MP-WFRFT and Chaotic Scrambling Aided Directional Modulation Technique for Physical Layer Security Enhancement

Directional modulation (DM) technique based on artificial noise (AN) enables the physical layer security (PLS) for wireless communications in free space. However, on one hand, the introduction of AN results in less power efficient for a DM system; on the other hand, the AN-aided DM technique is strongly dependent on the channel state information (CSI) of transceivers, which greatly limits its practical application. What is more, when the eavesdropper (EVE) is slowly approaching the legitimate user (LU) or the EVE and the LU are in the same direction, the transmission security cannot be guaranteed. To circumvent these problems, DM technique with multiple parameters weighted-type fractional Fourier transform (MP-WFRFT) and chaotic scrambling (CS) aided is proposed in this paper to realize the power-efficient and security-enhanced wireless transmissions. Then, the symbol error rate (SER), secrecy rate, robustness, and anti-interception performance of the proposed method are analyzed and simulated. The simulation results are presented to verify that the proposed method is more power-efficient than the traditional AN-aided DM schemes, and the PLS is guaranteed due to the proposed approach, albeit knowing the intended direction for an EVE.