Secure Communications in SWIPT-Enabled Two-Way Relay Networks

This paper investigates the secrecy performance of a wireless-powered two-way relay network in the presence of an eavesdropper. Based on adaptive time allocation (TA) and power splitting (PS), a novel secure relaying protocol is proposed. For the purpose of secrecy capacity maximization, the optimal TA ratio and PS ratio, which are adaptively adjusted according to instantaneous channel state information, are derived in high signal-to-noise ratio regime through a split-step iterative method. Numerical results show that in the case of unknown wiretap channels, the proposed protocol can also obtain near-optimal secrecy capacity. Moreover, the proposed protocol has better secrecy capacity performance than the PS relaying protocol in various scenarios.