Power control based on combined quality estimates

• US 6,490,461 B1
• Filed: 06/24/1999
• Issued: 12/03/2002
• Est. Priority Date: 06/24/1999
• Status: Expired due to Term

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Müller, Walter
• Primary Examiner(s): Urban, Edward F.
• Assistant Examiner(s): CRAVER, CHARLES R
• Application Number:
  US09/344,121
• Time in Patent Office: 1,258 Days
• Field of Search: 455/522, 455/63, 455/67.1, 455/67.3, 455/226.1, 455/226.2, 455/226.3, 455/423, 455/550, 455/560, 455/561, 455/245.1, 455/69, 375/221-227
• US Class Current: 455/522
• CPC Class Codes: H04W 52/12 Outer and inner loops
• CPC Class Codes: H04W 52/146 Uplink power control
• CPC Class Codes: H04W 52/20 using error rate
• CPC Class Codes: H04W 52/241 taking into account channel quality metrics, e.g. SIR, SNR, CIR, Eb/lo

Abstract

A wireless telecommunications system is described in which mobile station power control is affected by a functional combination of signal-to-interference sampling, bit error rate sampling, and frame error rate sample. The signal-to-interference sampling provides rapid power control adjustment, while the bit error rate and frame error rate factors provide less speedy but better power control adjustment. The power control function has applicability in single link and multiple link power control adjustments.

Claims

1. Radio power control circuitry providing transmission power control for a connection between a radio network and a mobile radio station, comprising:

a first power control loop, operating on a first time scale, for estimating a signal-to-interference ratio for a communications channel, comparing the estimated signal-to-interference ratio to a target signal-to-interference ratio to produce a signal-to-interference ratio difference, and generating a power control command for transmitting a signal over the communications channel based on the signal-to-interference ratio difference;

a second power control loop, operating on a second time scale slower than the first time scale, for estimating a bit error rate for the communications channel, comparing the estimated bit error rate with a target bit error rate to produce a bit error rate difference, and updating the target signal-to-interference ratio based on the bit error rate difference; and

a third power control loop, operating on a third time scale slower than the second time scale, for estimating a frame error rate for the communications channel, comparing the estimated frame error rate with a target frame error rate to produce a frame error rate difference, and updating the target signal-to-interference ratio based on the frame error rate difference.

2. The radio station power control circuitry in claim 1, wherein the first time scale corresponds to the duration of a time slot.

3. The radio station power control circuitry in claim 1, wherein the second time scale corresponds to the duration of a frame including one or more time slots.

4. The radio station power control circuitry in claim 1, wherein the third time scale corresponds to the duration of two frames, each of which includes one or more time slots.

5. The radio station power control circuitry in claim 1, wherein the signal-to-interference ratio is determined approximately for every pilot symbol transmitted by the mobile radio.

6. The radio station power control circuitry in claim 1, wherein the bit error rate is determined approximately for every frame transmitted by the mobile radio.

7. The radio station power control circuitry in claim 1, wherein each frame includes a code indicator and the frame error rate is determined by a comparison of actual CRC mismatches to a predetermined mismatch frequency threshold.

8. The radio station power control circuitry in claim 1, wherein the connection is supported by plural radio links, the circuitry further including first, second, and third power control loops corresponding to each radio link, each power control loop adjusting the signal to interference ratio target for its corresponding radio link.

9. The radio station power control circuitry in claim 8, wherein the bit error rate target for each radio link and the frame error rate target for each link are modified to take in account an effect of combining signals from each radio link associated with the connection.

10. The radio station power control circuitry in claim 1, wherein the radio station power control circuitry is included in a mobile radio.

11. The radio station power control circuitry in claim 1, wherein the radio station power control circuitry is included in the radio network.

12. A transmission power control method for a communication between a mobile radio station and a telecommunications network, comprising:

in a first power control loop operating on a first time scale, estimating for a communications channel a received signal-to-interference ratio,

a receive channel bit error rate on a second time scale longer than the first time scale, comparing the estimated signal-to-interference ratio to a signal-to-interference ratio target to produce a signal-to-interference ratio difference, and generating a power control command for transmitting a signal over the communications channel based on the signal-to-interference ratio difference;

in a second power control loop, operating on a second time scale slower than the first time scale, estimating a bit error rate for the communications channel, comparing the estimated bit error rate with a target bit error rate to produce a bit error rate difference, and updating the signal-to-interference ratio target based on the bit error rate difference;

in a third power control loop, operating on a third time scale slower than the second time scale, for estimating a frame error rate for the communications channel, comparing the estimated frame error rate with a target frame error rate to produce a frame error rate difference, and updating the signal-to-interference ratio target based on the frame error rate difference.

13. The method in claim 12, wherein the first time scale corresponds to the duration of a time slot.

14. The method in claim 12, wherein the second time scale corresponds to the duration of a frame including one or more time slots.

15. The method in claim 12, wherein the third time scale corresponds to the duration of at least two frames, each of which includes one or more time slots.

16. The method in claim 12, wherein the signal-to-interference ratio is determined approximately for every pilot symbol transmitted by the mobile radio.

17. The method in claim 12, wherein each frame includes a CRC indicator and the frame error rate is determined by a comparison of actual CRC mismatches to a predetermined mismatch frequency threshold.

18. The method in claim 12, wherein the connection is supported by plural radio links, the circuitry further including first, second, and third power control loops corresponding to each radio link, each power control loop adjusting the signal to interference ratio target for its corresponding radio link.

19. The method in claim 18, wherein the bit error rate target for each radio link and the frame error rate target for each link are modified to take in account an effect of combining signals from each radio link associated with the connection.

20. The method in claim 12 implemented in the mobile radio.

21. The method in claim 12 implemented in the radio network.