Design and Performance of Adaptive Coded Modulation over Slow Frequency-Selective Fading Channels

Adaptive coded modulation is a technique for improving throughput over time-varying channels. Maximizing throughput of an adaptive coded modulation system involves determining the optimum operating packet error rates (PER) for each of the coded modulation schemes and then identifying a good channel quality metric that yields fast and accurate estimation of the PER. We present a simple analysis for determining the optimum operating PER based on previous analysis of TCP traffic over a lossy wireless link. We investigate several potential channel quality metrics that could be used to choose the correct coded modulation scheme. In scenarios with variable delay spread it may not be possible to find a unique channel quality metric that applies to all channels. For such scenarios, we present a threshold-adaptive algorithm that is applicable to slowly varying channels with a wide range of multipath profiles.