Coordinated satellite-terrestrial frequency reuse

• US 6,892,068 B2
• Filed: 08/01/2001
• Issued: 05/10/2005
• Est. Priority Date: 08/02/2000
• Status: Expired due to Term

• Current Assignee: ATC Technology Corporation (FedEx Corporation)
• Original Assignee: Mobile Satellite Venture LP
• Inventors: Karabinis, Peter D., Singh, Rajendra, Olexa, George Ronald, Badipour, Bahman
• Primary Examiner(s): Nguyen, Lee
• Application Number:
  US09/918,709
• Publication Number:
  US 20020041575A1
• Time in Patent Office: 1,378 Days
• Field of Search: 455/427, 455/429, 455/430, 455/431, 455/447, 455/448, 455/426.1, 455/12.1
• US Class Current: 455/429
• CPC Class Codes: H04B 7/18539 Arrangements for managing radio, resources, i.e. for establishing or releasing a connection
• CPC Class Codes: H04B 7/18563 Arrangements for interconnecting multiple systems data switching networks H04L12/00
• CPC Class Codes: H04B 7/2041 Spot beam multiple access
• CPC Class Codes: H04W 16/14 Spectrum sharing arrangements between different networks

Abstract

A system and method of operation for efficiently reusing and/or sharing at least a portion of the frequency spectrum between a first satellite spot beam and a second satellite spot beam, and/or an underlay terrestrial network associated with a second satellite spot beam. The spectrum is efficiently reused and/or shared between respective spot beams and/or associated underlay terrestrial systems in a manner minimizes interference between the respective satellite and terrestrial systems.

Claims

1. A method of at least one of assigning and reusing frequencies between one or more communication systems, comprising the steps of:

configuring a first satellite spot beam having a first set of frequencies associated therewith and comprising a first substantially central portion and a first plurality of subareas, each of the first plurality of subareas extending substantially from a periphery of the first substantially central portion to substantially near a circumference of the first satellite spot beam;

configuring a second satellite spot beam having a second set of frequencies associated therewith and comprising a second substantially central portion and a second plurality of subareas, each of the second plurality of subareas extending substantially from a periphery of the second central portion to substantially near a circumference of the second satellite spot beam;

configuring at least one terrestrial cell that at least partially overlaps the first satellite spot beam having a third set of frequencies associated therewith; and

at least one of assigning, reusing and borrowing, by the terrestrial system, at least one of a portion of the second set of frequencies and a portion of the first set of frequencies used in the first central portion, responsive to predetermined criteria associated with the third set of frequencies, including at least one of assigning, reusing and borrowing at least one of the second set of frequencies when the second set of frequencies are at least substantially geographically distant from the first satellite spot beam.

2. The method of claim 1 wherein the first plurality of subareas are substantially equal sized cells having a first size and the second plurality of subareas are substantially equal sized cells having a second size.

3. The method of claim 2 wherein the first size and the second size are approximately equal.

4. The method of claim 1 wherein the second set of frequencies are substantially distant from the first satellite spot beam when they are at least one of assigned, reused and borrowed for use in those first plurality of subareas not sharing a common boundary with the second satellite spot beam.

5. The method of claim 1 wherein the first set of frequencies used in the first central portion comprise at least one of those frequency sets respectively associated with satellite spot beams directly adjacent to the first satellite spot beam.

6. The method of claim 1 wherein said step of assigning, reusing and borrowing is based on prioritization rules.

7. The method of claim 6 wherein the prioritization rules include dynamic load and capacity constraints of cells that frequencies are taken from.

8. The method of claim 1 wherein a subscriber terminal positioned within the first central portion can be assigned, reuse and/or borrow use any of the respective set of frequencies associated with the at least one second satellite spot beam.

9. The method of claim 1 wherein a subscriber terminal positioned within the first central portion can be assigned, reuse and/or borrow use any of the respective set of frequencies associated with any spot beams adjacent the first satellite spot beam.

10. The method of claim 1 wherein a subscriber terminal positioned within a subarea of the first spot beam not sharing at least a portion of a common boundary with the second satellite spot beam can be assigned, reuse and/or borrow any of the second set of frequencies associated with the second satellite spot beam.

11. The method of claim 1 wherein the predetermined criteria is at least one of load balancing, maintaining a reserve of frequencies, and received signal strength interference.

12. The method of claim 1 further comprising the steps of:

configuring a second terrestrial cell that at least partially overlaps the second satellite spot beam having a fourth set of frequencies associated therewith; and

at least one of assigning, reusing and borrowing, by the second terrestrial cell, at least one of the first set of frequencies and the frequencies used in the second central portion, responsive to predetermined criteria associated with the fourth set of frequencies, including at least one of assigning, reusing and borrowing at least one of the first set of frequencies when the first set of frequencies are at least substantially geographically distant from the second satellite spot beam.

13. The method of claim 1 wherein the first central portion and the second central portion comprise approximately twenty five percent of the area covered by the first satellite spot beam and the second satellite spot beam, respectively.

14. The method of claim 1 wherein the first set of frequencies and the second set of frequencies comprise a plurality of paired uplink and downlink frequencies.

15. The method of claim 14 wherein a downlink frequency of a frequency set is used in a first subarea of the first spot beam, and wherein a corresponding one of the uplink frequencies is reused in a second subarea of the first spot beam.

16. The method of claim 1 wherein the area of coverage of a spot beam comprises an area having a radius substantially equal to a distance from a center of the spot beam having a substantially maximum signal strength to a distance from the center of the spot beam where the signal strength of the spot beam is attenuated by approximately 3 dB.

17. The method of claim 1 wherein an area of coverage of at least one of a spot beam and a terrestrial cell comprises an area corresponding to a bit error rate in the range of at least one of 10⁻

2 to 10<sup>−

3</sup> for voice and 10<sup>−

5</sup> to 10<sup>−

6</sup> for data.

18. The method of claim 1 wherein the number of subareas is equal to a number of spot beams comprising a cluster minus one.

