On the Similarity of Sidelobes Signal Embedding in DFRC Systems and Directional Modulations

Dual Function radar communication systems (DFRC) allow the two functions of radar sensing and information transmission to be performed jointly. When the radar beam is paramount to the sensing function, embedding the communication signals can be performed along the beam sidelobes. Designing multiple beams which exhibit desired common main beam shape and width and different sidelobe complex values at the different user positions is referred to as DFRC sidelobe signal embedding. Except from maintaining the main beam intact and satisfying a mandatory sidelobe level threshold constraint, sidelobe signal embedding at core amounts to directional modulation (DM) which puts more emphasis on communication security. In this paper, we tie in these two independently developed areas in radar and communications and compare them, in their basic forms, in relation to security. We examine the difference in signal constellations received by the intended users and eavesdroppers. The bit error rates are used to highlight the respective performance.