End-to-end transmission techniques for a processing satellite system

• US 6,366,776 B1
• Filed: 09/29/1999
• Issued: 04/02/2002
• 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: Wright, David A., Linsky, Stuart T., Jue, Reginald, Nivens, Dennis A.
• Primary Examiner(s): Maung, Nay
• Assistant Examiner(s): Vuong, Quochien B.
• Application Number:
  US09/408,225
• Time in Patent Office: 916 Days
• Field of Search: 455/427, 455/12.1, 455/13.1, 455/13.2, 455/13.4, 455/522, 455/38.3, 455/422, 370/336, 370/337, 370/347, 370/442, 370/445, 342/352, 342/353, 342/354, 342/356, 342/358
• US Class Current: 455/427
• CPC Class Codes: H04B 7/18513 Transmission in a satellite or space-based system

Abstract

Coordination of processing satellite uplink transmission and downlink transmission is achieved by an uplink encoder (418) and uplink modulator (420) which incorporate an adjustable IF amplifier (417) at a ground terminal (400). Information about data traffic transmission errors detected in a satellite (100) is formed into ATM traffic report cells by a cell former (157). The traffic report cells are sent on the downlink to the ground terminal. The traffic report cells are used to adjust the power level of the IF amplifier for the particular channel and slot for which errors were detected.

Claims

1. In a processing satellite communication system comprising an uplink for transmitting uplink data cells on an uplink beam from a ground terminal to said satellite and a downlink for transmitting downlink data cells on a downlink beam from the satellite to a ground terminal, apparatus for controlling the transmission of said uplink data cells comprising in combination:

an encoder arranged to group said uplink data cells with an error correction code and for locating said uplink data cells in predetermined uplink time slots within uplink frames comprising said uplink data cells;

a modulator connected to modulate said uplink frames by a predetermined form of modulation to enable placement of the modulated uplink frames into a plurality of uplink channels suitable for transmission to said satellite on said uplink beam, said uplink channels comprising a plurality of said uplink time slots;

an adjustable amplifier arranged to adjust the power level at which said uplink beam may be transmitted to said satellite;

a demodulator suitable for use in said satellite arranged to demodulate said channels into demodulated uplink frames;

a decoder arranged to decode said error correction code, to detect errors in said correction code and to make at least an error estimate of errors in said correction code;

a cell former arranged to form report cells comprising error information in response to said error estimate, addresses identifying destinations and identifiers indicating that said report cells contain said error information;

a frame organizer arranged to generate downlink frames comprising said report cells for transmission on said downlink beam; and

a processor responsive to said downlink beam arranged to unpack said report cells from said downlink frames and to adjust said amplifier based on said error information in said report cells.

2. Apparatus, as claimed in claim 1, wherein said error estimate comprises an indication of a relationship between the number of errors in said error estimate and a threshold number of errors.

3. Apparatus, as claimed in claim 1, wherein said error information comprises a plurality of error bits, each error bit corresponding to one of said time slots of one of said channels.

4. Apparatus, as claimed in claim 3, wherein said report cells maintain said error bits in an order so that the time slots corresponding to said error bits can be determined.

5. Apparatus, as claimed in claim 1, wherein said report cells comprise ATM cells.

6. Apparatus, as claimed in claim 1, wherein said processor is capable of adjusting the amplifier separately for each of said time slots based on said error information.

7. Apparatus, as claimed in claim 6, wherein said error information comprises a plurality of error bits, each error bit corresponding to one of said time slots, and wherein said processor determines the time slot corresponding to said error bits in order to adjust said amplifier.

8. Apparatus, as claimed in claim 1, and further comprising a reference oscillator and wherein said uplink data cells comprise uplink symbols transmitted on said uplink beam at a first frequency, wherein said report cells comprise downlink symbols transmitted on said downlink beam at a second frequency, wherein said processor comprises a downlink symbol clock derived from said reference oscillator arranged to clock said downlink symbols at said second frequency, and wherein said modulator comprises an uplink symbol clock derived from said reference oscillator arranged to clock said uplink symbols at said first frequency which is an integer multiple of said second frequency.

9. Apparatus, as claimed in claim 8, wherein said downlink frames comprise frame markers and wherein the timing of said reference oscillator, said downlink symbol clock and said uplink symbol clock are varied depending on the times of arrival of said frame markers at said processor.

10. Apparatus, as claimed in claim 9, wherein the frequency of said reference oscillator and the phase of said downlink symbol clock and said uplink symbol clock are varied depending on the times of arrival of said frame marker at said processor.

11. Apparatus, as claimed in claim 1, wherein said encoder, modulator, amplifier and processor are located at one or more of said ground terminals and wherein said demodulator, decoder, cell former and frame organizer are located at said satellite.

