Advances and Challenges in Physical Layer Security: A Comprehensive Review

Physical layer security (PLS) has emerged as a promising approach to enhance the security of wireless communication systems. This paper provides a comprehensive review of PLS, including its basic concepts, key techniques, and recent developments. We begin by introducing the basic principles of PLS, including the concept of secrecy capacity and the key assumptions underlying PLS. We then discuss various techniques that have been proposed to enhance PLS, such as artificial noise, cooperative jamming, and beamforming. Next, we review recent research on PLS in different scenarios, including multi-user systems, cognitive radio networks, and wireless sensor networks. Finally, we conclude by discussing future research directions and open challenges in PLS.