Downlink transmission and reception techniques for a processing communication satellite

• US 6,512,749 B1
• Filed: 09/29/1999
• Issued: 01/28/2003
• Est. Priority Date: 09/29/1999
• Status: Expired due to Term

• Current Assignee: Northrop Grumman Systems Corporation (Northrop Grumman Corporation)
• Original Assignee: TRW Limited (Zeppelin - Stiftung der Stadt Friedrichshafen)
• Inventors: Perahia, Eldad, Wright, David A., Linsky, Stuart T., Wilcoxson, Donald C., Caso, Gregory S.
• Primary Examiner(s): Urban, Edward F.
• Assistant Examiner(s): BEAMER, TEMICA M
• Application Number:
  US09/408,041
• Time in Patent Office: 1,217 Days
• Field of Search: 370/315, 370/316, 370/318, 370/319, 370/321, 370/337, 370/347, 370/442, 375/243, 375/246, 375/253, 375/265, 455/427, 455/12.1, 455/13.4
• US Class Current: 370/316
• CPC Class Codes: H04B 7/18515 Transmission equipment in satellites or space-based relays

Abstract

Communication satellite downlink transmitting and reception techniques includes circuitry which groups a predetermined number of data cells with a predetermined error correction code to generate frame bodies. The circuitry also groups the frame bodies with header symbols and trailer symbols to generate data frames. One or more modulators enable the placement of the modulated data frames into a plurality of frequency bands having a predetermined frequency range and a predetermined transmission rate. One or more antennas transmit the modulated data frames over one or more beams with different forms of polarization to other antennas. A demodulator is connected to demodulate the radio carrier signals and the beams into data frames from a plurality of frequency bands. Decoders are connected to decode the frame bodies with header symbols and with trailer symbols from the data frames and to decode four data cells as a group by using a predetermined error correction code.

Claims

1. In a processing satellite communication system, apparatus for generating and transmitting data in an available spectrum of frequencies suitable for use by a downlink transmitting system of a processing satellite comprising in combination:

a terminal connected to receive data cells for transmission;

a scheduler connected to generate a first frame type signal and a second frame type signal;

one or more encoders connected to group a predetermined number of the data cells with a predetermined error correction code;

a frame organizer connected to generate from said data cells a first type of frame body in response to said first frame type signal and to generate a second type of frame body in response to said second frame type signal and to group the frame bodies with header symbols and with trailer symbols to generate data frames comprising a predetermined number of symbols;

one or more modulators connected to modulate the data frames by a predetermined form of modulation to enable placement of the modulated data frames into a plurality of frequency bands having a predetermined frequency range and having a predetermined transmission rate definable in megasymbols per second;

a radio frequency transmitter connected to transmit the modulated data frames over one or more beams with a predetermined form of polarization; and

a gate arranged to reduce power in response to said second frame type signal.

2. Apparatus, as claimed in claim 1, wherein said first type of frame body comprises more data than said second type of frame body.

3. Apparatus, as claimed in claim 1, wherein at least some of said beams are limited to a single predetermined form of polarization and wherein said modulators modulate the data frames to generate a serial TDM stream of modulated data frames for each of said beams limited to said single predetermined form of polarization.

4. Apparatus, as claimed in claim 1, wherein said header symbols comprise:

frame marker symbols for delineating said data frames and for resolving modulation ambiguity;

non-repeating frame number symbols indicating frame numbers of said data frames which do not repeat over the expected life of said satellite; and

frame type symbols indicating different types of said data frames.

5. Apparatus, as claimed in claim 4, wherein said frame type comprises an indicator of the inner code being used in the frame.

6. Apparatus, as claimed in claim 4, wherein said frame marker symbols enable tracking by correlation with a known pattern of such marker symbols.

7. Apparatus, as claimed in claim 4, wherein said frame type symbols comprise redundant and error control coding.

8. Apparatus, as claimed in claim 1, wherein said frame bodies comprise inner code blocks and outer code blocks and wherein said inner code blocks are partitioned into two separate independently decodable quadrature components.

9. Apparatus, as claimed in claim 8, wherein said inner code blocks are modulated with quaternary phase shift keying (QPSK).

