Method and apparatus for adjusting power control setpoint in a wireless communication system

• US 6,763,244 B2
• Filed: 03/15/2001
• Issued: 07/13/2004
• Est. Priority Date: 03/15/2001
• Status: Expired due to Fees

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Wheatley, Charles E. III, Chen, Tao, Ling, Fuyun, Sindhushayana, Nagabhushana, Holtzman, Jack M., Saints, Keith
• Primary Examiner(s): Maung, Nay
• Assistant Examiner(s): SOBUTKA, PHILIP
• Application Number:
  US09/810,685
• Publication Number:
  US 20020165004A1
• Time in Patent Office: 1,216 Days
• Field of Search: 455/522, 455/69, 455/67.11, 455/115.1, 375/316, 375/317, 375/147
• US Class Current: 455/522
• CPC Class Codes: H04L 1/0051 Stopping criteria
• CPC Class Codes: H04L 1/0066 Parallel concatenated codes
• CPC Class Codes: H04L 1/208 involving signal re-encoding
• CPC Class Codes: H04W 52/12 Outer and inner loops
• CPC Class Codes: H04W 52/20 using error rate
• CPC Class Codes: H04W 52/36 with a discrete range or set of values, e.g. step size, ramping or offsets

Abstract

Techniques to adjust the setpoint of a power control loop in a wireless communication system. The setpoint may be adjusted based on frame status indicative of erased/good decoded frames, one or more (typically soft) metrics indicative of the confidence in the decoded results, power surplus/deficit indicative of the difference between the received signal quality and the setpoint, setpoint surplus/deficit indicative of the difference between the setpoint and a threshold E_b/N_t needed for the desired level of performance, or a combination thereof. The metrics may include re-encoded symbol error rate, re-encoded power metric, modified Yamamoto metric, minimum or average LLR among decoded bits, number of decoding iterations, and possibly others. The setpoint may be adjusted in different manners and/or by different amounts depending on the above-noted factors. The techniques may be employed for forward and/or reverse links in CDMA systems.

Claims

1. In a wireless communication system, a method for adjusting a power control loop setpoint of a received signal comprising:

decoding one or more received frames in accordance with a particular decoding scheme to provide one or more decoded frames;

obtaining one or more metrics, at least including one of a re-encoded power metric and a modified Yamamoto metric, for the one or more decoded frames; and

adjusting the setpoint based at least in part on the one or more metrics.

2. The method of claim 1, wherein each of the one or more metrics is indicative of confidence of the decoded frames based on a respective criteria.

3. The method of claim 1, wherein the re-encoded power metric is indicative of correlation between symbols in a received frame and symbols generated by re-encoding a decoded frame.

4. The method of claim 1, wherein the modified Yamamoto metric is indicative of confidence of the decoded frames based on a selected decoded frame and a next best possible decoded frame.

5. The method of claim 1, wherein the setpoint is increased if the one or more metrics indicate weak confidence of the decoded frames.

6. The method of claim 1, wherein the wireless communication system is a CDMA system that conforms to cdma2000 standard or W-CDMA standard, or both.

7. The method of claim 1, further comprising:

for each decoded frame, determining a power surplus or deficit indicative of the received signal quality for the frame being respectively greater than or less than the setpoint, and

wherein the setpoint is adjusted based in part on the determined power surplus or deficit.

8. The method of claim 7, further comprising:

for each decoded frame, determining a step size for adjusting the setpoint based at least in part on the one or more metrics and the power surplus or deficit, and

wherein the setpoint is adjusted based on the determined step size.

9. The method of claim 1, further comprising:

determining a setpoint surplus or deficit indicative of a difference between the setpoint and a threshold signal quality needed to achieve a particular level of performance, and

wherein the setpoint is adjusted based in part on the determined setpoint surplus or deficit.

10. The method of claim 9, further comprising:

for each decoded frame, determining a step size for adjusting the setpoint based at least in part on the one or more metrics and the setpoint surplus or deficit, and

wherein the setpoint is adjusted based on the determined step size.

11. The method of claim 1, further comprising:

for each decoded frame, determining a step size for adjusting the setpoint, and

wherein the setpoint is adjusted based on the determined step size.

12. The method of claim 11, wherein the step size is variable and dependent on values for the one or more metrics.

13. The method of claim 11, wherein the step size is determined based at least in part on the confidence of the decoded frames as indicated by the one or more metrics.

14. The method of claim 13, wherein the step size is increased if the one or more metrics indicate strong confidence of the decoded frames.

15. The method of claim 13, wherein the step size is decreased if the one or more metrics indicate weak confidence of the decoded frames.

16. In a wireless communication system, a method for adjusting a power control loop setpoint of a received signal comprising:

decoding one or more received frames in accordance with a particular decoding scheme to provide one or more decoded frames;

obtaining one or more metrics, at least including one of a re-encoded power metric and a modified Yamamoto metric, for the one or more decoded frames;

determining a power surplus or deficit indicative of the received signal being respectively greater than or less than the setpoint; and

adjusting the setpoint based at least in part on the one or more metrics and power surplus or deficit.

17. The method of claim 16, wherein the power surplus or deficit is determined for each received frame based on an averaged received signal quality for the frame and the setpoint for the frame.

18. The method of claim 16, further comprising:

for each decoded frame, determining a step size for adjusting the setpoint based at least in part on the determined status and power surplus or deficit, and

wherein the setpoint is adjusted based on the determined step size.

19. The method of claim 16, wherein the step size is scaled by a larger scaling factor if a received frame is correctly decoded and a power deficit exists for the frame.

20. The method of claim 16, wherein the step size is scaled by a smaller scaling factor if a received frame is correctly decoded and a power surplus exists for the frame.

21. The method of claim 16, wherein the step size is scaled by a larger scaling factor if a received frame is erased and a power surplus exists for the frame.

22. The method of claim 16, wherein the step size is scaled by a smaller scaling factor if a received frame is erased and a power deficit exists for the frame.

23. A power control unit for use in a wireless communication system, comprising:

a decoder configured to decode received frames in accordance with a particular decoding scheme to provide decoded frames;

a metric calculation unit configured to provide one or more metrics, at least including one of a re-encoded power metric and a modified Yamamoto metric for the one or more decoded frames; and

a power control processor configured to receive the one or more metrics for the decoded frames and to adjust a setpoint for a power control loop based at least in part on the one or more metrics, wherein the setpoint is indicative of a target received signal quality for the received frames.

24. The power control unit claim 23, further comprising:

a signal quality measurement unit configured to receive and process symbols for the received frames to provide estimates of the received signal quality for the received frames, and

wherein the power control processor is further configured to receive the received signal quality estimates, determine a power surplus or deficit between the received signal quality and the setpoint, and adjust the setpoint based in part on the determined power surplus or deficit.

25. The power control unit claim 23, wherein for each decoded frame the power control processor is configured to adjust the setpoint by a particular amount based in part on values for the one or more metrics.

26. The power control unit claim 23, and operative on a forward link of a CDMA system.

27. The power control unit claim 23, and operative on a reverse link of a CDMA system.