Cell organization and transmission schemes in a wide area positioning system (WAPS)

• US 9,372,266 B2
• Filed: 08/02/2012
• Issued: 06/21/2016
• Est. Priority Date: 09/10/2009
• Status: Active Grant

• Current Assignee: NextNav, LLC
• Original Assignee: NextNav, LLC
• Inventors: Krasner, Norman, Raghupathy, Arun
• Primary Examiner(s): Liu, Harry
• Application Number:
  US13/565,723
• Publication Number:
  US 20130063308A1
• Time in Patent Office: 1,419 Days
• Field of Search: 342/393
• US Class Current: 1/1
• CPC Class Codes: G01S 19/05 providing aiding data
• CPC Class Codes: G01S 19/071 DGPS corrections
• CPC Class Codes: G01S 19/11 wherein the cooperating elements are pseudolites or satellite radio beacon positioning system signal repeaters
• CPC Class Codes: G01S 19/21 Interference related issues ; Issues related to cross-correlation, spoofing or other methods of denial of service
• CPC Class Codes: G01S 19/45 by combining measurements of signals from the satellite radio beacon positioning system with a supplementary measurement
• 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

Abstract

A position location system comprises transmitters that broadcast positioning signals. Each broadcasted positioning signal comprises a pseudorandom ranging signal. The position location system includes a remote receiver that acquires and measures the time of arrival of the positioning signals received at the remote receiver. During an interval of time, at least two positioning signals are transmitted concurrently by the transmitters and received concurrently at the remote receiver. The two positioning signals have carrier frequencies offset from one another by an offset that is less than approximately twenty-five percent of the bandwidth of each positioning signal of the two positioning signals. Cross-interference between the positioning signals is reduced by tuning the remote receiver to a frequency of a selected signal of the two positioning signals and correlating the selected signal with a reference pseudorandom ranging signal matched to a transmitted pseudorandom ranging signal of the selected signal.

Claims

1. A method for reducing cross-interference of a first positioning signal having a first pseudorandom ranging signal upon a second positioning signal having a second pseudorandom ranging signal, the method comprising:

reducing cross-interference of the first positioning signal upon the second positioning signal by tuning a receiver to a frequency of the second positioning signal and correlating the second positioning signal with a reference pseudorandom ranging signal matched to the second pseudorandom ranging signal,

wherein the first and second positioning signals are included among a plurality of two or more positioning signals concurrently transmitted by a plurality of transmitters located at different locations,

wherein each of the plurality of positioning signals includes a respective pseudorandom ranging signal modulated on a carrier having a carrier frequency selected from a finite set of values,

wherein the first pseudorandom ranging signal of the first positioning signal is modulated on one carrier having a first carrier frequency,

wherein the second pseudorandom ranging signal of the second positioning signal is modulated on one carrier having a second carrier frequency that is offset from the first carrier frequency by an offset that is less than or equal to twenty-five percent of the bandwidth of each positioning signal of the first and second positioning signals.

2. The method of claim 1, wherein the offset is a multiple of a sum of (i) a frame rate of the pseudorandom ranging signals included in the first and second positioning signals and (ii) a fraction 1/n of the frame rate, where n is an integer.

3. The method of claim 1, wherein the first pseudorandom ranging signal is received a plurality of times in succession, and wherein the second pseudorandom ranging signal is received a plurality of times in succession.

4. The method of claim 1, the method comprising:

receiving two additional positioning signals non-concurrently transmitted by two of the plurality of transmitters.

5. The method of claim 1, wherein the plurality of positioning signals are received from at least m transmitters using n time slots in a time multiplexing frame to broadcast the plurality of positioning signals, where m and n are positive integers.

6. The method of claim 5, wherein m is less than or equal to n.

7. The method of claim 5, wherein m is greater than n.

8. The method of claim 1, the method comprising:

receiving one of the plurality of positioning signals using at least two time multiplexing frames.

9. The method of claim 1, the method comprising:

receiving one of the plurality of positioning signals using at least two successive time multiplexing frames comprising a primary frame and a secondary frame, wherein positioning data of the received positioning signal is received in the primary frame, and security data or authentication data of the received positioning signal is received in the secondary frame.

