RIS-Aided Low Complexity Waveform Design for Joint Sensing and Communications

In this chapter, we aim to devise an efficient reconfigurable intelligent surface-aided joint sensing and communication (JSAC) system that minimizes hardware complexity. We implement this system using a simplified analog architecture comprising a phase-shifting network and a variable gain amplifier. The innovative design of our system leverages multiple antennas at the transmitter to facilitate concurrent communication with multiple downlink users while detecting radar targets. To ensure optimal performance, we engineer the transmit waveform of our JSAC system to minimize downlink multiuser interference, simultaneously achieving the desired radar beam pattern and satisfying architecture-specific constraints. This results in a nonconvex optimization problem. To that end, we present an efficient primal-dual algorithm to solve the problem. The numerical results highlight the superior performance of our proposed approach compared to the prevailing state-of-the-art fully digital method and the advantage of using RIS for such systems.