Infrastructure-based enabling indication for dynamic frequency selection in wireless networks

• US 7,944,886 B2
• Filed: 08/21/2007
• Issued: 05/17/2011
• Est. Priority Date: 08/21/2007
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Meil, Christopher, Stephenson, David S., Hart, Brian Donald, O'Hara, Robert B. Jr.
• Primary Examiner(s): Jain; Raj K
• Application Number:
  US11/842,601
• Publication Number:
  US 20090052382A1
• Time in Patent Office: 1,365 Days
• Field of Search: None
• US Class Current: 370/331
• 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

Abstract

A wireless access point selection system. In particular implementations, a method includes receiving a notification that identifies a wireless access point that detects radar on an operating channel and identifies the operating channel; updating neighbor lists of one or more neighboring wireless access points to remove the wireless access point from the neighbor list, where the neighbor list comprises neighbor wireless access points, corresponding operating channels, and corresponding enable indications, where each enable indication indicates if a channel availability check is required before performing active scanning; and transmitting the updated neighbor list to the neighboring wireless access points. In one implementation, a system provides a DFS enable indication to wireless clients so they can know whether a channel availability check is required prior to transmitting.

Claims

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

receive a notification that identifies a wireless access point that detects radar on an operating channel and identifies the operating channel;

update neighbor lists of one or more neighboring wireless access points to remove the wireless access point from the neighbor list, wherein the neighbor list comprises neighbor wireless access points, corresponding operating channels, and corresponding enable indications, wherein each enable indication indicates if a channel availability check is required before performing active scanning; and

transmit the updated neighbor list to the neighboring wireless access points.

2. The logic of claim 1 wherein the logic is further operable to reassign a new operating channel to the wireless access point.

3. The logic of claim 2 wherein, to reassign the new operating channel to the wireless access point, the logic is further operable to:

select a new operating channel and transmit an indication of the new operating channel to the wireless access point;

determine if the wireless access point detects radar on the new operating channel;

if the wireless access point detects radar on the new operating channel, select and transmit an alternative operating channel to the wireless access point;

if the wireless access point does not detect radar on the new operating channel, update the neighbor lists to include the wireless access point, the new operating channel, and an enable indication indicating that a channel availability check is not required before performing active scanning; and

transmit the updated neighbor lists to the wireless access point and the neighbor wireless access points listed in the neighbor list.

4. The logic of claim 1 wherein the enable indication is a bit that toggles between “

1” and

“

0,”

wherein a “

1”

indicates that a channel availability check is not required before performing active scanning, and wherein a “

0”

indicates that a channel availability check is required before performing active scanning.

5. The logic of claim 1 wherein when other central controllers receive the radar detection indication, the other central controllers update their neighbor lists.

6. A method comprising:

receiving, at one or more computing devices, a notification that identifies a wireless access point that detects radar on an operating channel and identifies the operating channel;

updating, by the one or more computing devices, neighbor lists of one or more neighboring wireless access points to remove the wireless access point from the neighbor list, wherein the neighbor list comprises neighbor wireless access points, corresponding operating channels, and corresponding enable indications, wherein each enable indication indicates if a channel availability check is required before performing active scanning; and

transmitting, by the one or more computing devices, the updated neighbor list to the neighboring wireless access points.

7. The method of claim 6 further comprising reassigning a new operating channel to the wireless access point.

8. The method of claim 7 further comprising:

selecting a new operating channel and transmitting an indication of the new operating channel to the wireless access point;

determining if the wireless access point detects radar on the new operating channel;

if the wireless access point detects radar on the new operating channel, selecting and transmitting an alternative operating channel to the wireless access point;

if the wireless access point does not detect radar on the new operating channel, updating the neighbor lists to include the wireless access point, the new operating channel, and an enable indication indicating that a channel availability check is not required before performing active scanning; and

transmitting the updated neighbor lists to the wireless access point and the neighbor wireless access points listed in the neighbor list.

9. The method of claim 6 wherein the enable indication is a bit that toggles between “

1” and

“

0,”

wherein a “

1”

indicates that a channel availability check is not required before performing active scanning, and wherein a “

0”

indicates that a channel availability check is required before performing active scanning.

