Learning-Based Blockage-Resilient Beam Training in Near-Field Terahertz Communications

TL;DR

This paper proposes a novel blockage-resilient beam training method for near-field Terahertz communications using Airy beams and a deep learning network, significantly reducing training overhead while effectively mitigating obstacles.

Contribution

It introduces a self-accelerating Airy beam-based approach and a lightweight attention network for efficient, blockage-resilient near-field beam training in THz communications.

Findings

Airy beams can circumvent obstacles in near-field THz communications.

The proposed AMPBt-Net predicts beam parameters with high accuracy.

The scheme reduces training overhead comparable to exhaustive methods.

Abstract

Terahertz (THz) band is considered a promising candidate to meet the high-throughput requirement for future sixth-generation (6G) wireless communications due to its ultrawide bandwidth. However, due to the high penetration loss at high-frequencies, blockage becomes a serious problem in THz communications, especially in near-field indoor communications with numerous obstacles. To address this issue, this paper investigates blockage-resilient near-field beam training based on self-accelerating Airy beam, which can propagate along a curved trajectory to circumvent obstacles. Specifically, we first analyze the trajectory of the Airy beam and the beam pattern at the receiver using a discrete Fourier transform (DFT) codebook in the presence of obstacles. Interestingly, we reveal that the beam pattern not only captures the receiver's location information but also implicitly encodes the spatial relationship between the receiver and obstacle, which facilitates identifying the optimal Airy beam configuration. Based on this insight, we formulate the blockage-resilient beam training task as a multitask learning problem and propose a lightweight attention-based multi-parameter beam training network (AMPBT-Net) to jointly predict the angle, distance, and curvature parameters of the optimal Airy beam based on the beam pattern. Finally, simulation results demonstrate that the Airy beam effectively mitigates blockage effects and the proposed scheme achieves comparable performance to exhaustive beam sweeping while significantly reducing training overhead.