Near-Field Wideband Beam Training Based on Distance-Dependent Beam Split
<|reference_start|>Near-Field Wideband Beam Training Based on Distance-Dependent Beam Split: Near-field beam training is essential for acquiring channel state information in 6G extremely large-scale multiple input multiple output (XL-MIMO) systems. To achieve low-overhead beam training, existing method has been proposed to leverage the near-field beam split effect, which deploys true-time-delay arrays to simultaneously search multiple angles of the entire angular range in a distance ring with a single pilot. However, the method still requires exhaustive search in the distance domain, which limits its efficiency. To address the problem, we propose a distance-dependent beam-split-based beam training method to further reduce the training overheads. Specifically, we first reveal the new phenomenon of distance-dependent beam split, where by manipulating the configurations of time-delay and phase-shift, beams at different frequencies can simultaneously scan the angular domain in multiple distance rings. Leveraging the phenomenon, we propose a near-field beam training method where both different angles and distances can simultaneously be searched in one time slot. Thus, a few pilots are capable of covering the whole angle-distance space for wideband XL-MIMO. Theoretical analysis and numerical simulations are also displayed to verify the superiority of the proposed method on beamforming gain and training overhead.<|reference_end|>
@article{zheng2024near-field,
    title={Near-Field Wideband Beam Training Based on Distance-Dependent Beam Split},
    author={Tianyue Zheng, Mingyao Cui, Zidong Wu, Linglong Dai},
    journal={arXiv preprint arXiv:2406.07989},
    year={2024},
    archivePrefix={arXiv},
    eprint={2406.07989},
    primaryClass={cs.IT eess.SP math.IT}
}