Cooperative Beamforming and Artificial Noise Design for Secure Multi-pair Communications in Wireless Two-Way Relay Networks

In this paper, a secure cooperative beamforming and artificial noise design scheme is developed for multi-pair two-way relay networks. We derive the secrecy sum rate for multi-pair two-way relaying, where each communication pair exchanges information through multiple friendly and cooperating relays while under the interception of multiple passive eavesdroppers. We formulate the secrecy sum rate maximization problem and show its non-convexity. We then propose a beamforming and artificial noise design scheme by transforming this problem into a series of convex problems by a tight semidefinite relaxation (SDR) and Taylor approximation. Simulations show that the proposed method converges fast with a high secure sum rate.