DFT-Based Multi-Directions Directional Modulation

In this letter, a physically secure multi-directions directional modulation scheme is proposed. The scheme provides an adaptive beam-width assignment, where each user is granted a different beam width based on its channel condition. The scheme can be efficiently implemented using a discrete Fourier transform (DFT)-based algorithm that divides the spatial dimension into orthogonal narrow sub-beams. Each user is assigned multiple sub-beams that satisfies its pre-set direction of transmission and beam-width requirements. The scheme preserves the secrecy properties of directional modulation algorithms, where each legitimate user is guaranteed a secure communication link to its trusted receiver. The proposed scheme is practically efficient since it can be directly implemented using a DFT-based signal processing core. 2012 IEEE.This work was supported in part by the Qatar National Research Fund (a member of the Qatar Foundation) under Grant NPRP 7-923-2-344, and in part by the U.S. National Science Foundation under Grant ECCS-1609581. The statements made herein are the sole responsibility of the authors. The associate editor coordinating the review of this paper and approving it for publication was C. Huang. (Corresponding author: Mohammed Hafez.) M. Hafez is with the Department of Electrical Engineering, University of South Florida, Tampa, FL 33620 USA (e-mail: mhafez@mail.usf.edu).Scopu