Communication system employing reuse of satellite spectrum for terrestrial communication

• US 6,735,437 B2
• Filed: 06/26/1998
• Issued: 05/11/2004
• Est. Priority Date: 06/26/1998
• Status: Expired due to Term

• Current Assignee: Hughes Electronics Corporation (AT&T, Inc.)
• Original Assignee: Hughes Electronics Corporation (AT&T, Inc.)
• Inventors: Novak, John I. III, Chang, Donald C. D., Mayfield, William W.
• Primary Examiner(s): Maung, Nay
• Assistant Examiner(s): GELIN, JEAN ALLAND
• Application Number:
  US09/105,622
• Publication Number:
  US 20030078040A1
• Time in Patent Office: 2,146 Days
• Field of Search: 455/427, 455/429, 455/430, 455/11.1, 455/12.1, 455/13.2, 455/447, 455/444, 370/311, 370/318, 370/320, 370/330, 370/348, 370/433, 342/352
• US Class Current: 455/427
• CPC Class Codes: H04B 7/18563 Arrangements for interconnecting multiple systems data switching networks H04L12/00
• CPC Class Codes: H04W 16/16 for PBS [Private Base Station] arrangements

Abstract

A terrestrial communication system using satellite uplink and downlink frequencies is disclosed. A terrestrial cell site produces a signal at a satellite uplink frequency that is transmitted to a terrestrial user terminal. The terrestrial cell site receives a signal at a satellite downlink frequency that was transmitted by a terrestrial user terminal. The terrestrial cell site may include a signal nulling means in the direction of a satellite producing signals at the uplink and downlink frequencies.

Claims

1. A terrestrial communication system using satellite uplink and downlink frequencies comprising:

a terrestrial cell site producing a first signal at a satellite uplink frequency that is transmitted directly to a terrestrial terminal unit, and

said terrestrial cell site directly receiving a second signal at a satellite downlink frequency that was transmitted by said terrestrial terminal unit.

2. The terrestrial communication system of claim 1, wherein said terrestrial cell site includes a signal nulling means in the direction of a satellite that produces signals using said uplink and said downlink frequencies.

3. A terrestrial communication system using satellite uplink and downlink frequencies comprising:

a terrestrial terminal unit producing a first signal at a satellite downlink frequency that is transmitted directly to a terrestrial cell site, and

said terrestrial terminal unit receiving a second signal at a satellite uplink frequency that was transmitted directly by said terrestrial cell site.

4. The terrestrial communication system of claim 3, wherein a satellite ground user using said uplink and said downlink frequencies is geographically isolated from said terrestrial terminal unit.

5. A method of integrating a terrestrial communication system into a satellite communication frequency spectrum comprising:

producing a first signal at a satellite uplink frequency that is transmitted directly from a terrestrial cell site to a terrestrial user terminal, and

receiving a second signal at a satellite downlink frequency that was produced by said terrestrial user terminal and transmitted directly to said terrestrial cell site.

6. A method of providing terrestrial communication services, comprising:

using a first signal at a satellite uplink frequency that is transmitted from a terrestrial source to a terrestrial user terminal, and

using a second signal at a satellite downlink frequency that is transmitted from the terrestrial user terminal to the terrestrial source.

7. A method of providing terrestrial communications comprising:

transmitting a first signal at a satellite uplink frequency to a terrestrial user terminal from a terrestrial site; and

transmitting a second signal at a satellite downlink frequency from the terrestrial user terminal to the terrestrial site.

8. A method for minimizing interference between a satellite communication system and a terrestrial communication system without a satellite, having at least one terrestrial site and reusing satellite frequencies, comprising:

reversing the transmission and reception frequency bands for the terrestrial communication system relative to the satellite communication system; and

generating at least one pattern null with an antenna at the at least one terrestrial site to reduce satellite interference.

9. The method of claim 8, wherein generating at least one pattern null further comprises generating a fixed null towards a satellite direction and a relatively high gain in the horizontal direction.

10. The method of claim 8, wherein generating at least one pattern null comprises utilizing a sidelobe cancellation technique.

11. The method of claim 8, wherein generating at least one pattern null comprises using weighting control of signals from antenna elements.

12. The method of claim 8, wherein generating at least one pattern null comprises using a nulling technique.

13. The method of claim 8, wherein said antenna comprises antenna elements and wherein the step generating at least one pattern null comprises using at least one low gain element added to the antenna elements.

14. The method of claim 8, wherein generating at least one pattern null comprises creating an independent null in an interference direction and adjusting said at least one low gain element to add amplitudes and phases destructively.

