System and method for CDMA geolocation

• US 20050192026A1
• Filed: 12/10/2004
• Published: 09/01/2005
• Est. Priority Date: 06/04/2003
• Status: Active Grant

• Current Assignee: Outdoor Wireless Networks LLC (CommScope Holding Company, Inc.)
• Original Assignee: Andrew LLC (CommScope Holding Company, Inc.)
• Inventors: Carlson, John Peter, Kennedy, Joseph P., Gravely, Thomas Booker
• Granted Patent: US 7,429,914 B2
• Time in Patent Office: Days
• US Class Current: 455/456.1
• CPC Class Codes: G01S 5/06 Position of source determined by co-ordinating a plurality of position lines defined by path-difference measurements G01S5/12 takes precedence
• CPC Class Codes: H04W 4/02 Services making use of location information
• CPC Class Codes: H04W 4/029 Location-based management or tracking services
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management

Abstract

A system and method is disclosed for determining the location of a mobile appliance using the reverse pilot channel provided in CDMA 2000 communication systems to determine an attribute (e.g., time of arrival, angle of arrival, time difference of arrival, received power level) of a reverse pilot signal at one or more wireless location sensors. A network overlay of wireless location sensors monitors the reverse pilot channel for a target mobile'"'"'s reverse pilot signal. The monitored signal may be compared to a reference signal to determine a correlation and thereby determine an attribute of the target mobile'"'"'s reverse pilot signal. The method may be performed independently from the communication system and without requiring retrieval of information bits from the mobile appliance. The reference signal may be generated from the unique long spreading code mask of the target mobile appliance which is typically a function of the ESN of the target mobile appliance.

Claims

1. A method of determining the location of a first mobile appliance which emits a pilot signal that is different from pilot signals emitted by other mobile appliances, comprising the steps of:

(a) receiving at a wireless location sensor said pilot signal emitted from said first mobile appliance;

(b) determining an attribute of said pilot signal emitted by said first mobile appliance at said wireless location sensor; and

(c) determining the location of said first mobile appliance as a function of said attribute.

2. The method of claim 1 wherein said attribute is time of arrival.

3. The method of claim 1 wherein said attribute is angle of arrival.

4. The method of claim 1 wherein said attribute is received power level.

5. The method of claim 1 wherein said first mobile appliance is operating in a wireless communication system having at least one base station for communicating with said mobile appliance.

6. The method of claim 5 wherein said attribute is selected from the group consisting of time of arrival, angle of arrival, and received power level.

7. The method of claim 5 including a plurality of wireless location sensors.

8. The method of claim 7 wherein said attribute is time difference of arrival.

9. The method of claim 8 wherein the step of determining the time difference of arrival includes correlating said pilot signal with a reference signal.

10. The method of claim 8 wherein the step of determining the time difference of arrival includes ambiguity function processing of said pilot signal with a reference signal.

11. The method of claim 5 wherein said wireless location sensor is geographically spaced apart from said at least one base station.

12. The method of claim 5 wherein the wireless communication system is an asynchronous system.

13. The method of claim 5 wherein the wireless communication system is a CDMA system.

14. The method of claim 5 wherein the wireless communication system is WCDMA compliant as specified by the Third Generation Partnership Project.

15. The method of claim 5 wherein said pilot signal emitted from said first mobile appliance is used by said at least one base station to coherently demodulate a traffic signal emitted by said first mobile appliance.

16. The method of claim 1 wherein said pilot signal emitted from said first mobile appliance is generated as a function of a long spreading code for said first mobile appliance.

17. The method of claim 1 wherein said pilot signal emitted from said first mobile appliance is a CDMA2000 reverse pilot signal as specified by the Telecommunications Industry Association.

18. The method of claim 1 wherein the location of the first mobile appliance is determined independent of the state of said first mobile appliance.

19. In a method of determining the location of a first mobile appliance wherein a wireless location sensor receives signals emitted from said first mobile appliance, the improvement wherein the location of said first mobile appliance is determined at least in part from an attribute of a pilot signal emitted by said first mobile appliance wherein said pilot signal is different from pilot signals emitted by other mobile appliances.

20. The method of claim 19 wherein said attribute is time of arrival.

21. The method of claim 19 wherein said attribute is angle of arrival.

22. The method of claim 19 wherein said attribute is received power level.

23. The method of claim 19 wherein said first mobile appliance is operating in a wireless communication system having at least one base station for communicating with said mobile appliance.

