Synchronization of upstream and downstream data transfer in wireless mesh topologies

• US 20050238058A1
• Filed: 04/26/2004
• Published: 10/27/2005
• Est. Priority Date: 04/26/2004
• Status: Abandoned Application

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Peirce, Kenneth Leigh Jr., Dietrich, Paul F.
• Application Number:
  US10/831,908
• Publication Number:
  US 20050238058A1
• Time in Patent Office: Days
• US Class Current: 370/503
• CPC Class Codes: H04J 3/0638 Clock or time synchronisation among nodes; Internode synchronisation synchronization for ring networks H04L12/422; data switching networks with synchronous transmission H04L12/43
• CPC Class Codes: H04W 40/00 Communication routing or communication path finding
• CPC Class Codes: H04W 56/00 Synchronisation arrangements
• CPC Class Codes: H04W 72/535 based on resource usage policies
• CPC Class Codes: H04W 84/12 WLAN [Wireless Local Area Networks]

Abstract

Methods, apparatuses and systems directed to synchronizing upstream and downstream transmissions across routing nodes in a wireless mesh network. The present invention, in one implementation, reduces radio interference between routing nodes in a wireless mesh network. In one implementation, the present invention, also allows for the use of a single radio dedicated to wireless backbone transmissions thereby reducing the cost of routing nodes. In one implementation, at least some of the routing nodes in the wireless mesh network include a second radio and associated wireless communication functionality to provide wireless access to mobile stations.

Claims

1. In a wireless mesh environment comprising first, second and third wireless routing nodes, a method facilitating the transfer of data between wireless routing nodes, comprising

receiving a synchronization token from a first wireless routing node;

initiating a timer based on receipt of the synchronization token;

wirelessly communicating with the first wireless routing node, during a first time interval, to transmit or receive at least one wireless frame; and

upon expiration of the first time interval,

wirelessly communicating with the third wireless routing node, during a second time interval, to transmit or receive at least one wireless frame.

2. The method of claim 1 further comprising

transmitting a synchronization token to the third wireless routing node before the second communicating step.

3. The method of claim 1 further comprising

upon expiration of the second time interval, iteratively performing the first and second communicating steps upon expiration of the respective first and second time intervals.

4. The method of claim 2 further comprising

upon expiration of the second time interval, iteratively performing the first and second communicating steps upon expiration of the respective first and second time intervals.

5. The method of claim 2 further comprising

upon expiration of the second time interval, iteratively performing the receiving, initiating, and first and second communicating steps upon expiration of the respective first and second time intervals.

6. The method of claim 2 further comprising

upon expiration of the second time interval, iteratively performing the receiving, initiating, first and second communicating, and transmitting steps upon expiration of the respective first and second time intervals.

7. The method of claim 1 wherein the first and second time intervals are equal.

8. The method of claim 1 wherein wireless frames are 802.11 frames.

9. The method of claim 1 wherein the first wireless routing node is a parent routing node in a hierarchical mesh network.

10. The method of claim 9 wherein the third wireless routing node is a child routing node in a hierarchical mesh network.

11. The method of claim 1 wherein the first wireless routing node is a child routing node in a hierarchical mesh network.

12. The method of claim 11 wherein the third wireless routing node is a parent routing node in a hierarchical mesh network.

13. The method of claim 1 wherein at least one wireless frame transmitted to the first wireless routing node in the first communicating step was received from the third wireless routing node.

14. The method of claim 13 wherein at least one wireless frame transmitted to the third wireless routing node in the second communicating step was received from the first wireless routing node.

15. The method of claim 1 wherein at least one wireless frame transmitted to the third wireless routing node in the second communicating step was received from the first wireless routing node.

16. The method of claim 3 further comprising

wireless communicating with at least one wireless client device, concurrently with the first and second communicating steps;

and

transmitting wireless frames received from the at least one wireless client device for transmission to the first wireless routing node during the third communicating step.

17. The method of claim 16 wherein at least one wireless frame received during the first or second communicating step is addressed to the at least one wireless client device;

and wherein the method further comprises

transmitting the at least one wireless frame to the at least one wireless client device.

18. In a hierarchical wireless mesh environment comprising first, second and third wireless routing nodes, wherein the first wireless routing node is a parent of the second wireless routing node, and wherein the second wireless routing node is a parent of the third wireless routing node, a method facilitating the transfer of data between wireless routing nodes, comprising

receiving, at the second wireless routing node, a synchronization token from the first wireless routing node;

calibrating a timer based on receipt of the synchronization token;

wirelessly communicating with the first wireless routing node, during a first time interval, to transmit or receive at least one wireless frame; and

upon expiration of the first time interval,

wirelessly communicating with the third wireless routing node, during a second time interval, to transmit or receive at least one wireless frame.

19. The method of claim 18 further comprising

transmitting a synchronization token to the third wireless routing node during the second communicating step.

20. The method of claim 18 further comprising

upon expiration of the second time interval, iteratively performing the first and second communicating steps upon expiration of the respective first and second time intervals.

