超大型天天天线阵列近战地宽带波束成型 (Near-Field Wideband Beamforming for Extremely Large Antenna Array)

from arxiv, The near-field beam split effect, which is a fundamental difference between large antenna array and extremely large antenna array, is revealed and addressed. We also define a more accurate metric called effective Rayleigh distance to divide the near-field and far-field. Simulation codes will be provided after publication: http://oa.ee.tsinghua.edu.cn/dailinglong/publications/publications.html

Extremely large antenna array for wideband communications is a promising technology to achieve a Tbps data rate for next-generation communications. However, due to the extremely large bandwidth and antenna array aperture, the near-field beam split effect will severely decrease the actual transmission rates, which has not been investigated in existing works. To solve this challenging problem, we first reveal the near-field beam split effect and analyze the corresponding array gain loss. Then, a piecewise-far-field model with piecewise-linear phase property is proposed to approximate the near-field channel, based on which we propose a phase-delay focusing method to effectively mitigate the near-field beam split effect. Moreover, a new metric called effective Rayleigh distance is defined, which is more accurate than the classical Rayleigh distance to distinguish the far-field and near-field regions for practical communications. Finally, theoretical and numerical results are provided to demonstrate the effectiveness of our methods.

翻译：宽带通信极大型天线阵列是实现下一代通信Tbps数据率的极大天线阵列是一项很有希望的技术,然而,由于带宽和天线阵列孔径极为庞大,近地波束的分裂效应将大大降低实际传输率,而现有工程尚未对此进行过调查。为了解决这一具有挑战性的问题,我们首先揭示近地波束的分裂效应,分析相应的阵列增益损失。然后,提出一个带有小针线性相位属性的片段远地模型,以接近近地通道,在此基础上,我们提出一个分阶段聚焦方法,以有效减轻近地波波束的分裂效应。此外,还定义了称为有效雷利距离的新的指标,该指标比古典莱利距离更准确,以区分远地和近地区域的实际通信。最后,提供了理论和数字结果,以证明我们方法的有效性。