Method and apparatus for controlling transmission power while in soft handoff

• US 8,285,318 B2
• Filed: 10/18/2004
• Issued: 10/09/2012
• Est. Priority Date: 12/03/1998
• Status: Expired due to Fees

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Chen, Tao, Holtzman, Jack M., Razoumov, Leonid, Patel, Shimman, Saints, Keith, Tiedemann, Edward G. Jr.
• Primary Examiner(s): NGUYEN, HAI V
• Application Number:
  US10/968,788
• Publication Number:
  US 20050054366A1
• Time in Patent Office: 2,913 Days
• Field of Search: 455/552, 455/522
• US Class Current: 455/522
• CPC Class Codes: H04W 52/12 Outer and inner loops
• CPC Class Codes: H04W 52/362 Aspects of the step size
• CPC Class Codes: H04W 52/40 during macro-diversity or soft handoff

Abstract

Method and apparatus for adjusting the transmission power of base stations in simultaneous communication with a mobile station. The methods described provide for the transmission power of the base stations to be aligned. In the first exemplary embodiment, the transmitters are attached to a separate control unit through communication links. The control unit then derives the most likely command stream and send that to the base stations. In the second exemplary embodiment, the control unit periodically receives the final or average transmit level in a period and an aggregate quality measure for the feedback during a period from each of the transmitters. The control unit determines the aligned power level and transmits a message indicative of the aligned power level to the transmitters.

Claims

1. A method comprising:

receiving a first transmission power message for determining a power level of a transmission of a forward link signal between a mobile station and a first base station;

receiving a second transmission power message for determining a power level of transmission of a redundant version of said forward link signal between said mobile station and a second base station;

generating an aligned power control command based, at least in part, on said first and second transmission power messages, and first and second indications of quality of one or more reverse link signals received from said mobile station by said first and second base stations, respectively; and

sending said aligned power control command to said first base station and sending said aligned power control command to said second base station, wherein said aligned power control command is for producing correlating patterns of power control adjustments at said first base station for transmissions of said forward link signal from said first base station to said mobile station, and at said second base station for transmissions of said redundant version of said forward link signal from said second base station to said mobile station.

2. The method of claim 1, wherein said first transmission power message is based, at least in part, on a first estimation of a power control command sent by said mobile station, and said second transmission power message is based, at least in part, on a second estimation of said power control command sent by said mobile station.

3. The method of claim 1, wherein said first transmission power message indicates said power level of said transmission of said forward link signal between said mobile station and said first base station.

4. The method of claim 1, wherein at least one of said first or second transmission power messages is based, at least in part, on a reverse link quality metric accumulated over a predetermined period of time.

5. The method of claim 1, wherein said aligned power control command produces no change in power for transmissions of said forward link signal from said first base station to said mobile station in response to a signal to noise ratio of feedback received over a reverse link from said mobile station being below a threshold.

6. The method of claim 1, further comprising:

generating said aligned power control command based further, at least partially, on a weighted average based, at least partially, on a strength of a reverse link pilot signal received at said first and second base stations identified in said first and second transmission power messages, respectively.

7. An apparatus comprising:

means for determining a power level of a transmission of a forward link signal between a mobile station and a first base station based, at least in part, on a first transmission power message;

means for determining a power level of transmission of a redundant version of said forward link signal between said mobile station and a second base station based, at least in part, on a second transmission power message; and

means for generating an aligned power control command based, at least in part, on said first and second transmission power messages, and first and second indications of quality of one or more reverse link signals received from said mobile station by said first and second base stations, respectively;

means for sending said aligned power control command to said first base station; and

means for sending said aligned power control command to said second base station, wherein said aligned power control command is for producing correlating patterns of power control adjustment at said first base station for transmissions of said forward link signal from said first base station to said mobile station, and at said second base station for transmissions of said redundant version of said forward link signal from said second base station to said mobile station.

8. The apparatus of claim 7, wherein said first transmission power message is based, at least in part, on a first estimation of a power control command sent by said mobile station, and said second transmission power message is based, at least in part, on a second estimation of said power control command sent by said mobile station.

9. The apparatus of claim 7, wherein said first transmission power message indicates said power level of said transmission of said forward link signal between said mobile station and said first base station.

