An Angular Sweeping-Based Beam Training Scheme for Extremely Large Antenna Array

In the extremely large antenna array (ELAA) system, the region of near-field can’t be neglected. The far-field beam training scheme searching the optimal angle is unsuitable for the near-field. To address this problem, we begin by defining the angular support interval to represent the angular region where the signal gain is exhibited during angle beam sweeping. Subsequently, a beam training scheme with two-stage angle beam sweeping is introduced, where wide-angle beam sweeping and narrow-angle beam sweeping are performed sequentially. After the angle beam sweeping, the angular support interval can be obtained and the optimal beamforming vector is estimated. Simulation results verify the superior performance and low overhead of the proposed scheme.