Communications systems including adaptive antenna systems and methods for inter-system and intra-system interference reduction

• US 20060292990A1
• Filed: 06/08/2006
• Published: 12/28/2006
• Est. Priority Date: 06/21/2005
• Status: Active Grant

• Current Assignee: ATC Technology Corporation (FedEx Corporation)
• Original Assignee: ATC Technology Corporation (FedEx Corporation)
• Inventors: Karabinis, Peter D., Zheng, Dunmin
• Granted Patent: US 7,817,967 B2
• Time in Patent Office: Days
• US Class Current: 455/63.4
• CPC Class Codes: H01Q 3/2611 Means for null steering; Adaptive interference nulling
• CPC Class Codes: H04B 7/18513 Transmission in a satellite or space-based system

Abstract

Methods of forming a downlink beam in an adaptive antenna system of a communications system that may reduce inter-system and/or intra-system interference include receiving vectors of signals including signals transmitted by user terminals of the communications system and signals transmitted by transceivers of an independent communications system, obtaining spatial information for the user terminals of the communications system and the transceivers of the independent communications system, generating complex transmitting weights that form spatial nulls directed at the transceivers of the independent communications system, and transmitting a downlink communications signal using the complex transmitting weights. Related systems are also disclosed.

Claims

1. A method of forming a downlink beam in an adaptive antenna system of a communications system, comprising:

receiving vectors of signals including signals transmitted by user terminals of the communications system and signals transmitted by transceivers of an independent communications system;

obtaining spatial information for the user terminals of the communications system and the transceivers of the independent communications system;

generating complex transmitting weights that form spatial nulls directed at the transceivers of the independent communications system; and

transmitting a downlink communications signal using the complex transmitting weights.

2. The method of claim 1, wherein receiving vectors of signals comprises receiving vectors of signals using an antenna comprising an array of antenna feed elements, and wherein a respective one of the complex transmitting weights is associated with a corresponding one of the antenna feed elements.

3. The method of claim 1, wherein obtaining spatial information for the user terminals of the communications system and the transceivers of the independent communications system comprises obtaining the spatial information using the received vectors of signals.

4. The method of claim 3, wherein obtaining spatial information for the user terminals of the communications system comprises performing pseudo uplink beamforming, and wherein obtaining spatial information for the transceivers of the independent communications system comprises using blind spatial channel estimation.

5. The method of claim 3, wherein obtaining spatial information comprises generating estimates of an array covariance matrix using the signals transmitted by the user terminals of the communications system and the signals transmitted by the transceivers of an independent communications system.

6. The method of claim 5, wherein generating estimates of the array covariance matrix comprises obtaining estimates of spatial signatures of the user terminals of the communications system using a preamble or pilot signal reference.

7. The method of claim 5, wherein generating estimates of the array covariance matrix comprises:

estimating a covariance matrix for the transceivers of the independent communications system;

estimating a covariance matrix for the user terminals of the communications system; and

deriving a composite covariance matrix by combining the covariance matrix for the transceivers of the independent communications system with the covariance matrix for the user terminals of the communications system.

8. The method of claim 7, further comprising:

performing frequency transformation of the covariance matrix for the transceivers of the independent communications system to transform a frequency of the covariance matrix for the transceivers of the independent communications system to a frequency of the communications system.

9. The method of claim 7, wherein generating complex transmitting weights comprises generating a set of pseudo uplink beamforming weights by combining the estimates of the spatial signatures of user terminals of the communications system with the composite covariance matrix, and wherein transmitting a downlink communications signal using the complex transmitting weights comprises transmitting a downlink communications signal using the pseudo uplink beamforming weights transmitting weights.

10. The method of claim 1, wherein obtaining spatial information for the user terminals of the communications system and/or the transceivers of the independent communications system comprises obtaining spatial signatures using an angle of arrival estimation algorithm.

11. The method of claim 10, wherein obtaining spatial information for the transceivers of the independent communications system further comprises estimating angle of arrival information of the signals from the transceivers of the independent communications system using a maximum likelihood angle of arrival estimation algorithm, and generating spatial signatures of the transceivers of the independent communications system using the angle of arrival information.