15. The method of claim 8, wherein generating at least one pattern null comprises adding wide band nulls using multiple low gain elements.

16. The method of claim 15, wherein said at least one of said multiple low gain elements has multiple taps to produce nulls at multiple frequencies.

17. The method of claim 8, adding at least one pattern null includes dynamically adjusting the at least one pattern null.

18. The method of claim 17, wherein dynamically adjusting comprises dynamically adjusting the at least one pattern null using a table-look-up.

19. The method of claim 18, wherein using a table lookup comprises using said look-up table within a closed loop feedback system and employing a steepest descent search algorithm and a least-mean-square as the optimization criteria.

20. A terrestrial communication system comprising:

a terrestrial source; and

a terrestrial user terminal;

said terrestrial source transmitting a first signal at a satellite uplink frequency to said terrestrial user terminal and receiving a second signal transmitted from said terrestrial user terminal at a satellite downlink frequency and said terrestrial user terminal for receiving the first signal at the satellite uplink frequency and transmitting the second signal at the satellite downlink frequency without satellite interference.

21. A terrestrial communication system that reuses satellite frequencies used by a satellite communication system without satellite interference comprising:

a terrestrial site communicating with a terrestrial user terminal using transmission and reception frequency bands that are reversed relative to the satellite communication system, and having at least one antenna with at least one pattern null in at least one satellite direction to block satellite interference.

22. The system of claim 21, wherein said at least one antenna has a fixed null towards a satellite direction and comparatively high gain in the horizontal direction.

23. The system of claim 21, wherein said at least one antenna has sidelobe cancellation used to create the at least one pattern null.

24. The system of claim 21, wherein said at least one antenna comprises a plurality of elements and weighting control to create the at least one pattern null.

25. The system of claim 21, further comprising at least one low gain element, said at least one antenna comprising a plurality of the elements and the at least one low gain element.

26. The system of claim 25, wherein said at least one antenna has an independent null in an interference direction and said at least one low gain element adds amplitudes and phases destructively.

27. The system of claim 25, wherein said at least one low gain element has multiple taps to produce nulls at multiple frequencies.

28. The system of claim 21, wherein said at least one antenna comprises multiple low gain elements for wide band null creation.

29. The system of claim 21, further comprising means for dynamic adjustment of the at least one pattern null.

30. The system of claim 21, further comprising a table-look-up for dynamic adjustment of the at least one pattern null.

31. The system of claim 30, further comprising a closed loop feedback system employing a steepest descent search algorithm and a least-mean-square as the optimization criteria.

32. A terrestrial communication system integrated with and operable using radio frequency spectrum allocated to a satellite communication system having satellites comprising:

at least one terrestrial cell site communicating with at least one terrestrial terminal user, directly without using said satellites, using transmission and reception frequency bands that are reversed relative to the satellite user, said at least one terrestrial cell site having at least one antenna with a pattern null in the direction of the satellite.

33. The system of claim 32, wherein the pattern null of the at least one antenna includes a fixed null towards a satellite direction and comparatively high gain in the horizontal direction.

34. The system of claim 32, wherein sidelobe cancellation is used to create the pattern nulls.

35. The system of claim 32, wherein weighting control of the signals from the antennas is used to create the pattern null.

36. The system of claim 32, wherein nulling is used to create the pattern nulls.

37. The system of claim 32, further comprising at least one low gain element coupled to said at least one antenna.

38. The system of claim 37, wherein said at least one antenna has independent nulls in interference directions and said at least one low gain element adds amplitudes and phases destructively.

39. The system of claim 37, wherein said at least one low gain element has multiple taps to produce nulls at multiple frequencies.

40. The system of claim 32, further comprising multiple low gain elements for wide band null creation.

41. The system of claim 38, further comprising means for dynamically adjusting the pattern nulls.

42. The system of claim 38, further comprising a table-look-up for dynamic adjustment of the pattern nulls.

43. The system of claim 42, further comprising a closed loop feedback system employing a steepest descent search algorithm and a least-mean-square as an optimization criteria.

44. The system of claim 32, wherein said satellites comprise mobile satellites.

45. A communication system comprising:

a satellite producing downlink signals at a satellite downlink frequency and receiving uplink signals at a satellite uplink frequency;

a plurality of terrestrial terminal units;

a terrestrial cell site;

at least one of said terrestrial terminal units producing a first signal at the satellite downlink frequency that is transmitted directly to said terrestrial cell site;

at least one of said terrestrial terminal units receiving a second signal at a satellite uplink frequency that was transmitted directly by said terrestrial cell site;

said terrestrial cell site producing a third signal at the satellite uplink frequency that is transmitted directly to at least one of said terrestrial terminal units; and

said terrestrial cell site directly receiving a fourth signal at the satellite downlink frequency that was transmitted by at least one of said terrestrial terminal units.

