Security Transmission Designs in Two-Way Relay Wireless Networks

In this paper, we investigate physical-layer transmission security problem of a two-way relay wireless network consisting of two legitimate terminal nodes who wants to communicate with each other in presence of one eavesdropper, with help of N intermediate nodes. We propose a cooperative relaying and jamming strategy, which selecting one intermediate node to create intentional interference upon the eavesdropper, while other K = N −1 intermediate nodes operating in relay mode and assisting the source nodes to deliver data to their corresponding destinations using an amplify-and-forward (AF) protocol. All N intermediate nodes in this system are under a per-node power constraint. When K ≥ 3, we propose two different system design criteria based on null-space beamforming, to maximize secrecy sum rate by rate-splitting method with a bisection numerical algorithm iteratively getting the maximal secrecy sum rate, or to maximize the minimum rate between the two terminals. And we also propose the modified security schemes when the number of intermediate nodes is not enough for the previously mentioned schemes (K < 3).