12. The method of claim 1, wherein the communications system is configured to communicate with user terminals using a time division duplex communications protocol.

13. The method of claim 1, wherein obtaining spatial information for the transceivers of the independent communications system comprises generating estimates of a covariance matrix using the signals transmitted by the transceivers of an independent communications system and decomposing the covariance matrix to obtain the principal eigenvector of the covariance matrix or the K eigenvectors corresponding to the K largest eigenvalues, where K represents the number of transceivers of the independent communications system.

14. The method of claim 1, wherein receiving signals transmitted by transceivers of an independent communications system comprises receiving pilot or carrier signals transmitted by the transceivers of the independent communications system.

15. The method of claim 1, wherein receiving signals transmitted by transceivers of an independent communications system comprises receiving beacon signals transmitted by the transceivers of the independent communications system.

16. The method of claim 15, further comprising:

forming an uplink antenna pattern using the complex transmitting weights;

receiving the beacon signals using the uplink antenna pattern; and

measuring strength of the beacon signals received using the uplink antenna pattern, wherein the strength of the beacon signals received using the uplink antenna pattern provides an error signal associated with the complex transmitting weights.

17. The method of claim 16, further comprising adjusting the complex transmitting weights to reduce the strength of the beacon signals.

18. The method of claim 1, wherein the adaptive antenna system comprises a vertical uniform linear array of radiating elements, and wherein generating complex transmitting weights that form spatial nulls directed at the transceivers of the independent communications system comprises generating complex transmitting weights that form spatial nulls directed at angles of arrival associated with the transceivers of the independent communications system.

19. The method of claim 1, wherein the adaptive antenna system comprises a phased array antenna, and wherein generating complex transmitting weights that form spatial nulls directed at the transceivers of the independent communications system comprises generating complex transmitting weights that form spatial nulls directed at azimuth/elevation coordinates associated with the transceivers of the independent communications system.

20. The method of claim 1, further comprising:

receiving the downlink communications signal at a user terminal of the communication system.

21. The method of claim 1, wherein the communications system comprises a terrestrial communications system.

23. The method of claim 21, wherein the adaptive antenna comprises a plurality of vertical uniform linear array antennas, and wherein generating complex transmitting weights comprises generating complex transmitting weights that form a spatial null directed at an elevation associated with the transceiver of the independent communications system.

24. The method of claim 21, wherein obtaining location information for the transceiver of the independent communications system comprises receiving a beacon signal from the transceiver of the independent communications system.

25. The method of claim 24, wherein the beacon signal comprises an unmodulated carrier signal, a control channel signal and/or a traffic channel signal.

26. The method of claim 24, wherein generating the complex transmitting weights comprises:

forming an uplink antenna pattern using the complex transmitting weights;

receiving the beacon signal using the uplink antenna pattern; and

measuring strength of the beacon signal received using the uplink antenna pattern, wherein the strength of the beacon signal received using the uplink antenna pattern provides an error signal associated with the complex transmitting weights.

27. The method of claim 26, further comprising adjusting the complex transmitting weights to reduce the strength of the beacon signals.

22. A method of generating a downlink transmission signal from a base transceiver system to a user terminal associated with the base transceiver system, comprising:

obtaining location information for a transceiver of an independent communications system not associated with the base transceiver system;

generating complex transmitting weights for an adaptive antenna associated with the base transceiver system that form a spatial null directed at the transceiver of the independent communications system; and

transmitting a downlink communications signal over the adaptive antenna system to the user terminal using the complex transmitting weights.

28. The method of claim 22, wherein transmitting the downlink communications signal comprises transmitting a signal that is Left Hand Circularly Polarized (LHCP), Right Hand Circularly Polarized (RHCP), or Linearly Polarized (LP).

29. The method of claim 22, further comprising receiving the downlink communications system at a user terminal of the communications system.

30. The method of claim 22, wherein the base transceiver system is terrestrially based.

31. A base transceiver system of a communications system, comprising:

an antenna array configured to receive vectors of signals including signals transmitted by user terminals of the communications system and signals transmitted by transceivers of an independent communications system; and

an electronics system coupled to the antenna array and configured to obtain spatial information for the user terminals of the communications system and the transceivers of the independent communications system, to generate complex transmitting weights that form spatial nulls directed at the transceivers of the independent communications system, and to transmit a downlink communications signal over the antenna array using the complex transmitting weights.

