Enhancing Secrecy With Random Frequency Variation in mmWave Communication Systems

In this letter, we propose a physical-layer security (PLS) scheme for millimeter-wave systems. Our scheme employs analog beamforming with random frequency variation (RFV) for transmitted symbols. We derive the exact closed-form expression of the secrecy rate of our RFV scheme. Furthermore, we verify the superior performance of RFV scheme compared to previously proposed PLS schemes. In particular, the RFV scheme provides higher secrecy rate for more than 70% of the angular range, when the bandwidth is 10% of the carrier frequency. Furthermore, there is no array gain loss at the legitimate user, compared to previously proposed PLS schemes.