Digraph network timing synchronization

• US 8,059,629 B1
• Filed: 06/13/2005
• Issued: 11/15/2011
• Est. Priority Date: 03/27/2004
• Status: Active Grant

• Current Assignee: Analog Devices International Unlimited Company (Analog Devices, Inc.)
• Original Assignee: Dust Networks Incorporated (Analog Devices, Inc.)
• Inventors: Pister, Kristofer S. J.
• Primary Examiner(s): Duong; Frank
• Application Number:
  US11/152,025
• Time in Patent Office: 2,346 Days
• Field of Search: 370328-350, 370503-510
• US Class Current: 370/350
• CPC Class Codes: H04L 45/026 Details of "hello" or keep-alive messages
• CPC Class Codes: H04W 40/02 Communication route or path selection, e.g. power-based or shortest path routing
• CPC Class Codes: H04W 52/0219 where the power saving management affects multiple terminals
• 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
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

A method for synchronizing a digraph network is disclosed. The method comprises receiving timing information from a first node at a second node over a first connection specified by a first digraph link, wherein the first digraph link is a directional link specifying routing information at the first node in a network, and wherein the network includes a plurality of nodes each with a plurality of digraph links. The method further comprises calculating a synchronized time using the received timing information and a local time and sending timing information from the second node to a third node over a second connection specified by a second digraph link.

Claims

1. A method for synchronizing a digraph network comprising:

receiving timing information from a first node at a second node over a first connection specified by a first digraph link, wherein the first digraph link is a directional link specifying routing information at the first node in a network, and wherein the network includes a plurality of nodes each with a plurality of digraph links;

calculating a synchronized time using the received timing information and a local time; and

sending timing information from the second node to a third node over a second connection specified by a second digraph link.

2. A method as recited in claim 1, wherein the received timing information is obtained from a start symbol of a transmission packet.

3. A method as recited in claim 1, wherein the received timing information is obtained from a time of arrival of a start symbol of a transmission packet.

4. A method as recited in claim 1, wherein the received timing information is obtained from a start symbol of an acknowledgement packet.

5. A method as recited in claim 1, wherein the received timing information is obtained from a time of arrival of a start symbol of an acknowledgement packet.

6. A method as recited in claim 1, wherein the received timing information is obtained from a multicast transmission packet.

7. A method as recited in claim 1, wherein local time is a temperature corrected local time.

8. A method as recited in claim 1, wherein local time is a temperature corrected local time wherein the temperature corrected local time is calculated using a temperature measurement and a local clock time.

9. A method as recited in claim 1, wherein the synchronized time calculation uses recently received timing information as well as other past received timing information.

10. A method as recited in claim 1, wherein the synchronized time calculation uses an average of timing information received.

11. A method as recited in claim 1, wherein the synchronized time is calculated periodically based on the received timing information.

12. A method as recited in claim 1, wherein the timing information sent from the second node to the third node includes a correction calculated at the second node.

13. A system for synchronizing a digraph network comprising:

a radio receiver for receiving timing information from a first node at a second node over a first connection specified by a first digraph link, wherein the first digraph link is a directional link specifying routing information at the first node in a network, and wherein the network includes a plurality of nodes each with a plurality of digraph links;

a processor for calculating a synchronized time using the received timing information and a local time; and

a radio transmitter for sending timing information from the second node to a third node over a second connection specified by a second digraph link.

14. A system as recited in claim 13, wherein the received timing information is obtained from a start symbol of a transmission packet.

15. A system as recited in claim 13, wherein the received timing information is obtained from a time of arrival of a start symbol of a transmission packet.

16. A system as recited in claim 13, wherein the received timing information is obtained from a start symbol of an acknowledgement packet.

17. A system as recited in claim 13, wherein the received timing information is obtained from the time of arrival of a start symbol of an acknowledgement packet.

18. A system as recited in claim 13, wherein the received timing information is obtained from a multicast transmission packet.

19. A system as recited in claim 13, wherein the local time is a temperature corrected local time.

20. A system as recited in claim 13, wherein the local time is a temperature corrected local time wherein the temperature corrected local time is calculated using a temperature measurement and a local clock time.

21. A system as recited in claim 13, wherein the synchronized time calculation uses recently received timing information as well as other past received timing information.

22. A system as recited in claim 13, wherein the synchronized time calculation uses an average of timing information received.

23. A system as recited in claim 13, wherein the synchronized time is calculated periodically based on the received timing information.

24. A system as recited in claim 13, wherein the timing information sent from the second node to the third node includes a correction calculated at the second node.

25. A non-transitory computer program product for synchronizing a digraph network, the computer program product being embodied in a non-transitory computer readable medium and comprising computer instructions for:

receiving timing information from a first node at a second node over a first connection specified by a first digraph link, wherein the first digraph link is a directional link specifying routing information at the first node in a network, and wherein the network includes a plurality of nodes each with a plurality of digraph links;

calculating a synchronized time using the received timing information and a local time; and

sending timing information from the second node to a third node over a second connection specified by a second digraph link.

26. A computer program product as recited in claim 25, wherein the received timing information is obtained from a start symbol of a transmission packet.

27. A computer program product as recited in claim 25, wherein the received timing information is obtained from a time of arrival of a start symbol of a transmission packet.

28. A computer program product as recited in claim 25, wherein the received timing information is obtained from a start symbol of an acknowledgement packet.

29. A computer program product as recited in claim 25, wherein the received timing information is obtained from the time of arrival of a start symbol of an acknowledgement packet.

30. A computer program product as recited in claim 25, wherein the received timing information is obtained from a multicast transmission packet.

31. A computer program product as recited in claim 25, wherein the local time is a temperature corrected local time.

32. A computer program product as recited in claim 25, wherein the local time is a temperature corrected local time wherein the temperature corrected local time is calculated using a temperature measurement and a local clock time.

33. A computer program product as recited in claim 25, wherein the synchronized time calculation uses recently received timing information as well as other past received timing information.

34. A computer program product as recited in claim 25, wherein the synchronized time calculation uses an average of timing information received.

35. A computer program product as recited in claim 25, wherein the synchronized time is calculated periodically based on the received timing information.

36. A computer program product as recited in claim 25, wherein the timing information sent from the second node to the third node includes a correction calculated at the second node.