19. A method of making a telephone call using a satellite-terrestrial communications system that at least one of assigns and reuses frequencies between a first satellite spot beam and a second satellite spot beam, comprising the steps of:

a first user using a subscriber terminal to dial a telephone number within an area of a first terrestrial cell associated with a first satellite spot beam having a first set of frequencies associated therewith, the first satellite spot beam comprising a first substantially central portion and a first plurality of subareas, each of the first plurality of subareas extending substantially from a periphery of the first substantially central portion to substantially near a circumference of the first satellite spot beam;

determining because of at least one of unavailability of the first set of frequencies or weak signal strength that a connection cannot be established, using the first set of frequencies, with a communications device having the dialed telephone number associated therewith;

configuring a second satellite spot beam having a second set of frequencies associated therewith; and

establishing a connection between the subscriber terminal and the communications device by at least one of assigning, reusing and borrowing, by the first spot beam, at least one of the second set of frequencies, responsive to predetermined criteria including at least one of assigning, reusing and borrowing at least one of the second set of frequencies when the mobile terminal is substantially geographically distant from the second satellite spot beam.

20. A method of at least one of assigning and reusing frequencies, comprising the steps of:

configuring a first communications area having a first set of frequencies associated therewith and comprising a first substantially central portion and a first plurality of subareas, each of the first plurality of subareas extending substantially from a periphery of the first substantially central portion to substantially near a circumference of the first communications area;

configuring a second communications area having a second set of frequencies associated therewith and comprising a second substantially central portion and a second plurality of subareas, each of the second plurality of subareas extending substantially from a periphery of the central portion to substantially near a circumference of the second communications area;

configuring at least one third communications area that at least partially overlaps the first communications area, having a third set of frequencies associated therewith; and

at least one of assigning, reusing and borrowing, by the third communications area, at least one of a portion of the second set of frequencies and a portion of the first set of frequencies used in the first central portion, responsive to predetermined criteria associated with the third set of frequencies, including at least one of assigning, reusing and borrowing at least one of the second set of frequencies when the second set of frequencies are at least substantially geographically distant from the first satellite spot beam.

21. The method of claim 20 wherein the first plurality of subareas are substantially equal sized cells having a first size and the second plurality of subareas are substantially equal sized cells having a second size.

22. The method of claim 21 wherein the first size and the second size are approximately equal.

23. The method of claim 20 wherein the second set of frequencies are substantially distant from the second communications area when they are at least one of assigned, reused and borrowed for use in those first plurality of subareas not sharing a common boundary with the second communications area.

24. The method of claim 20 wherein the first set of frequencies used in the first central portion comprise at least one of those frequency sets respectively associated with communication areas external to and directly adjacent to the first communications area.

25. The method of claim 20 wherein said step of assigning, reusing and borrowing is based on prioritization rules.

26. The method of claim 25 wherein the prioritization rules include dynamic load and capacity constraints of candidate cells that frequencies are being taken from.

27. The method of claim 20 wherein a user positioned within the first central portion can be assigned, reuse and/or borrow use any of the respective set of frequencies associated with the at least one second satellite spot beam.

28. The method of claim 20 wherein a user positioned within the first central portion can be assigned, reuse and/or borrow use any of the respective set of frequencies associated with any communication areas adjacent the first satellite spot beam.

29. The method of claim 20 wherein a user positioned within a subarea not sharing at least a portion of a common boundary with the second communications area can be assigned, reuse and/or borrow any of the second set of frequencies associated with the second communications area.

30. The method of claim 20 wherein the predetermined criteria is at least one of load balancing, maintaining a reserve of frequencies, and received signal strength interference.

31. The method of claim 20 further comprising the steps of:

configuring a fourth communications area within the second communications area having a fourth set of frequencies associated therewith; and

at least one of assigning, reusing and borrowing, by the fourth communications area, at least one of the first set of frequencies and the frequencies used in the second central portion, responsive to predetermined criteria associated with the fourth set of frequencies, including at least one of assigning, reusing and borrowing at least one of the first set of frequencies when the first set of frequencies are at least substantially geographically distant from the second communications area.

32. The method of claim 20 wherein the first central portion and the second central portion comprise approximately twenty five percent of the area covered by the first communications area and the second communications area, respectively.

33. The method of claim 20 wherein the first and second set of frequencies comprise a plurality of paired uplink and downlink frequencies, wherein a downlink frequency of a frequency set is used in a first subarea of the first communications area, and wherein a corresponding one of the uplink frequencies is reused in a second subarea of the first communications area.

34. The method of claim 20 wherein the area of coverage of a communications area comprises an area having a radius substantially equal to a distance from a center of the communications area having a substantially maximum signal strength to a distance from the center of the communications area where the signal strength of the communications area is attenuated by approximately 3 dB.

35. The method of claim 20 wherein an area of coverage of at least one of a spot beam and a terrestrial cell comprises an area corresponding to a bit error rate in the range of at least one of 10⁻

2 to 10<sup>−

3</sup> for voice and 10<sup>−

5</sup> to 10<sup>−

6</sup> for data.

36. A method of at least one of assigning and reusing frequencies between one or more communication systems, comprising the steps of:

configuring a first satellite spot beam having a first set of frequencies associated therewith and comprising a first substantially central portion and a first plurality of subareas, each of the first plurality of subareas extending substantially from a periphery of the first substantially central portion to substantially near a circumference of the first satellite spot beam;

configuring a second satellite spot beam having a second set of frequencies associated therewith and comprising a second substantially central portion and a second plurality of subareas, each of the second plurality of subareas extending substantially from a periphery of the central portion to substantially near a circumference of the second satellite spot beam;

configuring at least one terrestrial cell that at least partially overlaps the first satellite spot beam having a third set of frequencies associated therewith; and

at least one of assigning, reusing and borrowing, by the second satellite spot beam, at least one of a portion of the third set of frequencies responsive to predetermined criteria, including at least one of assigning, reusing and borrowing at least one of the third set of frequencies associated with the at least one terrestrial cell when the terrestrial cell is at least substantially geographically distant from the second set of frequencies.

37. A method of at least one of assigning and reusing frequencies between one or more communication systems, comprising the steps of:

configuring a first satellite spot beam having a first set of frequencies associated therewith and comprising a first substantially central portion and a first plurality of subareas, each of the first plurality of subareas extending substantially from a periphery of the first substantially central portion to substantially near a circumference of the first satellite spot beam;

configuring a second satellite spot beam having a second set of frequencies associated therewith;

configuring at least one terrestrial cell that at least partially overlaps the first satellite spot beam having a third set of frequencies associated therewith; and

at least one of assigning, reusing and borrowing, by the terrestrial cell, at least one of a portion of the second set of frequencies and a portion of the first set of frequencies used in the first central portion, responsive to predetermined criteria associated with the third set of frequencies, including at least one of assigning, reusing and borrowing at least one of the second set of frequencies when the second set of frequencies are at least substantially geographically distant from the terrestrial cell.