21. The method of claim 19 further comprising

upon expiration of the second time interval, iteratively performing the first and second communicating steps upon expiration of the respective first and second time intervals.

22. The method of claim 19 further comprising

upon expiration of the second time interval, iteratively performing the receiving, calibrating, and first and second communicating steps upon expiration of the respective first and second time intervals.

23. The method of claim 19 further comprising

upon expiration of the second time interval, iteratively performing the receiving, calibrating, first and second communicating, and transmitting steps upon expiration of the respective first and second time intervals.

24. The method of claim 18 wherein the first and second time intervals are equal.

25. The method of claim 18 wherein wireless frames are 802.11 frames.

26. The method of claim 18 wherein the first wireless routing node is a parent routing node in a hierarchical mesh network.

27. The method of claim 26 wherein the third wireless routing node is a child routing node in a hierarchical mesh network.

28. A method facilitating the transfer of data between wireless routing nodes, comprising

receiving a synchronization token;

calibrating a timer based on receipt of the synchronization token; and

cycling, based on the timer, between an upstream transmission phase and a downstream transmission phase;

wherein the upstream transmission phase comprises

receiving wireless frames from a parent wireless routing node;

storing at least one received wireless frames in a downstream buffer;

transmitting at least one wireless frame stored in an upstream buffer to the parent wireless routing node;

wherein the downstream transmission phase comprises

receiving wireless frames from at least one child wireless routing node;

storing at least one received wireless frame in the upstream buffer;

transmitting at least one wireless frame stored in the downstream buffer to the at least one child routing node.

29. The method of claim 28 further comprising transmitting a synchronization token to the at least one child node at the start of the first iteration of the downstream transmission phase.

30. The method of claim 28 wherein the synchronization token is received from the parent wireless routing node.

31. The method of claim 29 wherein the synchronization token is received from the parent wireless routing node.

32. The method of claim 28 wherein the synchronization token is received from at least one child wireless routing node.

33. The method of claim 28 wherein the downstream buffer is a queue structure.

34. The method of claim 28 wherein the upstream buffer is a queue structure.

35. The method of claim 28 wherein the downstream phase further comprises transmitting a synchronization token to the at least one child node at the start of the downstream transmission phase;

and

wherein the upstream phase comprises

before performing the receiving, storing and transmitting steps, listening for a synchronization packet; and

upon receipt of a synchronization token from the parent wireless routing node, resetting the timer.

36. The method of claim 28 further comprising

receiving subsequent synchronization packets from the parent wireless routing node;

and

updating the timer based on receipt of the subsequent synchronization packets.

37. The method of claim 28 wherein the calibrating step comprises initiating the timer based on receipt of the synchronization token.

38. An apparatus for use in a wireless network, comprising

a wireless interface operative to wirelessly communicate with an upstream routing node and at least one downstream routing node.

a routing node control processor, operably connected to the wireless interface, and comprising a duty cycle timer;

wherein the routing node control processor is operative to

calibrate the duty cycle timer based on receipt, at the wireless interface, of a synchronization token from an upstream routing node; and

cycle, based on the duty cycle timer, between an upstream transmission phase and a downstream transmission phase;

wherein, in the upstream transmission phase, the routing node control processor is operative to

store at least one wireless frame received from the upstream routing node in a downstream buffer; and

transmit from the wireless interface at least one wireless frame stored in an upstream buffer to the upstream routing node; and

wherein, in the downstream transmission phase, the routing node control processor is operative to

store at least one wireless frame received from the downstream routing node in a upstream buffer; and

transmit from the wireless interface at least one wireless frame stored in a downstream buffer to the downstream routing node.

39. The apparatus of claim 38 wherein the wireless interface comprises at least one antenna.

40. The apparatus of claim 38 wherein the wireless interface comprises an upstream antenna and a downstream antenna.

41. A method facilitating the transfer of data between wireless routing nodes, comprising

receiving a synchronization token;

calibrating a timer based on receipt of the synchronization token; and

cycling, based on the timer, between an upstream transmission phase and a downstream transmission phase;

wherein the upstream transmission phase comprises

receiving wireless frames from a parent wireless routing node;

storing at least one received wireless frames in a downstream buffer;

transmitting at least one wireless frame stored in an upstream buffer to the parent wireless routing node;

receiving a synchronization token and re-calibrating the time based on receipt of the synchronization token;

wherein the downstream transmission phase comprises

receiving wireless frames from at least one child wireless routing node;

storing at least one received wireless frame in the upstream buffer;

transmitting at least one wireless frame stored in the downstream buffer to the at least one child routing node.

42. The method of claim 41 wherein the downstream transmission phase further comprises

transmitting a synchronization token to at least one child routing node at the midpoint of the downstream transmission phase.

43. The method of claim 41 wherein the synchronization token is received from the parent wireless routing node.

44. The method of claim 42 wherein the synchronization token is received from the parent wireless routing node.

45. The method of claim 41 wherein the downstream buffer is a queue structure.

46. The method of claim 41 wherein the upstream buffer is a queue structure.