SYSTEM AND METHOD FOR USING A SATELLITE POSITIONING SYSTEM TO FILTER WLAN ACCESS POINTS IN A HYBRID POSITIONING SYSTEM

• US 20090303121A1
• Filed: 06/05/2009
• Published: 12/10/2009
• Est. Priority Date: 06/06/2008
• Status: Active Grant

• Current Assignee: Skyhook Wireless Incorporated (Liberty Broadband Corp.)
• Original Assignee: Skyhook Wireless Incorporated (Liberty Broadband Corp.)
• Inventors: ALIZADEH-SHABDIZ, Farshid
• Granted Patent: US 7,999,742 B2
• Time in Patent Office: Days
• US Class Current: 342/357.250
• CPC Class Codes: G01S 19/34 Power consumption
• CPC Class Codes: G01S 19/46 the supplementary measurement being of a radio-wave signal type
• CPC Class Codes: G01S 19/48 by combining or switching between position solutions derived from the satellite radio beacon positioning system and position solutions derived from a further system

Abstract

This disclosure describes a system and method for using a satellite positioning system to filter WLAN access points in a hybrid positioning system. In some embodiments, the method can include detecting WLAN APs in range of the WLAN and satellite enabled device, obtaining satellite measurements from at least two satellites to provide a plurality of possible satellite locations of the device, and providing a weight for each AP based on the distance from the WLAN APs to the possible satellite locations of the device.

Claims

1. A method of determining the location of a WLAN and satellite enabled device by using satellite measurements to weigh WLAN access points (APs), the method comprising:

detecting WLAN APs in range of the WLAN and satellite enabled device;

obtaining satellite measurements from at least two satellites to provide a plurality of possible satellite locations of the device; and

providing a weight for each AP based on the distance from the WLAN APs to the possible satellite locations of the device.

2. The method of claim 1 comprising using the weight for each AP in a location algorithm to determine the location of the device.

3. The method of claim 1, wherein the possible satellite locations of the device comprises a region of possible location solutions for the device.

4. The method of claim 1, wherein a high weight corresponds to an AP that is close to the possible satellite locations of the device.

5. The method of claim 4, wherein close to the satellite estimate of the location of the device comprises a distance within one order of magnitude of the coverage area of the AP.

6. The method of claim 1, wherein a low weight corresponds to an AP that is far from the satellite estimation of the location of the device.

7. The method of claim 6, wherein a WLAN AP is far from the location of the device if the AP is located at a distance an order of magnitude above the coverage area of the AP.

8. The method of claim 6, wherein if the WLAN AP is determined to be far from the possible satellite locations of the device, the position of the WLAN and satellite enabled device is calculated without data from the far WLAN AP.

9. The method of claim 1, wherein the weight is based on the consistency between the location of the WLAN APs and the possible satellite locations of the device.

10. The method of claim 1 comprising:

eliminating WLAN APs which are not consistent with the possible satellite locations of the device.

11. The method of claim 10, wherein the WLAN AP location consistency with the satellite information is measured by applying each of the WLAN AP locations to the satellite measurements and calculating the internal SPS receiver clock bias for each WLAN AP location.

12. The method of claim 10 comprising calculating an internal SPS receiver clock bias by considering the location of each WLAN AP as an initial position and the measurements from each satellite.

13. The method of claim 10, wherein the consistency of the internal SPS receiver clock bias for each of the WLAN AP locations are used as an indication of distance between the WLAN AP location and the possible satellite device locations.

14. The method of claim 10, wherein calculating the consistency of the internal SPS receiver clock bias for each WLAN AP location comprises calculating the standard deviation or the mean square error of the internal SPS receiver clock bias.

22. The system of claim 1, WLAN APs which are not consistent with the possible satellite locations of the device are eliminated.

15. A system for determining the location of a WLAN and satellite enabled device by using satellite measurements to weigh WLAN access points (APs), the system comprising:

a hybrid positioning module comprising;

a WLAN module for receiving information from one or more WLAN access points;

a satellite positioning module for providing a plurality of possible device locations of the device based on satellite information from at least two different satellites; and

logic contained in the positioning module for providing a weight for each AP based on the distance from the WLAN APs to the possible satellite device locations of the device.

16. The system of claim 15, wherein a high weight corresponds to an AP that is close to the possible satellite locations of the device.

17. The system of claim 16, wherein close to the satellite estimate of the location of the device comprises a distance within one order of magnitude of the coverage area of the AP.

18. The system of claim 15, wherein a low weight corresponds to an AP that is far from the satellite estimation of the location of the device.

19. The system of claim 18, wherein a WLAN AP is far from the location of the device if the AP is located at a distance an order of magnitude above the coverage area of the AP.

20. The system of claim 19, wherein if the WLAN AP is determined to be far from the possible satellite locations of the device, the position of the WLAN and satellite enabled device is calculated without data from the far WLAN AP.

21. The system of claim 15, wherein the weight is based on the consistency between the location of the WLAN APs and the possible satellite locations of the device.

23. The system of claim 21, wherein the WLAN AP location consistency with the satellite information is measured by applying each of the WLAN AP locations to the satellite measurements and calculating the internal SPS receiver clock bias for each WLAN AP location.

24. The system of claim 21 comprising calculating an internal SPS receiver clock bias by considering the location of each WLAN AP as an initial position and the measurements from each satellite.

25. The system of claim 21, wherein the consistency of the internal SPS receiver clock bias for each of the WLAN AP locations are used as an indication of distance between the WLAN AP location and the possible satellite device locations.

26. The system of claim 21, wherein calculating the consistency of the internal SPS receiver clock bias for each WLAN AP location comprises calculating the standard deviation or the mean square error of the internal SPS receiver clock bias.