METHOD AND DEVICE FOR TIME-SYNCHRONIZATION IN AD HOC NETWORK

• US 20140029603A1
• Filed: 09/26/2013
• Published: 01/30/2014
• Est. Priority Date: 03/29/2011
• Status: Active Grant

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: INAO, Yuichi, NOMURA, Yayoi, OKAMASU, Takayuki D., KUROGI, Yasuhiro, YAMADA, Kenji, KOGA, Syunsuke
• Granted Patent: US 9,585,113 B2
• Time in Patent Office: Days
• US Class Current: 370/350
• CPC Class Codes: H04W 56/0015 one node acting as a reference for the others
• CPC Class Codes: H04W 56/002 Mutual synchronization
• CPC Class Codes: H04W 84/18 Self-organising networks, e.g. ad-hoc networks or sensor networks

Abstract

A method and a device perform time-synchronization with an ad hoc network configured by a plurality of nodes. The method includes: transmitting a time-synchronization request frame including an address of one of the plurality of nodes which belong to the ad hoc network to one of the plurality of nodes having a function of receiving the time-synchronization request frame and transmitting a time-synchronization reply frame including time-synchronization information; receiving the time-synchronization reply frame including the time-synchronization information from one of the plurality of nodes which receive the time-synchronization request frame; and performing time-synchronization with one of the plurality of nodes using the time-synchronization information included in the time-synchronization reply frame.

Claims

1. A method for time synchronization between an ad hoc network which is configured by a plurality of time-synchronized nodes and a new node, the method comprising:

transmitting a time-synchronization request frame including an address of one of the plurality of nodes which belong to the ad hoc network to one of the plurality of nodes having a function of receiving the time-synchronization request frame and transmitting a time-synchronization reply frame including time-synchronization information;

receiving the time-synchronization reply frame including the time-synchronization information from one of the plurality of nodes which receive the time-synchronization request frame; and

performing time-synchronization with one of the plurality of nodes using the time-synchronization information included in the time-synchronization reply frame.

2. A method for time synchronization between an ad hoc network which is configured by a plurality of time-synchronized nodes and a new node, the method comprising:

receiving a message including an address of one of the plurality of nodes which belong to the ad hoc network from one of the plurality of nodes having a function of receiving the time-synchronization request frame and transmitting a time-synchronization reply frame including time-synchronization information;

transmitting to one of the plurality of nodes a time-synchronization request frame including an address of one of the plurality of nodes;

receiving the time-synchronization reply frame including the time-synchronization information from one of the plurality of nodes which receive the time-synchronization request frame; and

performing time-synchronization with one of the plurality of nodes using the time-synchronization information included in the time-synchronization reply frame.

3. The method according to claim 2, wherein a node to which the message is transmitted transmits to one of the plurality of nodes the time-synchronization request frame when signal intensity of the message is equal to or exceeds a specified threshold.

4. The method according to claim 2, wherein

the time-synchronization request frame is transmitted when the message is received a specified number of times or more continuously within a specified time period.

5. A device for time synchronization between an ad hoc network which is configured by a plurality of time-synchronized nodes and a new node, the device comprising:

a message receptortime-synchronization request frame transmitter which transmits a time-synchronization request frame including an address of one of the plurality of nodes which belong to the ad hoc network to one of the plurality of nodes having a function of receiving the time-synchronization request frame and transmitting a time-synchronization reply frame including time-synchronization information;

a time-synchronization reply frame receptor which receives the time-synchronization reply frame including the time-synchronization information from one of the plurality of nodes which receive the time-synchronization request frame; and

a time-synchronizer which performs time-synchronization with one of the plurality of nodes using the time-synchronization information included in the time-synchronization reply frame.

6. A device for time synchronization between an ad hoc network which is configured by a plurality of time-synchronized nodes and a new node, the device comprising:

a message receptor which receives a message including an address of one of the plurality of nodes which belong to the ad hoc network from one of the plurality of nodes having a function of receiving the time-synchronization request frame and transmitting a time-synchronization reply frame including time-synchronization information;

a message receptortime-synchronization request frame transmitter which transmits to one of the plurality of nodes a time-synchronization request frame including an address of one of the plurality of nodes;

a time-synchronization reply frame receptor which receives the time-synchronization reply frame including the time-synchronization information from one of the plurality of nodes which receive the time-synchronization request frame; and

a time-synchronizer which performs time-synchronization with one of the plurality of nodes using the time-synchronization information included in the time-synchronization reply frame.

7. The device according to claim 6, further comprising

a node selector which controls the message receptortime-synchronization request frame transmitter so that the time-synchronization request frame is transmitted to one of the plurality of nodes when signal intensity of the message is equal to or exceeds a specified threshold.

8. The device according to claim 6, wherein

the message receptortime-synchronization request frame transmitter transmits the time-synchronization request frame when the message is received a specified number of times or more continuously within a specified time period.

9. A method for allowing a new node to entering an ad hoc network which is configured by a plurality of time-synchronized nodes, the method comprising:

receiving a message including an address of one of the plurality of nodes which belong to the ad hoc network from one of the plurality of nodes having a function of receiving the time-synchronization request frame and transmitting a time-synchronization reply frame including time-synchronization information;

transmitting the time-synchronization request frame including an address of one of the plurality of nodes to one of the plurality of nodes which belong to the ad hoc network;

receiving the time-synchronization reply frame including the time-synchronization information from one of the plurality of nodes which receive the time-synchronization request frame; and

performing time-synchronization with one of the plurality of nodes using the time-synchronization information included in the time-synchronization reply frame, thereby entering the ad hoc network.

10. A network, comprising:

a first node which belongs to an ad hoc network configured by a plurality of time-synchronized node, and has a function of receiving a time-synchronization request frame and transmitting a time-synchronization reply frame including time-synchronization information; and

a second node which transmits the time-synchronization request frame including an address of the first node, receives the time-synchronization reply frame including time-synchronization information from the first node which has received the time-synchronization request frame, and performs time-synchronization with the first node using the time-synchronization information included in the time-synchronization reply frame.

11. A network, comprising:

a first node which belongs to an ad hoc network configured by a plurality of time-synchronized nodes, has a function of transmitting a message including an address of the first node, and receiving a time-synchronization request frame and transmitting a time-synchronization reply frame including time-synchronization information; and

a second node which receives from the first node a message including an address of the first node, transmits the time-synchronization request frame to the address of the first node, receives the time-synchronization reply frame including time-synchronization information from the first node which receives the time-synchronization request frame, and performs time-synchronization with the first node using the time-synchronization information included in the time-synchronization reply frame.