10. Apparatus, as claimed in claim 8, wherein said inner code blocks are convolutionally coded.

11. Apparatus, as claimed in claim 1, wherein said predetermined frequency range divided by said predetermined transmission rate is in the range of 1.2 to 1.3.

12. Apparatus, as claimed in claim 1, wherein said predetermined form of modulation further comprises square-root raised cosine pulse shaping on quadraphase phase shift keying.

13. Apparatus,as claimed in claim 1, wherein the one or more modulators increase the rates of the generated frequencies to form carrier frequencies and wherein the carrier frequencies are transmitted by said transmitter with at least two different forms of polarization.

14. Apparatus, as claimed in claim 13, wherein the different forms of polarization comprise forms of polarization selected from the group consisting of right hand circular polarization, left hand circular polarization and both right hand and left hand circular polarization.

15. Apparatus, as claimed in claim 1, wherein the one or more beams comprises a plurality of beams transmitted to a plurality of earth locations using at least some of the same carrier frequencies so that the carrier frequencies may be reused spatially by the satellite.

16. Apparatus, as claimed in claim 1, wherein the one or more modulators generate a sufficient number of different frequencies so as to allow up to a predetermined number of bands of frequencies within the available spectrum of frequencies and wherein the beams are arranged in a cluster configuration in which each cluster includes the predetermined number of bands and each band occupies a different portion of the available spectrum of frequencies.

17. Apparatus, as claimed in claim 16, wherein the predetermined number of bands is four.

18. Apparatus, as claimed in claim 16, wherein the bands are transmitted with at least two different polarizations.

19. Apparatus, as claimed in claim 1, wherein the predetermined number of data cells is four.

20. Apparatus, as claimed in claim 1, wherein the predetermined error correction code comprises Reed-Solomon code.

21. Apparatus, as claimed in claim 1, wherein the frame bodies bear four times K ATM cells and comprises K code words where K=3 or 6.

22. Apparatus, as claimed in claim 1, wherein the transmission rate of at least some of the bands is 90-100 megasymbols per second.

23. Apparatus, as claimed in claim 22, wherein the frequency range of at least some of the bands is substantially 125 MHz.

24. Apparatus, as claimed in claim 1, wherein at least some of the frames include null symbols so that each frame includes a predetermined number of symbols irrespective of the amount of data in the frame.

25. Apparatus, as claimed in claim 1, wherein the one or more encoders comprise an inner encoder, wherein the correction code comprises an inner code generated by the inner encoder and wherein at least some of the frames include flush bits resulting from tailing off of the inner encoder.

26. Apparatus, as claimed in claim 25, wherein said inner code defines an inner code rate of substantially 3/8 or 6/8.

27. Apparatus, as claimed in claim 1, wherein the one or more encoders comprise an outer encoder connected to generate blocks of outer code in at least some of the data frames and wherein the blocks including outer code are interleaved.

28. Apparatus, as claimed in claim 27, wherein the interleaved code blocks comprise three or six outer code blocks depending on whether the coding is light or heavy.

29. In a processing satellite communication system, a method of generating and transmitting data in an available spectrum of frequencies suitable for use by a downlink transmitting system of a processing satellite comprising the steps of:

receiving data cells for transmission;

generating a first frame type signal;

generating a second frame type signal;

grouping a predetermined number of the data cells with a predetermined error correction code to generate a first type of frame body in response to said first frame type signal and to generate a second type of frame body in response to said second frame type signal;

grouping the frame bodies with header symbols and with trailer symbols to generate data frames comprising a predetermined number of symbols;

modulating the data frames by a predetermined form of modulation to enable placement of the modulated data frames into a plurality of frequency bands having a predetermined frequency range and having a predetermined transmission rate definable in megasymbols per second; and

transmitting the modulated data frames over one or more beams with a predetermined form of polarization; and

reducing power in response to said first frame type signal.

30. A method, as claimed in claim 29, wherein said first type of frame body comprises more data than said second type of frame body.

31. A method, as claimed in claim 29, wherein the predetermined form of modulation further comprises square-root raised cosine pulse shaping on quadraphase phase shift keying.

32. A method, as claimed in claim 29, wherein the transmission rate of at least some of the bands is 90-100 megasymbols per second.

