SYSTEM AND METHOD FOR REFINING A WLAN-PS ESTIMATED LOCATION USING SATELLITE MEASUREMENTS IN A HYBRID POSITIONING SYSTEM

• US 20090303112A1
• 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 8,089,399 B2
• Time in Patent Office: Days
• US Class Current: 342/357.480
• 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 refining a WLAN-PS estimated location using satellite measurements. In some embodiments, the disclosure relates to a method of determining the location of a WLAN and satellite enabled device by using two or more satellite measurements to refine an initial WLAN based location determination. The method can include estimating a position of the WLAN and satellite enabled device using a WLAN positioning system, gathering satellite location measurements from at least two satellites, determining an uncertainty area around the WLAN location estimate based on the expected error of the WLAN location estimate, wherein the uncertainty area has a plurality of possible location solutions, and determining the device location estimate inside the WLAN location uncertainty that best satisfies the satellite measurements.

Claims

1. A method of determining the location of a WLAN and satellite enabled device by using two or more satellite measurements to refine an initial WLAN based location determination, the method comprising:

estimating a position of the WLAN and satellite enabled device using a WLAN positioning system;

gathering satellite location measurements from at least two satellites;

determining an uncertainty area around the WLAN location estimate based on the expected error of the WLAN location estimate, wherein the uncertainty area has a plurality of possible location solutions; and

determining the device location estimate inside the WLAN location uncertainty that best satisfies the satellite measurements.

2. The method of claim 1 comprising dividing the uncertainty area into a grid.

3. The method of claim 2 comprising evaluating the WLAN location estimate using the satellite measurements at each point on the grid.

4. The method of claim 3 further comprising determining the internal SPS receiver clock bias of the satellite measurements at each grid point.

5. The method of claim 4 comprising using the consistency of the internal SPS receiver clock bias of the satellite measurements to determine the location of the device.

6. The method of claim 5, wherein the location of device is the grid point which provides the most consistent internal SPS receiver clock bias for the satellite measurements.

7. The method of claim 2, wherein the size of the grid is based on an accuracy requirement for the location determination.

8. The method of claim 7, wherein the accuracy requirement is about ten meters.

9. A system for increasing the accuracy of a WLAN based position estimate using satellite positioning information, the system comprising:

a hybrid positioning module comprising;

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

a satellite positioning module for obtaining satellite information from at least two different satellites;

logic in the WLAN positioning module for determining an uncertainty area around the WLAN location estimate based on the expected error of the WLAN location estimate, wherein the area has a plurality of possible location solutions; and

logic in the hybrid positioning module for determining the device location as the WLAN location estimate that best satisfies the satellite measurements.

10. The system of claim 9, wherein the uncertainty area is divided into a grid.

11. The system of claim 10, wherein the logic in the WLAN positioning module evaluates the WLAN location estimate using the satellite measurements at each point on the grid.

12. The system of claim 11, wherein the logic in the WLAN positioning module determines the internal SPS receiver clock bias of the satellite measurements at each grid point.

13. The system of claim 12 wherein the consistency of the internal SPS receiver clock bias of the satellite measurements is used to determine the location of the device.

14. The system of claim 13, wherein the location of device is the grid point which provides the most consistent internal SPS receiver clock bias for the satellite measurements.

15. The system of claim 10, wherein the size of the grid is based on an accuracy requirement for the location determination.

16. The system of claim 15, wherein the accuracy requirement is about ten meters.