38. The method of claim 37 wherein the first plurality of subareas are substantially equal sized.

39. The method of claim 37 wherein the second set of frequencies are substantially distant from the first satellite spot beam when they are at least one of assigned, reused and borrowed for use in those first plurality of subareas not sharing a common boundary with the second satellite spot beam.

40. The method of claim 37 wherein the first set of frequencies used in the first central portion comprise at least one of those frequency sets respectively associated with one or more satellite spot beams directly adjacent to the first satellite spot beam.

41. The method of claim 37 wherein said step of assigning, reusing and borrowing is based on prioritization rules.

42. The method of claim 41 wherein the prioritization rules include dynamic load and capacity constraints of candidate cells that frequencies are being taken from.

43. The method of claim 37 wherein a user positioned within the first central portion can be assigned, reuse and/or borrow use any of the respective set of frequencies associated with the second satellite spot beam.

44. The method of claim 37 wherein a subscriber terminal positioned within the first central portion can be assigned, reuse and/or borrow use any of the respective set of frequencies associated with any spot beams adjacent the first satellite spot beam.

45. The method of claim 37 wherein a subscriber terminal positioned within a subarea of the first spot beam not sharing at least a portion of a common boundary with the second satellite spot beam can be assigned, reuse and/or borrow any of the second set of frequencies associated with the second satellite spot beam.

46. The method of claim 37 wherein the predetermined criteria is at least one of load balancing, maintaining a reserve of frequencies, and received signal strength interference.

47. The method of claim 37 further comprising the steps of:

configuring a second terrestrial cell that at least partially overlaps the second satellite spot beam having a fourth set of frequencies associated therewith; and

at least one of assigning, reusing and borrowing, by the second terrestrial cell, at least one of the first set of frequencies and the frequencies used in the second central portion, responsive to predetermined criteria associated with the fourth set of frequencies, including at least one of assigning, reusing and borrowing at least one of the first set of frequencies when the first set of frequencies are at least substantially geographically distant from the second terrestrial cell.

48. The method of claim 37 wherein the first central portion comprises approximately twenty five percent of the area covered by the first satellite spot beam.

49. The method of claim 37 wherein the first and second set of frequencies comprise a plurality of paired uplink and downlink frequencies, wherein a downlink frequency of a frequency set is used in a first subarea of the first spot beam, and wherein a corresponding one of the uplink frequencies is reused in a second subarea of the first spot beam.

50. The method of claim 37 wherein the area of coverage of a spot beam comprises an area having a radius substantially equal to a distance from a center of the spot beam having a substantially maximum signal strength to a distance from the center of the spot beam where the signal strength of the spot beam is attenuated by approximately 3 dB.

51. The method of claim 37 wherein an area of coverage of at least one of a spot beam and a terrestrial cell comprises an area corresponding to a bit error rate in the range of at least one of 10⁻

2 to 10<sup>−

3</sup> for voice and 10<sup>−

5</sup> to 10<sup>−

6</sup> for data.

52. A method of at least one of assigning and reusing frequencies between one or more communication systems, comprising the steps of:

configuring a first satellite spot beam having a first set of frequencies associated therewith and comprising a first plurality of subareas, each of the first plurality of subareas extending from a substantially center area of the first satellite spot beam to substantially near a circumference of the first satellite spot beam in a fan-like manner thereby forming the first plurality of subareas;

configuring a second satellite spot beam having a second set of frequencies associated therewith;

configuring at least one terrestrial cell that at least partially overlaps the first satellite spot beam having a third set of frequencies associated therewith; and

at least one of assigning, reusing and borrowing, by the at least one terrestrial cell, at least one of a portion of the second set of frequencies and a portion of the first set of frequencies used in the first central portion, responsive to predetermined criteria associated with the third set of frequencies for communication therewith, including at least one of assigning, reusing and borrowing at least one of the second set of frequencies when the second set of frequencies are at least substantially geographically distant from the first spot beam.

53. The method of claim 52 wherein the first plurality of subareas are substantially equal sized.

54. The method of claim 52 wherein the second set of frequencies are substantially distant from the second satellite spot beam when they are at least one of assigned, reused and borrowed for use in those first plurality of subareas not sharing a common boundary with the second satellite spot beam.

55. The method of claim 52 wherein the first set of frequencies used in the first central portion comprise those frequency sets respectively associated with at least one of the satellite spot beams directly adjacent to the first satellite spot beam.

56. The method of claim 52 wherein said step of assigning, reusing and borrowing is based on prioritization rules.

57. The method of claim 56 wherein the prioritization rules include dynamic load and capacity constraints of candidate cells that frequencies are being taken from.

58. The method of claim 56 wherein the prioritization rules further include at least one of signal strength and quality of service.

59. The method of claim 52 wherein a user positioned within the first central portion can be assigned, reuse and/or borrow use any of the respective set of frequencies associated with the second satellite spot beam.

60. The method of claim 52 wherein a user positioned within the first central portion can be assigned, reuse and/or borrow use any of the respective set of frequencies associated with any spot beams adjacent the first satellite spot beam.

61. The method of claim 52 wherein a user positioned within a subarea not sharing at least a portion of a common boundary with the second satellite spot beam can be assigned, reuse and/or borrow any of the second set of frequencies associated with the second satellite spot beam.

62. The method of claim 52 wherein the predetermined criteria comprise at least one of load balancing, maintaining a reserve of frequencies, and received signal strength interference.

63. The method of claim 52 further comprising the steps of:

configuring a terrestrial cell that at least partially overlaps the second satellite spot beam having a fourth set of frequencies associated therewith; and

at least one of assigning, reusing and borrowing, by the terrestrial cell, at least one of the first set of frequencies and the frequencies used in the second central portion, responsive to predetermined criteria associated with the fourth set of frequencies, including at least one of assigning, reusing and borrowing at least one of the first set of frequencies when the first set of frequencies are at least substantially geographically distant from the terrestrial cell.

64. The method of claim 52 wherein the first and second set of frequencies comprise a plurality of paired uplink and downlink frequencies.

65. The method of claim 64 wherein a downlink frequency of a frequency set is used in a first subarea of the first spot beam, and wherein a corresponding one of the uplink frequencies is used in a second subarea of the first spot beam.

