Wireless signal model updating using determined distances

• US 20130237246A1
• Filed: 04/09/2013
• Published: 09/12/2013
• Est. Priority Date: 11/21/2008
• Status: Abandoned Application

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: AGGARWAL, Alok, Naguib, Ayman Fawzy, Sridhara, Vinay, Das, Saumitra Mohan
• Application Number:
  US13/859,658
• Publication Number:
  US 20130237246A1
• Time in Patent Office: Days
• US Class Current: 455/456.1
• CPC Class Codes: G01S 13/765 with exchange of information between interrogator and responder
• CPC Class Codes: G01S 5/10 Position of receiver fixed by co-ordinating a plurality of position lines defined by path-difference measurements , e.g. omega or decca systemsG01S5/12 takes precedence ; beacons and receivers cooperating therewith G01S1/306, G01S1/308
• CPC Class Codes: G01S 5/14 Determining absolute distances from a plurality of spaced points of known location
• CPC Class Codes: H04W 24/00 Supervisory, monitoring or testing arrangements
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management

Abstract

An example method for updating a wireless signal model includes: measuring a distance from a mobile station to each wireless access point, of multiple wireless access points, based upon a wireless signal model; calculating a position of the mobile station based upon the measured distance; determining a computed distance to each wireless access point based upon the calculated position of the mobile station; updating the wireless signal model based upon the measured and computed distances to each wireless access point; and determining whether the wireless signal model has converged.

Claims

1. A method for updating a wireless signal model, the method comprising:

measuring a distance from a mobile station to each wireless access point, of a plurality of wireless access points, based upon a wireless signal model;

calculating a position of the mobile station based upon the measured distance;

determining a computed distance to each wireless access point based upon the calculated position of the mobile station;

updating the wireless signal model based upon the measured and computed distances to each wireless access point; and

determining whether the wireless signal model has converged.

2. The method according to claim 1, further comprising:

repeating the method of claim 1 when the wireless signal model has not converged.

3. The method according to claim 1, further comprising:

determining that the wireless signal model has not converged;

refining the distance measurement to each wireless access point based upon the updated wireless signal model;

calculating a refined position of the mobile station based upon the refined distance measurement;

determining another computed distance to each wireless access point based upon the refined position of the mobile station; and

updating the wireless signal model based upon the refined measurement and computed distances to each wireless access point.

4. The method according to claim 1, wherein the wireless signal model relates the distance between the mobile station and each wireless access point to a round trip time (RTT) of the wireless signal.

5. The method according to claim 4, further comprising:

measuring a round trip time (RTT) to each of the wireless access points;

determining a first distance to each wireless access point based upon the round trip time delay;

determining a second distance to each wireless access point based upon supplemental information;

calculating the position of the mobile station using the first and second distances to each wireless access point; and

updating the initial processing time for each of the wireless access points based upon the calculated position of the mobile station.

6. The method according to claim 5 further comprising:

determining that at least one of the updated processing times have not converged;

measuring the round trip time delay to each of the plurality of wireless access points;

determining a revised first distance to each wireless access point based upon the round trip time delay and the updated processing time associated with each wireless access point;

calculating a subsequent position of the mobile station using the revised first distance and the second distance to each wireless access point; and

refining the updated processing time for each of the wireless access points based upon the subsequent position of the mobile station.

7. The method according to claim 5, wherein the supplemental information may be derived from RSSI models, a previous position estimate, information provided by Bluetooth, beacons, RFID tags, coordinates from a map, and/or Satellite Positioning System (SPS) signals.

8. The method according to claim 1, wherein the wireless signal model relates the distance between the mobile station and each wireless access point to received signal strength intensity (RSSI) of the wireless signal.

9. The method of claim 8, wherein the model assumes an indoor environment and further comprises:

receiving an initial model of the indoor environment;

calculating an initial position of the mobile station based upon the initial distance to each wireless access point; and

updating the initial model using the calculated initial position and the received signal strength of the packet.

10. The method of claim 9, further comprising:

updating the model of the indoor environment based upon subsequent positions and received signal strength measurements as the mobile station moves within the indoor environment.

11. The method of claim 9, wherein the initial model is generated based upon ray tracing a map of the indoor environment.

