Directional modulation via weighted fractional Fourier transform - A way to enhance security

Wireless communication provides a wide coverage at the cost of exposing information to unintended users. Thus, the security issues in wireless communication are drawing more and more attentions. Directional Modulation (DM) is an emerging technology for securing wireless communication at the physical layer. The promising technology offers security by transmitting digitally modulated information signals along a-prior assigned directions while simultaneously distorting the constellation formats of the same signals in all other directions. In this paper, we employ weighted fractional Fourier transform (WFRFT) to enhance the security performance of conventional directional modulation. The proposed method adds extra security to physical layer communication by scrambling constellations in all directions. Therefore, the information could not be demodulated albeit with knowing the intended direction for an eavesdropper. Simulation results are presented to verify that the proposed method is much safer and has a better performance than traditional directional modulation signal.