Group-pilot-aided time-varying channel estimation for high-speed railway OFDM system

Doppler expansion generated under high mobility is represented by equivalent time-varying channel, which tends to destroy the orthogonality of OFDM system. As a result, the OFDM system experiences significant inter-carrier interference (ICI). The channel estimation, based on Basis Expansion Model (BEM), turns time-varying channel estimation into estimation of basis function parameters, which are estimated by pilot-assisted method. However, in the case of high mobility, severe ICI could give rise to increased error of basis function parameters, which may worsen performance. Based on the analysis of the power distribution of ICI, this paper presents the time-varying channel estimation based on frequency pilot-aided method. Simulation findings show that, compared with traditional comb-type BEM methods, the method proposed in this paper can effectively reduce ICI and improve the performance of time-varying channel estimation. ©, 2015, Science Press. All right reserved.