10. The method of claim 1, wherein each carrier frequency is generated as a sum of a base frequency plus an element of a set of offsets, wherein each offset in the set of offsets is a multiple of a minimum nonzero offset.

11. The method of claim 10, wherein the set of offsets corresponds to 0, k₀R+R/Q, 2 k₀R+2R/Q, 3 k₀R+3R/Q ... ,(Q−

1)k₀R+(Q−

1)R/Q, where R represents PN frame rate, k₀represents a nonzero integer, and Q represents an integer equal to a number of offsets.

12. The method of claim 11, wherein the integer k₀ has magnitude that is at least one of equal to and greater than two.

13. The method of claim 11, the method comprising:

coherently integrating positioning signal PN frames equal to Q, or equal to an integer multiple of Q.

14. The method of claim 11, wherein Q equals the number of transmitter groups forming a supergroup of transmitters that include the plurality of transmitters, the method comprising:

coherently integrating a number of positioning signal PN frames that is greater than Q.

15. The method of claim 1, wherein the plurality of transmitters are members of a supergroup of transmitters that includes a plurality of transmitter groups arranged in a geometric pattern, wherein each transmitter group includes a plurality of transmitters.

16. The method of claim 15, wherein the supergroup comprises at least seven groups, and each group in the supergroup comprises at least seven transmitters.

17. The method of claim 15, wherein the first positioning signal and the second positioning signal are received from transmitters in one of the transmitter groups.

18. The method of claim 15, wherein the first positioning signal and the second positioning signal are received from transmitters in different transmitter groups.

19. The method of claim 15, the method comprising:

receiving positioning signals from each of the plurality of transmitter groups using an offset in frequency for transmissions from that group that is different than the offsets for transmissions from the other groups.

20. The method of claim 16, the method comprising:

receiving positioning signals from each of the transmitter groups using a different pseudorandom code for each of the transmitter groups.

21. The method of claim 16, the method comprising:

receiving positioning signals from each transmitter in one of the transmitter groups using a different pseudorandom code for each transmitter.

22. The method of claim 16, the method comprising:

receiving positioning signals from each transmitter in one of the transmitter groups using the same pseudorandom code for each transmitter.

23. The method of claim 16, the method comprising:

receiving positioning signals from each of the transmitter groups using the same set of pseudorandom codes for each of the transmitter groups.

24. The method of claim 16, the method comprising:

receiving positioning signals from each transmitter in the supergroup using a different pseudorandom code for each transmitter.

25. The method of claim 1, wherein the first and second positioning signals include the same pseudorandom code constructed using a maximal length pseudorandom sequence or a Gold code.

26. A non-transitory processor readable memory storing an application adapted to run on at least one processor to implement a method for reducing cross-interference of a first positioning signal having a first pseudorandom ranging signal upon a second positioning signal having a second pseudorandom ranging signal, the method comprising:

reducing cross-interference of the first positioning signal upon the second positioning signal by tuning a receiver to a frequency of the second positioning signal and correlating the second positioning signal with a reference pseudorandom ranging signal matched to the second pseudorandom ranging signal,

wherein the first and second positioning signals are included among a plurality of two or more positioning signals concurrently transmitted by a plurality of transmitters located at different locations,

wherein each of the plurality of positioning signals includes a respective pseudorandom ranging signal modulated on a carrier having a carrier frequency selected from a finite set of values,

wherein the first pseudorandom ranging signal of the first positioning signal is modulated on one carrier having a first carrier frequency,

wherein the second pseudorandom ranging signal of the second positioning signal is modulated on one carrier having a second carrier frequency that is offset from the first carrier frequency by an offset that is less than or equal to twenty-five percent of the bandwidth of each positioning signal of the first and second positioning signals.

27. The non-transitory processor readable memory of claim 26, wherein the offset is a multiple of a sum of (i) a frame rate of the pseudorandom ranging signals included in the first and second positioning signals and (ii) a fraction 1/n of the frame rate, where n is an integer.

28. The non-transitory processor readable memory of claim 26, wherein the first pseudorandom ranging signal is received a plurality of times in succession, and wherein the second pseudorandom ranging signal is received a plurality of times in succession.

29. The non-transitory processor readable memory of claim 26, the method comprising:

receiving two additional positioning signals non-concurrently transmitted by two of the plurality of transmitters.

