Communication system transmit power control method
View Patent ↗A method for adjusting an OLT for power control, which is capable of closely tracking a low tFER. The OLT is adjusted based on frame quality indicator FQI and channel quality metrics. FQI and channel quality metrics are generated at the receiver of a base transceiver station after reception of a frame. If FQI equal to a logic zero was generated, the OLT is adjusted upwards using a first stepsize. If FQI equal to a logic one was generated for a certain amount of consecutive frames, the OLT is adjusted downwards using a second stepsize. The OLT is also fine-tuned during the intervals between the transitions caused by applying the first stepsize or second stepsize. The first and second stepsizes and the amount of consecutive frames of FQI=1 before OLT is adjusted downwards are determined adaptively according to time-varying channel conditions and received frame quality indicator.
1. In a communication system receiver, a method of adjusting an outer loop threshold (OLT) for power control comprising:
obtaining a frame quality indicator; and
obtaining a channel quality metric Eb/Nt;
wherein when the frame quality indicator is equal to a logic zero,
obtaining an average Eb/Nt (avgEbNt); and
using Eb/Nt and avgEbNt to calculate a stepsize used to increase the OLT; wherein the stepsize is calculated using upDelta=baseUpDelta*(Eb/Nt)/avgEbNt and wherein baseUpDelta is a predetermined scaling factor.
2. The method of claim 1 wherein the OLT is increased using the equation OLT(n)=OLT(n−1)×upDelta.
3. The method of claim 1 wherein the channel quality metric Eb/Nt is calculated using the equation
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4. In a communication system receiver having a target frame error rate (tFER), a method of adjusting an outer loop threshold (OLT) for power control comprising:
obtaining a frame quality indicator;
wherein when the frame quality indicator is not equal to a logic zero and the frame quality indicator is not equal to a logic one for an adaptively determined amount of consecutive frames, adjusting the OLT according to a comparison of a fadeDepth(i) and a fadeDepth(i−1).
5. The method of claim 4 wherein the OLT is adjusted using the equation OLT(i)=OLT(i−1)*floatDelta, when fadeDepth(i)>fadeDepth(i−1); wherein floatDelta is a predefined constant.
6. The method of claim 4 wherein the OLT is adjusted using the equation OLT(i)=OLT(i−1)/floatDelta, when fadeDepth(i)<fadeDepth(i−1); wherein floatDelta is a predefined constant.