33. A method, as claimed in claim 29, wherein the frequency range of at least some of the bands is substantially 125 MHz.

34. A method, as claimed in claim 29, wherein the step of modulating comprises the step of increasing the rates of the generated frequencies to form carrier frequencies and wherein the step of transmitting comprises the step of transmitting the carrier frequencies with at least two different forms of polarization.

35. A method, as claimed in claim 34, wherein the predetermined forms of polarization comprise forms of polarization selected from the group consisting of right hand circular polarization, left hand circular polarization and both right hand and left hand circular polarization.

36. A method, as claimed in claim 29, wherein the one or more beams comprises a plurality of beams transmitted to a plurality of earth locations using at least some of the same carrier frequencies so that the carrier frequencies may be reused spatially by the satellite.

37. A method, as claimed in claim 29, wherein the step of modulating comprises the step of generating a sufficient number of different frequencies so as to allow up to a predetermined number of bands of frequencies within the available spectrum of frequencies and arranging the beams in a cluster configuration in which each cluster includes the predetermined number of bands and each band occupies a different portion of the available spectrum of frequencies.

38. A method, as claimed in claim 37, wherein the predetermined number of bands is four.

39. A method, as claimed in claim 29, wherein the bands are transmitted with at least two different polarizations.

40. A method, as claimed in claim 29, wherein at least some of the frames include null symbols so that each frame includes a predetermined number of symbols irrespective of the amount of data in the frame.

41. A method, as claimed in claim 29, wherein said steps of grouping comprise the step of generating an inner code and wherein at least some of the frames include flush bits resulting from tailing off of the inner code generating.

42. A method, as claimed in claim 29, wherein the steps of grouping comprise the step of generating blocks of an outer code in at least some of the frame bodies and further comprise the step of interleaving the blocks including the outer code.

43. A method, as claimed in claim 29, wherein at least some of said beams are limited to a single predetermined form of polarization and wherein said modulating comprises generating a serial TDM stream of modulated data frames for each of said beams limited to said single predetermined form of polarization.

44. A method, as claimed in claim 29, wherein said header symbols comprise:

frame marker symbols for delineating said data frames and for resolving modulation ambiguity;

non-repeating frame number symbols indicating frame numbers of said data frames which do not repeat over the expected life of said satellite; and

frame type symbols indicating different types of said data frames.

45. A method, as claimed in claim 44, wherein said frame type comprises an indicator of the inner code being used in the frame.

46. A method, as claimed in claim 44, wherein said frame marker symbols enable tracking by correlation with a known pattern of such marker symbols.

47. A method, as claimed in claim 44, wherein said frame type symbols comprise redundant and error control coding.

48. A method, as claimed in claim 29, wherein said frame bodies comprise inner code blocks and outer code blocks and wherein said inner code blocks are partitioned into two separate independently decodable quadrature components.

49. A method, as claimed in claim 48, wherein said inner code blocks are modulated with quaternary phase shift keying (QPSK).

50. A method, as claimed in claim 48, wherein said inner code blocks are convolutionally coded.

51. A method, as claimed in claim 29, wherein said predetermined frequency range divided by said predetermined transmission rate is in the range of 1.2 to 1.3.

52. A method, as claimed in claim 29, wherein the frame bodies bear four times K ATM cells and comprises K code words where K=3 or 6.

53. A method, as claimed in claim 41, wherein said inner code defines an inner code rate of substantially 3/8 or 6/8.

54. A method, as claimed in claim 42, wherein the blocks including outer code comprise three or six outer code blocks depending on whether the coding is light or heavy.

55. A method, as claimed in claim 29, wherein the predetermined number of data cells is four.

56. A method, as claimed in claim 29, wherein the predetermined error correction code comprises Reed-Solomon code.

57. In a processing satellite communication system, apparatus suitable for receiving and processing radio carrier signals in an available spectrum of frequencies transmittable by a processing satellite in a downlink comprising in combination:

one or more antennas connected to respond one or more beams of the radio carrier signals having one or more forms of polarization;

one or more demodulators connected to demodulate the radio carrier signals into data frames comprising a frame body and a header including a frame type from a plurality of frequency bands having a predetermined frequency range and having a predetermined transmission rate definable in megasymbols per second;

a header processor connected to decode the frame type into a first frame type and a second frame type;

one or more decoders connected to decode said frame bodies of said data frames into a predetermined number of data cells in response to the first frame type; and

an output terminal connected to transmit a first number of the data cells for further processing in response to the first frame type and to transmit less than the first number of data cells for further processing in response to the second frame type.

