Joint Subcarrier Mapping with Relay Selection-Based Physical Layer Security Scheme for OFDM System

Abstract

Providing secure communication between the wireless networks is a major issue. Particularly, providing confidentiality is the major concern in the multiple relay assisted wireless networks. Generally, conventional cryptography methods are being adapted to provide various security services. But the conventional encryption techniques cannot be always used in wireless devices, where the resources such as power and energy are limited. However, physical layer security is a recently emerging technique to provide security in wireless networks. In this work, a novel physical layer security scheme for orthogonal frequency division multiplexing (OFDM) with joint relay selection, and subcarrier mapping is proposed to improve the secrecy rate. To improve the systems secrecy rate, the proposed technique selects the optimal relay from among the available N relays for subcarrier mapping. The best channel gain between source and relay is mapped with the best channel gain between relay and destination in subcarrier mapping. In order to improve the secrecy rate further, the optimum power allocation is performed to allocate the power for subcarriers at the source node and relay node. Simulation results show that the proposed method outperforms existing method in terms of secrecy and confidentiality. Also the proposed method provides good secrecy rate even at low transmitted power with nearby eavesdropper.