Near-Field Beam Training in THz Communications: The Merits of Uniform Circular Array
Near-Field Beam Training in THz Communications: The Merits of Uniform Circular Array
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DOI：
10.1109/lwc.2023.3234001
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发表时间：
2023-04-01
影响因子：
6.3
通讯作者：
Chen, Zhi
中科院分区：
文献类型：
--
作者：
Xie, Yuxin;Ning, Boyu;Chen, Zhi
由于太赫兹（THz）信道中视距传播分量占主导地位，波束训练被认为是一种有效的太赫兹通信波束形成策略。在菲涅耳区域中，近场效应提高了用于波束训练的码本大小，因为每个近场波束仅将辐射集中在小区域中，而不是沿着方向而不管距离如何。在这封信中，我们建议使用均匀圆形阵列（UCA）在太赫兹近场通信，受益于其在波束训练的几何优势。具体地说，提出了一个明确的模型来描述UCA的波束方向图。基于该模型，我们提出了一种用于近场波束训练的码本设计，其中预定义的训练波束旨在覆盖用户的区域。与传统的均匀线阵相比，UCA在理论上具有减小近场通信码本尺寸的优势。数值结果验证了波束形状模型的有效性，并显示了我们提出的UCA近场码书的优点。
As the line-of-sight propagation component is dominant in Terahertz (THz) channels, beam training is regarded as an efficient beamforming strategy for THz communications. In the Fresnel region, the near-field effect boosts the codebook size for the beam training since each near-field beam merely concentrates the radiation in a small area, rather than along a direction regardless of distance. In this letter, we propose to use the uniform circular array (UCA) in THz near-field communications, benefiting from its geometric advantage in beam training. Specifically, an explicit model is proposed for characterizing the beam pattern of UCA. Based on this model, we propose a codebook design for the near-field beam training, where the predefined training beams aim at covering the user's area. Compared to the conventional uniform linear array (ULA), the UCA theoretically shows the advantage of reducing the codebook size in near-field communications. Numerical results validate the effectiveness of the beam-shape model and show the merits of our proposed near-field codebook of UCA.