58. Apparatus, as claimed in claim 57, wherein said first type of frame body comprises more data than said second type of frame body.

59. Apparatus, as claimed in claim 57, wherein at least some of said beams are limited to a single predetermined form of polarization and wherein said one or more demodulators demodulate the data frames from a serial TDM stream of modulated data frames for each of said beams limited to said single predetermined form of polarization.

60. Apparatus, as claimed in claim 57, wherein said header symbols comprise:

frame marker symbols for delineating said data frames and for resolving modulation ambiguity;

non-repeating frame number symbols indicating frame numbers of said data frames which do not repeat over the expected life of said satellite; and

frame type symbols indicating different types of said data frames.

61. Apparatus, as claimed in claim 57, wherein said frame type comprises an indicator of the inner code being used in the frame.

62. Apparatus, as claimed in claim 60, wherein said frame marker symbols enable tracking by correlation with a known pattern of such marker symbols.

63. Apparatus, as claimed in claim 60, wherein said frame type symbols comprise redundant and error control coding.

64. Apparatus, as claimed in claim 57, wherein said frame bodies comprise inner code blocks and outer code blocks and wherein said inner code blocks are partitioned into two separate independently decodable quadrature components.

65. Apparatus, as claimed in claim 64, wherein said inner code blocks are modulated with quaternary phase shift keying (QPSK).

66. Apparatus, as claimed in claim 64, wherein said inner code blocks are convolutionally coded.

67. Apparatus, as claimed in claim 57, wherein said predetermined frequency range divided by said predetermined transmission rate is in the range of 1.2 to 1.3.

68. Apparatus, as claimed in claim 57, wherein the predetermined form of modulation further comprises square-root raised cosine pulse shaping on quadraphase phase shift keying.

69. Apparatus, as claimed in claim 57, wherein the one or more demodulators demodulate a sufficient number of different frequencies so as to allow up to a predetermined number of bands of frequencies within the available spectrum of frequencies.

70. Apparatus, as claimed in claim 57, wherein the transmission rate of at least some of the bands is 90-100 megasymbols per second.

71. Apparatus, as claimed in claim 57, wherein the frequency range of at least some of the bands is substantially 125 MHz.

72. Apparatus, as claimed in claim 57, wherein the one or more antennas respond to at least two different forms of polarization.

73. Apparatus, as claimed in claim 57, wherein the one or more forms of polarization comprises a form of polarization selected from the group consisting of right hand circular polarization, left hand circular polarization and both right hand and left hand circular polarization.

74. Apparatus, as claimed in claim 57, wherein the one or more beams comprises a plurality of beams transmitted to a plurality of earth locations using at least some of the same carrier frequencies so that the carrier frequencies may be reused spatially by the satellite.

75. Apparatus, as claimed in claim 57, wherein the one or more demodulators demodulate a sufficient number of different frequencies so as to allow up to a predetermined number of bands of frequencies within the available spectrum of frequencies and wherein the beams are arranged in a cluster configuration in which each cluster includes the predetermined number of bands and each band occupies a different portion of the available spectrum of frequencies.

76. Apparatus, as claimed in claim 57, wherein the predetermined number of bands is four.

77. Apparatus, as claimed in claim 57, wherein the bands are received with at least two different polarizations.

78. Apparatus, as claimed in claim 57, wherein at least some of the frames include null symbols so that each frame includes a predetermined number of symbols irrespective of the amount of data in the frame.

79. Apparatus, as claimed in claim 57, wherein the one or more decoders comprise an inner decoder, wherein the correction code comprises an inner code decoded by the inner decoder and wherein at least some of the frames include flush bits resulting from tailing off of the inner decoder.

80. Apparatus, as claimed in claim 79, wherein the inner code rate is substantially 3/8 or 6/8.

81. Apparatus, as claimed in claim 79, wherein the inner code is partitioned into two separate independently decodable quadrature components.

