A Channel Estimation and Tracking Method for OFDM Signal under High Mobile Environments

Abstract

A loss of subcarrier orthogonality in orthogonal frequency division multiplexing (OFDM) system under high mobile environments causes an inter-carrier interference (ICI) which would lead fatal degradation of bit error rate (BER) performance. To solve the problem, this paper proposes a high accuracy time domain channel impulse response (CIR) estimation and tracking method based on pilots. Firstly, the CIR for noise suppression is obtained by using the pilots in OFDM symbols based on DFT time-frequency domain transformation. Secondly, the third-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 method effectively filters the channel noise and improves the tracking performance over the fast-varying channels. Simulation results show that, the proposed method outperforms other traditional methods in terms of the channel estimation accuracy and the bit error rate. Further, the method has no complex matrix operation and has better engineering applicability than other methods.