Communication timing control apparatus, communication timing control method, node, and communication system

• US 20050195827A1
• Filed: 03/07/2005
• Published: 09/08/2005
• Est. Priority Date: 03/08/2004
• Status: Active Grant

• Current Assignee: OKI Electric Industry Company Limited
• Original Assignee: OKI Electric Industry Company Limited
• Inventors: Morita, Yukihiro, Date, Masaaki, Yao, Taketsugu, Fukunaga, Shigeru
• Granted Patent: US 7,606,271 B2
• Time in Patent Office: Days
• US Class Current: 370/395.4
• CPC Class Codes: H04J 3/0676 Mutual
• CPC Class Codes: H04W 12/069 using certificates or pre-shared keys
• CPC Class Codes: H04W 48/08 Access restriction or access information delivery, e.g. discovery data delivery signalling during connection H04W76/00
• CPC Class Codes: H04W 48/16 Discovering, processing access restriction or access information
• CPC Class Codes: H04W 56/00 Synchronisation arrangements

Abstract

Each node in a communication system receives state variable signals from other nodes indicating the internal operating states or internal timing of the other nodes, and transmits a state variable signal indicating its own internal operating state or timing. Each node also determines whether each received state variable signal is valid. Transitions in the internal operating state or timing of a node take place at a basic transition rate but at times adjusted according to the valid state variable signals received from other nodes. A group of neighboring nodes transmitting data signals can thereby autonomously reach a steady state in which their data signals do not collide, without having their timing control disrupted by reflected state variable signals or other invalid state variable signals.

Claims

1. A communication timing control apparatus for use in an arbitrary node in a communication system that includes a plurality of nodes, the communication timing control apparatus comprising:

a state variable signal communication unit for intermittently transmitting, to at least one other node in the communication system, an output state variable signal indicating an operating state or operating timing of the arbitrary node, and receiving, from the at least one other node in the communication system, an input state variable signal indicating an operating state or operating timing of the at least one other node;

a validity decision unit for determining whether each state variable signal received by the state variable signal communication unit is valid; and

a timing decision unit for causing transitions in the operating state or operating timing of the arbitrary node to occur according to a basic transition rate and the valid state variable signals received from the at least one other node, generating the output state variable signal by taking said transitions into account, and sending the output state variable signal to the state variable signal communication unit.

2. The communication timing control apparatus of claim 1, wherein the validity decision unit measures timing differences between pairs of input state variable signals and timing differences between input state variable signals and output state variable signals, takes statistics on the measured timing differences, and uses the statistics to decide whether each input state variable signal is valid.

3. The communication timing control apparatus of claim 1, wherein the input state variable signals and output state variable signals include identifying information, and the validity decision unit includes:

an extracting unit for extracting the identifying information from each input state variable signal;

an identifying unit for adding the identifying information to each output state variable signal; and

a storage and decision unit for storing the identifying information extracted from valid input state variable signals and the identifying information added to output state variable signals and deciding whether each input state variable signal is valid by comparing its identifying information with the stored identifying information.

4. The communication timing control apparatus of claim 3, wherein the storage and decision unit discards the stored identifying information according to a predetermined rule.

5. The communication timing control apparatus of claim 3, wherein the state variable signal generating unit adds to each output state variable signal, as said identifying information, information obtained by performing an operation on the identifying information stored in the storage and decision unit.

6. The communication timing control apparatus of claim 5, wherein the identifying information comprises a count value and the operation comprises incrementing the count value.

7. The communication timing control apparatus of claim 3, wherein the identifying information is a random number.

8. The communication timing control apparatus of claim 7, wherein the identifying unit changes the random number added as identifying information to each output state variable signal each time a new output state variable signal is generated.

9. The communication timing control apparatus of claim 7, wherein:

the storage and decision unit sends an update request to the identifying unit if the random number added as identifying information to an output state variable signal duplicates identifying information already stored in the storage and decision unit; and

the state variable signal generating unit changes the random number added as identifying information to each output state variable signal when it receives the update request from the storage and decision unit.

10. The communication timing control apparatus of claim 3, wherein the validity decision unit also generates a duplication signal and sends the duplication signal to the at least one other node when identical identifying information is extracted from two valid input state variable signals.

11. The communication timing control apparatus of claim 3, wherein the identifying information is node identification information.

12. The communication timing control apparatus of claim 1, wherein the input state variable signals and output state variable signals include security information, and the validity decision unit includes:

an extracting unit for extracting the security information from each input state variable signal;

an information generating unit for generating authentication information from one part of the extracted security information; and

an authentication unit for comparing the authentication information with another part of the extracted security information to decide whether the input state variable signal from which the security information was extracted is valid.

13. The communication timing control apparatus of claim 12, further comprising a random number generator for generating a random number, wherein:

the information generating unit also generates authentication information from the random number generated by the random number generator; and

the state variable signal communication unit adds both the random number and the authentication information generated from the random number to each output state variable signal.

14. A node in a communication system, the node including the communication timing control apparatus of claim 1.

15. A communication system including a plurality of nodes as described in claim 14.

16. A node in a communication system comprising a plurality of nodes, the node having a communication timing control apparatus that includes:

a state variable signal communication unit for intermittently transmitting, to at least one other node in the communication system, an output state variable signal indicating an operating state or operating timing of the node including the communication timing control apparatus, and receiving, from the at least one other node in the communication system, an input state variable signal indicating an operating state or operating timing of the at least one other node;

an authentication unit for distinguishing between input state variable signals generated by the nodes in the communication system and input state variable signals generated by a source other than the nodes in the communication system, and validating the input state variable signals generated by the nodes in the communication system;

a reflection decision unit for distinguishing between input state variable signals received directly from the nodes in the communication system and input state variable signals received by reflection, and validating the input state variable signals received directly from the nodes in the communication system; and

a timing decision unit for causing transitions in the operating state or operating timing of the node including the communication timing control apparatus to occur according to a basic transition rate and the input state variable signals validated by both the authentication unit and the reflection decision unit, generating the output state variable signal by taking said transitions into account, and sending the output state variable signal to the state variable signal communication unit.

17. A communication system including a plurality of nodes as described in claim 16.

18. A communication timing control method carried out by each of a plurality of nodes in a communication system, comprising:

receiving, from at least one other node in the communication system, input state variable signals indicating an operating state or operating timing of said at least one other node;

determining whether each of the input state variable signals is valid;

generating transitions in an internal operating state or operating timing at a basic transition rate, at times adjusted according to the valid input state variable signals received from said at least one other node;

generating an output state variable signal according to said transitions; and

transmitting the output state variable signal to said at least one other node.

19. The method of claim 18, wherein determining whether each of the input state variable signals is valid comprises distinguishing input state variable signals received directly from the nodes in the communication system from input state variable signals received by reflection.

20. The method of claim 18, wherein determining whether each of the input state variable signals is valid comprises using authentication information to decide whether each input state variable signal was received from a node in the communication system.