NETWORK-CENTRIC DETERMINATION OF NODE PROCESSING DELAY

• US 20100128637A1
• Filed: 11/19/2009
• Published: 05/27/2010
• Est. Priority Date: 11/21/2008
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Naguib, Ayman Fawzy, Sridhara, Vinay, Aggarwal, Alok
• Granted Patent: US 9,645,225 B2
• Time in Patent Office: Days
• US Class Current: 370/254
• CPC Class Codes: G01S 5/021 Calibration, monitoring or correction G01S5/0252 takes precedence
• CPC Class Codes: G01S 5/0284 Relative positioning
• CPC Class Codes: G01S 5/06 Position of source determined by co-ordinating a plurality of position lines defined by path-difference measurements G01S5/12 takes precedence
• CPC Class Codes: H04L 67/52 specially adapted for the location of the user terminal
• CPC Class Codes: H04W 4/021 Services related to particular areas, e.g. point of interest [POI] services, venue services or geofences
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management

Abstract

Apparatus and methods are directed to calibrating a delay within a wireless access point for determining a position of a mobile station. One method includes receiving an initial packet at an eavesdropping device, receiving a response packet, sent by another entity, at the eavesdropping device, computing a time difference based upon the packet arrival times, and providing the time difference to a position determination entity. Another method includes providing a request to appropriate eavesdropping devices to send information, receiving, from each appropriate eavesdropping device, a time difference which represents a difference in a time of arrival of a packet transmitted by the wireless access point and a time of arrival of a packet transmitted by the mobile station, determining a processing delay estimate based upon the time differences, and determining a position of the mobile station based upon the processing delay estimate and the received time differences.

Claims

1. A method of calibrating a delay within a wireless access point for determining a position of a mobile station, comprising:

receiving an initial packet, sent by the mobile station, at an eavesdropping device;

receiving a response packet, sent by the wireless access point, at the eavesdropping device;

computing a time difference based upon the initial packet and the response packet arrival times; and

providing the time difference to a position determination entity.

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

measuring a first arrival time corresponding to the initial packet;

measuring a second arrival time corresponding to the response packet; and

determining a difference between the second and the first arrival times.

3. The method according to claim 1, wherein the wireless access point comprises a conventional wireless access point or femtocell, and/or the mobile device comprises a conventional mobile device.

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

determining an initial estimate of a processing delay associated with the wireless access point;

determining at least one appropriate eavesdropping device to request information; and

obtaining the requested information from each appropriate eavesdropping device.

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

providing a request to the appropriate eavesdropping devices to send information;

receiving, from each appropriate eavesdropping device, a time difference which represents difference in a time of arrival of the packet transmitted by the wireless access point and a time of arrival of a packet transmitted by the mobile station;

refining the initial estimate of the processing delay based upon the received time differences; and

determining a position of the mobile station based upon the refined processing delay and the received time differences.

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

bounding the processing delay of the wireless access point based upon the received time differences.

7. The method according to claim 6, wherein the processing delay is bound by a triangle inequality.

8. A method of refining calibrating a delay within a wireless access point for determining a position of a mobile station, comprising:

providing a request to appropriate eavesdropping devices to send information;

receiving, from each appropriate eavesdropping device, a time difference which represents a difference in a time of arrival of a packet transmitted by the wireless access point and a time of arrival of a packet transmitted by the mobile station;

determining a processing delay estimate based upon the time differences; and

determining a position of the mobile station based upon the processing delay estimate and the received time differences.

9. The method according to claim 8, wherein determining the processing delay estimate further comprises:

determining a range for the processing delay by using the received time differences in a triangle inequality.

10. The method according to claim 8, wherein determining the processing delay estimate further comprises:

determining a relative geometry of the mobile device, the wireless access point and each eavesdropping device;

determining a range for the processing delay by using the received time differences in a triangle inequality; and

selecting a value from the range based upon the determined relative geometry.

11. The method according to claim 10, wherein it is determined the relative geometry is substantially collinear, and the wireless access point is between the mobile station and the eavesdropping device, or the mobile station is between the wireless access point and the eavesdropping device, the method further comprises:

selecting a value from the upper end of the range as the refined processing delay.

12. The method according to claim 10, wherein it is determined the relative geometry is substantially collinear, and the eavesdropping device is between the mobile station and the wireless access point, the method further comprises:

selecting a value from the lower end of the range as the refined processing delay.

