Integrity monitoring in a position location system utilizing knowledge of local topography

• US 20040192330A1
• Filed: 04/18/2002
• Published: 09/30/2004
• Est. Priority Date: 04/18/2002
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Gaal, Peter
• Granted Patent: US 8,160,604 B2
• Time in Patent Office: Days
• US Class Current: 455/456.1
• CPC Class Codes: G01S 19/22 Multipath-related issues
• 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 2013/466 by Trilateration, i.e. two antennas or two sensors determine separately the distance to a target, whereby with the knowledge of the baseline length, i.e. the distance between the antennas or sensors, the position data of the target is determined
• CPC Class Codes: G01S 5/0036 of measured values, i.e. measurement on mobile and position calculation on base station
• CPC Class Codes: G01S 5/0054 of actual mobile position, i.e. position calculation on base station
• CPC Class Codes: G01S 5/02527 Detecting or resolving anomalies in the radio frequency fingerprints of the radio-map
• CPC Class Codes: G01S 5/0268 by deriving positions from different combinations of signals or of estimated positions in a single positioning system
• CPC Class Codes: G01S 5/0273 using multipath or indirect path propagation signals in position determination
• CPC Class Codes: G01S 5/0278 involving statistical or probabilistic considerations G01S5/0252, G01S5/0294 take precedence
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management

Abstract

A system for and method of deriving a position estimate of a receiver from a plurality of parameter measurements is provided. Each measurement is derived from a correlation function, which in turn is derived by correlating a signal received at the receiver with an identification code uniquely identifying a transmitter visible to the receiver. A plurality of position estimates are derived, each from a different subset of the plurality of measurements. Based on local topography, one of the position estimates is selected as the best estimate of the position of the receiver.

Claims

1. A method of deriving a position estimate of a receiver from a plurality of parameter measurements, each derived from a correlation function which in turn is derived by correlating a signal received at the receiver with an identification code uniquely identifying a transmitter visible to the receiver, comprising:

deriving a plurality of position estimates, each from a different subset of the plurality of measurements;

deriving a cost of each of the position estimates;

refining the costs based on local topography; and

selecting one of the position estimates responsive to the refined costs.

2. The method of claim 1 wherein the parameter measurements are time-of-arrival measurements.

3. The method of claim 1 wherein the identification codes are pseudo noise (PN) codes.

4. The method of claim 1 wherein the cost of an estimate is the RMS of the residual errors of the measurements used in deriving that position estimate.

5. The method of claim 1 wherein the refining step comprises performing the following substeps for each measurement:

estimating, based on local topography, the expected correlation function for the corresponding transmitter;

comparing the expected correlation function with the actual correlation function which is obtained at the receiver; and

adjusting, based on the comparison, the cost for each of the position estimates derived from the measurement, if the divergence between the expected and actual correlation function is sufficiently great.

6. The method of claim 5 wherein the comparing substep comprises comparing the expected peak amplitude with the amplitude of the earliest non-sidelobe peak of the actual correlation function.

7. The method of claim 5 wherein the comparing substep comprises comparing the expected shape of the correlation function with the actual shape of the correlation function.

8. The method of claim 1 tangibly embodied as a series of instructions stored in a memory.

9. A system comprising a processor and the memory of claim 8, wherein the memory is accessible by the processor, and the processor is configured to access and execute the instructions stored in the memory.

10. A method of deriving a position estimate of a receiver from a plurality of parameter measurements, each derived from a correlation function which in turn is derived by correlating a signal received at the receiver with an identification code uniquely identifying a transmitter visible to the receiver, comprising:

excluding, based on local topography, any of the plurality of measurements which are determined to be unreliable;

deriving a plurality of position estimates, each from a different subset of the remaining measurements;

deriving a cost of each of the position estimates; and

selecting one of the position estimates responsive to the costs.

11. The method of claim 10 wherein the identification codes are pseudo noise (PN) codes.

12. The method of claim 10 wherein the measurements are time-of-arrival measurements.

13. The method of claim 10 wherein the excluding step comprises performing, for each measurement, the following substeps:

estimating, based on local topography, the expected correlation function for the corresponding transmitter;

comparing the expected correlation function with the actual correlation function from which the measurement is derived;

determining, based on the comparison, whether the measurement is unreliable; and

excluding the measurement from further consideration if determined to be unreliable.

