Wireless-based positioning adjustments using a motion sensor

1. A method for adjusting a wireless-based position estimate of a mobile station using a relative motion sensor, comprising:

estimating a position of a mobile station based upon wireless signal measurements;

measuring a movement of the mobile station using the relative motion sensor;

detecting a displacement of the mobile station based upon the measured movement;

determining that the displacement is below a threshold; and

adjusting the estimated position of the mobile station using information from the relative motion sensor.

2. The method of claim 1 , further comprising:

determining that the displacement is above a threshold; and

updating the position of the mobile station using additional wireless measurements.

3. The method of claim 1 , further comprising:

detecting substantially no displacement based upon the movement data;

determining that the mobile station in a power saving mode; and

entering a reduced power consumption state.

4. The method of claim 1 , wherein the estimating a position of a mobile station further comprises:

determining the mobile station position based upon Satellite Positioning System (SPS) signal measurements.

5. The method of claim 1 , wherein the measuring a movement of the mobile station further comprises:

measuring an acceleration of the mobile station;

integrating the acceleration to determine a distance;

determining an orientation angle corresponding to the movement of the mobile station; and

combining the acceleration and orientation angle to determine a vector describing the displacement of the mobile station.

6. The method of claim 5 , wherein the detecting a displacement of the mobile station further comprises:

thresholding the distance to classify the state of the mobile station as being stationary or moving.

7. The method of claim 1 , further comprising:

detecting substantially no displacement based upon the movement data;

determining an updated position of the mobile station based upon additional wireless signal measurements; and

combining the estimated and updated positions of the mobile station to produce an improved position estimate.

8. The method of claim 7 , wherein the combining the estimated and updated positions of the mobile station further comprises:

filtering multiple measurements of position derived using the wireless signal measurements to refine a processing delay associated with each wireless access point.

9. The method of claim 7 , wherein the mobile station and the wireless access points operate in accordance with IEEE 802.11 standards.

10. The method of claim 1 , wherein the estimating a position of a mobile station further comprises:

determining a distance to each of a plurality of wireless access points based upon a propagation delay and a processing delay associated with each wireless access point; and

calculating the position of the mobile station using the distance to each wireless access point.

11. The method of claim 10 , wherein the adjusting the estimated position of the mobile station further comprises:

deriving a displacement vector using the information from the relative motion sensor; and

refining the processing delay associated with each wireless access point using the derived displacement vector.

12. The method of claim 10 , wherein the adjusting the estimated position of the mobile station further comprises:

deriving a displacement vector using the information from the relative motion sensor; and

combining the estimated position of the mobile station with the displacement vector to determine a new position.

13. An apparatus for adjusting a wireless-based position estimate of a mobile station using a relative motion sensor, comprising:

a wireless transceiver;

a relative motion sensor;

a processor coupled to the wireless transceiver and the relative motion sensor; and

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

estimate a position of the mobile station based upon measurements of wireless signals received by the wireless transceiver,

determine that the mobile station is moving based upon information provided by the relative motion sensor,

calculate a displacement of the mobile station based upon the information provided by the relative motion sensor,

determine that the displacement is below a threshold, and

adjust the estimated position of the mobile station using the information from the relative motion sensor.

14. The apparatus of claim 13 , wherein the memory includes instructions further causing the processor to:

determine that the displacement is above a threshold, and

update the position of the mobile station using additional wireless measurements.

15. The apparatus of claim 13 , wherein the memory includes instructions further causing the processor to:

detect substantially no displacement based upon the movement data,

determine that the mobile station in a power saving mode, and

enter a reduced power consumption state.

16. The apparatus of claim 13 , wherein the memory includes instructions further causing the processor to

detect substantially no displacement based upon the movement data,

determine an updated position of the mobile station based upon additional wireless signal measurements, and

combining the estimated and updated positions of the mobile station to provide an improved position estimate.

17. The apparatus of claim 13 , wherein the memory includes instructions further causing the processor to:

determine a distance to each of a plurality of wireless access points based upon a propagation delay and a processing delay associated with each wireless access point; and

calculate the position of the mobile station using the distance to each wireless access point.

18. The apparatus of claim 13 , wherein the relative motion sensor comprises an accelerometer and/or an orientation sensor.

19. The apparatus of claim 13 , wherein the wireless transceiver comprises a wide area network transceiver and/or a local area network transceiver.

20. The apparatus of claim 19 , wherein the wide area network transceiver operates in accordance with WiMax (IEEE 801.16) and/or digital cellular networking standards.

21. The apparatus of claim 19 , wherein the local area network transceiver operates in accordance with WiFi (802.11x), cellular piconet, cellular femtocell, and/or Bluetooth networking standards.

22. The apparatus of claim 19 , further comprising: a Satellite Positioning System (SPS) receiver which receives wireless signals for performing position determination of the mobile station.

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

instructions to estimate a position of a mobile station based upon wireless signal measurements;

instructions to measure a movement of the mobile station using a relative motion sensor;

instructions to detect a displacement of the mobile station based upon the measured movement;

instructions to determine that the displacement is below a threshold; and instructions to adjust the estimated position of the mobile station using information from the relative motion sensor.

