An Improved BER-Optimal Relay Selection Scheme for Decode-and- Forward Cooperative Networks

We are concerned with the relay selection in a decode-and-forward cooperative network to minimize the bit error rate (BER) in a radio cell. This problem can be solved using maximum weighted (MW) matching algorithm, greedy matching algorithm or worst-link-first (WLF) matching algorithm. Among the algorithms, WLF matching algorithm has achieved much attention for its being less complex while the achieved performance is high. In order to further reduce the computational complexity, we propose an improved WLF relay selection scheme, in which relays are selected according to instantaneous channel state information (CSI) and a cooperative threshold is set up to eliminate some unsatisfying candidate relays from the set of alternative candidate relays and thus reduce the amount of calculation. Theory analysis and simulation results both show that the improved WLF relay selection scheme proposed can be easily implemented and achieve almost the same BER performance as that of WLF scheme while the computational complexity is much lower.