Time-modulated FDA for physical- layer security

摘要

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.