DC Programming and DCA for Enhancing Physical Layer Security via Relay Beamforming Strategies

Beside of cryptography - the primary traditional methods for ensuring information security and confidentiality, the appearance of the physical layer security approach plays an important role for not only enabling the data transmission confidentially without relying on higher-layer encryption, but also enhancing confidentiality of the secret key distribution in cryptography itself. In this paper, we mention a technique used in physical layer security, this is relay beamforming strategy with Decode-and-Forward relaying technique. The optimization problems with the aim of maximizing the sum of secrecy rates subject to individual relay power constraints are formulated as a nonconvex problem. These problems can be rewritten as DC (difference of two convex functions) programs. We apply the standard DCA scheme to find solution to this problem. The main benefit of the proposed method is that it provides an optimal value for the system secrecy rate while the previous existing methods only give its upper bound.