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

• US 6,075,974 A
• Filed: 11/20/1996
• Issued: 06/13/2000
• 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 S.
• Assistant Examiner(s): Gantt, Alan T.
• Application Number:
  US08/752,860
• Time in Patent Office: 1,301 Days
• Field of Search: 455/69, 455/522
• 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 the steps of:

a) at said base station, receiving a power control command from said user station;

b) providing said power control command to a base station controller;

c) providing from said base station controller to said base station a power adjustment command in accordance with said power control command, wherein said steps of providing said power control command to said base station controller and providing said power adjustment command to said base station in response thereto results in a response delay;

d) transmitting from said base station a current communication signal at a transmit power level based on said power adjustment command;

e) at said user station, receiving said current communication signal;

f) at said user station, determining a received power level of said current communication signal;

g) at said user station, adjusting a power level threshold based on a predetermined number of power control messages previously transmitted by said user station to said base station wherein said predetermined number is determined in accordance with said response delay;

h) at said user station, comparing the adjusted power level threshold to said received power level of said current communication signal;

i) at said user station, transmitting a current power control message based on said step of comparing; and

j) at said base station, transmitting a new communication signal at an adjusted power level in accordance with said 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 the step of generating a random value when said adjusted power level threshold is equal to said received power level of said current communication signal, and generating said current power control message from said random value.

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

a) at said base station, transmitting a current communication signal;

b) at a user station, receiving said current communication signal from said base station;

c) at said user station, decoding said current communication signal;

d) at said user station, performing a quality measurement of said current communication signal;

e) at said user station, determining the value of a current error indicator bit in accordance with said quality measurement of said decoded signal and at least one previously transmitted error indicator bit;

f) at said user station, transmitting said current error indicator bit; and

g) at said base station, transmitting a new communication signal at an adjusted power level based on said current error indicator bit.

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

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

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

8. The method of claim 4 wherein said step of performing a quality measurement further comprises evaluating the 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 the steps of:

a) at said base station, transmitting a current communication signal;

b) at a user station, receiving said current communication signal from said base station;

c) at said user station, determining a power level of said current communication signal;

d) at said user station, comparing a power level threshold to said power level of said current communication signal;

e) at said user station, generating a power control message based on said step of comparing;

f) at said user station, 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;

g) at said user station, transmitting said reversed power control message; and

h) at said base station, transmitting a new communication signal at an adjusted power level based on said reversed power control message.

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

a) at said base station, transmitting a current communication signal;

b) at a user station, receiving said current communication signal from said base station;

c) at said user station, computing a symbol error rate of said current communication signal;

d) at said user station, adjusting a symbol error rate threshold based on at least one prior power control message previously transmitted by said user station to said base station;

e) at said user station, comparing the adjusted symbol error rate threshold to said symbol error rate of said current communication signal;

f) at said user station, transmitting a current power control message based on said step of comparing; and

g) at said base station, transmitting a new communication signal at an adjusted power level based on said current power control message.