Mesh Tree Formation in Wireless Networks

• US 20090116411A1
• Filed: 11/05/2007
• Published: 05/07/2009
• Est. Priority Date: 11/05/2007
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Meil, Christopher Graham, Castagnoli, Neal Dante, Raju, Jyoti
• Granted Patent: US 8,654,782 B2
• Time in Patent Office: Days
• US Class Current: 370/256
• CPC Class Codes: H04W 16/14 Spectrum sharing arrangements between different networks
• CPC Class Codes: H04W 48/16 Discovering, processing access restriction or access information
• CPC Class Codes: H04W 8/005 Discovery of network devices, e.g. terminals
• CPC Class Codes: H04W 84/18 Self-organising networks, e.g. ad-hoc networks or sensor networks

Abstract

A mesh tree formation system. In particular implementations, a method includes responsive to a selection of a channel potentially bearing a higher priority use, entering a silent state and initiating a channel scan of the selected channel for a period of time. The method also includes, responsive to receipt of an enabling signal, entering a limited transmission state that enables transmission of wireless frames on the selected channel. The method also includes, responsive to termination of the period of time of the channel scan wherein no higher priority use is detected, entering a full transmission state comprising transmission of enabling signals corresponding to the selected channel.

Claims

1. A method comprising:

responsive to a selection of a channel potentially hearing a higher priority use, entering a silent state and initiating a channel scan of the selected channel for a period of time;

responsive to receipt of an enabling signal, entering a limited transmission state that enables transmission of wireless frames on the selected channel; and

responsive to termination of the period of time of the channel scan wherein no higher priority use is detected, entering a full transmission state comprising transmission of enabling signals corresponding to the selected channel.

2. The method of claim 1 further comprising transmitting mesh discovery and formation messages during the limited transmission state and the full transmission state.

3. The method of claim 1 further comprising exchanging routing information with one or more neighboring routing nodes during the limited transmission state and the full transmission state.

4. The method of claim 1 further comprising performing both master device functionality to enable transmission of wireless frames on the selected channel and slave device functionality to become enabled to transmit wireless frames on the selected channel.

5. The method of claim 1 further comprising transmitting enabling signals at lower data rate relative to regular transmissions.

6. The method of claim 1 wherein the enabling signals enable transmission of wireless frames in a plurality of mesh trees.

7. The method of claim 1 wherein the selected channel is a dynamic frequency selection (DFS) channel, and the enabling signals are DFS-enabling signals.

8. The method of claim 1 wherein the channel scan is a dynamic frequency selection (DFS) scan.

9. Logic encoded in one or more tangible media for execution and when executed operable to:

responsive to a selection of a channel potentially bearing a higher priority use, enter a silent state and initiating a channel scan of the selected channel for a period of time;

responsive to receipt of an enabling signal, enter a limited transmission state that enables transmission of wireless frames on the selected channel; and

responsive to termination of the period of time of the channel scan wherein no higher priority use is detected, enter a lull transmission state comprising transmission of enabling signals corresponding to the selected channel.

10. The logic of claim 9 wherein the logic is further operable to transmit mesh discovery and formation messages during the limited transmission state and the full transmission state.

11. The logic of claim 9 wherein the logic is further operable to exchange routing information with one or more neighboring routing nodes during the limited transmission state and the full transmission state.

12. The logic of claim 9 wherein the logic is further operable to perform both master device functionality to enable transmission of wireless frames on the selected channel and slave device functionality to become enabled to transmit wireless frames on the selected channel.

13. The logic of claim 9 wherein the logic is further operable to transmit enabling signals at lower data rate relative to regular transmissions.

14. The logic of claim 9 wherein the enabling signals enable transmission of wireless frames in a plurality of mesh trees.

15. The logic of claim 9 wherein the selected channel is a dynamic frequency selection (DFS) channel, and the enabling signals are DFS-enabling signals.

16. The logic of claim 9 wherein the channel scan is a dynamic frequency selection (DFS) scan.

17. An apparatus comprising:

one or more processors;

a memory;

one or more wireless network interfaces;

state transition logic encoded in one or more tangible media for execution and when executed operable to cause the one or more processors to;

transition from an initial state to a silent state if the apparatus performs at least one of detecting radar, initializing and being set to a channel potentially bearing a higher priority use, and switching to the channel;

transition from the silent state to a limited transmission state if the apparatus receives an enabling signal;

transition from the silent state to a full transmission state if the apparatus completes the channel availability check without detecting any higher priority use on the channel; and

transition from the limited transmission state to the full transmission state if the apparatus completes the channel availability check without detecting any higher priority use on the channel; and

mesh access point logic encoded in one or more tangible media for execution and when executed operative to cause the one or more processors to;

responsive to the silent state, suspend transmission of any data on the channel and perform a channel availability check;

responsive to the limited transmission state or the full transmission state, transmit messages comprising discovery and mesh formation information; and

responsive to the full transmission state, transmit enabling signals on the channel.

18. The apparatus of claim 17 wherein a master bit and a slave bit in the apparatus are set during the initial state and during the silent state.

19. The apparatus of claim 17 wherein a slave bit in the apparatus is cleared during the limited transmission state.

20. The apparatus of claim 17 wherein a master bit and a slave bit in the apparatus are cleared during the full transmission state.