30. The non-transitory processor readable memory of claim 26, wherein the plurality of positioning signals are received from at least m transmitters using n time slots in a time multiplexing frame to broadcast the plurality of positioning signals, where m and n are positive integers.

31. The non-transitory processor readable memory of claim 30, wherein m is less than or equal to n.

32. The non-transitory processor readable memory of claim 30, wherein m is greater than n.

33. The non-transitory processor readable memory of claim 26, the method comprising:

receiving one of the plurality of positioning signals using at least two time multiplexing frames.

34. The non-transitory processor readable memory of claim 26, the method comprising:

receiving one of the plurality of positioning signals using at least two successive time multiplexing frames comprising a primary frame and a secondary frame, wherein positioning data of the received positioning signal is received in the primary frame, and security data or authentication data of the received positioning signal is received in the secondary frame.

35. The non-transitory processor readable memory of claim 26, wherein each carrier frequency is generated as a sum of a base frequency plus an element of a set of offsets, wherein each offset in the set of offsets is a multiple of a minimum nonzero offset.

36. The non-transitory processor readable memory of claim 35, wherein the set of offsets corresponds to

0,k₀R+R/Q, 2 k₀R+2 R/Q, 3 k₀R+3R/Q ... ,(Q−

1)k₀R+(Q−

1)R/Q, where R represents PN frame rate, k₀ represents a nonzero integer, and Q represents an integer equal to a number of offsets.

37. The non-transitory processor readable memory of claim 36, wherein the integer k₀ has magnitude that is at least one of equal to and greater than two.

38. The non-transitory processor readable memory of claim 36, the method comprising:

coherently integrating positioning signal PN frames equal to Q, or equal to an integer multiple of Q.

39. The non-transitory processor readable memory of claim 36, wherein Q equals the number of transmitter groups forming a supergroup of transmitters that include the plurality of transmitters, the method comprising:

coherently integrating a number of positioning signal PN frames that is greater than Q.

40. The non-transitory processor readable memory of claim 26, wherein the plurality of transmitters are members of a supergroup of transmitters that includes a plurality of transmitter groups arranged in a geometric pattern, wherein each transmitter group includes a plurality of transmitters.

41. The non-transitory processor readable memory of claim 40, wherein the supergroup comprises at least seven groups, and each group in the supergroup comprises at least seven transmitters.

42. The non-transitory processor readable memory of claim 40, wherein the first positioning signal and the second positioning signal are received from transmitters in one of the transmitter groups.

43. The non-transitory processor readable memory of claim 40, wherein the first positioning signal and the second positioning signal are received from transmitters in different transmitter groups.

44. The non-transitory processor readable memory of claim 40, the method comprising:

receiving positioning signals from each of the plurality of transmitter groups using an offset in frequency for transmissions from that group that is different than the offsets for transmissions from the other groups.

45. The non-transitory processor readable memory of claim 41, the method comprising:

receiving positioning signals from each of the transmitter groups using a different pseudorandom code for each of the transmitter groups.

46. The non-transitory processor readable memory of claim 41, the method comprising:

receiving positioning signals from each transmitter in one of the transmitter groups using a different pseudorandom code for each transmitter.

47. The non-transitory processor readable memory of claim 41, the method comprising:

receiving positioning signals from each transmitter in one of the transmitter groups using the same pseudorandom code for each transmitter.

48. The non-transitory processor readable memory of claim 41, the method comprising:

receiving positioning signals from each of the transmitter groups using the same set of pseudorandom codes for each of the transmitter groups.

49. The non-transitory processor readable memory of claim 41, the method comprising:

receiving positioning signals from each transmitter in the supergroup using a different pseudorandom code for each transmitter.

