Enhanced coverage hole detection in wireless networks

• US 7,499,718 B2
• Filed: 08/01/2006
• Issued: 03/03/2009
• Est. Priority Date: 08/01/2006
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Douglas, Bretton Lee, Stephenson, David Sheldon, Olson, Timothy S.
• Primary Examiner(s): Taylor; Barry W
• Application Number:
  US11/496,946
• Publication Number:
  US 20080032727A1
• Time in Patent Office: 945 Days
• Field of Search: 455/513, 455/423, 455/67.11
• US Class Current: 455/513
• CPC Class Codes: H04W 24/00 Supervisory, monitoring or testing arrangements
• CPC Class Codes: H04W 24/08 Testing, supervising or monitoring using real traffic
• CPC Class Codes: H04W 84/12 WLAN [Wireless Local Area Networks]

Abstract

Methods, apparatuses and systems directed to identifying coverage holes in wireless networks. According to one implementation of the present invention, the wireless network infrastructure analyzes signal strength data to detect potential coverage holes associated with one or more wireless clients and validates the potential coverage holes based on observed coverage data.

Claims

1. A computer readable storage medium encoded with computer executable instructions for identifying coverage holes in a wireless network, the computer executable instructions are operable to:

analyze signal strength data associated with a wireless client; and

if the signal strength data indicates that communication quality with the wireless client falls below a first threshold, then

request a beacon report from the wireless client, wherein the beacon report includes one or more wireless access points discovered by the wireless client;

validate the beacon report by comparing a upstream Received Signal Strength Indicator (RSSI) value and a downstream RSSI value between the wireless client and a wireless access point associated with the wireless client when a time difference between obtaining the upstream RSSI value and the downstream RSSI value is less than or equal to a second threshold; and

if a difference between the upstream RSSI value and the downstream RSSI value is less than or equal to a third threshold, then determine whether the wireless client is in a coverage hole based on the beacon report.

2. The computer readable storage medium of claim 1 wherein the signal strength data is a RSSI histogram for the wireless client that corresponds to RSSI values obtained from the wireless client over a period of time.

3. The computer readable storage medium of claim 2 wherein the the signal strength data is a maximum RSSI histogram for the wireless client that corresponds to RSSI values obtained from the wireless client during a worst sub-period over the period of time.

4. The computer readable storage medium of claim 1 wherein the beacon report further includes a first time stamp.

5. The computer readable storage medium of claim 4 wherein the computer executable instructions are further operable to determine the time difference between obtaining the upstream RSSI value and the downstream RSSI value.

6. The computer readable storage medium of claim 5 wherein, to determine the time difference between obtaining the upstream RSSI value and the downstream RSSI value, the computer executable instructions are further operable to compare the first time stamp included in the beacon report with a second time stamp provided by the wireless access point associated with the wireless client, wherein the second time stamp indicates a time that the wireless access point receives a probe request in connection with the beacon report from the wireless client.

7. The computer readable storage medium of claim 6 wherein the beacon report improves accuracy in locating the one or more potential coverage holes.

8. The computer readable storage medium of claim 1 wherein the wireless client is in a coverage hole if the beacon report indicates that there is no wireless access point with a sufficient signal strength available to the wireless client.

9. The computer readable storage medium of claim 1 wherein the signal strength data comprises one or more of signal-to-noise ratio, signal-to-interference ratio, and signal-to-noise-plus-interference ratio.

10. The computer readable storage medium of claim 1 wherein the computer executable instructions are further operable to determine whether the overage hole is a false positive.

11. The computer readable storage medium of claim 1 wherein the computer executable instructions are further operable to locate multiple coverage holes for the wireless client.

12. A method for identifying coverage holes in a wireless network, the method comprising:

analyzing signal strength data associated with a wireless client; and

if the signal strength data indicates that communication quality with the wireless client falls below a first threshold, then

requesting a beacon report from the wireless client, wherein the beacon report includes one or more wireless access points discovered by the wireless client;

validating the beacon report by comparing a upstream Received Signal Strength Indicator (RSSI) value and a downstream RSSI value between the wireless client and a wireless access point associated with the wireless client when a time difference between obtaining the upstream RSSI value and the downstream RSSI value is less than or equal to a second threshold; and

if a difference between the upstream RSSI value and the downstream RSSI value is less than or equal to a third threshold, then determining whether the wireless client is in a coverage hole based on the beacon report.

13. The method of claim 12 wherein the signal strength data is a RSSI histogram for the wireless client that corresponds to RSSI values obtained from the wireless client over a period of time.

14. The method of claim 13 wherein the signal strength data is a maximum RSSI histogram for the wireless client that corresponds to RSSI values obtained from the wireless client during a worst sub-period over the period of time.

15. The method of claim 12 wherein the beacon report further includes a first time stamp.

16. The method of claim 15 further comprising determining the time difference between obtaining the upstream RSSI value and the downstream RSSI value.

17. The method of claim 16 further comprising comparing the first time stamp included in the beacon report with a second time stamp provided by the wireless access point associated with the wireless client, wherein the second time stamp indicates a time that the wireless access point receives a probe request in connection with the beacon report from the wireless client.

18. The method of claim 12 wherein the wireless client is in a coverage hole if the beacon report indicates that there is no wireless access point with a sufficient signal strength available to the wireless client.

19. The method of claim 12 wherein the signal strength data comprises one or more of signal-to-noise ratio, signal-to-interference ratio, and signal-to-noise-plus-interference ratio.

20. The method of claim 12 further comprising determining whether a the coverage holes is a false positive.

21. The method of claim 12 further comprising locating multiple coverage holes for the wireless client.

22. The method of claim 12 wherein the beacon report improves accuracy in locating the one or more potential coverage holes.

23. A system for identifying coverage holes in a wireless network, the system comprising:

a wireless network infrastructure node operable to

analyze signal strength data associated with a wireless client, and

if the signal strength data indicates that communication quality with the wireless client falls below a first threshold, then

request a beacon report from the wireless client, wherein the beacon report includes one or more wireless access points discovered by the wireless client,

validate the beacon report by comparing a upstream Received Signal Strength Indicator (RSSI) value and a downstream RSSI value between the wireless client and a wireless access point associated with the wireless client when a time difference between obtaining the upstream RSSI value and the downstream RSSI value is less than or equal to a second threshold, and

if a difference between the upstream RSSI value and the downstream RSSI value is less than or equal to a third threshold, then determine whether the wireless client is in a coverage hole based on the beacon report,

one or more wireless clients, each operable to provide a beacon report.