Detecting physical topology changes affecting cells and cell edge determination

• US 10,462,015 B1
• Filed: 08/01/2018
• Issued: 10/29/2019
• Est. Priority Date: 08/01/2018
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Henry, Jerome, Desai, Vishal S.
• Primary Examiner(s): Pham, Brenda H
• Application Number:
  US16/052,493
• Time in Patent Office: 454 Days
• Field of Search: 370248, 370252, 370332, 3703102, 370328, 370338, 370349, 370241
• CPC Class Codes: H04L 41/12 Discovery or management of network topologies
• CPC Class Codes: H04L 43/0894 Packet rate
• CPC Class Codes: H04L 43/12 Network monitoring probes
• CPC Class Codes: H04L 43/50 Testing arrangements
• CPC Class Codes: H04W 16/18 Network planning tools
• CPC Class Codes: H04W 24/10 Scheduling measurement reports ; Arrangements for measurement reports
• CPC Class Codes: H04W 64/003 locating network equipment
• CPC Class Codes: H04W 64/006 with additional information processing, e.g. for direction or speed determination
• CPC Class Codes: H04W 84/12 WLAN [Wireless Local Area Networks]
• CPC Class Codes: H04W 88/08 Access point devices

Abstract

The embodiments herein uses sensor APs (e.g., APs that do not associate with client devices) to detect changes in physical topology that affect cell coverage areas and determine cell edges for different client devices. In one embodiment, using test signals (e.g., test probes) transmitted by the sensor APs which are received at normal APs which do associate with client devices, a controller can generate baselines which characterize the signals received from the sensor APs at the normal APs. At intervals or in response to an unexpected action by a client device, one or more of the sensor APs can transmit another test signal. Because the test signal can be received at multiple normal APs, the controller can compare the test signal to the baselines to identify whether there has been a change in physical topology that affects the cell coverage area for the client device.

Claims

1. A system, comprising:

a plurality of access points (APs) disposed at a site, the plurality of APs configured to associate to client devices;

a sensor AP configured to transmit first test signals to the plurality of APs; and

a controller configured to;

determine, at a first time period, baselines for the sensor AP at a first AP of the plurality of APs and at a second AP of the plurality of APs that received the first test signals,

instruct the sensor AP to transmit second test signals to the plurality of APs at a second time period after the first time period, wherein the second test signals are received at the first and second APs, and

upon determining that a characteristic of the second test signals is substantially the same as the baseline corresponding to the first AP but is substantially different from the baseline corresponding to the second AP, determine a change in physical topology that affects a radio frequency (RF) environment at the site.

2. The system of claim 1, wherein the client devices are unable to associate to the sensor AP.

3. The system of claim 1, wherein the controller is configured to:

upon determining a characteristic of the second test signals is substantially different from the baselines of all the of the plurality of APs that received the second test signals, determine that the sensor AP has been moved to a different physical location since the first test signals were transmitted during first time period.

4. The system of claim 1, further comprising:

a plurality of sensor APs disposed at the site, the plurality of sensor APs including the sensor AP,

wherein the controller is configured to;

detect that a first client device of the client devices performed an unexpected action based on a current distance of the first client device to one of the plurality of APs to which the first client device is associated; and

select the sensor AP from the plurality of sensor APs based on a similar location attribute between the sensor AP and the first client device.

5. The system of claim 4, wherein the unexpected action comprises transmitting a probe request as part of a roaming process too earlier or reducing a data rate used when transmitting signals from the first client device to the one of the plurality of APs.

6. The system of claim 1, further comprising:

a plurality of sensor APs disposed at the site, the plurality of sensor APs including the sensor AP,

wherein the controller is configured to;

detect that a first client device of the client devices transmitted a probe request, wherein the first client device is currently associated to one of the plurality of APs,

select the sensor AP from the plurality of sensor APs based on a similar location attribute between the sensor AP and the first client device,

determine a transmit power and data rate used by the first client device when transmitting the probe request, and

instruct the selected sensor AP to transmit a probe request using the transmit power and data rate used by the first client device.

7. The system of claim 6, wherein the controller is configured to:

compare the probe request transmitted by the selected sensor AP to one of the baselines to determine whether the physical topology of the site has changed.

8. The system of claim 7, wherein the controller is configured to:

upon determining the physical topology is unchanged, determine a geographic location of the first client device based on the probe request transmitted by the first client device; and

correlate the geographic location of the first client device to a point of a cell edge for the one of the plurality of APs.