14. The method of claim 13 wherein the comparing substep comprises comparing the expected peak amplitude of the correlation function with the amplitude of the earliest non-sidelobe peak of the actual correlation function.

15. The method of claim 13 wherein the comparing substep comprises comparing the expected shape of the correlation function with the actual shape of the correlation function from which the measurement is derived.

16. The method of claim 10 tangibly embodied as a series of instructions stored in a memory.

17. A system comprising a processor and the memory of claim 16, wherein the memory is accessible by the processor, and the processor is configured to access and execute the instructions stored in the memory.

18. The method of claim 10 wherein at least one of the transmitters is a GPS satellite.

19. The method of claim 10 wherein at least one of the transmitters is a base station in a wireless communications system.

20. The method of claim 10 wherein at least one of the transmitters is a base station sector in a wireless communications system.

21. The method of claim 10 wherein the signal is received at the receiver through wireless transmission.

22. The method of claim 21 wherein the wireless transmission occurs in accordance with a multiple access protocol.

23. The method of claim 22 wherein the multiple access protocol is CDMA.

24. The method of claim 22 wherein the multiple access protocol is GSM.

25. The method of claim 22 wherein the multiple access protocol is WCDMA.

26. A method of deriving a position estimate of a receiver from a plurality of parameter measurements, each derived from a correlation function which in turn is derived by correlating a signal received at the receiver with an identification code uniquely identifying a transmitter visible to the receiver, comprising:

deriving a plurality of position estimates, each from a different subset of the plurality of measurements;

deriving, based on local topography, a reliability metric for each of position estimates; and

selecting, based on the reliability metrics, one of the position estimates.

27. The method of claim 26 wherein the step of deriving a reliability metric for a position estimate comprises performing the following substeps:

determining the expected correlation function corresponding to each of the measurements from which the position estimate is derived;

comparing, for each of the measurements, the expected correlation function with the actual correlation function from which the measurement is derived; and

deriving, based on the comparisons for each of the measurements, the reliability metric for the position estimate.

28. The method of claim 27 wherein the comparing step comprises comparing expected and actual peak amplitudes.

29. The method of claim 28 wherein the comparing step comprises comparing an expected peak amplitude for a line of sight transmission with the actual amplitude of the earliest non-sidelobe peak.

30. The method of claim 27 wherein the comparing step comprises comparing expected and actual shapes of correlation functions.

31. The method of claim 26 tangibly embodies a series of instructions stored in a memory.

32. A system comprising a processor and the memory of claim 31, wherein the memory is accessible by the processor, and the processor is configured to access and execute the instructions stored thereon.

33. The system of claim 32 in a subscriber station.

34. The system of claim 32 in a PDE.

35. A method of deriving a position estimate of a receiver from a plurality of parameter measurements, each derived from a correlation function which in turn is derived by correlating a signal received at the receiver with an identification code uniquely identifying a transmitter visible to the receiver, comprising:

deriving a plurality of position estimates, each from a different subset of the plurality of measurements; and

selecting, based on local topography, one of the position estimates.

36. A method of deriving a position estimate of a receiver from a plurality of parameter measurements, each derived from a correlation function which in turn is derived by correlating a signal received at the receiver with an identification code uniquely identifying a transmitter visible to the receiver, comprising:

a step for deriving a plurality of position estimates, each from a different subset of the plurality of measurements; and

a step for selecting, based on local topography, one of the position estimates.

37. A system for deriving a position estimate of a receiver from a plurality of parameter measurements, each derived from a correlation function which in turn is derived by correlating a signal received at the receiver with an identification code uniquely identifying a transmitter visible to the receiver, comprising:

first logic for deriving, from the plurality of measurements, a plurality of position estimates, each derived from a different subset of the measurements;

second logic for deriving a cost of each of the position estimates;

third logic for refining the costs based on local topography; and

fourth logic for selecting one of the position estimates responsive to the refined costs.

