The Channel Estimation and Tracking over Fast Time-varying Channel for OFDM Systems

In order to meet future communication system requirements, channel estimation and tracking over fast time- varying Channels is crucial. In this paper, channel estimation and tracking scheme based on pilots is proposed for Orthogonal Frequency Division Multiplexing (OFDM) systems. Firstly, the channel estimation for noise suppression is obtained by using the pilots in OFDM symbols based on DFT time-frequency domain transformation. Secondly, the second- order loop filter is applied to the time-domain channel estimation. Subsequently, the channel tracking and iterative equalization are carried out symbol-by-symbol. The proposed scheme effectively filters the channel noise and improves the tracking performance over the fast-varying channels. Simulation results show that, the proposed scheme outperforms other traditional methods in terms of the channel estimation accuracy and the bit error rate. Further, the scheme has no complex matrix operation and has better engineering applicability than other methods.