24. The machine-readable medium of claim 23 , further comprising:

instructions to determine that the displacement is above a threshold; and

instructions to update the position of the mobile station using additional wireless measurements.

25. The machine-readable medium of claim 23 , further comprising:

instructions to detect substantially no displacement based upon the movement data;

instructions to determine that the mobile station in a power saving mode; and

instructions to enter a reduced power consumption state.

26. The machine-readable medium of claim 23 , wherein the instructions to estimate a position of a mobile station further comprise:

instructions to determine the mobile station position based upon Satellite Positioning System (SPS) signal measurements.

27. The machine-readable medium of claim 23 , wherein the instructions to measure a movement of the mobile station further comprise:

instructions to measure an acceleration of the mobile station;

instructions to integrate the acceleration to determine a distance;

instructions to determine an orientation angle corresponding to the movement of the mobile station; and

instructions to combine the acceleration and orientation angle to determine a vector describing the displacement of the mobile station.

28. The machine-readable medium of claim 27 , wherein the instructions to detect a displacement of the mobile station further comprise:

instructions to threshold the distance to classify the state of the mobile station as being stationary or moving.

29. The machine-readable medium of claim 23 , further comprising:

instructions to detect substantially no displacement based upon the movement data;

instructions to determine an updated position of a mobile station based upon additional wireless signal measurements; and

instructions to combine the estimated and updated positions of the mobile station to provide an improved position estimate.

30. The machine-readable medium of claim 29 , wherein the instructions to combine the estimated and updated positions of the mobile station further comprise:

instructions to filter multiple measurements of position derived using the wireless signal measurements to refine a processing delay associated with each wireless access point.

31. The machine-readable medium of claim 23 , wherein the instructions to estimate a position of a mobile station further comprise:

instructions to determine a distance to each of a plurality of wireless access points based upon a propagation delay and a processing delay associated with each wireless access point; and

instructions to calculate the position of the mobile station using the distance to each wireless access point.

32. The machine-readable medium of claim 31 , wherein the instructions to adjust the estimated position of the mobile station further comprise:

instructions to derive a displacement vector using the information from the relative motion sensor; and

instructions to refine the processing delay associated with each wireless access point using the derived displacement vector.

33. The machine-readable medium of claim 31 , wherein the instructions to adjust the estimated position of the mobile station further comprise:

instructions to derive a displacement vector using the information from the relative motion sensor; and

instructions to combine the estimated position of the mobile station with the displacement vector to determine a new position.

34. An apparatus for adjusting a wireless-based position estimate of a mobile station using a relative motion sensor, comprising:

means for estimating a position of a mobile station based upon wireless signal measurements;

means for measuring a movement of the mobile station using the relative motion sensor;

means for detecting a displacement of the mobile station based upon the measured movement;

means for determining that the displacement is below a threshold; and

means for adjusting the estimated position of the mobile station using information from the relative motion sensor.

35. The apparatus of claim 34 , further comprising:

means for determining that the displacement is above a threshold; and

means for updating the position of the mobile station using additional wireless measurements.

36. The apparatus of claim 34 , further comprising:

means for detecting substantially no displacement based upon the movement data;

means for determining that the mobile station in a power saving mode; and

means for entering a reduced power consumption state.

37. The apparatus of claim 34 , wherein the means for estimating a position of a mobile station further comprises:

means for determining the mobile station position based upon Satellite Positioning System (SPS) signal measurements.

38. The apparatus of claim 34 , wherein the means for measuring a movement of the mobile station further comprises:

means for measuring an acceleration of the mobile station;

means for integrating the acceleration to determine a distance;

means for determining an orientation angle corresponding to the movement of the mobile station; and

means for combining the acceleration and orientation angle to determine a vector describing the displacement of the mobile station.

39. The apparatus of claim 38 , wherein the means for detecting a displacement of the mobile station further comprises:

means for thresholding the distance to classify the state of the mobile station as being stationary or moving.

40. The apparatus of claim 34 , further comprising:

means for detecting substantially no displacement based upon the movement data;

means for determining an updated position of a mobile station based upon additional wireless signal measurements; and

means for combining the estimated and updated positions of the mobile station to improve the accuracy thereof.

41. The apparatus of claim 40 , wherein the means for combining the estimated and updated positions of the mobile station further comprises:

means for filtering multiple measurements of position derived using the wireless signal measurements to refine a processing delay associated with each wireless access point.

42. The apparatus of claim 34 , wherein the means for estimating a position of a mobile station further comprises:

means for determining a distance to each of a plurality of wireless access points based upon a propagation delay and a processing delay associated with each wireless access point; and

means for calculating the position of the mobile station using the distance to each wireless access point.

43. The apparatus of claim 42 , wherein the means for adjusting the estimated position of the mobile station further comprises:

means for deriving a displacement vector using the information from the relative motion sensor; and

means for refining the processing delay associated with each wireless access point using the derived displacement vector.

44. The apparatus of claim 42 , wherein the means for adjusting the estimated position of the mobile station further comprises:

means for deriving a displacement vector using the information from the relative motion sensor; and

means for combining the estimated position of the mobile station with the displacement vector to determine a new position.