Systems and Methods for Reducing Variations in Received Signal Strength Indicator (RSSI) Measurements for Location Sensing

• US 20140185464A1
• Filed: 12/27/2012
• Published: 07/03/2014
• Est. Priority Date: 12/27/2012
• Status: Active Grant

• Current Assignee: Intel Corporation
• Original Assignee: Intel Corporation
• Inventors: Yang, Lei, Yang, Xue
• Granted Patent: US 9,310,465 B2
• Time in Patent Office: Days
• US Class Current: 370/252
• CPC Class Codes: G01S 11/06 using intensity measurements
• CPC Class Codes: G01S 5/0218 Multipath in signal reception
• CPC Class Codes: G01S 5/0252 Radio frequency fingerprinting
• CPC Class Codes: G01S 5/0273 using multipath or indirect path propagation signals in position determination
• CPC Class Codes: G01S 5/14 Determining absolute distances from a plurality of spaced points of known location

Abstract

Certain embodiments herein are directed to reducing variations in received signal strength indicator (RSSI) measurements that may be received by a wireless device over a network, such as a WiFi network including one or more access points. A signal sent from an access point may be received by a user device, where channel estimation results associated with the received signal may be analyzed to determine a more accurate location of the user device. The received signal may be converted to at least one of the time domain and the frequency domain, in which signal components associated with the received signal may be identified based on a determination that the signal components may be associated with multipath fading or other types of interference. Such identified signal components, whether in the frequency domain or the time domain) may be excluded from a determination of a signal strength measurement that may in turn be used to identify the location of the user device.

Claims

1. A method comprising:

receiving over a network, at a user device, from an access point, a signal comprising multiple signal components;

converting, by the user device, the signal to at least one of a frequency domain or a time domain such that the multiple signal components are associated with respective power values;

identifying, by the user device, at least a first portion of the multiple signal components associated with multipath fading based at least in part on the respective power values; and

determining, by the user device, a signal strength measurement based at least in part on the respective power values associated with at least a second portion of the multiple signal components.

2. The method of claim 1, wherein the network is a wireless fidelity (WiFi) network, and the signal comprises a beacon packet.

3. The method of claim 1, further comprising determining, by the user device, a location of the user device based at least in part on the signal strength measurement.

4. The method of claim 1, further comprising determining one or more thresholds for identifying the at least a first portion of the multiple signal components.

5. The method of claim 4, wherein when the signal is converted to the frequency domain, the respective power value associated with the at least a first portion is above a first threshold of the one or more thresholds or below a second threshold of the one or more thresholds.

6. The method of claim 4, wherein when the signal is converted to the time domain, the at least a second portion is associated with a dominant portion of the signal.

7. The method of claim 1, wherein the determination of the signal strength measurement is based at least in part on at least one of an average or a weighted average of respective power values associated with the at least a second portion, wherein the signal strength measurement is a received signal strength indicator (RSSI) measurement.

8. The method of claim 1, wherein the signal comprises channel estimation results, the channel estimation results comprising an identification of the access point and respective amplitudes and phases associated with the multiple signal components.

9. The method of claim 1, wherein the signal comprises a first signal that is received by a first antenna associated with the user device, wherein the signal strength is a first signal strength associated with the first signal, and wherein the method further comprises:

receiving a second signal at a second antenna associated with the user device;

determining a second signal strength measurement associated with the second signal; and

determining a third signal strength measurement based at least in part on the first signal strength measurement and the second signal strength measurement;

wherein the first signal strength is based at least in part on first channel estimation results that are different from second channel estimation results associated with the second signal strength.

10. One or more computer-readable media storing computer-executable instructions that, when executed by at least one processor, configure the at least one processor to perform operations comprising:

receiving, over the network from an access point, a signal comprising multiple signal components;

converting the signal to at least one of a frequency domain or a time domain such that the multiple signal components are associated with a respective power value;

identifying at least a first portion of the multiple signal components associated with multipath fading based at least in part on the respective power value; and

determining a signal strength measurement based at least in part on the respective power value associated with at least a second portion of the multiple signal components.

11. The one or more computer-readable media of claim 10, wherein the network is a wireless fidelity (WiFi) network, and the signal comprises a beacon packet.

12. The one or more computer-readable media of claim 10, the at least one processor further configured to determine a location of a user device based at least in part on the signal strength measurement.

13. The one or more computer-readable media of claim 10, the at least one processor further configured to determine one or more thresholds for identifying the at least a first portion of the multiple signal components.

14. The one or more computer-readable media of claim 13, wherein when the signal is converted to the frequency domain, the respective power value associated with the at least a first portion is above a first threshold of the one or more thresholds or below a second threshold of the one or more thresholds.

15. The one or more computer-readable media of claim 13, wherein when the signal is converted to the time domain, the at least a second portion is associated with a dominant portion of the signal.

16. The one or more computer-readable media of claim 10, wherein the determination of the signal strength measurement is based at least in part on at least one of an average or a weighted average of respective power values associated with the at least a second portion, wherein the signal strength measurement is a received signal strength indicator (RSSI) measurement.

17. The one or more computer-readable media of claim 10, wherein the signal comprises channel estimation results, the channel estimation results comprising an identification of the access point and respective amplitudes and phases associated with the multiple signal components.

18. The one or more computer-readable media of claim 10, wherein the signal comprises a first signal that is received by a first antenna associated with a user device, wherein the signal strength is a first signal strength associated with the first signal, and wherein the at least one processor is further configured to:

receive a second signal at a second antenna associated with the user device;

determine a second signal strength measurement associated with the second signal; and

determine a third signal strength measurement based at least in part on the first signal strength measurement and the second signal strength measurement;

wherein the first signal strength is based at least in part on first channel estimation results that are different from second channel estimation results associated with the second signal strength.

19. A device, comprising:

at least one memory that stores computer-executable instructions; and

at least one processor configured to access the at least one memory, wherein the at least one processor is configured to execute the computer-executable instructions to;

receive, over the network from one or more access points, a signal comprising multiple signal components;

convert the signal to a frequency domain signal such that the multiple signal components are associated with a first respective power value and a frequency;

convert the signal to a time domain signal such that the multiple signal components are associated with a second respective power value and a time unit;

determine a first signal strength measurement associated with the frequency domain signal based at least in part on the first respective power value;

determine a second signal strength measurement associated with the time domain signal based at least in part on the second respective power value; and

determine a combined signal strength measurement based at least in part on the first signal strength measurement and the second signal strength measurement.

20. The device of claim 19, the at least one processor further configured to determine a location of the user device based at least in part on the combined signal strength measurement.

21. The device of claim 19, wherein the determination of the first signal strength measurement comprises the at least one processor being further configured to:

identify at least a portion of the multiple signal components in the frequency domain signal having a respective power value that is located in a valley portion of the signal or a different respective power value that differs from a power value associated with a preceding portion by more than a threshold value;

wherein the determination of the first signal strength measurement does not include the at least a portion of the multiple signal components.

22. The device of claim 19, wherein the determination of the second signal strength measurement comprises the at least one processor being further configured to:

identify a dominant component in the time domain signal based at least in part on the second respective power value associated with the multiple signal components.

23. The device of claim 19, wherein the signal is modulated via Orthogonal Frequency Division Multiplexing (OFDM).