12. The method of claim 9, wherein the initial model is generated based upon generic models of indoor environments.

13. The method of claim 12, wherein the generic models of indoor environments include office environments, warehouse environments, and/or shopping mall environments.

14. The method of claim 9, wherein calculating an initial position of the mobile station further comprises:

determining an initial distance to each wireless access point based upon the initial model; and

performing trilateration using the initial distances.

15. The method of claim 9, wherein calculating an initial position of the mobile station further comprises:

matching observed RSSI values with a fingerprinting database.

16. The method of claim 1, wherein the determining the second distance to each wireless access point further comprises:

determining a mean RTT noise from the supplemental information;

subtracting the initial processing time and the mean RTT noise from the RTT to determine an adjusted time value; and

converting the adjusted time to the second distance.

17. The method of claim 16, wherein the mean RTT noise value is based upon a received signal strength intensity value associated with each wireless access point.

18. The method of claim 1, wherein it is determined that the wireless signal model has converged, further comprising:

storing parameters associated with the wireless signal model.

19. An apparatus for updating a wireless signal model, comprising:

a wireless transceiver;

a processor coupled to the wireless transceiver; and

a memory coupled to the processor, wherein the memory stores executable instructions and data for causing the processor to

measure a distance from a mobile station to each wireless access point, of a plurality of wireless access points, based upon a wireless signal model,

calculate a position of the mobile station based upon the measured distance,

determine a computed distance to each wireless access point based upon the calculated position of the mobile station,

update the wireless signal model based upon the measured and computed distances to each wireless access point, and

determine whether the wireless signal model has converged.

20. The apparatus according to claim 19, further comprising instructions causing the processor to

repeat the instructions of claim 19 when the wireless signal model has not converged.

21. The apparatus according to claim 19, further comprising instructions causing the processor to

determine that the wireless signal model has not converged,

refine the distance measurement to each wireless access point based upon the updated wireless signal model,

calculate a refined position of the mobile station based upon the refined distance measurement,

determine another computed distance to each wireless access point based upon the refined position of the mobile station, and

update the wireless signal model based upon the refined measurement and computed distances to each wireless access point.

22. The apparatus according to claim 19, wherein the wireless signal model relates the distance between the mobile station and each wireless access point to a round trip time (RTT) of the wireless signal.

23. The apparatus according to claim 22, further comprising instructions causing the processor to

measure a round trip time (RTT) to each of the wireless access points,

determine a first distance to each wireless access point based upon the round trip time delay,

determine a second distance to each wireless access point based upon supplemental information,

calculate the position of the mobile station using the first and second distances to each wireless access point, and

update the initial processing time for each of the wireless access points based upon the calculated position of the mobile station.

24. The apparatus according to claim 23 further comprising instructions causing the processor to

determine that at least one of the updated processing times have not converged,

measure the round trip time delay to each of the plurality of wireless access points,

determine a revised first distance to each wireless access point based upon the round trip time delay and the updated processing time associated with each wireless access point,

calculate a subsequent position of the mobile station using the revised first distance and the second distance to each wireless access point, and

refine the updated processing time for each of the wireless access points based upon the subsequent position of the mobile station.

25. The apparatus according to claim 23, wherein the supplemental information may be derived from RSSI models, a previous position estimate, information provided by Bluetooth, beacons, RFID tags, coordinates from a map, and/or Satellite Positioning System (SPS) signals.

26. The apparatus according to claim 19, wherein the wireless signal model relates the distance between the mobile station and each wireless access point to received signal strength intensity (RSSI) of the wireless signal.

27. The apparatus of claim 26, wherein the model assumes an indoor environment and the apparatus further comprises instructions causing the processor to

receive an initial model of the indoor environment,

calculate an initial position of the mobile station based upon the initial distance to each wireless access point, and

update the initial model using the calculated initial position and the received signal strength of the packet.

28. The apparatus of claim 27, further comprising instructions causing the processor to

update the model of the indoor environment based upon subsequent positions and received signal strength measurements as the mobile station moves within the indoor environment.

29. The apparatus of claim 27, wherein the initial model is generated based upon ray tracing a map of the indoor environment.

