Cooperative jamming and beamforming in amplify-and-forward relay systems for physical-layer security

In this paper, we propose a hybrid cooperative beamforming and jamming scheme to enhance the physical-layer security in the two-way relay network with an eavesdropper and a primary receiver. Cooperative beamforming and jamming are designed to maximize the secrecy rate with a total transmit power constraint of the relays and interference power constraint at the primary receiver. The beamformer weights can be obtained by solving a semidefinite programming (SDP). And a method based on the first order Taylor polynomial which has lower complexity but comparable performance is introduced. Simulations show the joint scheme greatly improves the security.