24. The method of claim 23 wherein said attribute is selected from the group consisting of time of arrival, angle of arrival, and received power level.

25. The method of claim 23 including a plurality of wireless location sensors.

26. The method of claim 25 wherein said attribute is time difference of arrival.

27. The method of claim 26 wherein the step of determining the time difference of arrival includes correlating said pilot signal with a reference signal.

28. The method of claim 26 wherein the step of determining the time difference of arrival includes ambiguity function processing of said pilot signal with a reference signal.

29. The method of claim 23 wherein said wireless location sensor is geographically spaced apart from said at least one base station.

30. The method of claim 23 wherein the wireless communication system is an asynchronous system.

31. The method of claim 23 wherein the wireless communication system is a CDMA system.

32. The method of claim 23 wherein the wireless communication system is WCDMA compliant as specified by the Third Generation Partnership Project.

33. The method of claim 23 wherein said pilot signal emitted from said first mobile appliance is used by said at least one base station to coherently demodulate a traffic signal emitted by said first mobile appliance.

34. The method of claim 19 wherein said pilot signal emitted from said first mobile appliance is generated as a function of a long spreading code for said first mobile appliance.

35. The method of claim 19 wherein said pilot signal emitted from said first mobile appliance is a CDMA2000 reverse pilot signal as specified by the Telecommunications Industry Association.

36. The method of claim 19 wherein the location of the first mobile appliance is determined independent of the state of said first mobile appliance.

37. A method of determining the location of a first mobile appliance in a wireless communication system, comprising the steps of:

(a) providing a reverse pilot channel;

(b) transmitting from said first mobile appliance a reverse pilot signal over said reverse pilot channel wherein said reverse pilot signal is different from reverse pilot signals emitted by other mobile appliances;

(c) receiving said first mobile appliance reverse pilot signal at a wireless location sensor;

(d) determining an attribute of said first mobile appliance reverse pilot signal a said wireless location sensor; and

,

(e) determining the location of said first mobile appliance as a function of said attribute.

38. The method of claim 37 wherein said attribute is selected from the group consisting of time of arrival, angle of arrival, and received power level.

39. The method of claim 37 wherein said first mobile appliance reverse pilot signal is received at a plurality of wireless location sensors.

40. The method of claim 39 wherein said attribute is time difference of arrival.

41. The method of claim 37 wherein said first mobile appliance reverse pilot signal is a digital signal generated from an information bit data sequence of zeros.

42. The method of claim 41 wherein said first mobile appliance reverse pilot signal is quadrature scrambled by a pseudo-random sequence that is a function of the ESN of said first mobile appliance.

43. The method of claim 37 wherein the reverse pilot signal of each mobile appliance is a pseudo-random sequence that is substantially orthogonal to the pseudo-random sequence generated by each of the other mobile appliances.

44. The method of claim 37 wherein step (c) includes the steps of:

(c)(i) providing a reference signal at said wireless location sensor; and

(c)(ii) detecting the presence of the first mobile appliance reverse pilot signal by cross-correlating in the time domain the received reverse pilot signal with said reference signal.

45. The method of claim 44 wherein step (c)(ii) includes cross-correlating in the time domain and the frequency domain the received reverse pilot signal with said reference signal.

46. The method of claim 44 wherein step (c)(ii) includes ambiguity function processing jointly in the time domain and the frequency domain the received reverse pilot signal with said reference signal.

47. The method of claim 44 wherein step (c)(i) comprises the steps of:

(c)(i)(A) generating a sequence of zeros;

(c)(i)(B) generating a long spreading code using the long code mask of said first mobile appliance; and

(c)(i)(C) applying said long spreading code to an I channel short code and applying said long spreading code to a Q channel short code.

48. The method of claim 37 wherein said wireless communication system includes at least one base station.

49. The method of claim 48 wherein said wireless location sensor is geographically spaced apart from said at least one base station.

50. The method of claim 37 wherein the wireless communication system is a CDMA communication system.

51. The method of claim 37 wherein the wireless communication system is WCDMA compliant as specified by the Third Generation Partnership Project.

52. The method of claim 37 wherein said reverse pilot channel is a CDMA2000 reverse pilot channel as specified by the Telecommunications Industry Association.

53. The method of claim 37 wherein said wireless communication system is an asynchronous system.

54. The method of claim 37 wherein the location of the first mobile appliance is determined independent of the state of said first mobile appliance.