30. The apparatus of claim 27, wherein the initial model is generated based upon generic models of indoor environments.

31. The apparatus of claim 30, wherein the generic models of indoor environments include office environments, warehouse environments, and/or shopping mall environments.

32. The apparatus of claim 27, wherein calculating an initial position of the mobile station further comprises instructions causing the processor to

determine an initial distance to each wireless access point based upon the initial model, and

perform trilateration using the initial distances.

33. The apparatus of claim 27, wherein calculating an initial position of the mobile station further comprises instructions causing the processor to

match observed RSSI values with a fingerprinting database.

34. The apparatus of claim 19, wherein the determining the second distance to each wireless access point further comprises instructions causing the processor to

determine a mean RTT noise from the supplemental information,

subtract the initial processing time and the mean RTT noise from the RTT to determine an adjusted time value, and

convert the adjusted time to the second distance.

35. The apparatus of claim 34, wherein the mean RTT noise value is based upon a received signal strength intensity value associated with each wireless access point.

36. The apparatus of claim 19, wherein it is determined that the wireless signal model has converged, further comprising instructions causing the processor to

store parameters associated with the wireless signal model.

37. An apparatus for updating a wireless signal model, comprising:

means for measuring a distance from a mobile station to each wireless access point, of a plurality of wireless access points, based upon a wireless signal model;

means for calculating a position of the mobile station based upon the measured distance;

means for determining a computed distance to each wireless access point based upon the calculated position of the mobile station;

means for updating the wireless signal model based upon the measured and computed distances to each wireless access point; and

means for determining whether the wireless signal model has converged.

38. The apparatus according to claim 37, further comprising:

means for repeating the functions of claim 37 when the wireless signal model has not converged.

39. The apparatus according to claim 37, further comprising:

means for determining that the wireless signal model has not converged;

means for refining the distance measurement to each wireless access point based upon the updated wireless signal model;

means for calculating a refined position of the mobile station based upon the refined distance measurement;

means for determining another computed distance to each wireless access point based upon the refined position of the mobile station; and

means for updating the wireless signal model based upon the refined measurement and computed distances to each wireless access point.

40. The apparatus according to claim 37, wherein the wireless signal model relates the distance between the mobile station and each wireless access point to a round trip time (RTT) of the wireless signal.

41. The apparatus according to claim 40, further comprising:

measuring a round trip time (RTT) to each of the wireless access points;

means for determining a first distance to each wireless access point based upon the round trip time delay;

means for determining a second distance to each wireless access point based upon supplemental information;

means for calculating the position of the mobile station using the first and second distances to each wireless access point; and

means for updating the initial processing time for each of the wireless access points based upon the calculated position of the mobile station.

42. The apparatus according to claim 41 further comprising:

means for determining that at least one of the updated processing times have not converged;

means for measuring the round trip time delay to each of the plurality of wireless access points;

means for determining a revised first distance to each wireless access point based upon the round trip time delay and the updated processing time associated with each wireless access point;

means for calculating a subsequent position of the mobile station using the revised first distance and the second distance to each wireless access point; and

means for refining the updated processing time for each of the wireless access points based upon the subsequent position of the mobile station.

43. The apparatus according to claim 37, wherein the wireless signal model relates the distance between the mobile station and each wireless access point to received signal strength intensity (RSSI) of the wireless signal.

44. The apparatus of claim 43, wherein the model assumes an indoor environment and further comprises:

means for receiving an initial model of the indoor environment;

means for calculating an initial position of the mobile station based upon the initial distance to each wireless access point; and

means for updating the initial model using the calculated initial position and the received signal strength of the packet.

45. The apparatus of claim 44, further comprising:

means for updating the model of the indoor environment based upon subsequent positions and received signal strength measurements as the mobile station moves within the indoor environment.

46. The apparatus of claim 44, wherein calculating an initial position of the mobile station further comprises:

means for determining an initial distance to each wireless access point based upon the initial model; and

means for performing trilateration using the initial distances.

47. The apparatus of claim 37, wherein the determining the second distance to each wireless access point further comprises:

means for determining a mean RTT noise from the supplemental information;

means for subtracting the initial processing time and the mean RTT noise from the RTT to determine an adjusted time value; and

means for converting the adjusted time to the second distance.