Multipath communication methods and apparatuses

• US 7,177,369 B2
• Filed: 04/25/2002
• Issued: 02/13/2007
• Est. Priority Date: 04/27/2001
• Status: Active Grant

• Current Assignee: XR Communications, LLC
• Original Assignee: Vivato, Inc. (Vivato Networks, LLC)
• Inventors: Crilly, Jr., William J.
• Primary Examiner(s): Corrielus, Jean B.
• Application Number:
  US10/131,864
• Publication Number:
  US 20020159537A1
• Time in Patent Office: 1,755 Days
• Field of Search: 375/267, 375/279, 375/147, 375/150, 375/220, 375/228, 375/229, 375/231, 375/346, 375/347, 375/296, 375/285, 370/203, 370/226, 370/229, 370/252
• US Class Current: 375/296
• CPC Class Codes: H04B 7/0617 for beam forming

Abstract

Methods, apparatuses and systems are provided for identifying at least one multipath transmission delay within a reverse path data signal, determining at least one forward path pre-equalization parameter based on the transmission delay, and modifying a forward path data signal based on the forward path pre-equalization parameter. A reverse link transmission is used to help characterize the multipath delays that may exist between communicating devices. The reverse path data signal can include a training sequence or other like known/substantially-known data that can be analyzed to detect transmission delays, especially delays that extend beyond established guard intervals. Such pre-equalization techniques can be advantageously combined, for example, with antenna arrangements that support transmission diversity, spatial division transmission, and/or other like techniques.

Claims

1. A method comprising:

identifying at least one multipath transmission delay within a reverse path data signal received from a receiving device;

determining at least one forward path pre-equalization parameter based on said at least one transmission delay; and

modifying a forward path data signal that is to be transmitted to the receiving device based on said at least one forward path pre-equalization parameter, where said modifying includes selectively setting different transmission power levels for at least two Orthogonal Frequency Division Multiplexing (OFDM) tones in said forward path data signal.

2. The method as recited in claim 1, further comprising:

receiving said reverse path data signal over at least one reverse transmission path.

3. The method as recited in claim 2, further comprising:

transmitting said modified forward path data signal over at least one forward transmission path.

4. The method as recited in claim 1, wherein said reverse path data signal includes at least one type of data selected from a group of different types of data comprising Orthogonal Frequency Division Multiplexing (OFDM) data and Quadrature Phase Shift Keying (QPSK) data.

5. The method as recited in claim 1, wherein said modified forward path data signal includes at least one type of data selected from a group of different types of data comprising Orthogonal Frequency Division Multiplexing (OFDM) data and Quadrature Phase Shift Keying (QPSK) data.

6. The method as recited in claim 5, wherein said modified forward path data signal includes sub-carrier pre-equalized OFDM data.

7. The method as recited in claim 6, further comprising:

generating corresponding Quadrature Phase Shift Keying (QPSK) modulation values based on said sub-carrier pre-equalized OFDM data.

8. The method as recited in claim 4, wherein identifying said at least one multipath transmission delay includes:

identifying at least one multipath transmission delay spread that is greater than a guard interval.

9. The method as recited in claim 1, wherein said reverse path data signal includes identifiable training data.

10. The method as recited in claim 9, further comprising:

comparing said identifiable training data to a local version of said training data to identify said at least one multipath transmission delay within said reverse path data signal.

11. The method as recited in claim 3, wherein modifying said forward path data signal based on at least one forward path pre-equalization parameter further includes:

selectively inverting arid applying a measured channel response to said forward path data signal to significantly reduce subsequent induced deleterious channel response changes to said modified forward path data signal during transmission over said at least one forward transmission path.

12. The method as recited in claim 3, wherein said at least one reverse transmission path is substantially reciprocal to said at least one forward transmission path.

13. The method as recited in claim 1, wherein identifying said at least one multipath transmission delay, determining said at least one forward path pre-equalization parameter, and modifying said forward path data signal are performed by a transmitting device.

14. The method as recited in claim 13, wherein said transmitting device includes a base station device that is operatively configured for use in a wireless communication system.

15. The method as recited in claim 13, further comprising:

using at least one transmitting device receive antenna operatively coupled to said transmitting device to receive said reverse path data signal over at least one reverse transmission path from the receiving device.

16. The method as recited in claim 15, wherein said receiving device includes a customer premise equipment (CPE) device that is operatively configured for use in a wireless communication system.

17. The method as recited in claim 16, wherein said CPE device includes at least one device selected from a group of devices comprising a computer, a portable computer, a personal digital assistant (PDA), and a mobile communication device.

18. The method as recited in claim 15, wherein said at least one transmitting device receive antenna includes at least one type of antenna selected from a group of suitable types of antennas comprising at least one omnidirectional type of antenna, at least one beam type of antenna, at least one phased array type of antenna, and at least one adaptive antenna.