13. The method according to claim 8, wherein determining the processing delay estimate further comprises:

receiving, from each of the appropriate eavesdropping devices, a signal strength value associated with the packets of the mobile station which were received at each eavesdropping device;

bounding the distance between the eavesdropping devices and the mobile station based upon the of the signal strength values.

14. The method according to claim 8, wherein determining the processing delay estimate further comprises:

determining a range for a distance between the mobile station and each eavesdropping device based upon received signal strength at the eavesdropping device;

estimating a distance between the mobile station and each eavesdropping device as the midpoint of the range;

calculating an estimate of the position of the mobile station using trilateration based upon the estimated distances;

calculating the distance between the mobile station and the wireless access point, and mobile station and each eavesdropping device, based upon the estimated position of the mobile device; and

refine the processing estimate based upon the calculated distances and the time differences.

15. The method according to claim 8, wherein determining the processing delay estimate further comprises:

calculating a first distance estimate between the mobile station and the wireless access point based upon a previous position of the mobile station;

calculating a second distance estimate between the mobile station and each eavesdropping device based upon the previous position of the mobile station;

determining processing delay estimates based upon the first distance estimate and each second distance estimate; and

refining processing delay estimate by combining the processing delay estimates.

16. The method according to claim 8, wherein determining a position of the mobile station further comprises:

adjusting each time difference using the processing delay;

determining distance differences by subtracting a distance between the wireless access point and each eavesdropping device from the adjusted time differences; and

performing multilateration using the distance differences to estimate the position of the mobile station.

17. An apparatus for calibrating a delay within a wireless access point and determining a position of a mobile station, 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;

receive a initial packet, sent by the mobile station, at an eavesdropping device,

receive a response packet, sent by the wireless access point, at the eavesdropping device,

compute a time difference based upon the initial packet and the response packet arrival times, and

provide the time difference to a position determination entity.

18. The apparatus according to claim 17, wherein the instructions further cause the processor to:

measure a first arrival time corresponding to the initial packet,

measure a second arrival time corresponding to the response packet, and

determine a difference between the second and the first arrival times.

19. The apparatus according to claim 17, wherein the wireless access point comprises a conventional wireless access point or femtocell, and/or the mobile device comprises a conventional mobile device.

20. The apparatus according to claim 17, wherein the instructions further cause the processor to:

determine an initial estimate of a processing delay associated with the wireless access point,

determine at least one appropriate eavesdropping device to request information, and

obtain the requested information from each appropriate eavesdropping device.

21. The apparatus according to claim 20, wherein the instructions further cause the processor to:

provide a request to the appropriate eavesdropping devices to send information,

receive, from each appropriate eavesdropping device, a time difference which represents difference in a time of arrival of the packet transmitted by the wireless access point and a time of arrival of the packet transmitted by the mobile station,

refine the initial estimate of the processing delay estimate based upon the received time differences, and

determine a position of the mobile station based upon the refined processing delay and the received time differences.

22. The apparatus according to claim 21, wherein the instructions further cause the processor to:

bound the processing delay of the wireless access point based upon the received time differences.

23. The apparatus according to claim 22 wherein the processing delay is bound by a triangle inequality.

24. An apparatus for calibrating a delay within a wireless access point and determining a position of a mobile station, comprising:

a network interface;

a processor coupled to the network interface; and

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

provide a request to appropriate eavesdropping devices to send information,

receive, from each appropriate eavesdropping device, a time difference which represents a difference in a time of arrival of a packet transmitted by the wireless access point and a time of arrival of a packet transmitted by the mobile station,

determine a processing delay estimate based upon the time differences, and

determine a position of the mobile station based upon the processing delay estimate and the received time differences.

25. The apparatus according to claim 24, wherein the instructions further cause the processor to:

determine a range for the processing delay by using the received time differences in a triangle inequality.

26. The apparatus according to claim 24, wherein the instructions further cause the processor to:

determine a relative geometry of the mobile device, the wireless access point and each eavesdropping device,

determine a range for the processing delay by using the received time differences in a triangle inequality, and

select a value from the range based upon the determined relative geometry.

27. The apparatus according to claim 26, wherein it is determined the relative geometry is substantially collinear, and the wireless access point is between the mobile station and the eavesdropping device, or the mobile station is between the wireless access point and the eavesdropping device, the instructions further cause the processor to:

select a value from the upper end of the range as a refined processing delay.

