Secrecy rate maximization in full-duplex multi-antenna decode-and-forward relay systems

摘要

This paper proposes optimum beamforming for a system consisting of a source, a full-duplex (FD) relay, an intended destination, and an eavesdropper. The source and destination are single-antenna nodes, whereas the FD relay is a multi-antenna node. Our objective is to find the optimum receive and transmit beamformers at the relay so that the secrecy rate is maximized. The joint optimization problem is equivalently expressed in terms of the transmit beamformer. The resulting optimization is non-convex. However, we equivalently reformulate it to a suitable form so that the optimum solution is obtained by solving semi-definite relaxation problem, in conjunction with a line search confined to a specific region. Computer simulations demonstrate significant increase in secrecy rate compared to the conventional secure half-duplex relay communications.