Performance Analysis for Amplify-and-Forward Relay Selection with Outdated CSI

The impact of outdated channel state information (CSI) on the performance of relay selections, including the partial relay selection and the best relay selection, is studied, with amplify-and-forward (AF) mode cooperative systems being considered. The proposed method is analyzed by deriving the asymptotic closed-form expressions for some figures of merit such as the outage probability and the symbol error probability (SEP). Moreover, the validity of the proposed theoretical analysis is also proven via simulations. Numerical results prove that the performance of the proposed scheme is impacted considerably by various parameters such as the number of candidate relays, the end-to-end signal-to-noise ratio (SNR), etc. In the presence of cooperative networks with outdated CSI feedback, a performance improvement of more than 3dB in terms of either outage probability or SEP can be observed by utilizing the source-to-destination (S→D) link than the method of simply increasing the number of relays.