12. Apparatus, as claimed in claim 1, wherein said apparatus further comprises a switch located in said satellite, wherein said downlink beam comprises a plurality of downlink beams, wherein said frame organizer comprises a plurality of frame organizers corresponding to said downlink beams, wherein said cell former is arranged to form downlink data cells in response to said uplink data cells, said downlink data cells comprising addresses identifying destinations, and is arranged to transmit said downlink data cells and said report cells to said switch, and wherein said switch directs said downlink data cells and said report cells to said frame organizers corresponding to said downlink beams based on said addresses, whereby said data cells arriving on said uplink beam can be directed to any of said downlink beams through the response of said switch to said addresses.

13. In a processing satellite communication system comprising an uplink for transmitting uplink data cells on an uplink beam from a ground terminal to said satellite and a downlink for transmitting downlink data cells on a downlink beam from the satellite to a ground terminal, a method of controlling the transmission of said uplink data cells comprising in combination:

grouping said uplink data cells with an error correction code;

locating said uplink data cells in predetermined uplink time slots within uplink frames comprising said uplink data cells;

modulating said uplink frames by a predetermined form of modulation to enable placement of the modulated uplink frames into a plurality of uplink channels suitable for transmission to said satellite on said uplink beam with an adjustable power level, said uplink channels comprising a plurality of said uplink time slots;

demodulating said channels into demodulated uplink frames;

decoding said error correction code, to detect errors in said correction code and to make at least an error estimate of errors in said correction code;

forming report cells comprising error information in response to said error estimate, addresses identifying destinations and identifiers indicating that said report cells contain said error information;

generating downlink frames comprising said report cells for transmission on said downlink beam;

unpacking said report cells from said downlink frames; and

adjusting said power level based on said error information in said report cells.

14. A method, as claimed in claim 13, wherein said error estimate comprises an indication of a relationship between the number of errors in said error estimate and a threshold number of errors.

15. A method, as claimed in claim 13, wherein said error information comprises a plurality of error bits, each error bit corresponding to one of said time slots of one of said channels.

16. A method, as claimed in claim 13, wherein said report cells maintain said error bits in an order so that the time slots corresponding to said error bits can be determined.

17. A method, as claimed in claim 13, wherein said report cells comprise ATM cells.

18. A method, as claimed in claim 13, wherein said adjusting comprises adjusting said power level separately for each of said time slots based on said error information.

19. A method, as claimed in claim 18, wherein said error information comprises a plurality of error bits, each error bit corresponding to one of said time slots, and wherein said unpacking determines the time slot corresponding to said error bits in order to adjust said power level.

20. A method, as claimed in claim 13, wherein said uplink data cells comprise uplink symbols transmitted on said uplink beam at a first frequency, wherein said report cells comprise downlink symbols transmitted on said downlink beam at a second frequency, and further comprising generating reference clock pulses, generating downlink symbol clock pulses derived from said reference pulses, clocking said downlink symbols with said downlink symbol clock pulses at said second frequency, generating uplink symbol clock pulses derived from said reference oscillator arranged to clock said uplink symbols at said first frequency which is an integer multiple of said second frequency.

21. A method, as claimed in claim 20, wherein said downlink frames comprise frame markers and wherein the timing of said reference pulses, said downlink symbol clock pulses and said uplink symbol clock pulses are varied depending on the times of arrival of said frame markers at said ground terminal.

22. A method, as claimed in claim 21, wherein the frequency of said reference pulses and the phase of said downlink symbol clock pulses and said uplink symbol clock pulses are varied depending on the times of arrival of said frame marker at said ground terminal.

23. A method, as claimed in claim 13, wherein said grouping, locating, modulating, unpacking and adjusting occur at one or more of said ground terminals and wherein said demodulating, decoding, forming and generating occur at said satellite.

24. A method, as claimed in claim 13, wherein said downlink beam comprises a plurality of downlink beams, wherein said forming report cells further comprises forming downlink data cells comprising addresses identifying destinations in response to said uplink data cells, wherein said generating downlink frames comprises generating downlink frames comprising said downlink data cells and report cells for transmission by one of said downlink beams based on said addresses, whereby said data cells arriving on said uplink beam can be directed to any of said downlink beams through the use of said addresses.