66. The method of claim 52 wherein the area of coverage of a spot beam comprises an area having a radius substantially equal to a distance from a center of the spot beam having a substantially maximum signal strength to a distance from the center of the spot beam where the signal strength of the spot beam is attenuated by approximately 3 dB.

67. The method of claim 52 wherein an area of coverage of at least one of a spot beam and a terrestrial cell comprises an area corresponding to a bit error rate in the range of 10⁻

2 to 10<sup>−

3</sup> for voice and 10<sup>−

5</sup> to 10<sup>−

6</sup> for data.

68. A system for at least one of assigning and reusing frequencies between one or more communication systems, comprising:

at least one satellite capable of configuring;

a) a first spot beam having a first set of frequencies associated therewith, the first spot beam comprising a first substantially central portion and a first plurality of subareas, each of the first plurality of subareas extending substantially from a periphery of the first substantially central portion to substantially near a circumference of the first satellite spot beam, and b) a second satellite spot beam having a second set of frequencies associated therewith, the second spot beam comprising a second substantially central portion and a second plurality of subareas, each of the second plurality of subareas extending substantially from a periphery of the second central portion to substantially near a circumference of the second satellite spot beam;

a terrestrial base station positioned within the first satellite spot beam for configuring a terrestrial cell having at least partially overlapping coverage with the first spot beam, the terrestrial cell having a third set of frequencies associated therewith and an area coverage at least partially overlapping with an area of coverage associated with the first spot beam;

a first subscriber terminal positioned within the terrestrial base station area of coverage; and

a network operations center (NOC) for at least one of assigning, reusing and borrowing, by the terrestrial base station and for use by said first subscriber terminal in communicating with at least one of a second subscriber terminal and other communications device, at least one of a portion of the second set of frequencies and a portion of the first set of frequencies used in the first central portion, responsive to predetermined criteria associated with the third set of frequencies, including at least one of assigning, reusing and borrowing at least one of the second set of frequencies when the second set of frequencies are at least substantially geographically distant from the second satellite spot beam.

69. The system of claim 68 wherein the first plurality of subareas are substantially equal sized and having a first size, and the second plurality of subareas are substantially and having a second size.

70. The system of claim 69 wherein the first size and the second size are approximately equal.

71. The system of claim 68 wherein the second set of frequencies are substantially distant from the second satellite spot beam when they are at least one of assigned, reused and borrowed for use by subscriber terminals positioned in those first plurality of subareas not sharing a common boundary with the second satellite spot beam.

72. The system of claim 68 wherein the first set of frequencies used by subscriber terminals positioned in the first central portion comprise at least one of those frequency sets respectively associated with one or more satellite spot beams directly adjacent to the first satellite spot beam.

73. The system of claim 68 wherein at least one of assigning, reusing and borrowing is based on prioritization rules.

74. The system of claim 73 wherein the prioritization rules include dynamic load and capacity constraints of cells that frequencies are taken from.

75. The system of claim 68 wherein a subscriber terminal positioned within the first central portion can be assigned, reuse and/or borrow any of the respective set of frequencies associated with the at least one second satellite spot beam.

76. The system of claim 68 wherein a subscriber terminal positioned within the first central portion can be assigned, reuse and/or borrow use any of the respective set of frequencies associated with any spot beam directly adjacent the first satellite spot beam.

77. The system of claim 68 wherein a subscriber terminal positioned within a subarea of the first spot beam not sharing at least a portion of a common boundary with the second satellite spot beam can be assigned, reuse and/or borrow any of the second set of frequencies associated with the second satellite spot beam.

78. The system of claim 68 wherein the predetermined criteria is at least one of load balancing, maintaining a reserve of frequencies, and received signal strength interference.

79. The system of claim 68 further comprising:

a second terrestrial base station positioned within the second satellite spot beam and having at least partially overlapping coverage with the first spot beam, for configuring at least one terrestrial cell therein, wherein the terrestrial cell has a fourth set of frequencies associated therewith; and

at least one of assigning, reusing and borrowing, by said second terrestrial base station, at least one of the first set of frequencies and the frequencies used in the second central portion, responsive to predetermined criteria associated with the fourth set of frequencies for establishing communication between the second subscriber unit positioned within an area of coverage of said second base station and at least one of the first subscriber terminal and other communications device, including at least one of assigning, reusing and borrowing at least one of the first set of frequencies when the first set of frequencies are at least substantially geographically distant from the second satellite spot beam.

80. The system of claim 68 wherein the first central portion and the second central portion comprise approximately twenty five percent of the area covered by the first satellite spot beam and the second satellite spot beam, respectively.

81. The system of claim 68 wherein the first and second set of frequencies comprise a plurality of paired uplink and downlink frequencies.

82. The system of claim 81 wherein a downlink frequency of a frequency set is used in a first subarea of the first spot beam, and wherein a corresponding one of the uplink frequencies is reused in a second subarea of the first spot beam.

83. The system of claim 68 wherein the area of coverage of a spot beam comprises an area having a radius substantially equal to a distance from a center of the spot beam having a substantially maximum signal strength to a distance from the center of the spot beam where the signal strength of the spot beam is attenuated by approximately 3 dB.

84. The system of claim 68 wherein an area of coverage of at least one of a spot beam and a terrestrial cell comprises an area corresponding to a bit error rate in the range of 10⁻

2 to 10<sup>−

3</sup> for voice and 10<sup>−

5</sup> to 10<sup>−

6</sup> for data.

85. The system of claim 68 wherein the number of subareas is equal to a number of spot beams comprising a cluster minus one.

86. A system for making a telephone call using a satellite-terrestrial communications system that at least one of assigns and reuses frequencies between a first satellite spot beam and a second satellite spot beam, comprising:

a subscriber terminal for dialing a telephone number to communicate with at least a second communications device;

a first terrestrial cell having said subscriber terminal positioned therein;

at least one satellite for configuring;

a) a first satellite spot beam associated with said first terrestrial cell and having a first set of frequencies associated therewith, the first satellite spot beam comprising a first substantially central portion and a first plurality of subareas, each of the first plurality of subareas extending substantially from a periphery of the first substantially central portion to substantially near a circumference of the first satellite spot beam, and b) a second satellite spot beam having the second communications device positioned therein and a second set of frequencies associated therewith; and

a network operations controller that establishes a connection between the subscriber terminal and at least the second communications device, by at least one of assigning, reusing and borrowing, by the first spot beam, at least one of the second set of frequencies, responsive to predetermined criteria including at least one of assigning, reusing and borrowing at least one of the second set of frequencies when the subscriber terminal is substantially geographically distant from the second satellite spot beam.

