Hybrid relaying and jamming for wireless physical layer security based on cooperative beamforming

Abstract

To improve the information-theoretic security of two-way wireless cooperative communication systems, we propose in this study a hybrid relaying and jamming mechanism based on multi-node cooperative beamforming to enhance the security of the physical layer transmission of information. The basic concept is that in the cooperative transmission phase, some intermediate nodes adopt distributed beamforming to help the transmitter send messages to legitimate users and simultaneously others jam the eavesdropper, which can significantly improve the security performance of the system in the broadcast phase. Two different cooperative beamforming schemes are proposed with and without the instantaneous channel state information (CSI) of the eavesdropper. We show that optimizing both the schemes requires the mathematical solving of one or a series of second-order convex cone programming (SOCP) problems, which can be executed by efficiently using the interior point method. Simulation and comparisons show that our proposed hybrid relaying, jamming mechanism and beamforming approaches significantly increase the security sum rate of the two source terminals and outperform both the relays-only and jammers-only mechanisms when the number of intermediate nodes is relatively large.