46. The system of claim 45, wherein said fourth signal is said first signal.

47. The system of claim 45, wherein said third signal is said second signal.

48. The system of claim 45, wherein said terrestrial cell site produces a fifth signal at the satellite uplink frequency that is transmitted to the satellite;

and

said terrestrial cell site receives a sixth signal at the satellite downlink frequency that was transmitted by the satellite.

49. The system of claim 45, wherein said terrestrial terminal unit produces a seventh signal at the satellite uplink frequency that is transmitted to the satellite;

and

said terrestrial terminal unit receives a sixth signal at the satellite downlink frequency that was transmitted by the satellite.

50. The system of claim 45, wherein said terrestrial cell site further comprises at least one antenna.

51. The system of claim 50, wherein said at least one antenna has a fixed null towards a satellite direction and comparatively high gain in the horizontal direction.

52. The system of claim 50, wherein said at least one antenna has sidelobe cancellation used to create the at least one pattern null.

53. The system of claim 52, wherein said at least one antenna comprises a plurality of elements and weighting control to create the at least one pattern null.

54. The system of claim 50, further comprising at least one low gain element, said at least one antenna comprising a plurality of the elements and the at least one low gain element.

55. The system of claim 54, wherein said at least one antenna has an independent null in an interference direction and said at least one low gain element adds amplitudes and phases destructively.

56. The system of claim 54, wherein said at least one low gain element has multiple taps to produce nulls at multiple frequencies.

57. The system of claim 54 further comprising multiple low gain elements for wide band null creation.

58. The system of claim 50 further comprising means for dynamic adjustment of the at least one pattern null.

59. The system of claim 50, further comprising a table-look-up for dynamic adjustment of the at least one pattern null.

60. The system of claim 50, further comprising a closed loop feedback system employing a steepest descent search algorithm and a least-mean-square as an optimization criteria.

61. The system of claim 50 wherein a satellite user is geographically isolated from a terrestrial user.

62. A communication system comprising:

a satellite operable using an allocated radio frequency spectrum;

a satellite user terminal communicating with said satellite using an uplink frequency and a downlink frequency;

at least one terrestrial cell site communicating with at least one terrestrial terminal unit using transmission and reception frequency bands that are reversed relative to the allocated radio frequency spectrum of said satellite, said at least one terrestrial cell site having at least one antenna.

63. The system of claim 62, wherein said at least one terrestrial cell site communicates with said satellite using said uplink frequency and said downlink frequency.

64. The system of claim 62, wherein said terrestrial cell site further comprises an antenna generating at least one pattern null.

65. The system of claim 64, wherein said at least one antenna has a fixed null towards a satellite direction and comparatively high gain in the horizontal direction.

66. The system of claim 64, wherein said at least one antenna has sidelobe cancellation used to create the at least one pattern null.

67. The system of claim 65, wherein said at least one antenna comprises a plurality of elements and weighting control to create the at least one pattern null.

68. The system of claim 65, wherein said at least one antenna comprising a plurality of elements and at least one low gain element.

69. The system of claim 68, wherein said at least one antenna has an independent null in an interference direction and said at least one low gain element adds amplitudes and phases destructively.

70. The system of claim 68, wherein said at least one low gain element has multiple taps to produce nulls at multiple frequencies.

71. The system of claim 68, further comprising multiple low gain elements for wide band null creation.

72. The system of claim 65, further comprising means for dynamic adjustment of the at least one pattern null.

73. The system of claim 72, further comprising a table-look-up for dynamic adjustment of the at least one pattern null.

74. The system of claim 65, further comprising a closed loop feedback system employing a steepest descent search algorithm and a least-mean-square as the optimization criteria.

91. The method of claim 70, wherein using a table lookup comprises using said look-up table within a closed loop feedback system and employing a steepest descent search algorithm and a least-mean-square as an optimization criteria.

75. A method of operating a communication system comprising:

in a satellite, producing downlink signals at a satellite downlink frequency and receiving uplink signals at a satellite uplink frequency;

in a terrestrial terminal unit, producing a first signal at the satellite downlink frequency that is transmitted directly to a terrestrial cell site, and receiving a second signal at a satellite uplink frequency that was transmitted directly by a terrestrial cell site;

in said terrestrial cell site, producing a third signal at the satellite uplink frequency that is transmitted directly to the terrestrial terminal unit, and receiving a fourth signal at the satellite downlink frequency that was transmitted by said terrestrial terminal unit.