10. The apparatus of claim 7, wherein at least one of said first or second transmission power messages is based, at least in part, on a reverse link quality metric accumulated over a predetermined period of time.

11. The apparatus of claim 7, wherein said aligned power control command produces no change in power for transmissions of said forward link signal from said first base station to said mobile station in response to a signal to noise ratio of feedback received over a reverse link from said mobile station being below a threshold.

12. The apparatus of claim 7, further comprising means for generating said aligned power control command based further, at least partially, on a weighted average based, at least partially, on a strength of a reverse link pilot signal received at said first and second base stations identified in said first and second transmission power messages, respectively.

13. The apparatus of claim 7, wherein said means for generating said aligned power control command operates selectively based, at least in part, on a determination that a transmit power of said first base station and a transmit power of said second base station have diverged beyond a threshold.

14. An apparatus comprising:

a receiver to receive a first transmission power message for determining a power level of a transmission of a forward link signal between a first base station and a mobile station, and a second transmission power message for determining a power level of transmission of a redundant version of said forward link signal between said mobile station and a second base station;

a processor to generate an aligned power control command based, at least in part, on said first and second transmission power messages, and first and second indications of quality of one or more reverse link signals received from said mobile station by said first and second base stations, respectively, and wherein said aligned power control command is for producing correlating patterns of power control adjustments at said first base station for transmissions of said forward link signal from said first base station to said mobile station, and at said second base station for transmissions of said redundant version of said forward link signal from said second base station to said mobile station; and

a transmitter to send said aligned power control command to said first base station and said second base station.

15. The apparatus of claim 14, wherein said first transmission power message is based, at least in part, on a first estimation of a power control command sent by said mobile station, and said second transmission power message is based, at least in part, on a second estimation of said power control command sent by said mobile station.

16. The apparatus of claim 14, wherein said first transmission power message indicates said power level of said transmission of said forward link signal between said mobile station and said first base station.

17. The apparatus of claim 14, wherein said processor to selectively generate said aligned power control command in response to a determination that a transmit power of said first base station and a transmit power of said second base station have diverged beyond a threshold.

18. The apparatus of claim 14, wherein at least one of said first or second transmission power messages is based, at least in part, on a reverse link quality metric accumulated over a predetermined period of time.

19. The apparatus of claim 14, wherein said aligned power control command produces no change in power for transmissions of said forward link signal from said first base station to said mobile station in response to a signal to noise ratio of feedback received over a reverse link from said mobile station being below a threshold.

20. The apparatus of claim 14, wherein said processor to generate said aligned power control command based further, at least partially, on a weighted average based, at least partially, on a strength of a reverse link pilot signal received at said first and second base stations identified in said first and second transmission power messages, respectively.

21. The apparatus of claim 14, wherein said apparatus comprises a base station controller.

22. A method comprising:

transmitting a first transmission power message for determining a power level of a transmission of a forward link signal between a mobile station and a first base station;

receiving an aligned power control command, said aligned power control command being based, at least in part, on said first transmission power message, a second transmission power message for determining a power level of transmission of a redundant version of said forward link signal between said mobile station and a second base station, and first and second indications of quality of one or more reverse link signals received from said mobile station by said first and second base stations, respectively; and

in response to said aligned power control command, affecting a power control adjustment for transmissions of said forward link signal from said first base station to said mobile station, wherein said aligned power control command is for producing correlating patterns of power control adjustments at said first base station for transmissions of said forward link signal from said first base station to said mobile station, and at said second base station for transmissions of said redundant version of said forward link signal from said second base station to said mobile station.

23. The method of claim 22, wherein said first transmission power message is based, at least in part, on a first estimation of a power control command sent by said mobile station, and said second transmission power message is based, at least in part, on a second estimation of said power control command sent by said mobile station.

24. The method of claim 22, wherein said first transmission power message indicates said power level of said transmission of said forward link signal between said mobile station and said first base station.

25. The method of claim 22, wherein said aligned power control command is based, at least in part, on a determination that a transmit power of said first base station and a transmit power of said second base station have diverged beyond a threshold.

26. The method of claim 22, wherein at least one of said first or second transmission power messages is based, at least in part, on a reverse link quality metric accumulated over a predetermined period of time.

27. The method of claim 22, wherein said aligned power control command produces no change in power for transmissions of said forward link signal from said first base station to said mobile station in response to a signal to noise ratio of feedback received over a reverse link from said mobile station being below a threshold.

