A power allocation scheme for physical layer security based on large-scale fading

This paper investigates a four-node wiretap network including one source (S), one relay (R), one legitimate receiver (D) and one eavesdropper (E) with cooperative jamming in a two-hop relay transmission. In the first phase, S transmits an useful signal to R while D transmits an interference signal with the purpose of confounding the eavesdropper. In the second phase, R broadcasts the mixture signal together to D. In this paper, based on large-scale fading, we propose two system models named One-link Wiretap Model and Three-link Wiretap Model to distinguish the receiving links at E. Then, a power allocation scheme is proposed to maximize the average secrecy capacity through two-dimension optimization. Meanwhile, we solve the optimization problem by two different methods called IBO and IAO. Simulation results show that the proposed power allocation strategy can achieve a higher average secrecy capacity than the reference scheme RJPA (Rate-optimal jamming power allocation) in the two models. Besides, a larger security range can be obtained by the proposed scheme.