87. A system for use in at least one of assigning and reusing frequencies, comprising:

at least a first satellite for;

a) configuring a first communications area having a first set of frequencies associated therewith, the communications area comprising a first substantially central portion and a first plurality of subareas, each of the first plurality of subareas extending substantially from a periphery of the first substantially central portion to substantially near a circumference of the first communications area, and for b) configuring a second communications area having a second set of frequencies associated therewith and comprising a second substantially central portion and a second plurality of subareas, each of the second plurality of subareas extending substantially from a periphery of the central portion to substantially near a circumference of the second communications area;

a terrestrial base station positioned within the first communications area and having at least partially overlapping coverage with the first communications area, that configures at least a third communications area within the first communications area, the third communications area having a third set of frequencies associated therewith; and

a network operations controller that at least one of assigns, reuses and borrows, by said terrestrial base station, at least one of a portion of the second set of frequencies and a portion of the first set of frequencies used in the first central portion for facilitating communications between a subscriber terminal positioned within the first communications area and a second communications device, and responsive to predetermined criteria associated with the third set of frequencies, including at least one of assigning, reusing and borrowing at least one of the second set of frequencies when the second set of frequencies are at least substantially geographically distant from the first satellite spot beam.

88. The system of claim 87 wherein the first plurality of subareas are substantially equal sized and having a first size and the second plurality of subareas are substantially equal sized and having a second size.

89. The system of claim 88 wherein the first size and the second size are approximately equal.

90. The system of claim 87 wherein the second set of frequencies are substantially distant from the second communications area when they are at least one of assigned, reused and borrowed for use in those first plurality of subareas not sharing a common boundary with the second communications area.

91. The system of claim 87 wherein the first set of frequencies used in the first central portion comprise those frequency sets respectively associated with communication areas external to and directly adjacent to the first communications area.

92. The system of claim 87 wherein the assigning, reusing and borrowing is based on prioritization rules.

93. The system of claim 92 wherein the prioritization rules comprise dynamic load and capacity constraints of candidate cells that frequencies are being taken from.

94. The system of claim 87 wherein a user positioned within the first central portion can be assigned, reuse and/or borrow use any of the respective set of frequencies associated with the second communications area.

95. The system of claim 87 wherein when the subscriber terminal is positioned within the first central portion it can be assigned, reuse and/or borrow any of the respective set of frequencies associated with any communication areas adjacent the first communications area.

96. The system of claim 87 wherein when the subscriber terminal is positioned within a subarea of the first communications area not sharing at least a portion of a common boundary with the second communications area it can be assigned, reuse and/or borrow any of the second set of frequencies associated with the second communications area.

97. The system of claim 87 wherein the predetermined criteria is at least one of load balancing, maintaining a reserve of frequencies, and received signal strength interference.

98. The system of claim 87, further comprising:

a second terrestrial base station positioned within the second communications area and having at least partially overlapping coverage with the second communications area, wherein the second communications area comprises at least one terrestrial cell within the second communications area, and wherein said second terrestrial base station has a fourth set of frequencies associated therewith; and

at least one of assigning, reusing and borrowing, by said second terrestrial base station, at least one of the first set of frequencies and the frequencies used in the second central portion, responsive to predetermined criteria associated with the fourth set of frequencies, for establishing communication between a second subscriber unit positioned within an area covered by said second terrestrial base station and at least one of the first subscriber unit and the second communication device, including at least one of assigning, reusing and borrowing at least one of the first set of frequencies when the first set of frequencies are at least substantially geographically distant from the second terrestrial base station.

99. The system of claim 87 wherein the first central portion and the second central portion comprise approximately twenty five percent of the area covered by the first communications area and the second communications area, respectively.

100. The system of claim 87 wherein the first and second set of frequencies comprise a plurality of paired uplink and downlink frequencies, wherein a downlink frequency of a frequency set is used in a first subarea of the first communications area, and wherein a corresponding one of the uplink frequencies is reused in a second subarea of the first communications area.

101. The system of claim 87 wherein the area of coverage of a communications area comprises an area having a radius substantially equal to a distance from a center of the communications area having a substantially maximum signal strength to a distance from the center of the communications area where the signal strength of the communications area is attenuated by approximately 3 dB.

102. The system of claim 87 wherein an area of coverage of at least one of a spot beam and a terrestrial cell comprises an area corresponding to a bit error rate in the range of 10⁻

2 to 10<sup>−

3</sup> for voice and 10<sup>−

5</sup> to 10<sup>−

6</sup> for data.

103. A system for at least one of assigning and reusing frequencies between a plurality of communication systems, comprising:

at least one satellite capable of;

a) configuring a first satellite spot beam having a first set of frequencies associated therewith and comprising a first substantially central portion and a first plurality of subareas, each of the first plurality of subareas extending substantially from a periphery of the first substantially central portion to substantially near a circumference of the first satellite spot beam, and b) configuring a second satellite spot beam having a second set of frequencies associated therewith and comprising a second substantially central portion and a second plurality of subareas, each of the second plurality of subareas extending substantially from a periphery of the central portion to substantially near a circumference of the second satellite spot beam;

a terrestrial base station positioned within the first satellite spot beam and having at least partially overlapping coverage with the first spot beam, for configuring at least one terrestrial cell within the first satellite spot beam having a third set of frequencies associated therewith and having an area of coverage at least partially overlapping with the first satellite spot beam; and

a network operations controller for at least one of assigning, reusing and borrowing, by the second satellite spot beam, at least one of a portion of the third set of frequencies responsive to predetermined criteria, including at least one of assigning, reusing and borrowing at least one of the third set of frequencies associated with the at least one terrestrial cell when the portion is at least substantially geographically distant from the second set of frequencies.

