EFFICIENT USE OF EXPECTED USER ALTITUDE DATA TO AID IN DETERMINING A POSITION OF A MOBILE STATION

• US 20090210156A1
• Filed: 02/20/2008
• Published: 08/20/2009
• Est. Priority Date: 02/20/2008
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Riley, Wyatt Thomas, Heshmati, Ardalan
• Granted Patent: US 8,700,322 B2
• Time in Patent Office: Days
• US Class Current: 701/300
• CPC Class Codes: G01S 19/05 providing aiding data
• CPC Class Codes: G01S 19/22 Multipath-related issues
• CPC Class Codes: G01S 19/50 whereby the position solution is constrained to lie upon a particular curve or surface, e.g. for locomotives on railway tracks

Abstract

A method and apparatus for using a predetermined portion of terrain elevation maps in a database for aiding in computing a three-dimensional position of a wireless station. Instead of using the entire terrain model of the earth or an entire country, the database consists of an incomplete model, which includes only the most populous areas or specific regions. This reduces the size of the information in the database, which in turn reduces the amount of time to compute the positions of the wireless device.

Claims

1. A method for computing a position of a mobile station, the method comprising the steps of:

storing at least one predetermined portion of an expected user altitude database in the mobile station;

providing a global elevation estimate;

estimating an initial position of the mobile station based on the global elevation estimate and at least three global positioning system satellite measurements;

determining an altitude estimate from the initial position of the mobile station, and at least one predetermined portion of the expected user altitude database; and

calculating the position of the mobile station.

2. The method of claim 1 further comprising calculating a mobile position uncertainty.

3. The method of claim 1 further comprising the steps of:

determining a second altitude estimate based on at least one predetermined portion of the expected user altitude database based on the second calculated position; and

re-calculating the position of the mobile station.

4. The method of claim 3 comprising a maximum number of recalculation iterations.

5. The method of claim 1 wherein the step of identifying a first selected area comprises identifying a smallest selected area in the at least one stored predetermined portion of the terrain database.

6. The method of claim 1 wherein the predetermined portion of the terrain database comprises a center, a radius, an average expected user height and an uncertainty of the expected user height.

7. The method of claim 1 wherein the step of storing comprises compressing the predetermined portion of the terrain database.

8. The method of claim 1 wherein the predetermined portion of the terrain database comprises identifying at least one most populated portion of a selected area.

9. The method of claim 1 further comprising the step of determining an altitude uncertainty from the expected user altitude database.

10. A system for computing a position of a mobile station, the system comprising:

means for storing at least one predetermined portion of an expected user altitude database in the mobile station;

means for providing a global elevation estimate;

means for estimating an initial position of the mobile station based on the global elevation estimate and at least three global positioning system satellites;

means for identifying a first selected area in the stored at least one predetermined portion of the expected user altitude database based on the estimated initial position;

means for determining an altitude from the first selected area in the database; and

means for calculating the position of the mobile station.

11. The system of claim 10 further comprising a means for calculating a mobile position uncertainty.

12. The system of claim 10 further comprising:

means for identifying a second selected area in the stored at least one predetermined portion of the expected user altitude database based on the calculated position; and

means for re-calculating the position of the mobile station.

13. The system of claim 10 wherein the means for identifying a first selected area comprises a means for identifying a smallest selected area in the at least one stored predetermined portion of the terrain database.

14. The system of claim 10 wherein the predetermined portion of the terrain database comprises a center, a radius, an average expected user height and an uncertainty of the expected user height.

15. The system of claim 10 wherein the means for storing comprises a means for compressing the predetermined portion of the terrain database.

16. The system of claim 10 wherein the predetermined portion of the terrain database comprises a means for identifying at least one most populated portion of a selected area.

17. A computer program product, comprising:

computer readable medium comprising;

code for causing a location of a mobile station to be computed, the computer code comprising;

code for causing at least one predetermined portion of a terrain database to be stored in the mobile station;

code for causing a global elevation to be estimated;

code for causing an initial position of the mobile station to be made based on the global elevation estimate and at least three global positioning lo system satellites;

code for causing a first selected area in the stored at east one predetermined portion to be selected based on the estimated initial position; and

code for causing the position of the mobile station to be calculated.

18. The computer program products of claim 17 further comprising code for causing a calculation of a mobile position uncertainty.

19. The computer program product of claim 17 further comprising:

code for causing a second selected area to be identified in the stored at least one predetermined portion of the expected user altitude database based on the calculated position; and

code for causing a re-calculation of the position of the mobile station.

20. A method for computing a position of a mobile station, the method comprising the steps of:

storing at least one predetermined portion of an expected user altitude database in the mobile station;

providing a global elevation estimate;

estimating an initial position and a velocity of the mobile station based on the global elevation estimate and at least three global positioning system satellites;

identifying a first selected area in the at least one stored predetermined portion of the expected user altitude database based on the estimated initial position;

providing at least one set mobile station level based on the estimated velocity;

determining an altitude and altitude uncertainty from the first selected area in the database and the provided at least one mobile station level; and

calculating the position of the mobile station.

21. The method of claim 20 wherein the estimated velocity for a first set mobile station level is determined using a zero vertical velocity assumption.

22. The method of claim 20 further comprising the steps of:

identifying a second selected area in the stored at least one predetermined portion of the expected user altitude database based on the calculated position; and

re-calculating the position and uncertainty of the mobile station.

23. The method of claim 20 wherein the step of identifying a first selected area comprises identifying a smallest selected area in the at least one stored predetermined portion of the terrain database.

24. A computer program product, comprising:

computer readable medium comprising;

code for causing a location of a mobile station to be computed, the computer code comprising;

code for causing at least one predetermined portion of an expected user altitude database be stored in the mobile station;

code for causing a global elevation estimate to be provided;

code for causing an initial position and a velocity of the mobile station be estimated based on the global elevation estimate and at least three global positioning system satellites;

code for causing a first selected area in the at least one stored predetermined portion of the expected user altitude database be identified based on the estimated initial position;

code for causing at one set mobile station level be provided based on the estimated velocity;

code for causing an altitude and altitude uncertainty be determined from the first selected area in the database and the at least one set mobile station level; and

code for causing the position of the mobile station be calculated.

25. The computer program product of claim 24 wherein the estimated velocity for a first set mobile station level comprises a zero vertical velocity.

26. The computer program product of claim 24 further comprising:

code for causing a second selected area in the stored at least one predetermined portion of the expected user altitude database be identified based on the calculated position; and

code for causing a re-calculation of the position and uncertainty of the mobile station.