38. The system of claim 37 wherein the parameter measurements are time-of-arrival measurements.

39. The system of claim 37 wherein the identification codes are pseudo noise (PN) codes.

40. The system of claim 37 wherein the cost of an estimate is the RMS of the residual errors of the measurements used in deriving that position estimate.

41. The system of claim 37 wherein the third logic is configured, for each measurement from which a position estimate is derived, to (a) estimate, based on local topography, the expected correlation function for the corresponding transmitter;

(b) compare the estimated correlation function with the actual correlation function; and

(c) adjust, based on the comparison, the cost for each of the position estimates derived from the measurement if the divergence between the expected and actual correlation functions is sufficiently great.

42. The system of claim 41 wherein the third logic is configured to compare the expected peak amplitude of the correlation function with the amplitude of the earliest non-sidelobe peak of the actual correlation function.

43. The system of claim 41 wherein the third logic is configured to compare the expected shape of the correlation function with the actual shape of the correlation function.

44. A system for deriving a position estimate of a receiver from a plurality of parameter measurements, each derived from a correlation function which in turn is derived by correlating a signal received at the receiver with an identification code uniquely identifying a transmitter visible to the receiver, comprising:

first logic for excluding, based on local topography, any of the plurality of measurements which are determined to be unreliable;

second logic for deriving a plurality of position estimates, each from a different subset of the remaining measurements;

third logic for deriving a cost of each of the position estimates; and

fourth logic for selecting one of the position estimates responsive to the costs.

45. The system of claim 44 wherein the identification codes are pseudo noise (PN) codes.

46. The system of claim 44 wherein the measurements are time-of-arrival measurements.

47. The system of claim 44 wherein the first logic is configured, for each measurement, to (a) estimate, based on local topography, the expected correlation function corresponding to the transmitter from which the measurement is derived;

(b) compare the expected correlation function with the actual correlation function from which the measurement is derived;

(c) determine, based on the comparison, whether the measurement is unreliable; and

(d) exclude the measurement from further consideration if determined to be unreliable.

48. The system of claim 47 wherein the first logic is configured to compare the expected peak amplitude with the amplitude of the earliest non-sidelobe peak of the actual correlation function from which the measurement is derived.

49. The system of claim 47 wherein the first logic is configured to compare the expected shape with the actual shape of the correlation function from which the measurement is derived.

50. A system for deriving a position estimate of a receiver from a plurality of parameter measurements, each derived from a correlation function which in turn is derived by correlating a signal received at the receiver with an identification code uniquely identifying a transmitter visible to the receiver, comprising:

first logic for deriving a plurality of position estimates, each from a different subset of the measurements;

second logic for deriving, based on local topography, a reliability metric for each of position estimates; and

third logic for selecting, based on the reliability metrics, one of the position estimates.

51. The system of claim 50 wherein the second logic is configured, for each position estimate, to (a) determine the expected correlation function corresponding to each of the measurements from which the position estimate is derived;

(b) compare, for each of the measurements, the expected correlation function with the actual correlation function from which the measurement is derived; and

(c) derive, based on the comparisons for each of the measurements, the reliability metric for the position estimate.

52. The system of claim 51 wherein the second logic is configured to compare expected and actual peak amplitudes.

53. The system of claim 52 wherein the second logic is configured to compare the expected peak amplitude for a line of sight transmission with the actual amplitude of the earliest non-sidelobe peak.

54. The system of claim 51 wherein the second logic is configured to compare expected and actual shapes of correlation functions.

55. The system of claim 50 in a subscriber station.

56. The system of claim 50 in a PDE.

57. A system for deriving a position estimate of a receiver from a plurality of parameter measurements, each derived from a correlation function which in turn is derived by correlating a signal received at the receiver with an identification code uniquely identifying a transmitter visible to the receiver, comprising:

first logic for deriving a plurality of position estimates, each from a different subset of the measurements; and

second logic for selecting, based on local topography, one of the position estimates.

58. A system for deriving a position estimate of a receiver from a plurality of parameter measurements, each derived from a correlation function which in turn is derived by correlating a signal received at the receiver with an identification code uniquely identifying a transmitter visible to the receiver, comprising:

means for deriving a plurality of position estimates, each from a different subset of the plurality of measurements; and

means for selecting, based on local topography, one of the position estimates.