Secure communication via an untrusted relay with unreliable backhaul connections

This paper studies the secrecy performance of a wireless energy harvesting system in which a source connected to wireless backhaul links sends information to a destination via an untrusted relay that not only helps the overall commutation but also overhears the sources confidential information. The secrecy capacity is created by using destination-assisted jamming signals. The jamming provides additional energy to the relay. To analyze the secrecy performance of the proposed system, we derived analytical expressions for the secrecy outage probability (SOP) and the average secrecy capacity, and the high-power approximations for the SOP. The accuracy of the calculations is verified by Monte Carlo simulations. Numerical results provide useful insight into the effects of the system parameters, such as the failure probability of unreliable backhaul links, the transmit powers, the power-splitting ratio, and the locations of the relay, on the secrecy performance.