Hybrid relaying and jamming for Physical layer security improvement in two-way relay networks

Cooperative relaying and jamming are two efficient schemes to improve the Physical-layer security of a wireless transmission in the presence of multiple eavesdroppers. In this paper, we consider their cooperation in the context of AF-based two-way relay. We propose a hybrid cooperative relaying and jamming mechanism to enhance the security of a two-way relay network, where all the intermediate nodes not only adopt distributed beamforming but also jam the eavesdroppers to maximize the sum secrecy rate of the two terminals. We give the closed form solution of jamming weight vector and present the optimal relay beamforming scheme as well as an efficient algorithm to compute the optimal beamforming matrix based on convex optimization techniques. Simulations show that the proposed scheme greatly improves the security of the two-way relay network.