Mesh tree formation in wireless networks

• US 8,654,782 B2
• Filed: 11/05/2007
• Issued: 02/18/2014
• 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
• Primary Examiner(s): Mian, Omer S
• Application Number:
  US11/935,033
• Publication Number:
  US 20090116411A1
• Time in Patent Office: 2,297 Days
• Field of Search: 370/348, 370/445, 370/444, 370/450, 370/406
• US Class Current: 370/445
• 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 dynamic frequency selection (DFS) channel, entering, at a mesh routing node, a silent state and initiating, by the mesh routing node, a DFS channel access scan of the selected channel for a radar signal for a period of time, wherein during the silent state the mesh routing node does not transmit any data;

responsive to receipt of a DFS enabling signal during the period of time, entering, at the mesh routing node, a limited transmission state during which the mesh routing node exchanges routing information with candidate parent mesh routing nodes on the selected channel and does not transmit DFS enabling signals while executing the DFS channel access scan for the radar signal for the period of time, wherein the DFS enabling signal indicates that the device transmitting the DFS enabling signal has performed a DFS channel access scan of the selected channel and has not detected the radar signal; and

responsive to termination of the period of time of the DFS channel scan initiated by the mesh routing node wherein the radar signal is not detected by the mesh routing node, entering, at the mesh routing node, a full transmission state comprising exchanging, by the mesh routing node, routing information with candidate parent mesh routing nodes and transmitting DFS enabling signals corresponding to the selected channel, wherein the DFS enabling signals are operative to cause one or more neighboring mesh routing nodes, upon receiving the DFS enabling signals, to enter the limited transmission state during respective DFS channel scans performed by the one or more neighboring mesh routing nodes;

wherein the routing information comprises discovery and mesh formation messages.

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

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

4. The method of claim 1 wherein the DFS enabling signals enable transmission of the routing information in a plurality of mesh trees.

5. One or more non-transitory, tangible computer readable media storing logic for execution and when executed operable to:

responsive to a selection of a dynamic frequency selection (DFS) channel, enter, at a mesh routing node, a silent state and initiating a DFS channel scan of the selected channel for a radar for a period of time, wherein during the silent state the mesh routing node does not transmit any data;

responsive to receipt of a DFS enabling signal during the period of time, enter, at the mesh routing node, a limited transmission state during which the mesh routing node exchanges routing information with candidate parent mesh routing nodes on the selected channel and does not transmit DFS enabling signals while executing the DFS channel access scan for the radar signal for the period of time, wherein the DFS enabling signal indicates that the device transmitting the DFS enabling signal has performed a DFS channel access scan of the selected channel and has not detected the radar signal; and

responsive to termination of the period of time of the DFS channel scan initiated by the mesh routing node wherein the radar signal is not detected by the mesh routing node, enter a full transmission state comprising exchanging, by the mesh routing node, routing information with candidate parent mesh routing nodes and transmitting DFS enabling signals corresponding to the selected channel, wherein the DFS enabling signals are operative to cause one or more neighboring mesh routing nodes, upon receiving the DFS enabling signals, to enter the limited transmission state during respective DFS channel scans performed by the one or more neighboring mesh routing nodes;

wherein the routing information comprises discovery and mesh formation messages.

6. The one or more non-transitory, tangible computer readable media of claim 5 wherein the logic is further operable to perform both master device functionality to enable transmission of routing information on the selected channel and slave device functionality to become enabled to transmit routing information on the selected channel.

7. The one or more non-transitory, tangible computer readable media of claim 5 wherein the logic is further operable to transmit DFS enabling signals at lower data rate relative to regular transmissions.

8. The one or more non-transitory, tangible computer readable media of claim 5 wherein the DFS enabling signals enable transmission of routing information in a plurality of mesh trees.

9. 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 dynamic frequency selection (DFS) channel, and switching to the DFS channel;

transition from the silent state to a limited transmission state if the apparatus receives a DFS enabling signal during a DFS channel availability check;

transition from the silent state to a full transmission state if the apparatus completes the DFS channel availability check without detecting a radar signal on the channel; and

transition from the limited transmission state to the full transmission state if the apparatus completes the DFS channel availability check without detecting the radar signal 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 DFS channel availability check;

responsive to the limited transmission state, transmit messages comprising discovery and mesh formation information, and not transmit DFS enabling signals while executing the DFS channel access scan for the radar signal for the period of time wherein the DFS enabling signal indicates that the device transmitting the DFS enabling signal has performed a DFS channel access scan of the selected channel and has not detected the radar signal; and

responsive to the full transmission state, transmit messages comprising discovery and mesh formation information, and DFS enabling signals on the channel, wherein the DFS enabling signals are operative to cause one or more neighboring mesh routing nodes, upon receiving the DFS enabling signals, to enter the limited transmission state during respective DFS channel scans performed by the one or more neighboring mesh routing nodes.

10. The apparatus of claim 9 wherein a master bit and a slave bit in the apparatus are set during the initial state and during the silent state.

11. The apparatus of claim 9 wherein a slave bit in the apparatus is cleared during the limited transmission state.

12. The apparatus of claim 9 wherein a master bit and a slave bit in the apparatus are cleared during the full transmission state.