Multiuser Beam Tracking and Target Detection in Integrated Sensing and Communication

In this paper, radar-aided multiuser beam tracking and target detection are investigated for integrated sensing and communication (ISAC). A multiuser beam tracking scheme based on the collaboration of radar sensing and uplink communication is proposed. It is first proved that the echoes of each communication signal can be extracted from the mixed echoes of multiple communication signals, by performing point-wise division and two-dimensional discrete Fourier transform. Based on it, the scheme enables the road side unit (RSU) to perform multiuser beam tracking and target detection with only two radio frequency chains, no matter how many users are served by the RSU. To distinguish the users from the targets and further improve the beam tracking by extended Kalman filtering, uplink pilots from the users to the RSU are employed. Then the digital beamformer can be designed to mitigate the multiuser interference. Simulation results show that the proposed scheme outperforms the conventional beam tracking scheme and can approach the performance of independent beam tracking of each user.