104. A system of at least one of assigning and reusing frequencies between a plurality of communication systems, comprising:

a first satellite capable of;

a) configuring a first satellite spot beam having a first set of frequencies associated therewith and comprising a first substantially central portion and a first plurality of subareas, each of the first plurality of subareas extending substantially from a periphery of the first substantially central portion to substantially near a circumference of the first satellite spot beam, and b) configuring a second satellite spot beam having a second set of frequencies associated therewith;

a terrestrial base station positioned within the first satellite spot beam and having at least partially overlapping coverage with the first spot beam, for configuring at least one terrestrial cell within the first satellite spot beam, the terrestrial cell having a third set of frequencies associated therewith and having an area of coverage at least partially overlapping with an area of coverage of the first satellite spot beam; and

a network operations controller for at least one of assigning, reusing and borrowing, by the terrestrial base station for use in establishing communications between a first subscriber terminal positioned within an area of coverage of said terrestrial base station and at least one of a second subscriber terminal and communications device, at least one of a portion of the second set of frequencies and a portion of the first set of frequencies used in the first central portion, responsive to predetermined criteria associated with the third set of frequencies, including at least one of assigning, reusing and borrowing at least one of the second set of frequencies when the second set of frequencies are at least substantially geographically distant from the first satellite spot beam.

105. The system of claim 104 wherein the first plurality of subareas are substantially equal sized.

106. The system of claim 104 wherein the second set of frequencies are substantially distant from the second satellite spot beam when they are at least one of assigned, reused and borrowed for use in those first plurality of subareas not sharing a common boundary with the second satellite spot beam.

107. The system of claim 104 wherein the first set of frequencies used in the first central portion comprise those frequency sets respectively associated with satellite spot beams directly adjacent to the first satellite spot beam.

108. The system of claim 104 wherein the assigning, reusing and borrowing is based on prioritization rules.

109. The system of claim 108 wherein the prioritization rules include dynamic load and capacity constraints of candidate cells that frequencies are being taken from.

110. The system of claim 104 wherein a subscriber terminal positioned within the first central portion can be assigned, reuse and/or borrow any of the respective set of frequencies associated with the second satellite spot beam.

111. The system of claim 104 wherein a subscriber terminal positioned within the first central portion can be assigned, reuse and/or borrow any of the respective set of frequencies associated with any spot beams adjacent the first satellite spot beam.

112. The system of claim 104 wherein a subscriber terminal positioned within a subarea not sharing at least a portion of a common boundary with the second satellite spot beam can be assigned, reuse and/or borrow any of the second set of frequencies associated with the second satellite spot beam.

113. The system of claim 104 wherein the predetermined criteria is at least one of load balancing, maintaining a reserve of frequencies, and received signal strength interference.

114. The system of claim 104 further comprising:

a second terrestrial base station positioned within the second satellite spot beam and having at least partially overlapping coverage with the second spot beam, wherein the second satellite spot beam further comprises at least one terrestrial cell having a fourth set of frequencies associated therewith, wherein said network operations controller facilitates at least one of assigning, reusing and borrowing, by said second terrestrial base station for use with a second subscriber terminal positioned within an area covered by said second terrestrial base station, at least one of the first set of frequencies and the frequencies used in the second central portion, responsive to predetermined criteria associated with the fourth set of frequencies for establishing communication between the second subscriber terminal and at least one of the first subscriber terminal and communications device, including at least one of assigning, reusing and borrowing at least one of the first set of frequencies when the first set of frequencies are at least substantially geographically distant from the second satellite spot beam.

115. The system of claim 104 wherein the first central portion comprises approximately twenty five percent of the area covered by the first satellite spot beam.

116. The system of claim 104 wherein the first and second set of frequencies comprise a plurality of paired uplink and downlink frequencies, wherein a downlink frequency of a frequency set is used in a first subarea of the first spot beam, and wherein a corresponding one of the uplink frequencies is reused in a second subarea of the first spot beam.

117. The system of claim 104 wherein an area of coverage of at least one of a spot beam and a terrestrial cell comprises an area corresponding to a bit error rate in the range of 10⁻

2 to 10<sup>−

3</sup> for voice and 10<sup>−

5</sup> to 10<sup>−

6</sup> for data.

118. The system of claim 104 wherein the area of coverage of a spot beam comprises an area having a radius substantially equal to a distance from a center of the spot beam having a substantially maximum signal strength to a distance from the center of the spot beam where the signal strength of the spot beam is attenuated by approximately 3 dB.

119. A system of at least one of assigning and reusing frequencies between a plurality of communication systems, comprising:

a first satellite capable of;

a) configuring a first satellite spot beam having a first set of frequencies associated therewith and comprising a first plurality of subareas, each of the first plurality of subareas extending from a substantially center area of the first satellite spot beam to substantially near a circumference of the first satellite spot beam in a fan-like manner thereby forming the first plurality of subareas, and b) configuring a second satellite spot beam having a second set of frequencies associated therewith;

a terrestrial base station positioned within the first satellite spot beam and having at least partially overlapping coverage with the first spot beam, for configuring a terrestrial cell, the terrestrial cell having a third set of frequencies associated therewith and having an area of coverage at least partially overlapping with an area of coverage associated with the first spot beam; and

a network controller for at least one of assigning, reusing and borrowing, by said terrestrial base station and for use by a first subscriber terminal in communicating with at least one of a second subscriber terminal or communications device, at least one of a portion of the second set of frequencies and a portion of the first set of frequencies used in the first central portion, responsive to predetermined criteria associated with the third set of frequencies, including at least one of assigning, reusing and borrowing at least one of the second set of frequencies when the second set of frequencies are at least substantially geographically distant from the first satellite spot beam.

120. The system of claim 119 wherein the first plurality of subareas are substantially equal sized.

121. The system of claim 119 wherein the second set of frequencies are substantially distant from the second satellite spot beam when they are at least one of assigned, reused and borrowed for use in those first plurality of subareas not sharing a common boundary with the second satellite spot beam.

122. The system of claim 119 wherein the assigning, reusing and borrowing is based on prioritization rules.

123. The system of claim 122 wherein the prioritization rules include dynamic load and capacity constraints of candidate cells that frequencies are being taken from.

124. The system of claim 119 wherein a subscriber terminal positioned within a subarea not sharing at least a portion of a common boundary with the second satellite spot beam can be assigned, reuse and/or borrow any of the second set of frequencies associated with the second satellite spot beam.

125. The system of claim 119 wherein the predetermined criteria is at least one of load balancing, maintaining a reserve of frequencies, and received signal strength interference.

