Physical layer security based on full duplex and half-duplex multi relay assisted OFDM system

ABSTRACT Broadcasting in wireless channels causes security vulnerabilities since both the intended receiver and the eavesdropper may receive the information. Physical layer security (PLS) ensures the confidentiality of information transmitted wireless medium, even in the presence of eavesdroppers, without relying on cryptographic techniques implemented at higher layers. A PLS method for cooperative relay based Orthogonal Frequency Division Multiplexing (OFDM) with optimal relay selection and power optimization is proposed. In order to increase the overall system’s secrecy rate, a hybrid relaying and water filling based optimal power allocation is performed for multi-relay assisted OFDM-based wireless networks. By changing the eavesdroppers’ distances, the performance efficiency of the proposed system is verified. The analysis is carried out for both Full Duplex (FD) and Half Duplex (HD) systems and their performances are compared with existing equal power allocation technique. The proposed method combines relay selection and novel power optimization process to improve secrecy rate than the existing power allocation methods for both HD and FD systems.