Near-Field ISAC: Beamforming for Multi-Target Detection

This letter develops multi-target detection in near-field (NF) integrated sensing and communication (ISAC) systems. Specifically, the base station (BS) operates in full-duplex mode to sense the environmental information from the targets while communicating with the users. To minimize BS transmit power and to satisfy communication and sensing rate targets, we design optimal transmit beamforming (for communication and sensing) and reception beamforming at the BS. We develop an iterative beamforming algorithm to solve the resulting non-convex optimization problem. Compared to the traditional far-field benchmark, the proposed NF approach with 255 BS transmit and reception antennas uses
$\sim {1118}\%$
(or
$\sim {6}~{\mathrm {dBm}}$
) less BS transmit power to satisfy the required rate requirements. Furthermore, our proposed approach provides precise multi-target location estimates, emphasizing the advantages of NF sensing.