Performance analysis for amplify-and-forward relay selection with outdated channel state information

The impact of outdated Channel State Information (CSI) on the performance of relay selections, including the partial relay selection and the best relay selection, is studied, with respect to Amplify-and-Forward (AF) mode cooperative systems. The proposed method is analysed 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 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 and the end-to-end Signal-to-Noise Ratio (SNR). In the presence of cooperative networks with outdated CSI feedback, a performance improvement of more than 3 dB in terms of either outage probability or SEP can be observed by utilizing the Source-to-Destination (S→D) link rather than the method of simply increasing the number of relays.