Beamforming and Tx power optimization for FD-ISAC with inter- and co-channel interference

Abstract

This paper studies the designs of the downlink (DL) transmit beamforming and uplink (UL) transmit power optmization for a full duplex integrated sensing and communications (FD-ISAC) system, where a FD-ISAC base station (BS) serves the DL and UL communication users (CUs) and also detects the radar target. Previous works have either excluded UL communication, avoiding the interference it introduces to DL communications and target detection, or have used the beam pattern gain as the radar performance metric in the objective function. In contrast, two optimization problems are proposed for the FD-ISAC BS that address these challenges. One is based on CU sum rate maximization subject to radar performance, and the other is based on the received radar SINR maximization subject to CUs' performance. The high complexity of the problems is tackled by applying the concave–convex procedure and quadratic transformation to the two proposed formulations, respectively. Finally, simulation results are provided under a single cell setup to illustrate the effectiveness of the proposed algorithms which converge within three to four iterations. In addition, the sum rate of the CUs and radar SINR showed doubled improvements compared to the baseline half-duplex schemes.