Time‐modulated FDA for physical‐layer security

Abstract

In this study, the authors propose a time-modulated frequency diverse array (FDA) by combining time-modulated array (TMA) and FDA for physical-layer security. The proposed scheme has two-folds: first, the information codes are specifically designed for the FDA elements switching alternatively, which produces a specified directional pattern projecting the phase-modulation signal as a constellation in the desired range–angle section while distorting in other areas. Second, a switching scheme is adapted for the TMA according to the spreading sequence associated with the transmitted signal and the desired receiver position. In such a fashion, only the receiver located at the pre-specified range–angle position can demodulate the received signal successfully but the distorted signals radiated to other undesired range–angle positions will be difficult to demodulate by the eavesdroppers even if with the knowledge of the spread sequence. Numerical results show that, due to the range–angle-dependent characteristics, the proposed method offers more secure transmission performance and outperforms the traditional phased-array-based directional modulation method.