55. A location system for estimating the location of a first mobile appliance, comprising:

said first mobile appliance including means for emitting a pilot signal different from pilot signals emitted by other mobile appliances;

at least one wireless location sensor including means for receiving said first mobile appliance pilot signal; and

a geolocation control server operatively connected to said at least one wireless location sensor for determining an attribute of said received pilot signal and estimating the location of said first mobile appliance as a function of said attribute.

56. The system of claim 55 wherein said attribute is time of arrival.

57. The system of claim 55 wherein said attribute is angle of arrival.

58. The system of claim 55 wherein said attribute is received power level.

59. The system of claim 55 wherein said first mobile appliance is operating in a wireless communication system having at least one base station for communicating with said mobile appliance.

60. The system of claim 59 wherein said attribute is selected from the group consisting of time of arrival, angle of arrival, and received power level.

61. The system of claim 59 including a plurality of wireless location sensors.

62. The system of claim 61 wherein said attribute is time difference of arrival.

63. The system of claim 62 wherein the step of determining the time difference of arrival includes correlating said pilot signal with a reference signal.

64. The method of claim 62 wherein the step of determining the time difference of arrival includes ambiguity function processing of said pilot signal with a reference signal.

65. The system of claim 59 wherein said wireless location sensor is geographically spaced apart from said at least one base station.

66. The system of claim 59 wherein the wireless communication system is an asynchronous system.

67. The system of claim 59 wherein the wireless communication system is a CDMA system.

68. The system of claim 59 wherein the wireless communication system is WCDMA compliant as specified by the Third Generation Partnership Project.

69. The system of claim 59 wherein said pilot signal emitted from said first mobile appliance is used by said at least one base station to coherently demodulate a traffic signal emitted by said first mobile appliance.

70. The system of claim 59 wherein said location system is a network overlay location system.

71. The system of claim 55 wherein said pilot signal emitted from said first mobile appliance is generated as a function of a long spreading code for said first mobile appliance.

72. The system of claim 55 wherein said pilot signal emitted from said first mobile appliance is a CDMA2000 reverse pilot signal as specified by the Telecommunications Industry Association.

73. The system of claim 55 wherein said geolocation control server includes:

a reference signal generator for generating a reference signal;

a cross-correlation or ambiguity function device for determining said attribute of said received pilot signal; and

a location estimator for estimating the location of said first mobile appliance as a function of said attribute.

74. The system of claim 73 wherein said cross-correlation or ambiguity function device determines the time difference of arrival of said received pilot signal for at least two of said wireless location sensors and wherein said location estimator estimates the location of said first mobile appliance as a function of said time difference of arrival.

75. The system of claim 55 wherein said first mobile appliance pilot signal is transmitted continuously.

76. The system of claim 55 wherein said first mobile appliance pilot signal is transmitted periodically.

77. The system of claim 55 wherein the location of the first mobile appliance is determined independent of the state of said first mobile appliance.

78. A method for estimating the location of a mobile appliance in a wireless communication system including at least one base station and a plurality of geolocation receiver sites, comprising the steps of:

transmitting from said mobile appliance a known spread spectrum sequence for establishing synchronization between said mobile appliance and said at least one base station;

receiving said sequence at ones of said plural geolocation receiver sites;

cross-correlating in the time domain and the frequency domain the received sequence with a reference sequence to thereby determine an attribute of said received sequence at said ones of said plural geolocation receiver sites; and

,

estimating the location of the mobile appliance as a function of said attribute.

79. The method of claim 78 wherein one of said plural geolocation receiver sites is geographically spaced apart from any of said at least one base station.

80. The method of claim 78 wherein said spread spectrum sequence is a CDMA2000 reverse pilot signal as specified by the Telecommunications Industry Association.

81. The method of claim 78, wherein said spread spectrum sequence is transmitted continuously.

82. The method of claim 78 wherein the wireless communication system is an asynchronous system.

83. The method of claim 78, wherein said communication system is a CDMA communication system.

84. The method of claim 78, wherein said communication system is WCDMA compliant as specified by the Third Generation Partnership Project.

85. The method of claim 78 wherein the location of the first mobile appliance is determined independent of the state of said first mobile appliance.

86. The method of claim 78 wherein the step of cross-correlating in the time domain and the frequency domain is replaced by ambiguity function processing jointly in the time domain and the frequency domain.

87. In a method of determining the location of a first mobile appliance wherein a wireless location sensor receives signals emitted from said first mobile appliance, the improvement wherein the location of said first mobile appliance is determined independent of the state of said first mobile appliance.