Novel channel estimation model for OFDM in time-varying channel

A new channel estimation method for orthogonal frequency division multiplexing (OFDM) system with large subcarriers and serious intercarrier interference (ICI) is proposed. The channel frequency-domain (CFD) matrix of each delay path is factorized to the product of a diagonal delay matrix and a circular ICI matrix in this model. To reduce the coefficient number, the circular ICI matrix is squeezed by using Hamming-window as the reshaping pulse in the transmitter. Meanwhile, the elements of the diagonal delay matrix are approximated with a discrete prolate spheroidal basis expansion model (DPS-BEM). A least-square (LS) estimator is used to estimate the reduced channel coefficients. The proposed method is theoretically derived and simulated. The simulation results indicate that the model has good performance and is appropriate for various channel environments. The method also has low complexity and good spectral efficiency.