Performance of Differential Amplify-and-Forward Relaying in Multinode Wireless Communications

This paper is concerned with the performance of differential amplify-and-forward (D-AF) relaying for multinode wireless communications over time-varying Rayleigh fading channels. A first-order autoregressive model (AR1) is utilized to characterize the time-varying nature of the channels. Based on the second-order statistical properties of the wireless channels, a new set of combining weights is proposed for signal detection at the destination. Expression of pairwise error probability (PEP) is provided and used to obtain the approximated total average bit error rate (BER). It is shown that the performance of the system is related to the autocorrelation of the direct and cascaded channels and an irreducible error floor exists at a high signal-to-noise ratio (SNR) region. The new weights lead to a better performance when compared with the conventional combining scheme. Computer simulation is carried out in different scenarios to support the analysis.