Security-reliability analysis and optimization for cognitive two-way relay network with energy harvesting

This paper investigates the security and reliability of information transmission within an underlay wiretap energy harvesting cognitive two-way relay network. In the network, energy-constrained secondary network (SN) nodes harvest energy from radio frequency signals of a multi-antenna power beacon. Two SN sources exchange their messages via a SN decode-and-forward relay in the presence of a multiantenna eavesdropper by using a four-phase time division broadcast protocol, and the hardware impairments of SN nodes and eavesdropper are modeled. To alleviate eavesdropping attacks, the artificial noise is applied by SN nodes. The physical layer security performance of SN is analyzed and evaluated by the exact closed-form expressions of outage probability (OP), intercept probability (IP), and OP+IP over quasistatic Rayleigh fading channel. Additionally, due to the complexity of OP+IP expression, a self-adaptive chaotic quantum particle swarm optimization-based resource allocation algorithm is proposed to jointly optimize energy harvesting ratio and power allocation factor, which can achieve security-reliability tradeoff for SN. Extensive simulations demonstrate the correctness of theoretical analysis and the effectiveness of the proposed optimization algorithm.