Method and apparatus for improving radio location accuracy with measurements

• US 20050192024A1
• Filed: 04/17/2003
• Published: 09/01/2005
• Est. Priority Date: 10/17/2002
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Sheynblat, Leonid
• Granted Patent: US 7,660,588 B2
• Time in Patent Office: Days
• US Class Current: 455/456.1
• 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
• CPC Class Codes: G01S 5/0263 by combining or switching between positions derived from two or more separate positioning systems
• CPC Class Codes: H04W 4/025 using location based information parameters
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management

Abstract

A method and apparatus to utilize a set of measurements (either partial or compete) to improve the accuracy of an initial position estimate for a wireless terminal. The initial position estimate for the terminal is first obtained (e.g., based on a cell-ID or an enhanced cell-ID solution). Measurements are obtained for the terminal. The initial position estimate is then updated with the measurements to obtain a revised position estimate for the terminal. The updating may be performed by (1) deriving a measurement vector based on the initial position estimate and the measurements, (2) forming an observation matrix for the measurements, (3) determining a matrix of weights, (4) deriving a correction vector based on the measurement vector, the observation matrix, and the weight matrix, and (5) updating the initial position estimate with the correction vector.

Claims

1. A method of determining a position estimate for a wireless terminal, comprising:

obtaining an initial position estimate for the terminal;

obtaining a set of measurements from one or more position determination systems; and

updating the initial position estimate with the set of measurements to obtain a revised position estimate for the terminal.

2. The method of claim 1, wherein the set of measurements is a partial set of measurements.

3. The method of claim 1, wherein the set of measurements is a complete set of measurements.

4. The method of claim 1, wherein the initial position estimate is obtained based on a cell-ID solution.

5. The method of claim 1, wherein the initial position estimate is obtained based on an enhanced cell-ID solution.

6. The method of claim 1, wherein the updating includes:

deriving a measurement vector based on the initial position estimate and the set of measurements,

forming an observation matrix for the set of measurements,

deriving a correction vector based on the measurement vector and the observation matrix, and

updating the initial position estimate with the correction vector.

7. The method of claim 6, wherein the deriving the measurement vector includes

determining a pseudo-range to each transmitter based on a corresponding measurement in the set of measurements,

computing a pseudo-range from the initial position estimate to each transmitter, and

determining a pseudo-range residual for each transmitter, and wherein the measurement vector includes pseudo-range residuals for transmitters whose measurements are in the set of measurements.

8. The method of claim 1, wherein the updating includes using maximum likelihood techniques.

9. The method of claim 1, further comprising determining weights for the initial position estimate and the set of measurements, and wherein the updating is performed using the weights.

10. The method of claim 1, wherein one or more dimensions are constrained for the revised position estimate.

11. The method of claim 10, wherein a vertical dimension is constrained for the revised position estimate.

12. The method of claim 1, wherein the set of measurements is obtained based on signals received from a satellite positioning system (SPS).

13. The method of claim 1, wherein the set of measurements is obtained based on signals received from a wireless communication system.

14. The method of claim 1, wherein the set of measurements is obtained based on signals received from at least one of a satellite positioning system (SPS) and a wireless communication system.

15. The method of claim 1, wherein the set of measurements includes at least one line of position (LOP).

16. A method of determining a position estimate for a wireless terminal, comprising:

obtaining an initial position estimate for the terminal;

obtaining a set of measurements for a plurality of transmitters, wherein each transmitter is either a satellite or a base station;

deriving a measurement vector based on the set of measurements;

forming an observation matrix for the set of measurements;

deriving a correction vector based on the measurement vector and the observation matrix; and

updating the initial position estimate with the correction vector to obtain a revised position estimate for the terminal.

17. The method of claim 16, wherein the set of measurements is a partial set of measurements.

18. The method of claim 16, wherein the set of measurements is a complete set of measurements.

19. The method of claim 16, wherein the measurement vector includes the initial position estimate.

20. The method of claim 16, wherein the observation matrix includes the initial position estimate.

21. The method of claim 16, further comprising determining weights for the initial position estimate, and wherein the updating is performed using the weights.

22. The method of claim 17, further comprising determining weights for the partial set of measurements, and wherein the updating is performed using the weights.

23. The method of claim 17, further comprising determining weights for the initial position estimate and the partial set of measurements, and wherein the updating is performed using the weights.

24. The method of claim 16, wherein the initial position estimate is obtained based on a cell-ID solution or an enhanced cell-ID solution.

25. The method of claim 16, wherein the initial position estimate is used to create equations for the observation matrix. (see 14.5)

26. The method of claim 25, wherein the initial position estimate uncertainty is used to create weights for the observation matrix. (see 14.6)

27. A method of determining a position estimate for a wireless terminal, comprising:

obtaining state domain information for the position estimate;

obtaining measurement domain information for the terminal, wherein the measurement domain information is insufficient to derive an independent position estimate for the terminal; and

combining the state domain information and measurement domain information to obtain the position estimate for the terminal.

28. A computer program product for determining a position estimate for a wireless terminal, comprising:

code for obtaining an initial position estimate for the terminal;

code for obtaining a set of measurements from one or more position determination systems;

code for updating the initial position estimate with the set of measurements to obtain a revised position estimate for the terminal; and

a computer-usable medium for storing the codes.

29. A digital signal processor comprising:

means for obtaining an initial position estimate for a wireless terminal;

means for obtaining a set of measurements from one or more position determination systems; and

means for updating the initial position estimate with the set of measurements to obtain a revised position estimate for the terminal.

30. The digital signal processor of claim 29, wherein the means for updating includes

means for deriving a measurement vector based on the initial position estimate and the set of measurements,

means for forming an observation matrix for the set of measurements,

means for deriving a correction vector based on the measurement vector and the observation matrix, and

means for updating the initial position estimate with the correction vector.

31. A receiver unit in a wireless communication system, comprising:

a first receiver operative to receive and process a received signal to provide data for a first position determination system;

a second receiver operative to receive and process the received signal to provide data for a second position determination system; and

a processing unit coupled to the first and second receivers-and operative to;

obtain an initial position estimate for the receiver unit,

obtain a set of measurements from the first or second position determination system, or both, and

update the initial position estimate with the set of measurements to obtain a revised position estimate for the receiver unit.

32. The receiver unit of claim 31, wherein the first receiver is operative to process signals from SPS satellites.

33. The receiver unit of claim 31, wherein the second receiver is operative to process signals from base stations in a wireless communication system.

34. The receiver unit of claim 31, wherein the processor is further operative to:

derive a measurement vector based on the initial position estimate and the set of measurements;

form an observation matrix for the set of measurements;

derive a correction vector based on the measurement vector and the observation matrix; and

update the initial position estimate with the correction vector.

35. A location server in a wireless communication system and operable to determine a position estimate for a wireless terminal, comprising:

means for obtaining an initial position estimate for the terminal;

means for obtaining a set of measurements from one or more position determination systems; and

means for updating the initial position estimate with the set of measurements to obtain a revised position estimate for the terminal.

36. A location determination system comprising two components:

means for obtaining an initial position estimate for the terminal in a first component of the system;

means for communicating the initial position estimate to a second component of the system;

means for obtaining a set of measurements from at least one position determination system; and

means for updating the initial position estimate with the set of measurements in the second component of the system.

37. The method of claim 36, wherein the initial position estimate is determine by the network.

38. The method of claim 36, wherein the initial position estimate is updated with a set of measurements by the terminal.