Best relay selection in decode and forward cooperative cognitive radio relay networks over Rayleigh fading channels

The performance of the best relay selection on the decode-and-forward (DF) mode cognitive radio relay networks is studied. Some important factors, such as the outage probability, the bit error ratio (BER), and the average channel capacity, are analysed in this paper. As compared to the conventional relay selection schemes, the impact of spectrum sensing process as well as the spectrum utilization efficiency of primary user on the performance of DF-based cognitive radio relay networks is considered. In particular, this paper has derived exact closed-form expressions for the outage probability, BER, and average capacity over independent and identically distributed (i.i.d.) Rayleigh fading channels, respectively. The proposed scheme is validated by simulations, and the analyses of closed-form expressions for some figures of merit, e.g., the outage probability, the BER and the average channel capacity, are all consistent with the outcomes of simulations. The simulations also prove that the performance of the proposed scheme is impacted considerably by some other critical parameters, such as the number of relays.