Security-enhanced directional modulation based on two-dimensional M-WFRFT

Directional modulation (DM) is one of the most promising secure communication techniques. However, when the eavesdropper is co-located with the legitimate receiver, the conventional DM has the disadvantages of weak anti-scanning capability, anti-deciphering capability, and low secrecy rate. In response to these problems, we propose a two-dimensional multi-term weighted fractional Fourier transform aided DM scheme, in which the legitimate receiver and the transmitter use different transform terms and transform orders to encrypt and decrypt the confidential information. In order to further lower the probability of being deciphered by an eavesdropper, we use the subblock partition method to convert the one-dimensional modulated signal vector into a two-dimensional signal matrix, increasing the confusion of the useful information. Numerical results demonstrate that the proposed DM scheme not only provides stronger anti-deciphering and anti-scanning capabilities but also improves the secrecy rate performance of the system.