ALOUINI AND GOLDSMITH: ADAPTIVE MODULATION OVER NAKAGAMI FADING CHANNELS 0 Adaptive Modulation over Nakagami Fading Channels

We rst study the capacity of Nakagami multipath fading (NMF) channels with an average power constraint for three power and rate adaptation policies. We obtain closed-form solutions for NMF channel capacity for each power and rate adaptation strategy. Results show that rate adaptation is the key to increasing link spectral eeciency. We analyze therefore the performance of constant-power variable-rate M-QAM schemes over NMF channels. We obtain closed-form expressions for the outage probability, spectral eeciency and average bit-error-rate (BER) assuming perfect channel estimation and negligible time delay. We also analyze the impact of time delay on the BER of adaptive M-QAM.