Orthogonal Frequency Division Multiplexing Directional Modulation Waveform Design for Integrated Sensing and Communication Systems

Orthogonal frequency division multiplexing (OFDM) signals have been widely studied as a potential waveform used in integrated sensing and communication (ISAC) systems. High-computational effort, however, is required to estimate the azimuth of the target and suppress the interference from the nontarget directions. Moreover, along the nontarget directions, the transmitted confidential information can be easily intercepted by the eavesdroppers. In this article, directional modulation (DM) technology combined with OFDM waveforms, namely, OFDM-DM, is proposed for ISAC systems. From the sensing perspective, the interference from the nontarget direction can be suppressed, and 3-D radar images can be calculated without consuming extra computational resources. From a communication perspective, the OFDM-DM signals provide a secured physical-layer wireless transmission link and thus the confidential information can be securely delivered to the target. The efficacy of the proposed OFDM-DM ISAC waveforms is validated via numerical results for both sensing and communication functionalities by comparison with the traditional OFDM ISAC waveforms.