10. The method of claim 6 wherein when other central controllers receive the radar detection, the other central controllers update their neighbor lists.

11. An apparatus comprising:

means for receiving a notification that identifies a wireless access point that detects radar on an operating channel and identifies the operating channel;

means for updating neighbor lists of one or more neighboring wireless access points to remove the wireless access point from the neighbor list, wherein the neighbor list comprises neighbor wireless access points, corresponding operating channels, and corresponding enable indications, wherein each enable indication indicates if a channel availability check is required before performing active scanning; and

means for transmitting the updated neighbor list to the neighboring wireless access points.

12. The apparatus of claim 11 further comprising means for reassigning a new operating channel to the wireless access point.

13. The apparatus of claim 12 further comprising:

means for selecting a new operating channel and transmitting an indication of the new operating channel to the wireless access point;

means for determining if the wireless access point detects radar on the new operating channel;

if the wireless access point detects radar on the new operating channel, means for selecting and transmitting an alternative operating channel to the wireless access point;

if the wireless access point does not detect radar on the new operating channel, means for updating the neighbor lists to include the wireless access point, the new operating channel, and an enable indication indicating that a channel availability check is not required before performing active scanning; and

means for transmitting the updated neighbor lists to the neighboring wireless access points and the neighbor wireless access points listed in the neighbor list.

14. The apparatus of claim 11 wherein the enable indication is a bit that toggles between “

1” and

“

0,”

wherein a “

1”

indicates that a channel availability check is not required before performing active scanning, and wherein a “

0”

indicates that a channel availability check is required before performing active scanning.

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

receive a neighbor list comprising neighbor wireless access points, corresponding operating channels, and corresponding enable indications, wherein each enable indication indicates if a channel availability check is required before performing active scanning; and

perform active scanning if a channel availability check is not required before performing active scanning.

16. The logic of claim 15 wherein the logic is further operable to prioritize wireless access points in a roaming table based on active scanning, wherein the roaming table includes neighbor wireless access points and corresponding received signal strength values.

17. The logic of claim 15 wherein the logic is further operable to perform passive scanning if a channel availability check is required before performing active scanning, and wherein passive scanning comprises monitoring for an enabling signal from a wireless access point.

18. The logic of claim 15 wherein the logic is further operable to perform passive scanning if a channel availability check is required before performing active scanning, wherein passive scanning comprises monitoring for an enabling signal from a wireless access point, and wherein the enabling signal indicates that the wireless access point has performed a channel availability check and that it is clear to transmit signals on the operating channel.

19. A method comprising:

receiving, at one or more computing devices, a neighbor list comprising neighbor wireless access points, corresponding operating channels, and corresponding enable indications, wherein each enable indication indicates if a channel availability check is required before performing active scanning; and

performing, by the one or more computing devices, active scanning if a channel availability check is not required before performing active scanning.

20. The method of claim 19 further comprising prioritizing wireless access points in a roaming table based on active scanning, wherein the roaming table includes neighbor wireless access points and corresponding received signal strength values.

21. The method of claim 19 further comprising performing passive scanning if a channel availability check is required before performing active scanning, and wherein passive scanning comprises monitoring for an enabling signal from a wireless access point.

22. The method of claim 19 further comprising performing passive scanning if a channel availability check is required before performing active scanning, wherein passive scanning comprises monitoring for an enabling signal from a wireless access point, and wherein the enabling signal indicates that the wireless access point has performed a channel availability check and that it is clear to transmit signals on the operating channel.

23. An apparatus comprising:

means for receiving a neighbor list comprising neighbor wireless access points, corresponding operating channels, and corresponding enable indications, wherein each enable indication indicates if a channel availability check is required before performing active scanning; and

means for performing active scanning if a channel availability check is not required before performing active scanning.

24. The apparatus of claim 23 further comprising means for prioritizing wireless access points in a roaming table based on active scanning, wherein the roaming table includes neighbor wireless access points and corresponding received signal strength values.

25. The apparatus of claim 23 further comprising means for performing passive scanning if a channel availability check is required before performing active scanning, and wherein passive scanning comprises monitoring for an enabling signal from a wireless access point.