9. The system of claim 8, wherein determining the geographic location of the first client device comprises:

determining a distance from the first client device to the selected sensor AP, wherein the selected sensor AP receives the probe request transmitted by the first client device.

10. A method comprising:

instructing a sensor AP to transmit first test signals to a plurality of APs deployed at a site;

determining, at a first time period, baselines for the sensor AP at a first AP of the plurality of APs and at a second AP of the plurality of APs that received the first test signals;

instructing the sensor AP to transmit second test signals to the plurality of APs at a second time period after the first time period, wherein the second test signals are received at the first and second APs; and

upon determining that a characteristic of the second test signals is substantially the same as the baseline corresponding to the first AP but is substantially different from the baseline corresponding to the second AP, detecting a change in physical topology that affects an RF environment at the site.

11. The method of claim 10, wherein client devices are unable to associate to the sensor AP.

12. The method of claim 10, further comprising:

detecting that a first client device performed an unexpected action based on a current distance of the first client device to one of the plurality of APs to which the first client device is associated; and

selecting the sensor AP from a plurality of sensor APs based on a similar location attribute between the sensor AP and the first client device.

13. The method of claim 10, further comprising:

detecting that a first client device transmitted a probe request, wherein the first client device is currently associated to one of the plurality of APs;

selecting the sensor AP from a plurality of sensor APs based on a similar location attribute between the sensor AP and the first client device;

determining a transmit power and data rate used by the first client device when transmitting the probe request;

instructing the selected sensor AP to transmit a probe request using the transmit power and data rate used by the first client device; and

comparing the probe request transmitted by the selected sensor AP to one of the baselines to determine whether the physical topology of the site has changed.

14. The method of claim 13, further comprising:

upon determining the physical topology is unchanged, determining a geographic location of the first client device based on the probe request transmitted by the first client device; and

correlating the geographic location of the first client device to a point of a cell edge for the one of the plurality of APs.

15. A non-transitory computer-readable medium for monitoring an RF environment at a site, the non-transitory computer-readable medium having program instructions embodied therewith, the program instructions executable by a processor to perform an operation comprising:

instructing a sensor AP to transmit first test signals to a plurality of APs deployed at the site;

determining, at a first time period, baselines for the sensor AP at a first AP of the plurality of APs and at a second AP of the plurality of APs that received the first test signals;

instructing the sensor AP to transmit second test signals to the plurality of APs at a second time period after the first time period, wherein the second test signals are received at the first and second APs; and

upon determining that a characteristic of the second test signals is substantially the same as the baseline corresponding to the first AP but is substantially different from the baseline corresponding to the second AP, detecting a change in physical topology that affects an RF environment at the site.

16. The non-transitory computer-readable medium of claim 15, wherein client devices are unable to associate to the sensor AP.

17. The non-transitory computer-readable medium of claim 15, wherein the operation further comprises:

detecting that a first client device performed an unexpected action based on a current distance of the first client device to one of the plurality of APs to which the first client device is associated; and

selecting the sensor AP from a plurality of sensor APs based on a similar location attribute between the sensor AP and the first client device.

18. The non-transitory computer-readable medium of claim 15, wherein the operation further comprises:

detecting that a first client device transmitted a probe request, wherein the first client device is currently associated to one of the plurality of APs;

selecting the sensor AP from a plurality of sensor APs deployed at the site based on a similar location attribute between the sensor AP and the first client device;

determining a transmit power and data rate used by the first client device when transmitting the probe request;

instructing the selected sensor AP to transmit a probe request using the transmit power and data rate used by the first client device; and

comparing the probe request transmitted by the selected sensor AP to one of the baselines to determine whether the physical topology of the site has changed.

19. The non-transitory computer-readable medium of claim 18, wherein the operation further comprises:

upon determining the physical topology is unchanged, determining a geographic location of the first client device based on the probe request transmitted by the first client device; and

correlating the geographic location of the first client device to a point of a cell edge for the one of the plurality of APs.

20. The non-transitory computer-readable medium of claim 15, wherein the operation further comprises:

upon determining a characteristic of the second test signals is substantially different from the baselines of all the of the plurality of APs that received the second test signals, determine that the sensor AP has been moved to a different physical location since the first test signals were transmitted during first time period.