28. The method of claim 22, wherein said aligned power control command is based, at least in partially, on a weighted average based, at least partially, on a strength of a reverse link pilot signal received at said first and second base stations identified in said first and second transmission power messages, respectively.

29. An apparatus for use in a first base station comprising:

means for transmitting a first transmission power message for determining a power level of a transmission of a forward link signal between a mobile station and said first base station;

means for receiving an aligned power control command, said aligned power control command being based, at least in part, on said first transmission power message, a second transmission power message for determining a power level of transmission of a redundant version of said forward link signal between said mobile station and a second base station, and first and second indications of quality of one or more reverse link signals received from said mobile station by said first and second base stations, respectively; and

means for affecting a power control adjustment for transmissions of said forward link signal from said first base station to said mobile station in response to said aligned power control command, and wherein said aligned power control command is for producing correlating patterns of power control adjustments at said first base station for transmissions of said forward link signal from said first base station to said mobile station, and at said second base station for transmissions of said redundant version of said forward link signal from said second base station to said mobile station.

30. The apparatus of claim 29, wherein said first transmission power message is based, at least in part, on a first estimation of a power control command sent by said mobile station, and said second transmission power message is based, at least in part, on a second estimation of said power control command sent by said mobile station.

31. The apparatus of claim 29, wherein said first transmission power message indicates said power level of said transmission of said forward link signal between said mobile station and said first base station.

32. The apparatus of claim 29, wherein said aligned power control command is based, at least in part, on a determination that a transmit power of said first base station and a transmit power of said second base station have diverged beyond a threshold.

33. The apparatus of claim 29, wherein at least one of said first or second transmission power messages is based, at least in part, on a reverse link quality metric accumulated over a predetermined period of time.

34. The apparatus of claim 29, wherein said aligned power control command produces no change in power for transmissions of said forward link signal from said first base station to said mobile station when a signal to noise ratio of feedback received over a reverse link from said mobile station is below a threshold.

35. The apparatus of claim 29, wherein said aligned power control command is based, at least in partially, on a weighted average based, at least partially, on a strength of a reverse link pilot signal received at said first and second base stations identified in said first and second transmission power messages, respectively.

36. An apparatus for use in a first base station, the apparatus comprising:

a transceiver to;

transmit a first transmission power message to a base station controller, said first transmission power message for determining a power level of a transmission of a forward link signal between a mobile station and said first base station, and receive an aligned power control command from said base station controller, said aligned power control command being based, at least in part, on said first transmission power message, a second transmission power message for determining a power level of transmission of a redundant version of said forward link signal between said mobile station and a second base station, and first and second indications of quality of one or more reverse link signals received from said mobile station by said first and second base stations, respectively; and

a processor to affect a power control adjustment for transmissions of said forward link signal from said first base station to said mobile station in response to said aligned power control command, and wherein said aligned power control command is for producing correlating patterns of power control adjustments at said first base station for transmissions of said forward link signal from said first base station to said mobile station, and at said second base station for transmissions of said redundant version of said forward link signal from said second base station to said mobile station.

37. The apparatus of claim 36, wherein said first transmission power message is based, at least in part, on a first estimation of a power control command sent by said mobile station, and said second transmission power message is based, at least in part, on a second estimation of said power control command sent by said mobile station.

38. The apparatus of claim 36, wherein said first transmission power message indicates said power level of said transmission of said forward link signal between said mobile station and said first base station.

39. The apparatus of claim 36, wherein said aligned power control command is based, at least in part, on a determination that a transmit power of said first base station and a transmit power of said second base station have diverged beyond a threshold.

40. The apparatus of claim 36, wherein at least one of said first or second transmission power messages is based, at least in part, on a reverse link quality metric accumulated over a predetermined period of time.

41. The apparatus of claim 36, wherein said aligned power control command produces no change in power for transmissions of said forward link signal from said first base station to said mobile station in response to a signal to noise ratio of feedback received over a reverse link from said mobile station being below a threshold.

42. The apparatus of claim 36, wherein said aligned power control command is based, at least in partially, on a weighted average based, at least partially, on a strength of a reverse link pilot signal received at said first and second base stations identified in said first and second transmission power messages, respectively.