50. A system for reducing cross-interference of a first positioning signal having a first pseudorandom ranging signal upon a second positioning signal having a second pseudorandom ranging signal, wherein the system:

reduces cross-interference of the first positioning signal upon the second positioning signal by tuning a receiver to a frequency of the second positioning signal and correlating the second positioning signal with a reference pseudorandom ranging signal matched to the second pseudorandom ranging signal,

wherein the first and second positioning signals are included among a plurality of two or more positioning signals concurrently transmitted by a plurality of transmitters located at different locations,

wherein each of the plurality of positioning signals includes a respective pseudorandom ranging signal modulated on a carrier having a carrier frequency selected from a finite set of values,

wherein the first pseudorandom ranging signal of the first positioning signal is modulated on one carrier having a first carrier frequency,

wherein the second pseudorandom ranging signal of the second positioning signal is modulated on one carrier having a second carrier frequency that is offset from the first carrier frequency by an offset that is less than or equal to twenty-five percent of the bandwidth of each positioning signal of the first and second positioning signals.

51. The system of claim 50, wherein the offset is a multiple of a sum of (i) a frame rate of the pseudorandom ranging signals included in the first and second positioning signals and (ii) a fraction 1/n of the frame rate, where n is an integer.

52. The system of claim 50, wherein the first pseudorandom ranging signal is received a plurality of times in succession, and wherein the second pseudorandom ranging signal is received a plurality of times in succession.

53. The system of claim 50, wherein the receiver receives two additional positioning signals non-concurrently transmitted by two of the plurality of transmitters.

54. The system of claim 50, wherein the plurality of positioning signals are received from at least m transmitters using n time slots in a time multiplexing frame to broadcast the plurality of positioning signals, where m and n are positive integers.

55. The system of claim 54, wherein m is less than or equal to n.

56. The system of claim 54, wherein m is greater than n.

57. The system of claim 50, wherein the receiver receives one of the plurality of positioning signals using at least two time multiplexing frames.

58. The system of claim 50, wherein the receiver receives one of the plurality of positioning signals using at least two successive time multiplexing frames comprising a primary frame and a secondary frame, wherein positioning data of the received positioning signal is received in the primary frame, and security data or authentication data of the received positioning signal is received in the secondary frame.

59. The system of claim 50, wherein each carrier frequency is generated as a sum of a base frequency plus an element of a set of offsets, wherein each offset in the set of offsets is a multiple of a minimum nonzero offset.

60. The system of claim 59, wherein the set of offsets corresponds to 0, k₀R+R/Q, 2 k₀R+2R/Q, 3 k₀R+3R/Q ... ,(Q−

1)k₀R+(Q−

1)R/Q, where R represents PN frame rate, k₀ represents a nonzero integer, and Q represents an integer equal to a number of offsets.

61. The system of claim 60, wherein the integer k₀ has magnitude that is at least one of equal to and greater than two.

62. The system of claim 60, wherein the receiver coherently integrates positioning signal PN frames equal to Q, or equal to an integer multiple of Q.

63. The system of claim 60, wherein Q equals the number of transmitter groups forming a supergroup of transmitters that include the plurality of transmitters, wherein the receiver coherently integrates a number of positioning signal PN frames that is greater than Q.

64. The system of claim 50, wherein the plurality of transmitters are members of a supergroup of transmitters that includes a plurality of transmitter groups arranged in a geometric pattern, wherein each transmitter group includes a plurality of transmitters.

65. The system of claim 64, wherein the supergroup comprises at least seven groups, and each group in the supergroup comprises at least seven transmitters.

66. The system of claim 64, wherein the first positioning signal and the second positioning signal are received from transmitters in one of the transmitter groups.

67. The system of claim 64, wherein the first positioning signal and the second positioning signal are received from transmitters in different transmitter groups.

68. The system of claim 64, wherein the receiver receives positioning signals from each of the plurality of transmitter groups using an offset in frequency for transmissions from that group that is different than the offsets for transmissions from the other groups.

69. The system of claim 65, wherein the receiver receives positioning signals from each of the transmitter groups using a different pseudorandom code for each of the transmitter groups.

70. The system of claim 65, wherein the receiver receives positioning signals from each transmitter in one of the transmitter groups using a different pseudorandom code for each transmitter.

71. The system of claim 65, wherein the receiver receives positioning signals from each transmitter in one of the transmitter groups using the same pseudorandom code for each transmitter.

72. The system of claim 65, wherein the receiver receives positioning signals from each of the transmitter groups using the same set of pseudorandom codes for each of the transmitter groups.

73. The system of claim 65, wherein the receiver receives positioning signals from each transmitter in the supergroup using a different pseudorandom code for each transmitter.