DC Programming and DCA for Enhancing Physical Layer Security in Amplify-and-Forward Relay Beamforming Networks Based on the SNR Approach

Physical layer security is an alternative approach to guarantee secure communication besides the traditional cryptography method. In the physical layer security literature, most of the studies are centered around the secrecy capacity, but a new approach based on signal-to-noise ratios (SNR) was proposed in recent years. In that approach, they considered the transmission of a confidential message over a wireless channel with the help of multiple cooperating relays in the Amplify-and-Forward cooperative scheme based on an SNR approach with the predefined threshold. The optimization problem with the aim of maximizing the received SNR at a legitimate receiver subjects to the conditions that the received SNR at each eavesdropper is below the target threshold, and the condition about relay power are formulated as a nonconvex problem. This problem was solved by Semi-definite Relaxation method. In this paper, we propose the well known method based on DC programming and DCA to solve this hard problem. The numerical results show that our proposed method give the better results compared with its obtained by the existing ones.