Method and apparatus for predictive parameter control with loop delay

• US 6,147,981 A
• Filed: 08/07/1997
• Issued: 11/14/2000
• Est. Priority Date: 08/07/1997
• Status: Expired due to Term

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Prescott, Tobin A.
• Primary Examiner(s): Vu, Huy D.
• Assistant Examiner(s): PHAN, MAN U
• Application Number:
  US08/908,525
• Time in Patent Office: 1,195 Days
• Field of Search: 370/318, 370/320, 370/335, 370/342, 370/331, 370/332, 370/333, 375/200, 375/205, 455/13.4, 455/522, 455/69, 455/126, 455/67
• US Class Current: 370/318
• CPC Class Codes: H04W 52/24 using SIR [Signal to Interference Ratio] or other wireless path parameters

Abstract

A method and apparatus for controlling a power level of a transmitted signal sent from a second station to a first station in a communication system maintains a desired power level of a signal received at the first station. The first station sends a power control command to the second station directing the second station to either increase or decrease the power level of the transmitted signal. The first station generates the power control command based on the power level of the received signal, the desired power level, and at least one pending power control command. Pending power control commands include those power control commands that are propagating between the first station and the second station.

Claims

1. A method for controlling a power level of a signal in a communication system a having a first station, a second station, and a satellite link coupling the first station and the second station, the communication system having a significant propagation delay between the first station and the second station, the method comprising the steps of:

measuring a received power level of the signal, wherein the signal is transmitted from the second station to the first station via the satellite link;

generating a power control command at the first station; and

sending said power control command from the first station to the second station,

wherein said step of generating a power control command generates said power control command as a function of said received power level, a desired power level, and at least one previous power control command sent from the first station to the second station.

2. The method of claim 1, wherein said step of generating a power control command generates said power control command as a function of said received power level, said desired power level, and at least one previous power control command sent from the first station to the second station that has not been received by the second station.

3. The method of claim 1, further comprising the step of:

receiving, at the second station, said power control command from the first station.

4. The method of claim 1, wherein said step of generating a power control command generates said power control command as a function of said received power level, said desired power level, and at least one previous power control command, sent from the first station to the second station, that has been received by the second station.

5. The method of claim 3, further comprising the step of:

adjusting a transmitted power level of the signal in response to said power control command to produce an adjusted signal at the second station.

6. The method of claim 5, wherein said step of generating a power control command generates said power control command as a function of said received power level, said desired power level, and at least one previous power control command, sent from the first station to the second station, that has not produced said adjusted signal at the second station.

7. The method of claim 5, further comprising the step of:

transmitting said adjusted signal from the second station to the first station.

8. The method of claim 7, wherein said step of generating a power control command generates said power control command as a function of said received power level, said desired power level, and at least one previous power control command, sent from the first station to the second station, that has produced said adjusted signal that has not been received by the first station.

9. The method of claim 5, wherein said step of adjusting comprises the step of:

adjusting said transmitted power level by a fixed amount in response to said power control command.

10. The method of claim 5, wherein said step of adjusting comprises the steps of:

increasing said transmitted power level by a first fixed amount in response to a power control command that directs the second station to increase said transmitted power level; and

decreasing said transmitted power level by a second fixed amount in response to a power control command that directs the second station to decrease said transmitted power level.

11. The method of claim 10, wherein said first fixed amount and said second fixed amount are equal.

12. A system for controlling a power level of a signal in a satellite communications system having a first station, a second station, and a satellite link coupling the first station and the second station, the system comprising:

means for measuring a received power level of the signal, wherein the signal is transmitted from the second station and received by the first station;

means for generating a power control command at the first station; and

means for sending said power control command from the first station to the second station,

wherein said means for generating a power control command generates said power control command as a function of said received power level, a desired power level, and at least one previous power control command sent from the first station to the second station.

13. The system of claim 12 wherein said means for generating a power control command generates said power control command as a function of said received power level, said desired power level, and at least one previous power control command, sent from the first station to the second station, that has not been received by the second station.

14. The system of claim 12 further comprising:

means for receiving, at the second station, said power control command from the first station.

15. The system of claim 12, wherein said means for generating a power control command generates said power control command as a function of said received power level, said desired power level, and at least one previous power control command, sent from the first station to the second station, that has been received by the second station.

16. The system of claim 14, further comprising:

means for adjusting a transmitted power level of the signal in response to said power control command to produce an adjusted signal at the second station.

17. The system of claim 16, wherein said means for generating a power control command generates said power control command as a function of said received power level, said desired power level, and at least one previous power control command, sent from the first station to the second station, that has not produced said adjusted signal at the second station.