32. The base transceiver system of claim 31, wherein the antenna array includes an array of antenna feed elements, and wherein respective ones of the complex transmitting weights are associated with corresponding ones of the antenna feed elements.

33. The base transceiver system of claim 31, wherein the electronics system is configured to obtain spatial information for the user terminals of the communications system and the transceivers of the independent communications system using the received vectors of signals.

34. The base transceiver system of claim 33, wherein the electronics system is configured to obtain spatial information for the user terminals of the communications system by performing pseudo uplink beamforming, and wherein the electronics system is configured to obtain spatial information for the transceivers of the independent communications system using blind spatial channel estimation.

35. The base transceiver system of claim 33, wherein the electronics system is configured to generate estimates of an array covariance matrix using the signals transmitted by the user terminals of the communications system and the signals transmitted by the transceivers of an independent communications system.

36. The base transceiver system of claim 35, wherein the electronics system is configured to obtain estimates of spatial signatures of the user terminals of the communications system using a preamble or pilot signal reference.

37. The base transceiver system of claim 35, wherein the electronics system is configured to generate estimates of the array covariance matrix by estimating a covariance matrix for the transceivers of the independent communications system, estimating a covariance matrix for the user terminals of the communications system, and deriving a composite covariance matrix by combining the covariance matrix for the transceivers of the independent communications system with the covariance matrix for the user terminals of the communications system.

38. The base transceiver system of claim 37, the electronics system is further configured to transform a frequency of the covariance matrix for the transceivers of the independent communications system to a frequency of the communications system.

39. The base transceiver system of claim 37, wherein the electronics system is configured to generate a set of pseudo uplink beamforming weights by combining the estimates of the spatial signatures of user terminals of the communications system with the composite covariance matrix, and wherein the electronics system is further configured to transmit the downlink communications signal using the pseudo uplink beamforming weights transmitting weights.

40. The base transceiver system of claim 31, wherein the electronics system is configured to obtain spatial signatures for the user terminals of the communications system and/or the transceivers of the independent communications system using an angle of arrival estimation algorithm.

41. The base transceiver system of claim 40 wherein the electronics system is configured to estimate angle of arrival information of the signals from the transceivers of the independent communications system using a maximum likelihood angle of arrival estimation algorithm, and to generate spatial signatures of the transceivers of the independent communications system using the angle of arrival information.

42. The base transceiver system of claim 31, wherein the communications system is configured to communicate with user terminals using a time division duplex communications protocol.

43. The base transceiver system of claim 31, wherein the electronics system is configured to generate estimates of a covariance matrix using the signals transmitted by the transceivers of an independent communications system and to decompose the covariance matrix to obtain the principal eigenvector of the covariance matrix or the K eigenvectors corresponding to the K largest eigenvalues, where K represents the number of transceivers of the independent communications system.

44. The base transceiver system of claim 31, wherein the antenna array is configured to receive pilot or carrier signals transmitted by the transceivers of the independent communications system.

45. The base transceiver system of claim 31, wherein the antenna array is configured to receive beacon signals transmitted by the transceivers of the independent communications system.

46. The base transceiver system of claim 45, wherein the electronics system is configured to form an uplink antenna pattern using the complex transmitting weights, to receive the beacon signals using the uplink antenna pattern, and to measure strength of the beacon signals received using the uplink antenna pattern, wherein the strength of the beacon signals received using the uplink antenna pattern provides an error signal associated with the complex transmitting weights.

47. The base transceiver system of claim 46, wherein the electronics system is configured to adjust the complex transmitting weights to reduce the strength of the beacon signals.

48. The base transceiver system of claim 31, wherein the antenna array comprises a vertical uniform linear array of radiating elements, and wherein the electronics system is configured to generate complex transmitting weights that form spatial nulls directed at angles of arrival associated with the transceivers of the independent communications system.

