CRB Optimization for Near-Field Covert ISAC Systems

In this paper, we study the beamforming design in near-field integrated sensing and covert communication systems, where the transmitter (Alice) covertly sends information to a legitimate user (Bob) and senses the target concurrently while hiding from illegal eavesdropper (Willie). Considering a perfect Willie-involved CSI scenario, we propose a beamforming optimization problem to minimize the Cramér-Rao bound for sensing parameters under the conditions of total transmit power, the minimum communication rate and covertness constraint. For this optimization problem, the global optimal solution is obtained by using the semidefinite relaxation (SDR). Compared with the near-field integrated sensing and communication (ISAC) systems without covert constraint, the numerical results verify the effectiveness and feasibility of the proposed scheme.