Location-Aided mMIMO Channel Tracking and Hybrid Beamforming for High-Speed Railway Communications: An Angle-Domain Approach

Abstract

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.