28. The apparatus according to claim 26, wherein it is determined the relative geometry is substantially collinear, and the eavesdropping device is between the mobile station and the wireless access point, the instructions further cause the processor to:

select a value from the lower end of the range as a refined processing delay.

29. The apparatus according to claim 24, wherein the instructions further cause the processor to:

receive, from each of the appropriate eavesdropping devices, a signal strength value associated with the packet of the mobile station which was received at each eavesdropping device;

bound the distance between the eavesdropping devices and the mobile station based upon the signal strength values.

30. The apparatus according to claim 24, wherein the instructions further cause the processor to:

determine a range for a distance between the mobile station and each eavesdropping device based upon received signal strength at the eavesdropping device,

estimate a distance between the mobile station and each eavesdropping device as the midpoint of the range,

calculate an estimate of the position of the mobile station using trilateration based upon the estimated distances,

calculate the distance between the mobile station and the wireless access point, and mobile station and each eavesdropping device, based upon the estimated position of the mobile device, and

refine the processing delay estimate based upon the calculated distances and the time differences.

31. The apparatus according to claim 24, wherein the instructions further cause the processor to:

calculate a first distance estimate between the mobile station and the wireless access point based upon a previous position of the mobile station,

calculate a second distance estimate between the mobile station and each eavesdropping device based upon the previous position of the mobile station,

determine processing delay estimates based upon the first distance estimate and each second distance estimate, and

refine processing delay estimate by combining the processing delay estimates.

32. The apparatus according to claim 24, wherein the instructions further cause the processor to:

adjust each time difference using the processing delay,

determine distance differences by subtracting a distance between the wireless access point and each eavesdropping device from the adjusted time differences, and

perform multilateration using the distance differences to estimate the position of the mobile station.

33. An apparatus for calibrating a delay within a wireless access point and determining a position of a mobile station, comprising:

means for receiving a initial packet, sent by the mobile station, at an eavesdropping device;

means for receiving a response packet, sent by the wireless access point, at the eavesdropping device;

means for computing a time difference based upon the initial packet and the response packet arrival times; and

means for providing the time difference to a position determination entity.

34. The apparatus according to claim 33, further comprising:

means for measuring a first arrival time corresponding to the initial packet;

means for measuring a second arrival time corresponding to the response packet; and

means for determining a difference between the second and the first arrival times.

35. An apparatus for calibrating a delay within a wireless access point and determining a position of a mobile station, comprising:

means for providing a request to appropriate eavesdropping devices to send information;

means for receiving, from each appropriate eavesdropping device, a time difference which represents a difference in a time of arrival of a packet transmitted by the wireless access point and a time of arrival of a packet transmitted by the mobile station;

means for determining a processing delay estimate based upon the time differences; and

means for determining a position of the mobile station based upon the processing delay estimate and the time differences.

36. The apparatus according to claim 35, wherein the means for determining the processing delay estimate further comprises:

means for determining a relative geometry of the mobile device, the wireless access point and each eavesdropping device;

means for determining a range for the processing delay by using the received time differences in a triangle inequality; and

means for selecting a value from the range based upon the determined relative geometry.

37. The apparatus according to claim 36, wherein it is determined the relative geometry is substantially collinear, and the wireless access point is between the mobile station and the eavesdropping device, or the mobile station is between the wireless access point and the eavesdropping device, the apparatus further comprises:

means for selecting a value from the upper end of the range as a refined processing delay.

38. The apparatus according to claim 35, wherein the means for determining the processing delay estimate further comprises:

means for receiving, from each of the appropriate eavesdropping devices, a signal strength value associated with the packet of the mobile station which was received at each eavesdropping device;

means for bounding the distance between the eavesdropping devices and the mobile station based upon the of the signal strength values.

39. The apparatus according to claim 35, wherein the means for determining the processing delay estimate further comprises:

means for determining a range for a distance between the mobile station and each eavesdropping device based upon received signal strength at the eavesdropping device;

means for estimating a distance between the mobile station and each eavesdropping device as the midpoint of the range;

means for calculating an estimate of the position of the mobile station using trilateration based upon the estimated distances;

means for calculating the distance between the mobile station and the wireless access point, and mobile station and each eavesdropping device, based upon the estimated position of the mobile device; and

means for refining the processing delay estimate based upon the calculated distances and the time differences.

