On the Performance of AF Opportunistic Relaying over Non-identically Distributed Links with Outdated CSI

This paper presents an analysis of the performance of amplify-and-forward (AF) opportunistic relaying systems over independent and non-identically distributed (i.ni.d.) Rayleigh fading links with outdated channel state information (CSI). A closed-form expression is derived for the moment generating function (MGF) of the end-to-end SNR at the destination under outdated CSI conditions. Using that expression, closed-form expressions are derived for the average bit error rate (BER) performance of several M-ary modulations, and the average SNR gains obtained from AF opportunistic relaying. Asymptotic analyses for the BER and achievable diversity order of the system are also presented. Using the derived analytical expressions the deteriorating effects of outdated CSI and the differences over i.i.d. and i.ni.d. Rayleigh fading links are evaluated and discussed.