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 non-target directions. Moreover, along the non-target directions, the transmitted confidential information can be easily intercepted by the eavesdroppers. In this paper, directional modulation (DM) technology combined with OFDM waveforms namely, OFDM-DM, is proposed for ISAC systems. From the sensing perspective, the interference from the non-target direction can be suppressed, and three-dimensional (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.