76. The method of claim 75, wherein said fourth signal is said first signal.

77. The method of claim 75, wherein said third signal is said second signal.

78. The method of claim 75, wherein in said terrestrial cell site producing a fifth signal at the satellite uplink frequency that is transmitted to the satellite;

and

receiving a sixth signal at the satellite downlink frequency that was transmitted by the satellite.

79. The method of claim 75, wherein in said terrestrial terminal unit, producing a seventh signal at the satellite uplink frequency that is transmitted to the satellite;

and

receiving a sixth signal at the satellite downlink frequency that was transmitted by the satellite.

80. The method of claim 75, further comprising generating at least one pattern null.

81. The method of claim 80, wherein generating at least one pattern null further comprises generating a fixed null towards a satellite direction and a comparatively high gain in the horizontal direction.

82. The method of claim 80, wherein generating at least one pattern null comprises using a sidelobe cancellation technique.

83. The method of claim 80, wherein generating at least one pattern null comprises using weighting control of the signals from the antenna elements.

84. The method of claim 80, wherein generating at least one pattern null comprises using a nulling technique.

85. The method of claim 80, wherein said terrestrial cell site comprises an antenna, wherein generating at least one pattern null comprises adding at least one low gain element to the antenna.

86. The method of claim 85, wherein said at least one low gain element has multiple taps to produce nulls at multiple frequencies.

87. The method of claim 85, wherein generating at least one pattern null comprises creating an independent null in an interference direction and adjusting said at least one low gain element to add amplitudes and phases destructively.

88. The method of claim 85, wherein generating at least one pattern null comprises adding wide band nulls using multiple low gain elements.

89. The method of claim 80, wherein generating at least one pattern null includes dynamically adjusting the at least one pattern null.

90. The method of claim 89, wherein dynamically adjusting comprises dynamically adjusting the at least one pattern null using a table-look-up.

92. A method of operating a terrestrial terminal unit comprising:

producing a first signal at a satellite downlink frequency that is transmitted directly to a terrestrial cell site, and

receiving a second signal at a satellite uplink frequency that was transmitted directly by said terrestrial cell site.

93. The method of claim 92, wherein said terrestrial terminal unit produces a third signal at the satellite uplink frequency that is transmitted to a satellite;

and

receiving a fourth signal at the satellite downlink frequency that was transmitted by the satellite.

94. A terrestrial terminal unit for use with a communication system having a terrestrial cell site, said terrestrial terminal unit adapted to produce a first signal at a satellite downlink frequency that is transmitted directly to the terrestrial cell site and receive a second signal at a satellite uplink frequency that was transmitted directly by said terrestrial cell site.

95. The terrestrial terminal unit of claim 94, wherein said terrestrial terminal unit produces a third signal at the satellite uplink frequency that is transmitted to a satellite;

and

said terrestrial terminal unit receives a fourth signal at the satellite downlink frequency that was transmitted by the satellite.

96. The terrestrial terminal unit of claim 94, further comprising at least one antenna.

97. The terrestrial terminal unit of claim 96, wherein said at least one antenna has a fixed null towards a satellite direction and comparatively high gain in the horizontal direction.

98. The terrestrial terminal unit of claim 96, wherein said at least one antenna has sidelobe cancellation used to create the at least one pattern null.

99. The terrestrial terminal unit of claim 98, wherein said at least one antenna comprises a plurality of elements and weighting control to create the at least one pattern null.

100. The terrestrial terminal unit of claim 96, further comprising at least one low gain element, said at least one antenna comprising a plurality of the elements and the at least one low gain element.

101. The terrestrial terminal unit of claim 100, wherein said at least one antenna has an independent null in an interference direction and said at least one low gain element adds amplitudes and phases destructively.

102. The terrestrial terminal unit of claim 100, wherein said at least one low gain element has multiple taps to produce nulls at multiple frequencies.

103. The terrestrial terminal unit of claim 100 further comprising multiple low gain elements for wide band null creation.

104. The terrestrial terminal unit of claim 96 further comprising means for dynamic adjustment of the at least one pattern null.

105. The terrestrial terminal unit of claim 96, further comprising a table-look-up for dynamic adjustment of the at least one pattern null.

106. The terrestrial terminal unit of claim 96, further comprising a closed loop feedback system employing a steepest descent search algorithm and a least-mean-square as an optimization criteria.