19. The method as recited in claim 15, wherein said transmitting device is operatively coupled to a plurality of first device receive antennas.

20. The method as recited in claim 13, further comprising;

receiving said reverse path data signal over at least one reverse transmission path; and

causing said transmitting device to post equalize at least a portion of said received reverse path signal.

21. The method as recited in claim 15, wherein determining said at least one forward path pre-equalization parameter based on said at least one transmission delay further includes:

determining at least one angle of arrival of said reverse path data signal with respect to said at least one transmitting device receive antenna.

22. The method as recited in claim 15, further comprising:

using at least one receiving device transmit antenna operatively coupled to said receiving device and configured to transmit said reverse path data signal over said at least one reverse transmission path to said transmitting device.

23. The method as recited in claim 22, wherein a plurality of receiving device transmit antennas are operatively coupled to said receiving device and configured to transmit said reverse path data signal over said at least one reverse transmission path to said transmitting device.

24. The method as recited in claim 22, further comprising:

causing said receiving device to transmit at least two reverse path data signals over said at least one reverse transmission path to said transmitting device.

25. The method as recited in claim 24, wherein said at least two reverse path data signals include Orthogonal Frequency-Division Multiple Access (OFDMA) data.

26. The method as recited in claim 22, further comprising:

causing said receiving device to transmit said reverse path data signal over said at least one reverse transmission path to said transmitting device at a bit rate less than about 6 Mbps.

27. The method as recited in claim 22, further comprising:

causing said receiving device to transmit corresponding receiving device transmission power level information to said transmitting device; and

causing said transmitting device to adjust at least one transmission power level associated with said forward path data signal based on said receiving device transmission power level information.

28. The method as recited in claim 13, further comprising:

using at least one transmitting device transmit antenna operatively coupled to said transmitting device to transmit said modified forward path data signal over at least one forward transmission path to the receiving device.

29. The method as recited in claim 28, wherein said at least one transmitting device transmit antenna is operatively configured to provide transmission diversity when transmitting said modified forward path data signal.

30. The method as recited in claim 28, wherein said at least one transmitting device transmit antenna is operatively configured to provide spatial division transmission utilizing a spatial division technique when transmitting said modified forward path data signal as a narrow signal to reduce multipath propagation.

31. The method as recited in claim 28, wherein said at least one transmitting device transmit antenna includes at least one type of antenna selected from a group of suitable types of antennas comprising at least one omnidirectional type of antenna, at least one beam type of antenna, at least one phased array type of antenna, and at least one adaptive antenna.

32. The method as recited in claim 28, further comprising:

setting at least one antenna pointing parameter associated with said at least one transmitting device transmit antenna based on said at least one forward path pre-equalization parameter.

33. The method as recited in claim 28, further comprising:

setting at least one phased array antenna transmission directing parameter associated with said at least one transmitting device transmit antenna based on said at least one forward path pre-equalization parameter.

34. The method as recited in claim 28, further comprising;

selectively transmitting said modified forward path data signal at one angle with respect to said transmitting device transmit antenna.

35. The method as recited in claim 28, further comprising:

selecting said at least one transmitting device transmit antenna from a plurality of transmitting device transmit antennas that are each operatively coupled to said transmitting device.

36. The method as recited in claim 35, further comprising:

selectively transmitting a plurality of beams using two or more transmitting device transmit antennas.

37. The method as recited in claim 36, wherein each of said transmitted plurality of beams is selectively adjusted in phase and amplitude to reduce multipath affects when received by said receiving device.

38. The method as recited in claim 28, further comprising:

using at least one receiving device receive antenna operatively coupled to said receiving device and configured to receive said modified forward path data signal over said at least one forward transmission path from said transmitting device.

39. The method as recited in claim 38, wherein a plurality of receiving device receive antennas are operatively coupled to said receiving device and configured to receive said modified forward path data signal over said at least one forward transmission path from said transmitting device.

40. The method as recited in claim 1, wherein determining said at least one forward path pre-equalization parameter based on said at least one transmission delay further includes:

iteratively selectively identifying different forward path pre-equalization parameters over time to operatively identify and subsequently ignore aliased multipath delays within said reverse path data signal.

41. The method as recited in claim 1, wherein determining said at least one forward path pre-equalization parameter based on said at least one transmission delay further includes:

sub-band equalizing said forward path data signal using corresponding frequency domain reverse path data.

