A Survey on Artificial Noise for Physical Layer Security: Opportunities, Technologies, Guidelines, Advances, and Trends

Due to the broadcast nature of wireless communications, physical-layer security has attracted increasing attention from both academia and industry. Artificial noise (AN), as one of the promising physical-layer security techniques, leverages the spatial degree-of-freedom of channels to effectively enhance the security of wireless communications. In contrast to other physical-layer security techniques, the key distinguishing feature of AN lies in its ability to generate specific interfering signals according to channel characteristics, thereby increasing the secrecy capacity by reducing the wiretap channel capacity without affecting the legitimate channel capacity. Hence, this paper provides a comprehensive and up-to-date survey of AN, including its evolution, modeling, background, applications, and future trends. Initially, we introduce the development, fundamentals, and technical background of AN. Subsequently, we review the current state of research across various AN-empowered scenarios and AN-combined technologies. Finally, we discuss open challenges and outline potential future directions for AN-aided wireless security.