On Physical-Layer Security of FDA Communications Over Rayleigh Fading Channels

In this paper, we investigate frequency diverse array (FDA) antenna for physical-layer security and analyze the system performance (i.e., average secrecy capacity and secrecy outage performance) over independent but not necessarily identical distributed Rayleigh fading channels. A single-antenna multiple-channel receiver structure is proposed to address the time-variance property of FDA antenna. The transmitter allocates part of its power to send artificial noise (AN) so as to ensure the security of communications, such that the channels other than the desired receiver's are degraded. Specifically, we derive the closed-form expressions for average secrecy capacity, probability of nonzero secrecy capacity, and secrecy outage probability, respectively. The correctness of the proposed analysis is corroborated via simulations. Furthermore, the corresponding asymptotic expressions for average secrecy capacity and secrecy outage probability in high signal-to-interference-plus-noise ratio (SINR) regime are also provided, respectively, to have deep insights into the performance of the considered system. Numerical results show that the FDA communications significantly outperforms the phased-array (PA) scheme in range dimension for secure communication.