  The beam squint phenomenon in massive multi-input and multi-output wideband
communications has been widely concerned recently, which generally deteriorates
the beamforming performance. In this paper, we find that with the aid of the
time-delay lines (TDs), the range and trajectory of the beam squint of a
near-field communications system can be freely controlled, and hence it is
possible to reversely utilize the beam squint for user localization. We derive
the trajectory equation for near-field beam squint points and design a way to
control the trajectory of these beam squint points. With the proposed design,
beamforming from different subcarriers would purposely point to different
angles and different distances such that users from different positions would
receive the maximum power at different subcarriers. Hence, one can simply find
the different users' position from the beam squint effect. Simulation results
demonstrate the effectiveness of the proposed scheme.