40. The apparatus according to claim 35, wherein the means for determining the processing delay estimate further comprises:

means for calculating a first distance estimate between the mobile station and the wireless access point based upon a previous position of the mobile station;

means for calculating a second distance estimate between the mobile station and each eavesdropping device based upon the previous position of the mobile station;

means for determining processing delay estimates based upon the first distance estimate and each second distance estimate; and

means for refining the processing delay estimate by combining the processing delay estimates.

41. The apparatus according to claim 35, wherein the means for determining a position of the mobile station further comprises:

means for adjusting each time difference using the processing delay estimate;

means for determining distance differences by subtracting a distance between the wireless access point and each eavesdropping device from the adjusted time differences; and

means for performing multilateration using the distance differences to estimate the position of the mobile station.

42. A machine-readable medium comprising instructions, which, when executed by a machine, cause the machine to perform operations, the instructions comprising:

instructions to receive a initial packet, sent by a mobile station, at an eavesdropping device;

instructions to receive a response packet, sent by a wireless access point, at the eavesdropping device;

instructions to compute a time difference based upon the initial packet and the response packet arrival times; and

instructions to provide the time difference to a position determination entity.

43. The machine-readable medium according to claim 42, further comprising:

instructions to measure a first arrival time corresponding to the initial packet;

instructions to measure a second arrival time corresponding to the response packet; and

instructions to determine a difference between the second and the first arrival times.

44. A machine-readable medium comprising instructions, which, when executed by a machine, cause the machine to perform operations, the instructions comprising:

instructions to provide a request to appropriate eavesdropping devices to send information;

instructions to receive, from each appropriate eavesdropping device, a time difference which represents a difference in a time of arrival of a packet transmitted by a wireless access point and a time of arrival of a packet transmitted by a mobile station;

instructions to determine a processing delay estimate based upon the time differences; and

instructions to determine a position of the mobile station based upon the processing delay estimate and the time differences.

45. The machine-readable medium according to claim 44, wherein the instructions to determine the processing estimate further comprise:

instructions to determine a relative geometry of the mobile device, the wireless access point and each eavesdropping device;

instructions to determine a range for the processing delay by using the received time differences in a triangle inequality; and

instructions to select a value from the range based upon the determined relative geometry.

46. The machine-readable medium according to claim 45, wherein it is determined the relative geometry is substantially collinear, and the wireless access point is between the mobile station and the eavesdropping device, or the mobile station is between the wireless access point and the eavesdropping device, the instructions further comprise:

instructions to select a value from the upper end of the range as a refined processing delay.

47. The machine-readable medium according to claim 44, wherein the instructions to determine the processing delay estimate further comprise:

instructions to receive, from each of the appropriate eavesdropping devices, a signal strength value associated with the packet of the mobile station which was received at each eavesdropping device; and

instructions to bound the distance between the eavesdropping devices and the mobile station based upon the of the signal strength values.

48. The machine-readable medium according to claim 44, wherein the instructions to determine the processing delay estimate further comprise:

instructions to determine a range for a distance between the mobile station and each eavesdropping device based upon received signal strength at the eavesdropping device;

instructions to estimate a distance between the mobile station and each eavesdropping device as the midpoint of the range;

instructions to calculate an estimate of the position of the mobile station using trilateration based upon the estimated distances;

instructions to calculate the distance between the mobile station and the wireless access point, and mobile station and each eavesdropping device, based upon the estimated position of the mobile device; and

instructions to refine the processing estimate based upon the calculated distances and the time differences.

49. The machine-readable medium according to claim 44, wherein the instructions to determine the processing delay estimate further comprise:

instructions to calculate a first distance estimate between the mobile station and the wireless access point based upon a previous position of the mobile station;

instructions to calculate a second distance estimate between the mobile station and each eavesdropping device based upon the previous position of the mobile station;

instructions to determine processing delay estimates based upon the first distance estimate and each second distance estimate; and

instructions to refine processing delay estimate by combining the processing delay estimates.

50. The machine-readable medium according to claim 44, wherein the instructions to determine a position of the mobile station further comprise:

instructions to adjust each time difference using the processing delay estimate;

instructions to determine distance differences by subtracting a distance between the wireless access point and each eavesdropping device from the adjusted time differences; and

instructions to perform multilateration using the distance differences to estimate the position of the mobile station.