Performance of Amplify and Forward Relays with Predicted CSI

In cooperative relay networks, Channel State Information (CSI) is estimated at receiver. The estimated CSI is sent back to the relays through feedback link. This estimated CSI is often outdated due to feedback delay and the estimated outdated CSI is used for relay selection and detection which affects the performance of the system. The outage and error rate performance of the relay selection schemes is highly dependent on the correlation between the actual channel and their corresponding outdated channel estimates. In this study, the first part of the work investigates the effect of feedback delay on the outage and error rate performance of Amplify and-Forward (AF) cooperative relay network. In the second part of the work, actual CSI is predicted using Minimum Mean Square Error (MMSE) prediction and this predicted CSI is used for relay selection and detection. The best relay selection and partial relay selection are considered in this study. From the simulation results it is observed that the effect of correlation coefficient between the actual channel and the corresponding channel estimate is more significant in the best relay selection than partial relay selection and also the improvement in outage and BER performance are evident if the actual CSI is predicted.