25. In a processing satellite communication system comprising an uplink for transmitting uplink data cells on an uplink beam from a ground terminal to said satellite and a downlink for transmitting downlink data cells on a downlink beam from the satellite to a ground terminal, apparatus for controlling the transmission of said uplink data cells data comprising in combination:

an uplink frame organizer arranged to locate burst signals in predetermined time slots within uplink frames comprising said uplink data cells;

an uplink unit arranged to launch said uplink frames at a predetermined adjustable time so as to place the uplink frames into a plurality of uplink channels suitable for transmission to said satellite on said uplink beam, said uplink channels comprising a plurality of said time slots;

an adjustable amplifier arranged to adjust the power level at which said uplink beam may be transmitted to said satellite;

a demodulator suitable for use in said satellite arranged to demodulate said channels into demodulated uplink frames;

an uplink processor responsive to said uplink beam arranged to make at least an estimate of the received energy of said burst signals or the time of arrival of said burst signals at said satellite;

a cell former arranged to form report cells comprising report information in response to said estimate of the received energy of said burst signal or the time of arrival of said burst signal at said satellite, addresses identifying destinations and identifiers indicating that said report cells contain said report information;

a downlink frame organizer arranged to generate downlink frames comprising said report cells for transmission on said downlink beam; and

a downlink processor responsive to said downlink beam arranged to unpack said report cells from said downlink frames, to adjust said amplifier based on said report information in said report cells in response to said estimate of the received energy of said burst signal or to adjust said adjustable time based on said report information in said report cells in response to said the time of arrival of said burst signals at said satellite.

26. Apparatus, as claimed in claim 25, wherein said downlink processor adjusts said amplifier for all said uplink channels.

27. Apparatus, as claimed in claim 25, wherein said downlink processor adjusts said adjustable time for all said uplink channels.

28. Apparatus, as claimed in claim 25, wherein said cell former forms report cells including report information in response to said estimate of the received energy of said burst signal and the time of arrival of said burst signal at said satellite, and wherein said downlink processor adjusts said amplifier based on said report information in said report cells in response to said estimate of the received energy of said burst signal and adjusts said adjustable time based on said report information in said report cells in response to said the time of arrival of said burst signals at said satellite.

29. Apparatus, as claimed in claim 25, wherein said error information comprises groups of bits, each group of bits corresponding to one of said time slots.

30. Apparatus, as claimed in claim 29, wherein said report cells maintain said groups of bits in an order so that the time slots corresponding to said groups of bits can be determined.

31. Apparatus, as claimed in claim 25, wherein said report cells comprise ATM cells.

32. Apparatus, as claimed in claim 25, wherein said uplink frame organizer, uplink unit, amplifier and downlink processor are located at one or more of said ground terminals and wherein said demodulator, uplink processor, cell former and downlink frame organizer are located at said satellite.

33. In a processing satellite communication system comprising an uplink for transmitting uplink data cells on an uplink beam from a ground terminal to said satellite and a downlink for transmitting downlink data cells on a downlink beam from the satellite to a ground terminal, a method of controlling the transmission of said uplink data cells data comprising in combination:

locating burst signals in predetermined time slots within uplink frames comprising said uplink data cells;

launching said uplink frames at a predetermined adjustable time so as to place the uplink frames into a plurality of uplink channels suitable for transmission to said satellite on said uplink beam at an adjustable power level, said uplink channels comprising a plurality of said time slots;

demodulating said channels into demodulated uplink frames;

making at least an estimate of the received energy of said burst signals or the time of arrival of said burst signals at said satellite;

forming report cells comprising report information in response to said estimate of the received energy of said burst signal or the time of arrival of said burst signal at said satellite, addresses identifying destinations and identifiers indicating that said report cells contain said report information;

generating downlink frames comprising said report cells for transmission on said downlink beam; and

unpacking said report cells from said downlink frames; and

adjusting said power level based on said report information in said report cells in response to said estimate of the received energy of said burst signal or said adjustable time based on said report information in said report cells in response to said the time of arrival of said burst signals at said satellite.

34. A method, as claimed in claim 33, wherein said adjusting said power level comprises adjusting said power level for all said uplink channels.

35. A method, as claimed in claim 33, wherein said adjusting said adjustable time comprises adjusting said adjustable time for all said uplink channels.

36. A method, as claimed in claim 33, wherein said forming forms report cells including report information in response to said estimate of the received energy of said burst signal and the time of arrival of said burst signal at said satellite, and wherein said adjusting said power level is based on said report information in said report cells in response to said estimate of the received energy of said burst signal and said adjusting said adjustable time is based on said report information in said report cells in response to said the time of arrival of said burst signals at said satellite.

37. A method, as claimed in claim 33, wherein said error information comprises groups of bits, each group of bits corresponding to one of said time slots.

38. A method, as claimed in claim 37, wherein said report cells maintain said groups of bits in an order so that the time slots corresponding to said groups of bits can be determined.

39. A method, as claimed in claim 33, wherein said report cells comprise ATM cells.

40. A method, as claimed in claim 33, wherein said locating, launching, unpacking and adjusting occur at one or more of said ground terminals and wherein said demodulating, making, forming and generating occur at said satellite.