Safeguarding Physical Layer Security Using Weighted Fractional Fourier Transform

In this paper, weighted fractional Fourier transform (WFRFT) is employed to safeguard the physical layer (PHY) security of wireless communications. By leveraging the features of WFRFT, we propose a PHY security modulation scheme, which significantly degrades the equivalent signal-to-noise ratio (SNR) of the unauthorized receiver while imposing no impact on the legitimate receiver. With the proposed scheme, a robust nonzero secrecy capacity can be guaranteed. Moreover, the proposed scheme can conceal the actual modulation paradigms to prevent malicious signal detection, due to the variation in signal characteristics. A higher order statistics (HOS) based classifier is used to investigate the anti- recognition performance. Meanwhile, the secrecy performance of the proposed scheme is evaluated in terms of both secrecy capacity and average bit error rate (BER) by numerical simulations. Finally, as a proof-of-concept, an all-digital field programmable gate array (FPGA) based prototype system is developed to validate the practicability of the proposed scheme.