other and are synchronized, comprising:

a receiving unit for receiving beacons including information about a priority; and

a synchronizing unit for comparing the priorities assigned to the beacons received with the receiving unit to synchronize the communication terminal with a beacon of the highest priority.

24. The communication terminal according to claim 23, further comprising:

a transmitting unit for transmitting the beacons,

wherein the synchronizing unit determines a priority assigned to the beacon to be sent from the transmitting unit based on priorities assigned to the beacons received with the receiving unit.