49. The base transceiver system of claim 31, wherein the antenna array comprises a phased array antenna, and wherein the electronics system is configured to generate complex transmitting weights that form spatial nulls directed at azimuth/elevation coordinates associated with the transceivers of the independent communications system.

50. A base transceiver system of a communication system, comprising:

an antenna array configured to receive vectors of signals including signals transmitted by user terminals of the communications system and signals transmitted by a transceiver of an independent communications system; and

an electronics system coupled to the antenna array and configured to obtain location information for a transceiver of the independent communications system, to generate complex transmitting weights for the antenna array that form a spatial null directed at the transceiver of the independent communications system, and to transmit a downlink communications signal over the adaptive antenna system to the user terminal using the complex transmitting weights.

51. The base transceiver system of claim 50, wherein the adaptive antenna comprises a plurality of vertical uniform linear array antennas, and wherein the electronics system is configured to generate complex transmitting weights that form a spatial null directed at an elevation associated with the transceiver of the independent communications system.

52. The base transceiver system of claim 50, wherein the antenna array is configured to receiving a beacon signal from the transceiver of the independent communications system.

53. The base transceiver system of claim 52, wherein the beacon signal comprises an unmodulated carrier signal, a control channel signal and/or a traffic channel signal.

54. The base transceiver system of claim 52, wherein the electronics system is configured to form an uplink antenna pattern using the complex transmitting weights, receive the beacon signal using the uplink antenna pattern, and to measure strength of the beacon signal received using the uplink antenna pattern, wherein the strength of the beacon signal received using the uplink antenna pattern provides an error signal associated with the complex transmitting weights.

55. The base transceiver system of claim 54, wherein the electronics system is configured to adjust the complex transmitting weights to reduce the strength of the beacon signals.

56. The base transceiver system of claim 50, wherein the antenna array is configured to transmit the downlink communications signal comprises transmitting a signal that is Left Hand Circularly Polarized (LHCP), Right Hand Circularly Polarized (RHCP), or Linearly Polarized (LP).

57. A communications system, comprising:

user terminals configured to generate communication signals in a first frequency band; and

a base transceiver system comprising;

an antenna array configured to receive vectors of signals including signals transmitted by the user terminals in the first frequency band and signals transmitted by transceivers of an independent communications system in a second frequency band and an electronics system coupled to the antenna array and configured to obtain spatial information for the user terminals of the communications system and the transceivers of the independent communications system, to generate complex transmitting weights that form spatial nulls directed at the transceivers of the independent communications system, and to transmit a downlink communications signal to at least one of the user terminals of the communications system over the antenna array using the complex transmitting weights

58. The communications system of claim 57, wherein the antenna array includes an array of antenna feed elements, and wherein respective ones of the complex transmitting weights are associated with corresponding ones of the antenna feed elements.

59. The communications system of claim 57, wherein the electronics system is configured to obtain spatial information for the user terminals of the communications system and the transceivers of the independent communications system using the received vectors of signals.

60. The communications system of claim 59, wherein the electronics system is configured to obtain spatial information for the user terminals of the communications system by performing pseudo uplink beamforming, and wherein the electronics system is configured to obtain spatial information for the transceivers of the independent communications system using blind spatial channel estimation.

61. The communications system of claim 59, wherein the electronics system is configured to generate estimates of an array covariance matrix using the signals transmitted by the user terminals of the communications system and the signals transmitted by the transceivers of an independent communications system.

62. The communications system of claim 61, wherein the electronics system is configured to obtain estimates of spatial signatures of the user terminals of the communications system using a preamble or pilot signal reference.

63. The communications system of claim 61, wherein the electronics system is configured to generate estimates of the array covariance matrix by estimating a covariance matrix for the transceivers of the independent communications system, estimating a covariance matrix for the user terminals of the communications system, and deriving a composite covariance matrix by combining the covariance matrix for the transceivers of the independent communications system with the covariance matrix for the user terminals of the communications system.

64. The communications system of claim 63, the electronics system is further configured to transform a frequency of the covariance matrix for the transceivers of the independent communications system to a frequency of the communications system.