18. The system of claim 16, further comprising:

means for transmitting said adjusted signal from the second station to the first station.

19. The system of claim 18, wherein said means for generating a power control command generates said power control command as a function of said received power level, said desired power level, and at least one previous power control command, sent from the first station to the second station, that has produced said adjusted signal that has not been received by the first station.

20. The system of claim 16, wherein said means for adjusting comprises:

means for adjusting said transmitted power level by a fixed amount in response to said power control command.

21. The system of claim 16, wherein said means for adjusting comprises:

means for increasing said transmitted power level by a first fixed amount in response to a power control command that directs the second station to increase said transmitted power level; and

means for decreasing said transmitted power level by a second fixed amount in response to a power control command that directs the second station to decrease said transmitted power level.

22. The system of claim 21, wherein said first fixed amount and said second fixed amount are equal.

23. An apparatus for controlling a power level of a transmitted signal in a satellite communications system having a first station, a second station, and a satellite link coupling the first station and the second station, wherein the transmitted signal experiences a propagation delay between the first station and the second station, the apparatus comprising:

a power level detector, located in the first station, for measuring a received power level of the signal transmitted from the second station to the first station;

a compensator, located at the first station, for generating a power control command that instructs the second station to adjust its transmit power; and

a transmitter for sending said power control command from the first station to the second station,

wherein said compensator generates a power control command as a function of said received power level, a desired power level, and at least one pending power control command sent from the first station to the second station.

24. The apparatus of claim 23, wherein said compensator comprises:

a pending command accumulator that accumulates pending power control commands sent from the first station to the second station; and

a comparator that compares said received power level adjusted by an output of said pending command accumulator with said desired power level to determine said power control command.

25. The apparatus of claim 24, wherein said pending command accumulator accumulates said pending power control commands, sent from the first station to the second station, that have not been received by the second station.

26. The apparatus of claim 24, wherein said pending command accumulator accumulates said pending power control commands, sent from the first station to the second station, that have not produced an adjusted signal sent from the second station.

27. The apparatus of claim 24, wherein said pending command accumulator accumulates said pending power control commands, sent from the first station to the second station, that have produced an adjusted signal sent from the second station to the first station that has not been received by the first station.

28. The apparatus of claim 24, wherein said pending command accumulator accumulates a number of pending power control commands, sent from the first station to the second station, based on the propagation delay and a loop iteration time associated with said compensator.

29. A method for controlling a parameter associated with a signal in a communication system a having a first station, a second station, and a satellite link coupling the first station and the second station, the communication system having a significant propagation delay between the first station and the second station, the method comprising the steps of:

measuring the parameter of the signal, wherein the signal is transmitted from the second station to the first station via the satellite link;

generating a control command at the first station; and

sending said control command from the first station to the second station,

wherein said step of generating a control command generates said control command as a function of said measured parameter, a desired level for the parameter, and at least one previous control command sent from the first station to the second station.

30. The method of claim 29, wherein said step of generating a control command generates said control command as a function of said measured parameter, said desired level for the parameter, and at least one previous control command, sent from the first station to the second station, that has not been received by the second station.

31. The method of claim 29, further comprising the step of:

receiving, at the second station, said control command from the first station.

32. The method of claim 29, wherein said step of generating a control command generates said control command as a function of said measured parameter, said desired level for the parameter, and at least one previous control command, sent from the first station to the second station, that has been received by the second station.

33. The method of claim 31, further comprising the step of:

adjusting the parameter of the signal in response to said control command to produce an adjusted signal at the second station.

34. The method of claim 33, wherein said step of generating a control command generates said control command as a function of said measured parameter, said desired level for the parameter, and at least one previous control command, sent from the first station to the second station, that has not produced said adjusted signal at the second station.

35. The method of claim 33, further comprising the step of:

transmitting said adjusted signal from the second station to the first station.

36. The method of claim 35, wherein said step of generating a control command generates said control command as a function of said measured parameter, said desired level for the parameter, and at least one previous control command, sent from the first station to the second station, that has produced said adjusted signal that has not been received by the first station.

37. The method of claim 33, wherein said step of adjusting comprises the step of:

adjusting a level of the parameter by a fixed amount in response to said control command.

38. The method of claim 33, wherein said step of adjusting comprises the steps of:

increasing a level of the parameter by a first fixed amount in response to a control command that directs the second station to increase said level of the parameter; and

decreasing said level of the parameter by a second fixed amount in response to a control command that directs the second station to decrease said level of the parameter.

39. The method of claim 38, wherein said first fixed amount and said second fixed amount are equal.

40. The method of claim 29, wherein the signal is a communication signal in a spread spectrum communication system.