Impact of outdated channel information on the bit error rate performance for amplify-and-forward selective relaying systems

In this article, the impact of outdated channel information on the average bit error rate (BER) performance of the opportunistic relay selection in amplify-and-forward cooperative systems is analysed and evaluated over Rayleigh fading channels. Using the moment generating function (MGF)-based approach closed-form analytical expressions are derived for the average BER performance of M-ary modulations and the average signal-to-noise-ratio (SNR) gain obtained from opportunistic relaying. Numerical evaluation results obtained from the analytical expressions are provided to study and quantify the deteriorating effects of outdated channel information on the BER performance and on the achievable diversity and SNR gain obtained from relay selection.