107. A method of operating a terrestrial cell site comprising:

producing a first signal at a satellite uplink frequency that is transmitted directly to a terrestrial terminal unit, and

receiving a second signal at a satellite downlink frequency that was transmitted by said terrestrial terminal unit.

108. The method of claim 107, further comprising generating at least one pattern null with an antenna to reduce satellite interference.

109. The method of claim 108, wherein generating at least one pattern null further comprises generating a fixed null towards a satellite direction and a relatively high gain in the horizontal direction.

110. The method of claim 108, wherein generating at least one pattern null comprises utilizing a sidelobe cancellation technique.

111. The method of claim 108, wherein generating at least one pattern null comprises using weighting control of signals from antenna elements.

112. The method of claim 108, wherein generating at least one pattern null comprises using a nulling technique.

113. The method of claim 108, wherein said antenna comprises the antenna elements and wherein the step generating at least one pattern null comprises using at least one low gain element added to the antenna elements.

114. The method of claim 108, wherein generating at least one pattern null comprises creating an independent null in an interference direction and adjusting said at least one low gain element to add amplitudes and phases destructively.

115. The method of claim 108, wherein generating at least one pattern null comprises adding wide band nulls using multiple low gain elements.

116. The method of claim 115, wherein said at least one of said multiple low gain elements has multiple taps to produce nulls at multiple frequencies.

117. The method of claim 108, adding at least one pattern null includes dynamically adjusting the at least one pattern null.

118. The method of claim 117, wherein dynamically adjusting comprises dynamically adjusting the at least one pattern null using a table-look-up.

119. The method of claim 108, wherein using a table lookup comprises using said look-up table within a closed loop feedback system and employing a steepest descent search algorithm and a least-mean-square as the optimization criteria.

120. The method of claim 107, wherein in said terrestrial cell site, producing a third signal at the satellite uplink frequency that is transmitted to the satellite;

and

receiving a fourth signal at the satellite downlink frequency that was transmitted by the satellite.

121. A terrestrial cell site for use with a communication system having a terrestrial terminal unit, said terrestrial cell site adapted to produce a first signal at a satellite uplink frequency that is transmitted directly to a terrestrial terminal unit, and receive a second signal at a satellite downlink frequency that was transmitted by said terrestrial terminal unit.

122. The terrestrial cell site of claim 121, wherein said terrestrial cell site produces a third signal at the satellite uplink frequency that is transmitted to a satellite;

and

receives a fourth signal at the satellite downlink frequency that was transmitted by the satellite.

123. A two-way communication system comprising:

a satellite producing downlink signals at a satellite downlink frequency and receiving uplink signals at a satellite uplink frequency;

a terrestrial terminal unit;

a terrestrial cell site;

said terrestrial terminal unit producing a first signal at the satellite downlink frequency that is transmitted directly to said terrestrial cell site;

said terrestrial terminal unit receiving a second signal at a satellite uplink frequency that was transmitted directly by said terrestrial cell site;

said terrestrial cell site producing the second signal at the satellite uplink frequency that is transmitted directly to the terrestrial terminal unit; and

said terrestrial cell site directly receiving the first signal at the satellite downlink frequency that was transmitted by said terrestrial terminal unit.

124. The system of claim 123 wherein the terrestrial cell site generates the uplink signals and receives the downlink signals.

125. The system of claim 123 wherein the terrestrial terminal unit generates the uplink signals and receives the downlink signals.

126. The system of claim 123 wherein a satellite user terminal generates the uplink signals and receives the downlink signals.

127. A method of operating a two-way communication system comprising:

in a satellite, producing downlink signals at a satellite downlink frequency and receiving uplink signals at a satellite uplink frequency;

in a terrestrial terminal unit, producing a first signal at the satellite downlink frequency that is transmitted directly to a terrestrial cell site, and receiving a second signal at a satellite uplink frequency that was transmitted directly by a terrestrial cell site;

in a terrestrial cell site, producing said second signal at the satellite uplink frequency that is transmitted directly to the terrestrial terminal unit, and receiving said first signal at the satellite downlink frequency that was transmitted by said terrestrial terminal unit.

128. The system of claim 127, wherein said terrestrial cell site produces a third signal at the satellite uplink frequency that is transmitted to the satellite;

and

receiving a fourth signal at the satellite downlink frequency that was transmitted by the satellite.

129. The system of claim 127, wherein said terrestrial terminal unit produces a seventh signal at the satellite uplink frequency that is transmitted to the satellite;

and

in said terrestrial terminal unit, receiving a sixth signal at the satellite downlink frequency that was transmitted by the satellite.