Method and apparatus for adjusting thresholds and measurements of received signals by anticipating power control commands yet to be executed

• US 6,374,085 B1
• Filed: 05/08/2000
• Issued: 04/16/2002
• Est. Priority Date: 11/20/1996
• Status: Expired due to Term

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Chen, Tao, Saints, Keith W.
• Primary Examiner(s): Hunter, Daniel
• Assistant Examiner(s): Gantt, Alan T.
• Application Number:
  US09/566,535
• Time in Patent Office: 708 Days
• Field of Search: 455/522, 455/69
• US Class Current: 455/69
• CPC Class Codes: H04W 52/08 Closed loop power control
• CPC Class Codes: H04W 52/12 Outer and inner loops
• CPC Class Codes: H04W 52/20 using error rate
• CPC Class Codes: H04W 52/221 using past power control commands
• CPC Class Codes: H04W 52/223 predicting future states of the transmission

Abstract

The present invention provides a method and apparatus for providing improved quality or power control by recognizing the delays inherent in a closed-loop communication system. The mobile station or receiver properly adjusts its forward link quality or power level thresholds or measurements with which it compares incoming frames or portions thereof to reflect the level it anticipates receiving (after the delay). For example, the mobile station can recognize that at a given measurement time, two outstanding messages have not been executed by the transmitter (where each message indicates a corresponding increase of 1 dB). As a result, the mobile station can adjust its measurement threshold down by 2 dB to more closely correspond to future power adjustments. If the currently received frame or portion thereof is still below the readjusted threshold, then the mobile station sends out a new message to request a further increase in the forward link channel.

Claims

1. A method for controlling the transmission power of communication signals transmitted by a base station, the method comprising:

receiving at a user station a current communication signal from the base station;

determining a received power level of the current communication signal;

adjusting a power level threshold based on a predetermined number of power control messages previously transmitted by the user station to the base station wherein said predetermined number is determined in accordance with a response delay inherent in a closed loop power control technique employed in the base station;

comparing the adjusted power level threshold to said received power level of the current communication signal;

generating a current power control message based on said comparing; and

transmitting from the user station to the base station the current power control message.

2. The method of claim 1 wherein said response delay is approximately two frames.

3. The method of claim 1 further comprising generating a random value when the adjusted power level threshold is equal to said received power level of the current communication signal, and wherein said generating is based on said random value.

4. A method for controlling transmission signal power of signals transmitted by a base station, the method comprising:

receiving at a user station a current communication signal from the base station;

performing a quality measurement of the current communication signal;

determining the value of a current indicator bit in accordance with said quality measurement and at least one previously transmitted indicator bit; and

transmitting from the user station said current indicator bit to the base station.

5. The method of claim 4 wherein said performing a quality measurement comprises measuring a signal to noise ratio of said current communication signal.

6. The method of claim 4 wherein said performing a quality measurement comprises measuring the symbol error rate of said current communication signal.

7. The method of claim 4 wherein said performing a quality measurement comprises measuring a Yamamoto metric of said current communication signal.

8. The method of claim 4 wherein said performing a quality measurement comprises evaluating a parity bit check indication of said current communication signal.

9. A method for controlling transmission signal power of communication signals transmitted by a base station, the method comprising:

receiving at a user station a current communication signal from the base station;

determining a received power level of said current communication signal;

comparing a power level threshold to said received power level of said current communication signal;

generating a power control message based on said comparing;

reversing the value of said power control message when a predetermined number of messages of like value have been generated, to produce a reversed power control message; and

transmitting said reversed power control message from the user station.

10. A method for controlling transmission signal power of communication signals transmitted by a base station, the method comprising:

receiving at a user station a current communication signal from the base station;

computing a received symbol error rate of said current communication signal;

adjusting a symbol error rate threshold to generate an adjusted symbol error rate threshold based on at least one prior power control message previously transmitted by the user station to the base station;

comparing the adjusted symbol error rate threshold to the received symbol error rate; and

transmitting from the user station a current power control message based on said comparing.

11. A user station apparatus comprising:

a quality measurement module configured to receive at least one parameter associated with a current communication signal received from a base station and generate quality measurement information associated with the current communication signal based on the at least one parameter;

a power control processor configured to determine a received power level of the current communication signal based on the quality measurement information, wherein said power control processor is further configured to adjust a power level threshold based on a predetermined number of power control messages previously transmitted by the user station to the base station, wherein said predetermined number is determined in accordance with a response delay inherent in a closed loop power control technique employed in the base station, said power control processor being further configured to generate a current power control message based on comparing the adjusted power level threshold to the received power level of the current communication signal; and

a transmitter configured to transmit the current power control message.

12. The user station apparatus of claim 11 wherein said response delay is approximately two frames.

13. The user station apparatus of claim 11 wherein said power control processor is further configured to generate a random value when the adjusted power level threshold is equal to said received power level of the current communication signal, and generate the current power control message based on said random value.

14. A user station apparatus comprising:

a receiver configured to measure at least one parameter associated with a current communication signal received from a base station;

a quality measurement module configured to generate quality measurement information based on the at least one parameter;

a power control processor configured to determine the value of a current indicator bit in accordance with the quality measurement information and at least one indicator bit transmitted previously by the user station; and

a transmitter configured to transmit the indicator bit.

15. The user station apparatus of claim 14 wherein said at least one parameter comprises a signal to noise ratio of the current communication signal.

16. The user station apparatus of claim 14 wherein said at least one parameter comprises a symbol error rate of said current communication signal.

17. The user station apparatus of claim 14 wherein said at least one parameter comprises a Yamamoto metric of said current communication signal.

18. The user station apparatus of claim 14 wherein said at least one parameter comprises a parity bit check indication of said current communication signal.

19. A user station apparatus comprising:

a receiver configured to receive a current communication signal from a base station and determine a received power level of the current communication signal;

a power control processor configured to compare a power level threshold to the received power level, generate a power control message based on the results of the comparison, and reverse the value of the power control message when a predetermined number of messages of like value have been generated, to produce a reversed power control message; and

a transmitter configured to transmit the reversed power control message.

20. A user station apparatus comprising:

a receiver configured to receive a current communication signal from a base station and compute a received symbol error rate of said current communication signal;

a power control processor configured to adjust a symbol error rate threshold to produce an adjusted symbol error rate threshold based on at least one prior power control message previously transmitted by the user station, and compare the adjusted symbol error rate threshold to the received symbol error rate, and generate a current power control message based on the results of the comparison; and

a transmitter configured to transmit the current power control message.