Performance Analysis for Opportunistic Full-Duplex Relay Selection in Underlay Cognitive Networks

The performance analysis of optimal decode-andforward (DF) relay selection for the full-duplex (FD) mode in underlay cognitive radio (CR) networks is studied, with the impact of critical parameters such as the residual selfinterference, the distributions of the received signal-to-noise ratio (SNR) and the outage probability, being analyzed. Different from the conventional relay selection schemes with half-duplex (HD) mode, the FD relay suffers from the impact of residual selfinterference due to its simultaneous transmission and reception using the same channel. Furthermore, the exact closed-form expressions for the outage probabilities of the proposed FD relay-selection scheme over both independent Nakagami-m and Rayleigh fading channels are derived, with the validity of the proposed analysis being proven by using simulation. Numerical results show that in the presence of multiple candidate relays, an optimum relay-selection solution in terms of outage probability can always be achievable within the SNR range of (10 dB, 15 dB).