I/Q Imbalance Aware Nonlinear Wireless-Powered Relaying of B5G Networks: Security and Reliability Analysis

Physical layer security is known as a promising paradigm to ensure secure performance for the future beyond 5G (B5G) networks. In light of this fact, this paper elaborates on a tractable analysis framework to evaluate the reliability and the security of wireless-powered decode-and-forward (DF) multi-relay networks. More practical, the nonlinear energy harvesters, in-phase and quadrature-phase imbalance (IQI) and channel estimation errors (CEEs) are taken into account. To further enhance the secure performance, two relay selection strategies are presented: 1) suboptimal relay selection (SRS); 2) optimal relay selection (ORS). Specifically, exact analytical expressions for the outage probability (OP) and the intercept probability (IP) are derived in closed-form. For the IP, we consider that the eavesdropper can wiretap the signal from the source or the relay. In order to obtain more deep insights, we carry out the asymptotic analysis as well as the diversity orders for the OP in the high signal-to-noise ratio (SNR) regimes. Numerical results show that: 1) Although the mismatches of amplitude/phase of transmitter (TX)/receiver (RX) limit the OP performance, it can enhance IP performance; 2) Large number of relays yields better OP performance; 3) There are error floors for the OP due to the CEEs; 4) There is a trade-off for the OP and IP to obtain the balance between reliability and security.