A Multiparameter Time Varying Channel Estimation method for High-Speed Trains Communications

In this article, we propose an uplink channel estimation scheme for high-speed railway communication systems. Through the radio remote unit (RRU) at the trackside, the base station (BS) communicates with the mobile relay (MR) at the top of the train, and the transmitted signal is affected by multipath and Doppler frequency offset (DFO). To counter the impact of multipath and DFO when the spatial resolution is insufficient, the relatively slow varying channel parameters are jointly estimated based on multiple received pilots. In order to utilize the possible similarity of channel parameters during multiple pilot transmissions, the Dirichlet process (DP) is introduced to model the time varying channel estimation problem, and the expectation maximization (EM) method is used to solve the problem. In E step, the path gains of the propagation paths are estimated jointly. In M step, the DFOs of the propagation paths are estimated. Based on the estimated path gains, time delays and effective DFOs are extracted. The simulation results verify the advantages of the proposed method.