Selection Diversity with Multiple Amplify-and-Forward Relays in Nakagami-m Fading Channels

We present an analytical performance study of selection diversity (SD) with multiple amplify-and-forward relays in independent and identically distributed (i.i.d.) Nakagami-m fading channels. Employing SD is an attractive approach to achieve bandwidth and power efficiencies, by utilizing only a single diversity path with the strongest end-to-end signal-to-noise ratio (SNR) to transmit. For such systems, we derive new closed-form expressions which closely approximate the exact outage probability and symbol error rate (SER), especially at medium to high SNRs. Further insights are drawn from new asymptotic expressions which show that SD achieves a full diversity order in Nakagami-m fading. Interestingly, the diversity order is found to be a product of the number of relays and the minimum per-hop fading parameter in the relay path plus the fading parameter of the direct path.