Method And Apparatus For Improving Radio Location Accuracy With Measurements

• US 20100203899A1
• Filed: 02/04/2010
• Published: 08/12/2010
• Est. Priority Date: 10/17/2002
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Sheynblat, Leonid, Riley, Wyatt Thomas
• Granted Patent: US 8,583,140 B2
• Time in Patent Office: Days
• US Class Current: 455/456.100
• 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 receiver unit in a wireless communication system, the receiver unit comprising:

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

a second receiver configured 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 configured 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,

determine measurement elements from the initial position estimate;

obtain observation values for the set of measurements; and

update the initial position estimate based on the measurement elements and the observation values to obtain an updated position estimate for the receiver unit.

2. The receiver unit of claim 1 wherein the set of measurements is a partial set of measurements that provide insufficient information from which to derive an independent position estimate of the wireless terminal with a predetermined quality of service that is dependent upon an application for the position estimate.

3. The receiver unit of claim 1 wherein the set of measurements is a complete set of measurements that provide sufficient information from which to derive a position estimate of the wireless terminal with a quality of service that is sufficient for, and dependent upon, an application for the position estimate.

4. The receiver unit of claim 1 wherein the processing unit is configured to obtain the initial position estimate based on a cell-ID solution.

5. The receiver unit of claim 1 wherein the processing unit is configured to obtain the initial position estimate based on an enhanced cell-ID solution.

6. The receiver unit of claim 1 wherein to determine the measurement elements the processing unit is configured to derive a measurement vector based on the initial position estimate and the set of measurements, to obtain the observation values the processing unit is configured to form an observation matrix for the set of measurements, and to update the initial position estimate the processing unit is configured to derive a correction vector based on the measurement vector and the observation matrix, and wherein the processing unit is configured to update the initial position estimate with the correction vector.

7. The receiver unit of claim 6 wherein to derive the measurement vector the processing unit is configured to:

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

compute a pseudo-range from the initial position estimate to each transmitter; and

determine a pseudo-range residual for each transmitter;

wherein the measurement vector includes pseudo-range residuals for transmitters whose measurements are in the set of measurements.

8. The receiver unit of claim 1 wherein to update the initial position estimate the processing unit is configured to use maximum likelihood techniques.

9. The receiver unit of claim 1 wherein the processing unit is further configured to determine weights for the initial position estimate and the set of measurements, and wherein the processing unit is configured to update the initial position estimate using the weights.

10. The receiver unit of claim 1 wherein the processing unit is configured to constrain one or more dimensions for the updated position estimate.

11. The receiver unit of claim 10 wherein the one or more dimensions includes a vertical dimension.

12. The receiver unit of claim 1 wherein the processing unit is configured to obtain the set of measurements based on signals received from a satellite positioning system (SPS).

13. The receiver unit of claim 1 wherein the processing unit is configured to obtain the set of measurements based on signals received from a wireless communication system.

14. The receiver unit of claim 1 wherein the processing unit is configured to obtain the set of measurements based on signals received from at least one of a satellite positioning system (SPS) and a wireless communication system.

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

16. A location determination system comprising:

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

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

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

determining means for determining measurement elements from the initial position estimate;

third obtaining means for obtaining observation values for the set of measurements; and

updating means for updating the initial position estimate based on the measurement elements and the observation values in the second component of the system.

17. The system of claim 16 wherein the first obtaining means are disposed outside the terminal.

18. The system of claim 16 wherein the first obtaining means are disposed in the terminal.

19. The system of claim 16 wherein the set of measurements is a partial set of measurements that provide insufficient information from which to derive an independent position estimate of the wireless terminal with a predetermined quality of service that is dependent upon an application for the position estimate.

20. The system of claim 16 wherein the set of measurements is a complete set of measurements that provide sufficient information from which to derive a position estimate of the wireless terminal with a quality of service that is sufficient for, and dependent upon, an application for the position estimate.

21. The system of claim 16 wherein the first obtaining means are configured to obtain the initial position estimate based on a cell-ID solution.

22. The system of claim 16 wherein the first obtaining means are configured to obtain the initial position estimate based on an enhanced cell-ID solution.

23. The system of claim 16 wherein the determining means are configured to derive a measurement vector based on the initial position estimate and the set of measurements, the third obtaining means are configured to form an observation matrix for the set of measurements, and the updating means are configured to derive a correction vector based on the measurement vector and the observation matrix and to update the initial position estimate with the correction vector.

24. The system of claim 23 wherein to derive the measurement vector the determining means are configured to:

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

compute a pseudo-range from the initial position estimate to each transmitter; and

determine a pseudo-range residual for each transmitter;

wherein the measurement vector includes pseudo-range residuals for transmitters whose measurements are in the set of measurements.

25. The system of claim 16 wherein the updating means are configured to use maximum likelihood techniques.

26. The system of claim 16 further comprising weighting means configured to determine weights for the initial position estimate and the set of measurements, and wherein the updating means are to update the initial position estimate using the weights.

27. The system of claim 16 wherein the updating means are configured to constrain one or more dimensions for the updated position estimate.

28. The system of claim 27 wherein the one or more dimensions includes a vertical dimension.

29. The system of claim 16 wherein the second obtaining means are configured to obtain the set of measurements based on signals received from a satellite positioning system (SPS).