42. A system comprising:

a first device operatively configured to connect to at least a second device over a wireless communication path, said first device having logic that is configured to detect a multipath transmission delay in at least one reverse path data signal transmitted by said second device, determine at least one forward path pre-equalization parameter based on said detected multipath transmission delay, and pre-equalize a forward path data signal that is to be transmitted to said second device based on said at least one forward path pre-equalization parameter;

said first device further comprising;

at least one first device antenna; and

at least one transceiver operatively coupled to said at least one first device antenna and said logic, said at least one transceiver being configured to receive said reverse path data signal over at least one reverse transmission path using said at least one first device antenna and provide said reverse path data signal to said logic, and transmit said forward path data signal from said logic over at least one forward transmission path;

wherein said logic is further configured to cause said transceiver to selectively establish different transmission power levels for at least two Orthogonal Frequency Division Multiplexing (OFDM) tones in said forward path data signal based on said at least one forward path pre-equalization parameter.

43. The system as recited in claim 42, wherein said reverse path data signal includes at least one type of data selected from a group of different types of data comprising Orthogonal Frequency Division Multiplexing (OFDM) data and Quadrature Phase Shift Keying (QPSK) data.

44. The system as recited in claim 42, wherein said forward path data signal includes at least one type of data selected from a group of different types of data comprising Orthogonal Frequency Division Multiplexing (OFDM) data and Quadrature Phase Shift Keying (QPSK) data.

45. The system as recited in claim 44, wherein said forward path data signal includes sub-carrier pre-equalized OFDM data.

46. The system as recited in claim 45, wherein said logic is further configured to produce corresponding Quadrature Phase Shift Keying (QPSK) modulation values based on said sub-carrier pre-equalized OFDM data.

47. The system as recited in claim 43, wherein said logic detects said multipath transmission delay by identifying at least one multipath transmission delay spread that is greater than a guard interval.

48. The system as recited in claim 42, wherein said reverse path data signal includes identifiable training data.

49. The system as recited in claim 48, wherein said logic is further configured to compare said identifiable training data to a non-multipath delayed version of said training data to detect said multipath transmission delay.

50. The system as recited in claim 43, wherein said logic is configured to selectively invert and apply a measured channel response to said forward path data signal to significantly reduce subsequent induced deleterious channel response changes to said forward path data signal during transmission over said at least one forward transmission path.

51. The system as recited in claim 43, wherein said at least one reverse transmission path is substantially reciprocal to said at least one forward transmission path.

52. The system as recited in claim 42, wherein said first device includes a base station device that is operatively configured for use in a wireless communication system.

53. The system as recited in claim 43, wherein said second device is a customer premise equipment (CPE) device that is operatively configured for use in a wireless communication system.

54. The system as recited in claim 53, wherein said CPE device includes at least one device selected from a group of devices comprising a computer, a portable computer, a personal digital assistant (PDA), and a mobile communication device.

55. The system as recited in claim 43, wherein said first device is operatively coupled to a plurality of first device receive antennas.

56. The system as recited in claim 43, wherein said logic is configured to post-equalize at least a portion of said received reverse path signal.

57. The system as recited in claim 43, wherein said logic is further configured to determine at least one angle of arrival of said reverse path data signal with respect to said at least one first device antenna.

58. The system as recited in claim 53, wherein said second device includes at least one second device antenna that is operatively configured to transmit said reverse path data signal over said at least one reverse transmission path to said first device and receive said transmitted forward path data signal from said first device over said at least one forward transmission path.

59. The system as recited in claim 58, wherein said second device includes a plurality of second device antennas that are operatively configured to transmit said reverse path data signal over said at least one reverse transmission path to said first device.

60. The system as recited in claim 58, wherein said second device is configured to transmit at least two reverse path data signals over said at least one reverse transmission path to said first device.

61. The system as recited in claim 60, wherein said at least two reverse path data signals include Orthogonal Frequency-Division Multiple Access (OFDMA) data.

62. The system as recited in claim 58, wherein said second device is configured to transmit said reverse path data signal over said at least one reverse transmission path to said first device at a bit rate less than about 6 Mbps.

63. The system as recited in claim 58, wherein said second device is configured to transmit corresponding second device transmission power level information to said first device, and said first device is further configured to adjust at least one transmission power level associated with said forward path data signal based on said second device transmission power level information.

64. The system as recited in claim 43, wherein said at least one first device antenna is operatively configured to provide transmission diversity when transmitting said forward path data signal.

65. The system as recited in claim 43, wherein said at least one first device antenna is operatively configured to provide spatial division transmission utilizing a spatial division technique when transmitting said forward path data signal as a narrow signal to reduce multipath propagation.

66. The system as recited in claim 43, wherein said at least one first device antenna includes at least one first device transmit antenna and at least one first device receive antenna.

67. The system as recited in claim 66, wherein said at least one first device transmit antenna includes at least one type of antenna selected from a group of suitable types of antennas comprising at least one omnidirectional type of antenna, at least one beam type of antenna, at least one phased array type of antenna, and at least one adaptive antenna.

68. The system as recited in claim 66, wherein said at least one first device receive antenna includes at least one type of antenna selected from a group of suitable types of antennas comprising at least one omnidirectional type of antenna, at least one beam type of antenna, at least one phased array type of antenna, and at least one adaptive antenna.

