Cell Organization and Transmission Schemes in a Wide Area Positioning System (WAPS)

• US 20130063308A1
• Filed: 08/02/2012
• Published: 03/14/2013
• Est. Priority Date: 09/10/2009
• Status: Active Grant

• Current Assignee: NextNav, LLC
• Original Assignee: Arun Raghupathy, Norman Krasner
• Inventors: KRASNER, Norman, RAGHUPATHY, Arun
• Granted Patent: US 9,372,266 B2
• Time in Patent Office: Days
• US Class Current: 342/393
• 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 of reducing cross-interference in a position location system, the method comprising:

broadcasting from a plurality of transmitters of a transmitter network a plurality of positioning signals comprising pseudorandom ranging signals, wherein during an interval of time at least two positioning signals are transmitted concurrently, each by a different member of the plurality of transmitters, wherein the at least two positioning signals comprise a first signal transmitted from a first member and a second signal transmitted from a second member, wherein the at least two positioning signals have different carrier frequencies, the carrier frequencies offset from one another by an amount that is at least one of equal to and less than twenty-five percent of the bandwidth of each positioning signal of the at least two positioning signals;

receiving in a remote receiver the at least two positioning signals; and

reducing the cross-interference of the second signal upon the first by tuning the remote receiver to a frequency of the first signal and correlating the received signal with a reference pseudorandom ranging signal matched to a transmitted pseudorandom ranging signal of the first signal.

2. The method of claim 1, wherein the offset is a multiple of a sum of a frame rate of the pseudorandom ranging signals and a fraction 1/n of the frame rate, where n is an integer.

3. The method of claim 1, comprising generating the at least two positioning signals to have different pseudorandom codes.

4. The method of claim 1, comprising generating the at least two positioning signals to have the same pseudorandom codes.

5. The method of claim 1, comprising repeating the pseudorandom ranging signals a plurality of times in succession.

6. The method of claim 1, comprising non-concurrently transmitting by the plurality of transmitters at least two additional positioning signals.

7. The method of claim 6, comprising generating the at least two additional positioning signals to have a same pseudorandom code.

8. The method of claim 1, comprising arranging the plurality of transmitters in a geometric pattern and using a plurality of time slots to broadcast the plurality of positioning signals.

9. The method of claim 8, wherein the plurality of transmitters comprises 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.

10. The method of claim 9, wherein m is greater than n.

11. The method of claim 9, wherein m is at least one of less than and equal to n.

12. The method of claim 9, comprising at least one of the at least m transmitters transmitting in more than one slot in a time multiplexing frame.

13. The method of claim 9, comprising transmitting the pseudorandom ranging signal from each of the at least m transmitters using a pseudorandom code selected among a set of k pseudorandom codes, wherein k is a number greater than 1.

14. The method of claim 13, wherein k is at least one of greater than and equal to n.

15. The method of claim 1, comprising transmitting from at least one transmitter of the plurality of transmitters a positioning signal in at least two successive time multiplexing frames of a positioning signal.

16. The method of claim 15, wherein the at least two successive time multiplexing frames comprise a primary frame and a secondary frame, wherein positioning data is transmitted in the primary frame.

17. The method of claim 16, comprising transmitting auxiliary data in the secondary frame, where the auxiliary data comprises at least one of security data and authentication data.

18. The method of claim 17, comprising transmitting positioning data in the secondary frame.

19. The method of claim 1, comprising transmitting the at least two positioning signals concurrently by at least two transmitters in a vicinity of one another, wherein the at least two positioning signals have at least one common parameter.

20. The method of claim 19, wherein the at least one common parameter is at least one of a pseudorandom code, and positioning signal data.

21. The method of claim 20, wherein the pseudorandom code is a maximal length pseudorandom code.

22. The method of claim 20, wherein the pseudorandom code is a Gold Code.

23. The method of claim 1, wherein the plurality of transmitters comprises a supergroup of transmitters, wherein the supergroup includes a plurality of groups of transmitters arranged in a geometric pattern, and each group includes a plurality of transmitters arranged in a geometric pattern.

24. The method of claim 23, wherein the plurality of groups of a supergroup comprises an n-group repeat pattern, wherein n is an integer

25. The method of claim 23, wherein the geometric pattern of the supergroup comprises a hexagonal pattern of groups

26. The method of claim 23, wherein the plurality of groups of a supergroup comprises seven (7) groups.

27. The method of claim 26, wherein each group comprises seven (7) transmitters.

28. The method of claim 23, wherein the supergroup comprises at least one of a time division multiplexing (TDMA) communication network, a code division multiplexing (CDMA) communication network, and a frequency offset multiplexing (FOM) network.

29. The method of claim 23, comprising transmitting the at least two positioning signals concurrently by at least two transmitters of a group of the plurality of groups.

30. The method of claim 23, comprising transmitting the at least two positioning signals concurrently by at least two transmitters that are in different groups.

31. The method of claim 23, wherein the plurality of positioning signals comprises a set of pseudorandom codes, wherein each group in the plurality of groups of transmitters utilizes a permutation of the set of pseudorandom codes.

32. The method of claim 31, wherein the permutation of the set of pseudorandom codes is cyclic with respect to a slot number of the transmitter.

33. The method of claim 31, wherein the permutation associates each pseudorandom code in the set to a geographical position of each transmitter in a group.

34. The method of claim 33, comprising associating a position of a transmitter in each group with a transmit time slot.

35. The method of claim 23, comprising each group of the plurality of groups using a plurality of time slots to broadcast the plurality of positioning signals.

