Angle-Domain Channel Tracking for High Speed Railway Communications with Massive ULA

High speed railway communications has received wide attention in the world. The Doppler shift from the motion of train induces inter-carrier interference. Meanwhile the doubly selective channel increases the difficulty of training and beamforming. In this paper, we propose an angle domain channel tracking scheme. The base station is equipped with large-scale uniform linear antennas array (ULA) to provide high angular resolution. The spatial property was investigated to decompose channel into angular information and beam gain. The former is acquired by aligning beams towards the direction of signals, based on which the Doppler frequency offset (DFO) is compensated. The latter is tracked by using linear Kalman filter, which is optimal for minimizing the mean square error (MSE). By combing the angular information and beam gain, the CSI is recovered. Simulation results show the superiority of proposed scheme.