126. The system of claim 119 further comprising:

a second terrestrial base station positioned within the second satellite spot beam and having at least partially overlapping coverage with the second spot beam, and associated with a terrestrial cell having a fourth set of frequencies associated therewith; and

at least one of assigning, reusing and borrowing, by said second terrestrial base station, at least one of the first set of frequencies and the frequencies used in spot beams adjacent to the second spot beam, responsive to predetermined criteria associated with the fourth set of frequencies, for establishing communication between a second subscriber terminal positioned within the area of coverage of said second terrestrial base station and at least one of a subscriber terminal and communications device, including at least one of assigning, reusing and borrowing at least one of the first set of frequencies when the first set of frequencies are at least substantially geographically distant from the second satellite spot beam.

127. The system of claim 119 wherein the first and second frequencies comprise a plurality of paired uplink and downlink frequencies, wherein one of the frequency sets is used in a first subarea of the first spot beam, and wherein a corresponding one of the uplink frequencies is reused in a second subarea of the first spot beam.

128. The system of claim 119 wherein an area of coverage of at least one of a spot beam and a terrestrial cell comprises an area corresponding to a bit error rate in the range of 10⁻

2 to 10<sup>−

3</sup> for voice and 10<sup>−

5</sup> to 10<sup>−

6</sup> for data.

129. The system of claim 119 wherein the area of coverage of a spot beam comprises an area having a radius substantially equal to a distance from a center of the spot beam having a substantially maximum signal strength to a distance from the center of the spot beam where the signal strength of the spot beam is attenuated by approximately 3 dB.

130. A system for at least one of assigning and reusing frequencies between one or more communication systems, comprising:

means for configuring;

a) a first spot beam having a first set of frequencies associated therewith, the first spot beam comprising a first substantially central portion and a first plurality of subareas, each of the first plurality of subareas extending substantially from a periphery of the first substantially central portion to substantially near a circumference of the first satellite spot beam, and b) a second satellite spot beam having a second set of frequencies associated therewith, the second spot beam comprising a second substantially central portion and a second plurality of subareas, each of the second plurality of subareas extending substantially from a periphery of the second central portion to substantially near a circumference of the second satellite spot beam;

means positioned within the first satellite spot beam for configuring a terrestrial cell having at least partially overlapping coverage with the first spot beam, the terrestrial cell having a third set of frequencies associated therewith and an area coverage at least partially overlapping with an area of coverage associated with the first spot beam;

a first subscriber terminal positioned within the terrestrial base station area of coverage; and

means for at least one of assigning, reusing and borrowing, by the terrestrial base station and for use by said first subscriber terminal in communicating with at least one of a second subscriber terminal and other communications device, at least one of a portion of the second set of frequencies and a portion of the first set of frequencies used in the first central portion, responsive to predetermined criteria associated with the third set of frequencies, including at least one of assigning, reusing and borrowing at least one of the second set of frequencies when the second set of frequencies are at least substantially geographically distant from the second satellite spot beam.

131. A system for making a telephone call using a satellite-terrestrial communications system that at least one of assigns and reuses frequencies between a first satellite spot beam and a second satellite spot beam, comprising:

a subscriber terminal for dialing a telephone number to communicate with at least a second communications device;

a first terrestrial cell having said subscriber terminal positioned therein;

means for configuring;

a) a first satellite spot beam associated with said first terrestrial cell, having a first set of frequencies associated therewith, and having at least partially overlapping coverage with the first terrestrial cell, the first satellite spot beam comprising a first substantially central portion and a first plurality of subareas, each of the first plurality of subareas extending substantially from a periphery of the first substantially central portion to substantially near a circumference of said first satellite spot beam, and b) a second satellite spot beam having the second communications device positioned therein and a second set of frequencies associated therewith; and

means for establishing a connection between said subscriber terminal and at least the second communications device, by at least one of assigning, reusing and borrowing, by the first spot beam, at least one of the second set of frequencies, responsive to predetermined criteria including at least one of assigning, reusing and borrowing at least one of the second set of frequencies when the subscriber terminal is substantially geographically distant from the second satellite spot beam.

132. A system for use in at least one of assigning and reusing frequencies, comprising:

means for configuring;

a) a first communications area having a first set of frequencies associated therewith, the communications area comprising a first substantially central portion and a first plurality of subareas, each of the first plurality of subareas extending substantially from a periphery of the first substantially central portion to substantially near a circumference of the first communications area, and b) a second communications area having a second set of frequencies associated therewith and comprising a second substantially central portion and a second plurality of subareas, each of the second plurality of subareas extending substantially from a periphery of the central portion to substantially near a circumference of the second communications area;

means positioned within the first satellite spot beam for configuring at least a third communications area within the first communications area, the third communications area having a third set of frequencies associated therewith and having at least partially overlapping coverage with the first spot beam; and

means for at least one of assigning, reusing and borrowing, by said terrestrial base station, at least one of a portion of the second set of frequencies and a portion of the first set of frequencies used in the first central portion for facilitating communications between a subscriber terminal positioned within the first spot beam and a second communications device, and responsive to predetermined criteria associated with the third set of frequencies, including at least one of assigning, reusing and borrowing at least one of the second set of frequencies when the second set of frequencies are at least substantially geographically distant from the first satellite spot beam.

133. A system for at least one of assigning and reusing frequencies between a plurality of communication systems, comprising:

means for;

a) configuring a first satellite spot beam having a first set of frequencies associated therewith and comprising a first substantially central portion and a first plurality of subareas, each of the first plurality of subareas extending substantially from a periphery of the first substantially central portion to substantially near a circumference of the first satellite spot beam, and b) configuring a second satellite spot beam having a second set of frequencies associated therewith and comprising a second substantially central portion and a second plurality of subareas, each of the second plurality of subareas extending substantially from a periphery of the central portion to substantially near a circumference of the second satellite spot beam;

means positioned within the first satellite spot beam for configuring at least one terrestrial cell within the first satellite spot beam having a third set of frequencies associated therewith and having an area of coverage at least partially overlapping with the first satellite spot beam; and

means for at least one of assigning, reusing and borrowing, by the second satellite spot beam, at least one of a portion of the third set of frequencies responsive to predetermined criteria, including at least one of assigning, reusing and borrowing at least one of the third set of frequencies associated with the at least one terrestrial cell when the portion is at least substantially geographically distant from the second set of frequencies.

