Secrecy Rate Optimization for Wireless Relay-Eavesdropper Channel with Energy Harvesting Constraints

This paper studies optimization problem of jointly energy save-ratio and power allocation, to maximize secrecy rate, in a Gaussian wiretap channel (GWT) self-powered wireless system with the existence of one eavesdropper. The system model assumes that each transmitter follows a save-then-transmit protocol. With backward induction, we formulate a two-step optimization scheme, which first derives the condition under the mode of deaf cooperation which improves over the secrecy capacity of the original wiretap, and then the optimal save-ratio and the relay power allocation are obtained by an available iterative algorithm. Simulation results show the algorithm has a fast convergence speed, and validates its effectiveness of improving secrecy rate.