Joint Transmit Waveform and Passive Beamforming Design for RIS-aided MIMO DFRC System

Abstract

This paper studies a reconfigurable intelligent surface (RIS)-aided multiple-input multiple-output (MIMO) dual-function radar-communication (DFRC) system, in which a RIS is equipped to assist wireless communication from the DFRC base station to several users and to create reflecting links for sensing targets at areas without line-of-sight (LoS) links, simultaneously. Our goal is to jointly optimize the output signal-to-interference-plus-noise ratio (SINR) at the DFRC radar receiver and the multi-user interference (MUI) at communication users. To tackle this issue, we propose an optimization method to jointly design the transmit waveform and the receive filter at the DFRC base station and the phase-shift matrix at the RIS, subject to the total DFRC transmit power. Specifically, an alternating optimization-based algorithm is proposed to solve the formulated problem after Dinkelbach's transform, where the transmit waveform and the RIS phase-shift matrix are respectively resolved by two variants of gradient projection method and the receive filter is obtained in light of the minimum variance distortionless response method. Numerical results show that the RIS-aided MIMO DFRC system can not only effectively sense the target at areas with LoS links blocked, but also improve the achievable sum-rate for multi-user communication.