Wireless Multiuser Relay Networks in Nakagami-m Fading Channels

We propose opportunistic scheduling with cooperative selection diversity (CSD) in wireless multiuser relay networks (MRN). In this policy, the destination with the highest instantaneous end-to-end signal-to-noise ratio (SNR), either directly from the source or indirectly through the relay, is scheduled for transmission. For the practical case of unbalanced Nakagami-m fading channels, we derive new exact closed-form expressions for the outage probability and the symbol error rate (SER) for amplify-and-forward (AaF) relaying. Next, we quantify the asymptotic network behavior in the low SER regime by presenting concise expressions for the diversity order and the array gain. We demonstrate that our two-step policy achieves the maximum diversity order. We further prove that both the diversity order and the array gain are jointly influenced by the direct link and the weaker hop of the relay link.