Nonregenerative Dual-Hop Cooperative Links with Selection Diversity

The end-to-end performance of dual-hop cooperative diversity systems equipped with nonregenerative relays and a selection combining receiver at the destination terminal over independent and nonidentical Nakagami-m fading channels is studied. Closed-form expressions for the cumulative distribution function and the probability density function of the end-to-end signalto-noise ratio (SNR) are presented, while analytical formulae are derived for the moments and the moment generating function. Using these statistical results, closed-form expressions for the outage probability are presented for both channel state information and fixed gain relays. Furthermore, for the case of fixed gain relay, the average end-to-end SNR, the amount of fading, and the average bit error rate can be numerically evaluated. The proposed mathematical analysis is complemented by numerical examples, including the effects on the overall performance of the SNRs unbalancing as well as the fading severity.