82. Apparatus, as claimed in claim 57, wherein the one or more decoders comprise an outer decoder, wherein the correction code comprises blocks of an outer code, wherein at least some of the frame bodies include blocks of the outer code and wherein the blocks including outer code are interleaved.

83. Apparatus, as claimed in claim 82, wherein the interleaver code blocks include three or six outer code blocks depending on whether the coding is light or heavy.

84. Apparatus, as claimed in claim 57, wherein the one or more decoders decode the frame bodies with error correction code comprising Reed-Solomon code.

85. Apparatus, as claimed in claim 57, wherein the frame bodies bear four times K ATM cells and comprises K code words where K=3 or 6.

86. In a processing satellite communication system, a method of receiving and processing radio carrier signals in an available spectrum of frequencies transmittable by a processing satellite in a downlink comprising the steps of:

receiving to one or more beams of the radio carrier signals having one or more forms of polarization;

demodulating the radio carrier signals into a plurality of frequency bands having a predetermined frequency range and having a predetermined transmission rate definable in megasymbols per second;

demodulating the frequency bands into data frames;

decoding the data frames into frame bodies with header symbols defining a frame type and with trailer symbols;

decoding the frame type into a first frame type and a second frame type;

decoding the frame bodies into a predetermined number of data cells using a predetermined error correction code;

transmitting a first number of the data cells for further processing in response to the first frame type; and

transmitting a second number of the data cells less than the first number for further processing in response to the second frame type.

87. A method, as claimed in claim 86, wherein the first frame type indicates a data frame with more data than the second frame type.

88. A method, as claimed in claim 86, wherein the predetermined error correction code comprises Reed-Solomon code.

89. A method, as claimed in claim 86, wherein the predetermined form of modulation comprises square-root raised cosine pulse shaping on quadraphase phase shift keying.

90. A method, as claimed in claim 86, wherein the transmission rate of at least some of the bands is 90-100 megasymbols per second.

91. A method, as claimed in claim 86, wherein the frequency range of at least some of the bands is substantially 125 MHz.

92. A method, as claimed in claim 86, wherein the step of receiving comprises the step of responding to at least two different forms of polarization.

93. A method, as claimed in claim 92, wherein the predetermined forms of polarization comprise forms of polarization selected from the group consisting of right hand circular polarization, left hand circular polarization and both right hand and left hand circular polarization.

94. A method, as claimed in claim 86, wherein the one or more beams comprises a plurality of beams transmitted to a plurality of earth locations using at least some of the same carrier frequencies so that the carrier frequencies may be reused spatially.

95. A method, as claimed in claim 86, wherein the step of demodulating comprises the step of demodulating a sufficient number of different frequencies so as to allow up to a predetermined number of bands of frequencies within the available spectrum of frequencies and wherein the beams are arranged in a cluster configuration in which each cluster includes the predetermined number of bands and each band occupies a different portion of the available spectrum of frequencies.

96. A method, as claimed in claim 95, wherein the predetermined number of bands is four.

97. A method, as claimed in claim 86, wherein the bands are received with at least two different polarizations.

98. A method, as claimed in claim 86, wherein at least some of the frames include null symbols so that each frame includes a predetermined number of symbols irrespective of the amount of data in the frame.

99. A method, as claimed in claim 86, wherein said header symbols comprise:

frame marker symbols for delineating said data frames and for resolving modulation ambiguity;

non-repeating frame number symbols indicating frame numbers of said data frames which do not repeat over the expected life of said satellite; and

frame type symbols indicating different types of said data frames.

100. A method, as claimed in claim 86, wherein said frame type comprises an indicator of the inner code being used in the frame.

101. A method, as claimed in claim 99, wherein said frame marker symbols enable tracking by correlation with a known pattern of such marker symbols.

102. A method, as claimed in claim 99, wherein said frame type symbols comprise redundant and error control coding.

103. A method, as claimed in claim 86, wherein said frame bodies comprise inner code blocks and outer code blocks and wherein said inner code blocks are partitioned into two separate independently decodable quadrature components.

104. A method, as claimed in claim 103, wherein said inner code blocks are modulated with quaternary phase shift keying (QPSK).

