Two-Stage Hierarchical Beam Training for Near-Field Communications

Understand

Extremely large-scale array (XL-array) has emerged as a promising technology to improve the spectrum efficiency and spatial resolution of future wireless systems.

• However, the huge number of antennas renders the users more likely to locate in the near-field (instead of the far-field) region of the XL-array with spherical wavefront propagation.
• This inevitably incurs prohibitively high beam training overhead since it requires a two-dimensional (2D) beam search over both the angular and distance domains.
• To address this issue, we propose in this paper an efficient two-stage hierarchical beam training method for near-field communications.