Method and apparatus for adjusting a signal-to-interference threshold in a closed loop power control communications system

• US 6,529,482 B1
• Filed: 06/30/1999
• Issued: 03/04/2003
• Est. Priority Date: 06/30/1999
• Status: Expired due to Term

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Lundby, Stein A.
• Primary Examiner(s): VANDERPUYE, KENNETH N
• Application Number:
  US09/340,499
• Time in Patent Office: 1,343 Days
• Field of Search: 375/130, 375/140, 375/148, 375/317, 375/219, 375/224, 455/522, 370/252, 370/342, 370/335, 370/441
• US Class Current: 370/252
• CPC Class Codes: H04W 52/12 Outer and inner loops
• CPC Class Codes: H04W 52/221 using past power control commands

Abstract

A method and apparatus for dynamically adjusting the signal-to-interference ratio (SIR) threshold used to control signal transmission power in closed loop communication systems. The closed loop power control comprises an inner loop that provides up/down transmission power control commands to a transmitter based upon a comparison of the SIR for a received signal to the threshold SIR. The outer loop dynamically adjusts the threshold SIR using historic inner loop power control information. When it is detected that the inner loop is not acceptably performing power control, the target SIR is not changed, or may increased or decreased more or less than 0.5 dB or 0.5 dB/99, respectively.

Claims

1. An apparatus used to adjust a signal-to-interference ratio (SIR) threshold used in a closed loop power control system of a wireless communications network, said closed loop power control system having an inner loop and an outer loop, comprising:

detection means for identifying typical inner loop power control command patterns, wherein said typical inner loop power control command patterns are indicative of said inner loop not correctly commanding that transmission power be changed; and

outer loop power control means, communicatively coupled to said detection means, for adjusting an SIR threshold in accordance with said inner loop power control patterns.

2. The apparatus recited in claim 1, wherein said inner loop power control command pattern indicative of said inner loop not correctly commanding that transmission power be changed occurs when more than N number of successive power up commands are communicated to the detection means by the inner loop.

3. The apparatus recited in claim 1, wherein said inner loop power control command pattern indicative of said inner loop not correctly commanding that transmission power be changed occurs when an estimated SIR for a last frame of information received is substantially below the SIR threshold.

4. The apparatus recited in claim 1, wherein said outer loop control means receives said typical inner loop power control command patterns indicative of said inner loop not correctly commanding that transmission power be changed if a verification check of a last frame of information received fails.

5. The apparatus recited in claim 4, wherein said verification check is a cyclic redundancy check (CRC).

6. The apparatus recited in claim 3, wherein said outer loop adjusts said SIR threshold in accordance with said inner loop power control patterns and the number of up power commands, consecutive or non-consecutive, made by said inner loop during the last K number of commands.

7. A method for adjusting a signal-to-interference ratio (SIR) threshold of a closed loop power control system used in a wireless communications network, said closed loop power control system having an inner loop and an outer loop, comprising the steps of:

generating inner loop power control commands in accordance with a comparison between a first quality metric and a variable threshold;

adjusting said variable threshold in accordance with said first quality metric unless a second quality metric indicates that said inner loop power control commands are not appropriate, and if said inner loop power commands are not appropriate, then either;

(a) suspending the adjustment of said variable threshold, or

(b) adjusting said variable threshold by an amount less than the amount the adjustment would have been if said adjustment had been made based only on said first quality metric.

8. The method recited in claim 7, wherein said inner loop power control commands are not appropriate when more than N number of successive power up commands are communicated to the transmitter by the inner loop.

9. The method recited in claim 7, wherein said adjustments to said variable threshold is made in accordance with said second quality metric and the number of up power control commands, consecutive or non-consecutive, made by said inner loop during the last K number of commands.

10. The method recited in claim 7, wherein said inner loop power control commands are not appropriate when an estimated SIR for a last frame of information received is substantially below the variable threshold.

11. The method recited in claim 7, wherein said second quality metric is used if a verification check of a last frame of information received fails.

12. The method recited in claim 11, wherein said verification check is a cyclic redundancy check (CRC).

13. A method for adjusting a signal-to-interference ratio (SIR) threshold used in a closed loop power control system of a wireless communications network, said closed loop power control system having an inner loop and an outer loop, comprising:

identifying typical inner loop power control command patterns, wherein said typical inner loop power control command patterns are indicative of said inner loop not correctly commanding that transmission power be changed; and

adjusting said SIR threshold in accordance with said inner loop power control patterns.

14. The method recited in claim 13, wherein said inner loop power control command pattern indicative of said inner loop not correctly commanding that transmission power be changed occurs when more than N number of successive power up commands are communicated by the inner loop.

15. The method recited in claim 13, wherein said inner loop power control command pattern indicative of said inner loop not correctly commanding that transmission power be changed occurs when an estimated SIR for a last frame of information received is substantially below the SIR threshold.

16. The method recited in claim 13, further including receiving said inner loop power control command patterns indicative of said inner loop not correctly commanding that transmission power be changed if a verification check of a last frame of information received fails.

17. The method recited in claim 16, wherein said verification check includes a cyclic redundancy check (CRC).

18. The method recited in claim 15, wherein said adjusting said SIR threshold includes adjusting said SIR threshold in accordance with said inner loop power control patterns and a number of up power commands, consecutive or non-consecutive, made by said inner loop during the last K number of commands.

19. A method for adjusting a signal-to-interference ratio (SIR) threshold of a closed loop power control system used a wireless communications network, said closed loop power control system having an inner loop and an outer loop, comprising:

generating inner loop power control commands in accordance with a comparison between a first quality metric and a variable threshold; and

adjusting said variable threshold in accordance with said first quality metric unless a second quality metric indicates that said inner loop power control commands are not appropriate.

20. The method recited in claim 19, wherein said inner loop power control commands are not appropriate when more than N number of successive power up commands are communicated by the inner loop.

21. The method recited in claim 19, wherein said inner loop power control commands are not appropriate when an estimated SIR for a last frame of information received is substantially below the variable threshold.

22. The method recited in claim 19, wherein said second quality metric is used if a verification check of a last frame of information received fails.

23. The method recited in claim 22, wherein said verification check is a cyclic redundancy check (CRC).

24. A computer readable medium embodying a method for adjusting a signal-to-interference ratio (SIR) threshold of a closed loop power control system used a wireless communications network, said closed loop power control system having an inner loop and an outer loop, the method comprising:

generating inner loop power control commands in accordance with a comparison between a first quality metric and a variable threshold; and

adjusting said variable threshold in accordance with said first quality metric unless a second quality metric indicates that said inner loop power control commands are not appropriate, and if said inner loop power commands are not appropriate, then either;

suspending the adjustment of said variable threshold, or

adjusting said variable threshold by an amount less than the amount the adjustment would have been if said adjustment had been made based only on said first quality metric.

25. An apparatus for adjusting a signal-to-interference ratio (SIR) threshold of a closed loop power control system used a wireless communications network, said closed loop power control system having an inner loop and an outer loop, comprising:

means for generating inner loop power control commands in accordance with a comparison between a first quality metric and a variable threshold; and

means for adjusting said variable threshold in accordance with said first quality metric unless a second quality metric indicates that said inner loop power control commands are not appropriate, and if said inner loop power commands are not appropriate, then said means for adjusting further including either;

means for suspending the adjustment of said variable threshold, or

means for adjusting said variable threshold by an amount less than the amount the adjustment would have been if said adjustment had been made based only on said first quality metric.