105. A method, as claimed in claim 103, wherein said inner code blocks are convolutionally coded.

106. A method, as claimed in claim 86, wherein said predetermined frequency range divided by said predetermined transmission rate is in the range of 1.2 to 1.3.

107. A method, as claimed in claim 86, wherein the correction code comprises an inner code and wherein at least some of the frames include flush bits and wherein the step of decoding comprises the step of decoding by the flush bits.

108. A method, as claimed in claim 107, wherein said inner code defines an inner code rate of substantially 3/8 or 6/8.

109. A method, as claimed in claim 86, wherein the correction code comprises an outer code, wherein at least some of the frame bodies include blocks of the outer code and wherein the blocks including outer code are interleaved.

110. A method, as claimed in claim 109, wherein the interleaved code blocks comprise three or six outer code blocks depending on whether the coding is light or heavy.

111. A method, as claimed in claim 86, wherein the predetermined number of data cells is four.

112. A method, as claimed in claim 86, wherein the frame bodies bear four times K ATM cells and comprises K code words where K=3 or 6.

113. A method of generating radio waves for use in the down link of a processing communication satellite, comprising:

generating said radio waves in one or more beams having one or more forms of polarization and a predetermined form of modulation, a first group of said beams being limited to a single form of said one or more forms of polarization;

generating said radio waves to represent a plurality of frequency bands having a predetermined frequency range and having a predetermined transmission rate definable in megasymbols per second, the ratio of the predetermined frequency range to the predetermined transmission rate being in the range of 1.2 to 1.3;

generating said radio waves to represent serial TDM streams of data frames, at least some of said streams being used with said first group of beams, said data frames comprising a predetermined number of symbols defining frame bodies with trailer symbols and with header symbols defining frame marker symbols for delineating said data frames and for resolving modulation ambiguity, non-repeating frame number symbols indicating frame numbers of said data frames which do not repeat over the expected life of said satellite and frame type symbols indicating different types of said data frames, said frame bodies comprising inner code blocks and outer code blocks wherein said inner code blocks are convolutionally coded and partitioned into two separate independently decodable quadrature components modulated by square-root raised cosine pulse shaping on quaternary phase shift keying; and

generating said radio waves to represent a predetermined number of data cells with a predetermined error correction code grouped within said data frames.

114. A method, as claimed in claim 113, wherein said frame type symbols comprise an indicator of the inner code being used in the frame.

115. A method, as claimed in claim 113, wherein the transmission rate of at least some of the bands is 90-100 megasymbols per second.

116. A method, as claimed in claim 113, wherein the frequency range of at least some of the bands is substantially 125 MHz.

117. A method, as claimed in claim 113, wherein said one or more forms of polarization comprise at least two different forms of polarization.

118. A method, as claimed in claim 113, wherein the forms of polarization comprise forms of polarization selected from the group consisting of right hand circular polarization, left hand circular polarization and both right hand and left hand circular polarization.

119. A method, as claimed in claim 113, wherein the one or more beams comprises a plurality of beams suitable for transmission to a plurality of earth locations using at least some of the same carrier frequencies so that the carrier frequencies may be reused spatially by the satellite.

120. A method, as claimed in claim 113, wherein said beams define a cluster configuration in which each cluster includes the predetermined number of bands and each band occupies a different portion of the available spectrum of frequencies.

121. A method, as claimed in claim 120, wherein the predetermined number of bands is four.

122. A method, as claimed in claim 113, wherein the bands have at least two different polarizations.

123. A method, as claimed in claim 113, wherein the inner code blocks and outer code blocks are interleaved.

124. A method, as claimed in claim 113, wherein at least some of the frame bodies bear four times K ATM cells and comprises K code words where K=3 or 6.

125. A method, as claimed in claim 113, wherein said inner code defines an inner code rate of substantially 3/8 or 6/8.

126. A method, as claimed in claim 113, wherein the blocks including outer code comprise three or six outer code blocks depending on whether the coding is light or heavy.

127. A method, as claimed in claim 113, wherein the predetermined number of data cells is four.

128. A method, as claimed in claim 113, wherein the predetermined error correction code comprises Reed-Solomon code.