Performance Analysis of Incremental-Best-Relay Amplify-and-Forward Technique

In this paper, we investigate amplify-and-forward (AF) incremental-best-relay cooperative diversity to make efficient use of the channel spectrum by exploiting a limited feedback from the destination terminal, e.g., a single bit indicating the success or failure of the direct transmission. If the destination provides a negative acknowledgment via feedback; in this case only, the best relay among M available relays retransmits the source signal in an attempt to exploit spatial diversity by combining the signals received at the destination from the source and the best relay. Closed-form expressions for the bit error rate, the outage probability and average channel capacity are determined over independent non-identical Rayleigh fading channels. Results show that the AF incremental-best-relay cooperative diversity can achieve the maximum possible diversity order, compared with the conventional cooperative-diversity networks, with higher channel utilization. In particular, the AF incremental-best-relay technique can achieve M + 1 diversity order at low signal-to noise ratio (SNR) and and exhibits a 20 to 30 dB gain relative to direct transmission, assuming single-antenna terminals at high SNR.