69. The system as recited in claim 66, wherein said logic is further configured to establish at least one antenna pointing parameter associated with said at least one first device transmit antenna based on said at least one forward path pre-equalization parameter.

70. The system as recited in claim 66, wherein said logic is further configured to establish at least one phased array antenna transmission directing parameter associated with said at least one first device transmit antenna based on said at least one forward path pre-equalization parameter.

71. The system as recited in claim 66, wherein said logic is further configured to cause said at least one transceiver to selectively transmit said forward path data signal at one angle with respect to said at least one first device transmit antenna.

72. The system as recited in claim 66, wherein said logic is further configured to cause said at least one transceiver to select said at least one first device transmit antenna from a plurality of first device transmit antennas that are each operatively coupled to said first device.

73. The system as recited in claim 72, wherein said logic is further configured to cause said at least one transceiver to selectively transmit a plurality of beams using two or more first device transmit antennas.

74. The system as recited in claim 73, wherein each of said transmitted plurality of beams is selectively adjusted in phase and amplitude to reduce multipath affects when received by said second device.

75. The system as recited in claim 58, wherein said at least one second device antenna includes at least one second device transmit antenna and at least one second device receive antenna.

76. The system as recited in claim 75, wherein said second device includes a plurality of second device receive antennas that are configured to receive said transmitted forward path data signal over said at least one forward transmission path from said first device.

77. The system as recited in claim 42, wherein said logic is further configured to iteratively selectively test different forward path pre-equalization parameters over time such that aliased multipath delays within said reverse path data signal are identifiable.

78. The system as recited in claim 42, wherein said logic is configured to provide sub-band equalizing of said forward path data signal using corresponding frequency domain reverse path data.

79. An apparatus comprising:

an Orthogonal Frequency Division Multiplexing (OFDM) processor configured to receive coded data and output corresponding OFDM data;

a pre-equalizer operatively coupled to said OFDM processor and configured to receive said OFDM data and output pre-equalized OFDM data based on gathered reverse link data;

at least one antenna;

an antenna signal processing component operatively coupled to said pre-equalizer and said at least one antenna, said antenna signal processing component being configured to receive said pre-equalized OFDM data from said pre-equalizer and apply a corresponding transmittable forward link data signal to said at least one antenna, the antenna signal processing component being further configured to receive a transmitted reverse link data signal using said at least one antenna and output corresponding reverse link data; and

reverse link logic operatively coupled to said at least one antenna, said reverse link logic being configured to detect at least one multipath induced delay in said reverse link data and provide said gathered reverse link data to said pre-equalizer based on said multipath induced delay, wherein said reverse link logic is further configured to cause selectively establishing different transmission power levels for at least two Orthogonal Frequency Division Multiplexing (OFDM) tones in said transmittable forward link data signal.

80. The apparatus as recited in claim 79, wherein said pre-equalized OFDM data includes sub-carrier pre-equalized OFDM data.

81. The apparatus as recited in claim 79, wherein said reverse link logic detects said at least one multipath induced delay by identifying at least one transmission delay spread that is greater than a guard interval.

82. The apparatus as recited in claim 79, wherein said reverse link data signal includes identifiable training data.

83. The apparatus as recited in claim 82, wherein said reverse link logic is further configured to compare said identifiable training data to a non-delayed version of said training data to detect said at least one transmission delay.

84. The apparatus as recited in claim 79, wherein said pre-equalizer is configured to selectively invert and apply a measured channel response to said OFDM data.

85. The apparatus as recited in claim 79, wherein a reverse transmission path carrying said transmitted reverse link data signal towards said antenna is at least substantially reciprocal to a forward transmission path carrying said transmittable forward link data signal away from said at least one antenna.

86. The apparatus as recited in claim 79, wherein said apparatus includes a base station device suitable for use in a wireless communication system.

87. The apparatus as recited in claim 79, wherein said at least one antenna is operatively configured to provide transmission diversity.

88. The apparatus as recited in claim 79, wherein said at least one antenna is operatively configured to provide a spatial division technique to transmit the data signal as a narrow signal to reduce multipath propagation.

89. The apparatus as recited in claim 79, wherein said at least one antenna includes at least one transmit antenna and at least one receive antenna.

90. The apparatus as recited in claim 89, wherein said at least one transmit antenna includes at least one type of antenna selected from a group of suitable types of antennas comprising at least one omnidirectional type of antenna, at least one beam type of antenna, at least one phased array type of antenna, and at least one adaptive antenna.

91. The apparatus as recited in claim 89, wherein said at least one receive antenna includes at least one type of antenna selected from a group of suitable types of antennas comprising at least one omnidirectional type of antenna, at least one beam type of antenna, at least one phased array type of antenna, and at least one adaptive antenna.