A Two-Stage Beamforming Design for Active RIS Aided Dual Functional Radar and Communication

Integrated dual functional radar and communication (DFRC) has been regarded as one of the most promising technologies. However, beamforming design in DFRC system is a challenge due to its nonconvexity. Inspired by the studies of active reconfigurable intelligent surface (RIS), we propose a joint transmitter and receiver design with adaptive beamforming for an active RIS aided DFRC system, where the active RIS is utilized to assist the DFRC to simultaneously detect targets and serve multiple users. Specifically, the WMMSE design criterion is exploited to design the transmit waveform of the DFRC by maximizing the sum-rate (SR) of users. Then, the Minorize-Maximization (MM) framework is derived to jointly optimize the amplification and phase shift coefficients of the active RIS. Simulation results show that when the active RIS is introduced, the SR of the system will improve greatly as compared to the scheme with passive RIS.