134. A system of at least one of assigning and reusing frequencies between a plurality of communication systems, comprising:

means for;

a) configuring a first satellite spot beam having a first set of frequencies associated therewith and comprising a first substantially central portion and a first plurality of subareas, each of the first plurality of subareas extending substantially from a periphery of the first substantially central portion to substantially near a circumference of the first satellite spot beam, and b) configuring a second satellite spot beam having a second set of frequencies associated therewith;

means positioned within the first satellite spot beam for configuring at least one terrestrial cell within the first satellite spot beam, the terrestrial cell having a third set of frequencies associated therewith and having an area of coverage at least partially overlapping with an area of coverage of the first satellite spot beam; and

means for at least one of assigning, reusing and borrowing, by the terrestrial base station for use in establishing communications between a first subscriber terminal positioned within an area of coverage of said terrestrial base station and at least one of a second subscriber terminal and communications device, at least one of a portion of the second set of frequencies and a portion of the first set of frequencies used in the first central portion, responsive to predetermined criteria associated with the third set of frequencies, including at least one of assigning, reusing and borrowing at least one of the second set of frequencies when the second set of frequencies are at least substantially geographically distant from the first satellite spot beam.

135. A system of at least one of assigning and reusing frequencies between a plurality of communication systems, comprising:

means for;

a) configuring a first satellite spot beam having a first set of frequencies associated therewith and comprising a first plurality of subareas, each of the first plurality of subareas extending from a substantially center area of the first satellite spot beam to substantially near a circumference of the first satellite spot beam in a fan-like manner thereby forming the first plurality of subareas, and b) configuring a second satellite spot beam having a second set of frequencies associated therewith;

means positioned within the first satellite spot beam for configuring a terrestrial cell, the terrestrial cell having a third set of frequencies associated therewith and having an area of coverage at least partially overlapping with an area of coverage associated with the first spot beam; and

means for at least one of assigning, reusing and borrowing, by said terrestrial base station and for use by a first subscriber terminal in communicating with at least one of a second subscriber terminal or communications device, at least one of a portion of the second set of frequencies and a portion of the first set of frequencies used in the first central portion, responsive to predetermined criteria associated with the third set of frequencies, including at least one of assigning, reusing and borrowing at least one of the second set of frequencies when the second set of frequencies are at least substantially geographically distant from the first satellite spot beam.

136. A method of at least one of assigning and reusing frequencies between one or more communication systems, comprising the steps of:

configuring a first satellite spot beam having a first set of frequencies associated therewith and comprising a first substantially central portion;

configuring a second satellite spot beam having a second set of frequencies associated therewith and comprising a second substantially central portion configuring at least one terrestrial cell within the first satellite spot beam having a third set of frequencies associated therewith and having at least partially overlapping coverage with the first spot beam; and

at least one of assigning, reusing and borrowing, by the terrestrial system, at least one of a portion of the second set of frequencies and a portion of the first set of frequencies used in the first central portion, responsive to predetermined criteria associated with the third set of frequencies, including at least one of assigning, reusing and borrowing at least one of the second set of frequencies when the second set of frequencies are at least substantially geographically distant from the first satellite spot beam.

137. The method of claim 136 wherein the second set of frequencies are substantially distant from the first satellite spot beam when they are used in subareas of the second spot beam that do not share a common boundary with the first satellite spot beam.

138. The system of claim 137 wherein an area of coverage of at least one of a spot beam and a terrestrial cell comprises an area corresponding to a bit error rate in the range of 10⁻

2 to 10<sup>−

3</sup> for voice and 10<sup>−

5</sup> to 10<sup>−

6</sup> for data.

139. The method of claim 136 wherein the first set of frequencies used in the first central portion comprise at least one of those frequency sets respectively associated with satellite spot beams directly adjacent to the first satellite spot beam.

140. The method of claim 136 wherein said step of assigning, reusing and borrowing is based on prioritization rules.

141. The method of claim 140 wherein the prioritization rules include dynamic load and capacity constraints of cells that frequencies are taken from.

142. The method of claim 136 wherein a subscriber terminal positioned within the first central portion can be assigned, reuse and/or borrow use any of the respective set of frequencies associated with the at least one second satellite spot beam.

143. The method of claim 136 wherein a subscriber terminal positioned within the first central portion can be assigned, reuse and/or borrow use any of the respective set of frequencies associated with any spot beams adjacent the first satellite spot beam.

144. The method of claim 136 wherein the predetermined criteria is at least one of load balancing, maintaining a reserve of frequencies, and received signal strength interference.

145. The method of claim 136 further comprising the steps of:

configuring a second terrestrial cell within the second satellite spot beam having a fourth set of frequencies associated therewith and having at least partially overlapping coverage with the second spot beam; and

at least one of assigning, reusing and borrowing, by the second terrestrial cell, at least one of the first set of frequencies and the frequencies used in the second central portion, responsive to predetermined criteria associated with the fourth set of frequencies, including at least one of assigning, reusing and borrowing at least one of the first set of frequencies when the first set of frequencies are at least substantially geographically distant from the second satellite spot beam.

146. The method of claim 136 wherein the first central portion and the second central portion comprise approximately twenty five percent of the area covered by the first satellite spot beam and the second satellite spot beam, respectively.

147. The method of claim 136 wherein the first set of frequencies and the second set of frequencies comprise a plurality of paired uplink and downlink frequencies, wherein a downlink frequency of a frequency set is used in the first spot beam, and wherein a corresponding one of the uplink frequencies is reused in the second spot beam.

148. The method of claim 136 wherein the area of coverage of a spot beam comprises an area having a radius substantially equal to a distance from a center of the spot beam having a substantially maximum signal strength to a distance from the center of the spot beam where the signal strength of the spot beam is attenuated by approximately 3 dB.

149. A method of making a telephone call using a satellite-terrestrial communications system that at least one of assigns and reuses frequencies between a first satellite spot beam and a second satellite spot beam, comprising the steps of:

a first user using a subscriber terminal to dial a telephone number within an area of a first terrestrial cell associated with a first satellite spot beam having a first set of frequencies associated therewith, the first satellite spot beam comprising a first substantially central portion;

determining because of at least one of unavailability of the first set of frequencies or weak signal strength that a connection cannot be established, using the first set of frequencies, with a communications device having the dialed telephone number associated therewith;

configuring a second satellite spot beam having a second set of frequencies associated therewith and having at least partially overlapping coverage with the second spot beam; and

establishing a connection between the subscriber terminal and the communications device by at least one of assigning, reusing and borrowing, by the first spot beam, at least one of the second set of frequencies, responsive to predetermined criteria including at least one of assigning, reusing and borrowing at least one of the second set of frequencies when the mobile terminal is substantially geographically distant from the second satellite spot beam.