Time-offset distribution to ensure constant satellite power

• US 6,721,538 B1
• Filed: 10/05/2000
• Issued: 04/13/2004
• Est. Priority Date: 10/05/2000
• Status: Expired due to Term

• Current Assignee: Hughes Network Systems LLC (Echostar Corporation)
• Original Assignee: Hughes Electronics Corporation (Rtx Corporation)
• Inventors: Sullivan, John, Roos, David, Parr, Michael
• Primary Examiner(s): Trost, William
• Assistant Examiner(s): EWART, JAMES D
• Application Number:
  US09/678,681
• Time in Patent Office: 1,286 Days
• Field of Search: 455/3.02, 455/12.1, 455/13.2, 455/13.4, 455/51.1, 455/98, 455/208, 455/427, 455/502, 455/522, 455/430, 370/100.1, 370/324, 370/350, 370/395.62, 370/503, 370/507
• US Class Current: 455/13.2
• CPC Class Codes: H04B 7/18517 Transmission equipment in earth stations

Abstract

An approach for minimizing variation in transmit power of synchronized signals that are destined to a satellite is disclosed. A gateway station system for communicating with a communication satellite includes a multiple signal sources which generate the synchronized signals. The gateway station system utilizes a control logic that is coupled to the signal sources. The control logic operates to offset selectively transmission times of a portion of the synchronized signals according to a predetermined distribution and an offset period. The predetermined distribution specifies about half the number of the synchronized signals are to be offset. The offset period is half a symbol period. The terminals within the satellite communication system has a receiver that receives the synchronized signal from the communication satellite. Each of the terminals also includes an offset-determination logic that is coupled to the receiver and determines whether the synchronized signals are offset based upon a received assignment message. The assignment message has a control flag field that indicates whether the received signal is offset.

Claims

1. A method of minimizing variation in transmit power in a satellite communication system, the method comprising:

generating a plurality of synchronized signals; and

minimizing the variation in the transmit power by selectively offsetting transmission times of a portion of the plurality of synchronized signals.

2. The method according to claim 1, wherein the selectively offsetting is performed according to a predetermined distribution and an offset period.

3. The method according to claim 2, wherein the predetermined distribution specifies about half the plurality of synchronized signals.

4. The method according to claim 2, wherein the offset period in the selectively offsetting is half a symbol period.

5. The method according to claim 4, wherein the symbol period is about 43 μ

s.

6. The method according to claim 1, wherein the selectively offsetting is performed by a control logic and the generating is performed by a plurality of signal sources corresponding to the synchronized signals.

7. The method according to claim 1, wherein the generating is performed by a plurality of modems.

8. The method according to claim 1, further comprising:

summing the plurality of synchronized signals;

upconverting the summed synchronized signals;

outputting an upconverted signal; and

amplifying the upconverted signal for transmission to a communication satellite.

9. The method according to claim 8, wherein the amplifying step is performed by a solid-state power amplifier.

10. The method according to claim 1, further comprising:

generating an assignment message having a control flag field, the assignment message corresponding to one of the plurality of synchronized signals; and

selectively setting the control flag field based upon determining whether to offset the one synchronized signal.

11. The method according to claim 10, wherein the assignment message in the step of generating the assignment message conforms with a GSM protocol.

12. The method of claim 1, wherein the minimizing the variation comprises selecting the transmission times to match a profile of an average power variation.

13. A gateway station system for communicating with a communication satellite, comprising:

a plurality of signal sources configured to generate synchronized signals; and

a control logic coupled to the plurality of signal sources and configured to minimize a power variation in transmission power by offsetting select transmission times of a portion of the synchronized signals.

14. The system according to claim 13, wherein the control logic offsets according to a predetermined distribution and an offset period.

15. The system according to claim 14, wherein the predetermined distribution specifies about half the number of the plurality of the synchronized signals.

16. The system according to claim 14, wherein the offset period is half a symbol period.

17. The system according to claim 16, wherein the symbol period is about 43 μ

s.

18. The system according to claim 13, wherein the plurality of signal sources are modems.

19. The system according to claim 13, further comprising:

a summing circuit coupled to the plurality of signal sources and configured to combine the synchronized signals;

an upconverter configured to receive the summed synchronized signals and to output an upconverted signal; and

an amplifier configured to amplify the upconverted signal for transmission to the communication satellite.

20. The system according to claim 19, wherein the amplifier is a solid-state power amplifier.

21. The system according to claim 13, wherein one of the plurality of signal sources generates an assignment message having a control flag field to specify whether a corresponding synchronized signal is offset.

22. The system according to claim 21, wherein the assignment message conforms with a GSM protocol.

23. The gateway station system of claim 13, wherein the control logic is configured to selectively offset the transmission times to match a profile of an average power variation.