Physical Layer Security Cognitive Decode-and-Forward Relay Beamforming Network with Multiple Eavesdroppers

Abstract

Physical layer security (PLS) approach for wireless communication can prevent eavesdropping without upper layer data encryption. In this paper, we consider the transmission of confidential message over wireless channel with the help of multiple cooperating relays in the Decode-and-Forward cooperative scheme. Based on an information-theoretic formulation of problem we take into account a wireless network system, in which an one-way relay wireless system including a source, a legitimate destination, multiple trusted relays and multiple eavesdroppers. For decode-and-forward beamforming protocol in the presence of one eavesdropper, the closed-form optimal solution is derived for the relay weights. For another case, when the communication system has the presence of multiple eavesdroppers, it becomes more difficult to find the optimal solution of the secrecy rate maximization problem. Hence, there are several criteria were considered leading to a suboptimal but simple solution. Specifically, nulling out the message signals completely at all eavesdroppers results in a simpler form of this problem and a suboptimal solution is explicitly obtained. In this paper, we propose a new approach based on the well known method, DC programming and DCA to solve the original problem, without considering any additional constraints.