标题： 太赫兹通信的混合场六维可动天线：信道建模与估计 显示英文标题

标题： Hybrid-Field 6D Movable Antenna for Terahertz Communications: Channel Modeling and Estimation

摘要： 在这项工作中，我们研究了一种六维可动天线（6DMA）增强的太赫兹（THz）网络，该网络通过控制基站（BS）上天线表面/子阵列的三维（3D）位置和3D旋转来支持大量用户，而只需少量天线。然而，由于太赫兹信号的短波长与较大的6DMA运动范围相结合，扩展了近场区域。因此，一个用户可能相对于某个6DMA表面的天线处于远场区域，同时相对于其他6DMA表面的天线则处于近场区域。此外，由于候选位置-旋转对之间的功率分布不均以及太赫兹频段中射频（RF）链数量有限，6DMA太赫兹信道估计面临着计算复杂度和导频开销增加的问题。为了解决这些问题，我们提出了一种高效的混合域广义6DMA太赫兹信道模型，该模型考虑了各个6DMA表面内的平面波传播以及不同6DMA表面间的球面波传播。此外，我们还提出了一种低开销的信道估计算法，利用方向稀疏性构建所有潜在天线位置-旋转对的完整信道图谱。数值结果显示，所提出的混合域信道模型实现了接近真实近场信道模型的总速率，并证实了信道估计算法能够以较低复杂度获得准确的结果。 显示英文摘要

摘要： In this work, we study a six-dimensional movable antenna (6DMA)-enhanced Terahertz (THz) network that supports a large number of users with a few antennas by controlling the three-dimensional (3D) positions and 3D rotations of antenna surfaces/subarrays at the base station (BS). However, the short wavelength of THz signals combined with a large 6DMA movement range extends the near-field region. As a result, a user can be in the far-field region relative to the antennas on one 6DMA surface, while simultaneously residing in the near-field region relative to other 6DMA surfaces. Moreover, 6DMA THz channel estimation suffers from increased computational complexity and pilot overhead due to uneven power distribution across the large number of candidate position-rotation pairs, as well as the limited number of radio frequency (RF) chains in THz bands. To address these issues, we propose an efficient hybrid-field generalized 6DMA THz channel model, which accounts for planar wave propagation within individual 6DMA surfaces and spherical waves among different 6DMA surfaces. Furthermore, we propose a low-overhead channel estimation algorithm that leverages directional sparsity to construct a complete channel map for all potential antenna position-rotation pairs. Numerical results show that the proposed hybrid-field channel model achieves a sum rate close to that of the ground-truth near-field channel model and confirm that the channel estimation method yields accurate results with low complexity.