36. The method of claim 35, wherein each group of the plurality of groups comprises n transmitters using n time slots to broadcast the plurality of positioning signals, where n is an integer.

37. The method of claim 35, comprising each group of the plurality of groups using a same set of time slots to broadcast the plurality of positioning signals.

38. The method of claim 37, comprising each transmitter of a group broadcasting in a different time slot from any other transmitter of the group.

39. The method of claim 35, comprising each group of the plurality of groups of a supergroup using at least one pseudorandom code that is different from the pseudorandom codes of any other group.

40. The method of claim 39, wherein the at least one pseudorandom code comprises a Gold Code.

41. The method of claim 39, comprising each group of the plurality of groups of the supergroup using an offset in frequency that is different than the offset of any other group.

42. The method of claim 35, comprising each group of the plurality of groups of the supergroup using an offset in frequency that is different than the offset of from any other group.

43. The method of claim 35, comprising the plurality of transmitters of the plurality of groups of a supergroup using a common pseudorandom code for a least a portion of their transmissions.

44. The method of claim 43, wherein the pseudorandom code comprises a Gold Code.

45. The method of claim 43, wherein the pseudorandom code comprises a maximal length pseudorandom sequence.

46. The method of claim 45, wherein the maximal length pseudorandom sequence comprises a first of two maximal length sequences forming a Gold Code.

47. The method of claim 35, comprising each transmitter of a group broadcasts using a different pseudorandom code from any other transmitter of the group.

48. The method of claim 47, comprising each group of the plurality of groups of a supergroup using a set of pseudorandom codes that is the same as every other group of the plurality of groups.

49. The method of claim 48, comprising each group of the plurality of groups of the supergroup using an offset in frequency that is different than the offset from any other group.

50. The method of claim 35, comprising each transmitter of the supergroup broadcasting using a different pseudorandom code from any other transmitter of the supergroup.

51. The method of claim 50, comprising each group of the plurality of groups of the supergroup using an offset in frequency that is different than the offset of from any other group.

52. The method of claim 35, comprising each group of the plurality of groups of a supergroup using at least one pseudorandom code in accordance with a maximal length pseudorandom sequence.

53. The method of claim 52, wherein the at least one pseudorandom code of each group of the supergroup is different from the pseudorandom codes of any other group of the supergroup.

54. The method of claim 53, comprising each group of the plurality of groups of the supergroup using an offset in frequency that is different than the offset of any other group of the supergroup.

55. The method of claim 35, comprising each group of the plurality of groups of the supergroup using an offset in frequency that is different than the offset of from any other group.

56. The method of claim 55, comprising each group of the supergroup using a pseudorandom code different from that of a pseudorandom code used by any other group of the supergroup.

57. The method of claim 23, comprising each group of the plurality of groups of a supergroup using a same set of pseudorandom codes, and permuting the pseudorandom codes of each group relative to slot numbers of every other group of the plurality of groups.

58. The method of claim 57, comprising each group of the plurality of groups of the supergroup using an offset in frequency that is different than the offset of from any other group.

59. The method of claim 23, wherein the plurality of transmitters comprises a plurality of supergroups of transmitters, wherein each supergroup of the plurality of supergroups comprises a plurality of groups of transmitters arranged in a geometric pattern.

60. The method of claim 59, comprising each transmitter of a group broadcasting using a different pseudorandom code from any other transmitter of the group.

61. The method of claim 60, comprising each supergroup of the plurality of supergroups using a same set of pseudorandom codes as every other supergroup of the plurality of supergroups, and permuting the pseudorandom codes of each supergroup relative to slot numbers of every other supergroup of the plurality of supergroups.

62. The method of claim 61, comprising each group of the plurality of groups of a supergroup using an offset in frequency that is different than the offset in frequency of any other group of that same supergroup

63. The method of claim 59, comprising, in each supergroup of the plurality of supergroups, each transmitter broadcasting using a different pseudorandom code from any other transmitter of that same supergroup.

64. The method of claim 63, comprising each supergroup using a same set of pseudorandom codes as used by every other supergroup, and permuting the pseudorandom codes of a supergroup relative to slot numbers of every other supergroup.

65. The method of claim 23, comprising measuring performance corresponding to the geometric pattern using a ratio of distance between transmitters having identical transmission parameters and a transmitter radius.

66. The method of claim 23, comprising measuring performance corresponding to the geometric pattern using correlation rejection associated with the multiplexing protocol used by the supergroup.

67. The method of claim 23, comprising generating each carrier frequency 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.

68. The method of claim 67, wherein the set of offsets corresponds to

0,k₀R+R/Q,2k₀R+2R/Q,3k₀R+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.

69. The method of claim 68, wherein the integer k₀ has magnitude that is at least one of equal to and greater than two (2).

70. The method of claim 68, wherein quantity Q equals a number of PN frames of the positioning signal coherently integrated by said remote receiver.

71. The method of claim 68, wherein the number of PN frames of the positioning signal coherently integrated by the remote receiver is equal to an integer multiple of Q.

72. The method of claim 68, wherein the quantity Q equals the number of groups of transmitters in the supergroup, and a number of PN frames of the positioning signal coherently integrated by said receiver is greater than the number of groups of transmitters in the supergroup.

73. The method of claim 23, comprising a set of carrier frequency offsets from a base frequency, wherein each offset in such set is no greater than twenty-five percent of the bandwidth of each of the plurality of positioning signals.