Performance analysis of amplify-and-forward relaying over Weibull-fading channels with multiple antennas

Amplify-and-forward (AF) relaying with multi-branch dual-hop relays in independent non-identical Weibull fading channels with multiple antennas at the destination is addressed. The authors consider orthogonal relaying and study conventional cooperative systems where all relays participate in the relaying phase as well as opportunistic cooperative systems where only the best relay participates in the relaying phase. An expression for the approximate probability density function (PDF) of the total instantaneous signal-to-noise ratio (SNR) at the destination is derived. Subsequently, expressions for the asymptotic average error rate and the outage probability are presented. The results provided are fairly simple and general for arbitrary values of the fading severity parameters. It is shown that opportunistic relaying does not necessarily outperform the conventional approach in terms of coding gain under equal energy allocation as in the Rayleigh fading case. Simulation results verify the tightness of the proposed analytical expressions in the high SNR region.