ISAC system assisted by RIS with sparse active elements

Abstract In this paper, we consider an integrated sensing and communications system assisted by a reconfigurable intelligent surface (RIS). A small number of sparsely placed active sensors are applied in the RIS to perform effective channels and, thereby, enable optimized beamforming for both objectives, namely, establishing reliable communication links with users (CUs) effectively localize targets. The time-varying multipath between CU as well channel targets estimated exploiting interpolated Hermitian Toeplitz covariance matrix followed direction-of-arrival estimation using MUSIC algorithm. Based on such results, jointly optimize transmit beamformer at base station unit-modulus passive beamformer. is maximize its minimum beam-pattern gain towards desired angles subject signal-to-noise ratio requirement CU. Simulation results verify effectiveness proposed approach, performance different sparse array configurations compared.