Wireless communication for high-speed railways (HSRs) has received considerable attention in recent years. The fast time-varying and doubly selective fading properties of channels pose a substantial threat to the link performance. Meanwhile, the nonnegligible Doppler frequency offset (DFO) resulting from the high-speed motion induces intercarrier interference. In this paper, we propose an angle-domain channel tracking and hybrid beamforming scheme for HSR by investigating the time and spatial properties of channels. A large-scale uniform linear antenna array is applied at the base station to provide high spatial resolution. The DFO is compensated through beam alignment and capturing the precise angular information from signals. Then, the spatial beam gain is tracked during the angle-of-arrival time, which can be used to reconstruct the full-dimensional channel state information. Finally, the hybrid beamforming is used to realize data transmission. The key idea of tracking is, applying a linear Kalman filter to modify the time-varying beam gain, while the main idea of hybrid beamforming is utilizing nonorthogonal beams to compress the channel dimension and decrease the computational complexity. The superiority of the proposed scheme is evaluated through simulations.

中文翻译：

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高速铁路通信中的位置辅助mMIMO信道跟踪和混合波束成形：角度域方法

近年来，高速铁路（HSR）的无线通信受到了广泛的关注。信道的快速时变和双重选择性衰落特性对链路性能构成了重大威胁。同时，由高速运动引起的不可忽略的多普勒频偏（DFO）引起载波间干扰。本文通过研究信道的时空特性，提出了一种用于高铁的角域信道跟踪和混合波束形成方案。大规模均匀线性天线阵列应用于基站，以提供高空间分辨率。通过光束对准并从信号中捕获精确的角度信息来补偿DFO。然后，在到达角时间内跟踪空间光束增益，可以用来重建全维信道状态信息。最后，利用混合波束成形实现数据传输。跟踪的关键思想是应用线性卡尔曼滤波器来修改随时间变化的波束增益，而混合波束成形的主要思想是利用非正交波束压缩信道尺寸并降低计算复杂度。通过仿真评估了所提出方案的优越性。