AF turbo-coded selective relaying with imperfect channel state information

In this paper, we study the performance of relay selection in variable-gain amplify-and-forward (AF) turbo-coded cooperative network in the presence of channel estimation errors. In particular, we assume M-ary phase shift keying (MPSK) modulation and consider a dual multi-relay cooperative scenario where the relay selection requires global knowledge (end-to-end) of the relaying link. We derive the probability density function (PDF) of the received signal-to-noise ratio (SNR) for the underlying relaying link, and an upper bound expression of the average pairwise error probability (PEP). Furthermore, we present the diversity analysis study in which we show that the effect of erroneous channel estimates reduce the diversity order at high SNR to zero. Using these results, we evaluate the performance of the coded cooperation scenario under study in terms of bit-error rate (BER). Monte-Carlo simulation results are presented to validate the accuracy of the analytical results.