Secure Full-Duplex Two-Way Relaying Networks with Optimal Relay Selection

The secrecy outage probability (SOP) of cooperative communication systems with optimal relay selection (ORS) scheme in the presence of an eavesdropper is investigated by implementing decode-and-forward-based full-duplex (FD) two-way relayingmode. Under Rayleigh fading assumptions, the closed-form expressions for the distributions of end-to-end signal-to-interference-plus-noise ratio in each wireless link are derived. Furthermore, the closed-form expression for the exact SOP of the proposed ORS scheme is given out. Numerical results show that the SOP of the proposed system can be substantially impacted by several parameters involved, including the number of relays, the average signal-to-noise ratio (SNR) of eavesdropper links, and the average residual self-interference (SI) imposed on the FD relays. In particular, the impact of residual SI is shown to be more obvious in terms of eroding the system's secrecy performance in a low-to-medium SNR regime than in a high-SNR regime. As long as the residual SI power is not beyond the background noise level, the proposed FD-TWC scheme can always outperform the conventional half-duplex mode in terms of SOP.