Method of reverse link dynamic power control in a wireless communication system using quality feedback from a delay-sensitive traffic stream or overhead channel
A closed loop power control based on receiving a continuous quality feedback is described. A main reverse link (RL) pilot is controlled by the quality feedback of a substantially continuous delay-sensitive traffic stream, such as Voice-over-IP (VoIP), when such a stream is enabled. When such a stream is not enabled, the quality of a continuous RL overhead channel is used to control the pilot power. At the same time, the Traffic-to-Pilot Ratios (TPR) of contemporaneously transmitted delay-sensitive data streams are independently adjusted based on a quality feedback associated with each such data stream.
1. A method in a wireless communication system in which an access terminal (AT) communicates with a base transceiver station (BTS) over a reverse link (RL) and a forward link (FL), the method comprising:
at the AT:
if a delay-sensitive traffic stream is enabled on the RL, dynamically controlling the power of a main RL pilot in response to a quality indication feedback received on the FL of the delay-sensitive traffic stream received by the BTS; and
if a delay-sensitive traffic stream is not enabled on the RL, dynamically controlling the power of the main RL pilot in response to a quality indication feedback received on the FL of a signal continuously transmitted on the RL on an overhead channel.
2. The method of claim 1 wherein the delay-sensitive traffic stream is a stream of delay-sensitive packets.
3. The method of claim 2 wherein the quality indication feedback of the delay-sensitive packets is a stream of ACKs and NAKs generated at the BTS in response to the received stream of packets.
4. The method of claim 3 wherein the stream of delay-sensitive packets is a stream of Voice-over-IP (VoIP) packets.
5. The method of claim 3 wherein the stream of delay-sensitive packets is a stream of Video Telephony (VT) packets.
6. The method of claim 3 further comprising:
if a NAK is received, adjusting the pilot power by a predetermined step upward; and
if an ACK is received, adjusting the pilot power by a predetermined step downward.
7. The method of claim 6 wherein the steps upward and downward are determined by a predetermined frame error rate of the delay-sensitive traffic stream and a desired throughput performance.
8. The method of claim 6 wherein if a NAK is received, the predetermined step upward is dependent on how many times a packet that the NAK is responsive to has been transmitted to the BTS by the AT.
9. The method of claim 6 wherein if the ACK is received before or at a termination target, the pilot level is set equal to the pilot level used when a first transmission of the packet to which the ACK is responsive was made by the AT minus a predetermined target-down-delta that is determined by a predetermined frame error rate.
10. The method of claim 1 wherein the signal continuously transmitted on the overhead channel on the RL comprises a stream of Channel Quality Indicator (CQI) words.
11. The method of claim 10 wherein the quality indication feedback of the stream of CQI words comprises a stream that indicates whether the received CQI words are “good” or “bad”.
12. The method of claim 11 further comprising:
if a “good” quality indication feedback is received, adjusting the pilot power by a predetermined step downward; and
If a “bad” quality indication feedback is received, adjusted the pilot power by a predetermined step upward.
13. The method of claim 12 wherein the predetermined steps upward and downward are determined by a CQI quality target.
14. The method of claim 1 wherein the pilot has predetermined upper limit a lower limits.
15. A method in a wireless communication system in which an access terminal (AT) communicates with a base transceiver station (BTS) over a reverse link (RL) and a forward link (FL), the method comprising:
at the BTS:
transmitting a quality indication on the FL wherein if a delay-sensitive traffic stream is enabled on the RL, the quality indication comprises a determined quality of a packet in a delay-sensitive traffic stream received from the AT, and if the delay-sensitive traffic stream is not enabled on the RL, the quality indication comprises a determined quality of a word in a stream of words continuously received from the AT on the RL on an overhead channel.
16. The method of claim 15 wherein the delay-sensitive traffic stream is a stream of delay-sensitive packets.
17. The method of claim 16 wherein the determined quality of the packet in the received stream of delay-sensitive traffic comprises an ACK if the packet is properly decoded and a NAK if a packet is not properly decoded.
18. The method of claim 15 wherein the word received from the AT on the overhead channel is a Channel Quality Indicator (CQI) word.
19. The method of claim 18 wherein the determined quality of the CQI comprises a “good” indication if the received CQI word is properly decoded and a “bad” indication if the received CQI word is improperly decoded.