30. The system of claim 16 wherein the second obtaining means are configured to obtain the set of measurements based on signals received from a wireless communication system.

31. The system of claim 16 wherein the second obtaining means are configured to obtain the set of measurements based on signals received from at least one of a satellite positioning system (SPS) and a wireless communication system.

32. The system of claim 16 wherein the set of measurements includes at least one line of position (LOP).

33. A computer program product residing on a processor-readable storage medium and comprising processor-readable instructions configured to cause a processor to:

obtain an initial position estimate for the terminal;

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

determine measurement elements from the initial position estimate;

obtain observation values for the set of measurements; and

update the initial position estimate based on the measurement elements and the observation values to obtain an updated position estimate for the terminal.

34. The computer-program product of claim 33 wherein the set of measurements is a partial set of measurements that provide insufficient information from which to derive an independent position estimate of the wireless terminal with a predetermined quality of service that is dependent upon an application for the position estimate.

35. The computer-program product of claim 33 wherein the set of measurements is a complete set of measurements that provide sufficient information from which to derive a position estimate of the wireless terminal with a quality of service that is sufficient for, and dependent upon, an application for the position estimate.

36. The computer-program product of claim 33 wherein the instructions configured to cause the processor to obtain the initial position estimate are configured to cause the processor to obtain the initial position estimate based on a cell-ID solution.

37. The computer-program product of claim 33 wherein the instructions configured to cause the processor to obtain the initial position estimate are configured to cause the processor to obtain the initial position estimate based on an enhanced cell-ID solution.

38. The computer-program product of claim 33 wherein:

the instructions configured to cause the processor to determine the measurement elements are configured to cause the processor to derive a measurement vector based on the initial position estimate and the set of measurements;

the instructions configured to cause the processor to obtain the observation values are configured to cause the processor to form an observation matrix for the set of measurements; and

the instructions configured to cause the processor to update the initial position estimate are configured to cause the processor to derive a correction vector based on the measurement vector and the observation matrix, and update the initial position estimate with the correction vector.

39. The computer-program product of claim 38 wherein the instructions configured to cause the processor to derive the measurement vector are configured to cause the processor to determine a pseudo-range to each transmitter based on a corresponding measurement in the set of measurements, compute a pseudo-range from the initial position estimate to each transmitter, and determine 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.

40. The computer-program product of claim 33 wherein the instructions configured to cause the processor to update are configured to cause the processor to use maximum likelihood techniques.

41. The computer-program product of claim 33 further comprising instructions configured to cause the processor to determine weights for the initial position estimate and the set of measurements, and wherein the instructions configured to cause the processor to update are configured to cause the processor to use the weights.

42. The computer-program product of claim 33 wherein the instructions configured to cause the processor to update are configured to cause the processor to constrain one or more dimensions for the revised position estimate.

43. The computer-program product of claim 42 wherein the one or more dimensions includes a vertical dimension.

44. The computer-program product of claim 33 wherein the instructions configured to cause the processor to obtain the set of measurements are configured to cause the processor to obtain the measurements based on signals received from a satellite positioning system (SPS).

45. The computer-program product of claim 33 wherein the instructions configured to cause the processor to obtain the set of measurements are configured to cause the processor to obtain the measurements based on signals received from a wireless communication system.

46. The computer-program product of claim 33 wherein the step of obtaining the set of measurements includes obtaining the measurements based on signals received from at least one of a satellite positioning system (SPS) and a wireless communication system.

47. 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;

determining measurement elements from the initial position estimate;

obtaining observation values for the set of measurements; and

updating the initial position estimate based on the measurement elements and the observation values to obtain an updated position estimate for the terminal.

48. The method of claim 47 wherein the set of measurements is a partial set of measurements that provide insufficient information from which to derive an independent position estimate of the wireless terminal with a predetermined quality of service that is dependent upon an application for the position estimate.

49. The method of claim 47 wherein the set of measurements is a complete set of measurements that provide sufficient information from which to derive a position estimate of the wireless terminal with a quality of service that is sufficient for, and dependent upon, an application for the position estimate.

50. The method of claim 47 wherein the initial position estimate is obtained based on a cell-ID solution.

51. The method of claim 47 wherein the initial position estimate is obtained based on an enhanced cell-ID solution.

52. The method of claim 47 wherein determining the measurement elements includes deriving a measurement vector based on the initial position estimate and the set of measurements, obtaining the observation values includes forming an observation matrix for the set of measurements, and updating the initial position estimate includes deriving a correction vector based on the measurement vector and the observation matrix, and updating the initial position estimate with the correction vector.

53. The method of claim 52 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.

54. The method of claim 47 wherein the updating includes using maximum likelihood techniques.

55. The method of claim 47 further comprising determining weights for the initial position estimate and the set of measurements, and wherein the updating is performed using the weights.

56. The method of claim 47 wherein one or more dimensions are constrained for the revised position estimate.

57. The method of claim 56 wherein a dimension which is a vertical one is constrained for the revised position estimate.

58. The method of claim 47 wherein the set of measurements is obtained based on signals received from a satellite positioning system (SPS).

59. The method of claim 47 wherein the set of measurements is obtained based on signals received from a wireless communication system.

60. The method of claim 47 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.

61. The method of claim 47 wherein the set of measurements includes at least one line of position (LOP).