Analysis of amplify-and-forward cooperative relaying with adaptive modulation in Nakagami-m fading channels

This article investigates the efficacy of a constant-power, rate-adaptive M-QAM transmission technique in amplify-and-forward cooperative wireless networks. Tight upper and lower bounds are derived for the mean achievable spectral efficiency, outage probability, and error probability performance of non-regenerative cooperative relay networks in Nakagami-m fading environments. We observe that the spectral efficiency of a practical discrete-rate MQAM comes within a constant gap of the theoretical ergodic capacity of that channel, although this gap is smaller for an adaptive continuous-rate M-QAM.