Improved amplify-and-forward relay selection with outdated channel state information

Feedback delay often exists in actual communication systems. Relay selection with feedback delay was based on outdated channel state information, which would seriously deteriorate the performance of cooperative communication system. In cooperative system, the best relay is selected to participate in process of information transmission, which can save system power and reduce costs. In this paper, we propose a method to optimizing relay selection to select the appropriate relay node. Simulation results show that the optimization opportunistic relay selection scheme reduces the average bit error rate and improves the channel capacity of the system, which optimizes the performance of the system.