65. The communications system of claim 63, wherein the electronics system is configured to generate a set of pseudo uplink beamforming weights by combining the estimates of the spatial signatures of user terminals of the communications system with the composite covariance matrix, and wherein the electronics system is further configured to transmit the downlink communications signal using the pseudo uplink beamforming weights transmitting weights.

66. The communications system of claim 57, wherein the electronics system is configured to obtain spatial signatures for the user terminals of the communications system and/or the transceivers of the independent communications system using an angle of arrival estimation algorithm.

67. The communications system of claim 66, wherein the electronics system is configured to estimate angle of arrival information of the signals from the transceivers of the independent communications system using a maximum likelihood angle of arrival estimation algorithm, and to generate spatial signatures of the transceivers of the independent communications system using the angle of arrival information.

68. The communications system of claim 57, wherein the communications system is configured to communicate with user terminals using a time division duplex communications protocol.

69. The communications system of claim 57, wherein the electronics system is configured to generate estimates of a covariance matrix using the signals transmitted by the transceivers of an independent communications system and to decompose the covariance matrix to obtain the principal eigenvector of the covariance matrix or the K eigenvectors corresponding to the K largest eigenvalues, where K represents the number of transceivers of the independent communications system.

70. The communications system of claim 57, wherein the antenna array is configured to receive pilot or carrier signals transmitted by the transceivers of the independent communications system.

71. The communications system of claim 57, wherein the antenna array is configured to receive beacon signals transmitted by the transceivers of the independent communications system.

72. The communications system of claim 71, wherein the electronics system is configured to form an uplink antenna pattern using the complex transmitting weights, to receive the beacon signals using the uplink antenna pattern, and to measure strength of the beacon signals received using the uplink antenna pattern, wherein the strength of the beacon signals received using the uplink antenna pattern provides an error signal associated with the complex transmitting weights.

73. The communications system of claim 72, wherein the electronics system is configured to adjust the complex transmitting weights to reduce the strength of the beacon signals.

74. The communications system of claim 57, wherein the antenna array comprises a vertical uniform linear array of radiating elements, and wherein the electronics system is configured to generate complex transmitting weights that form spatial nulls directed at angles of arrival associated with the transceivers of the independent communications system.

75. The communications system of claim 57, wherein the antenna array comprises a phased array antenna, and wherein the electronics system is configured to generate complex transmitting weights that form spatial nulls directed at azimuth/elevation coordinates associated with the transceivers of the independent communications system.

76. A communications system, comprising:

a base transceiver system comprising an antenna array configured to receive vectors of signals including signals transmitted by user terminals of the communications system and signals transmitted by a transceiver of an independent communications system, and an electronics system coupled to the antenna array and configured to obtain location information for a transceiver of the independent communications system, to generate complex transmitting weights for the antenna array that form a spatial null directed at the transceiver of the independent communications system, and to transmit a downlink communications signal over the adaptive antenna system to the user terminal using the complex transmitting weights.

77. The communications system of claim 76, wherein the adaptive antenna comprises a plurality of vertical uniform linear array antennas, and wherein the electronics system is configured to generate complex transmitting weights that form a spatial null directed at an elevation associated with the transceiver of the independent communications system.

78. The communications system of claim 76, wherein the antenna array is configured to receiving a beacon signal from the transceiver of the independent communications system.

79. The communications system of claim 78, wherein the beacon signal comprises an unmodulated carrier signal, a control channel signal and/or a traffic channel signal.

80. The communications system of claim 78, wherein the electronics system is configured to form an uplink antenna pattern using the complex transmitting weights, receive the beacon signal using the uplink antenna pattern, and to measure strength of the beacon signal received using the uplink antenna pattern, wherein the strength of the beacon signal received using the uplink antenna pattern provides an error signal associated with the complex transmitting weights.

81. The communications system of claim 80, wherein the electronics system is configured to adjust the complex transmitting weights to reduce the strength of the beacon signals.

82. The communications system of claim 76, wherein the antenna array is configured to transmit the downlink communications signal comprises transmitting a signal that is Left Hand Circularly Polarized (LHCP), Right Hand Circularly Polarized (RHCP), or Linearly Polarized (LP).

83. The communications system of claim 76, further comprising at least one user terminal configured to receive the downlink communications signal.