关键词: 正交频分复用（OFDM）, 信道估计, 离散傅里叶变换（DFT）, 迭代估计, 多普勒频移

Abstract: In Orthogonal Frequency Division Multiplexing（OFDM） systems, in order to solve the problem that the common channel estimation algorithms cannot suppress the noise in the channel impulse response within the length of cyclic prefix, an improved channel estimation algorithm based on Discrete Fourier Transform（DFT） is proposed, which works in an iterative fashion. The initial estimation of the channel is first calculated by the Least Square（LS） channel estimation algorithm based on the pilot sub-carriers. Then after IDFT, the distribution of channel impulse response in time domain can be obtained through the energy growth rate function which can be used to suppress the noise. Through the iterations, inter-carrier interference and additive white Gauss noise can be effectively depressed. Simulated with the LS channel estimation algorithm, the traditional channel estimation algorithm based on DFT and the channel estimation algorithm based on DFT with the threshold, the estimation performance of the proposed algorithm is best no matter the Doppler shift is small or large. When the bite error rate is [10-2], the system performance of the improved channel estimation algorithm based on DFT improves 3~5 dB compared with other algorithms.

Key words: Orthogonal Frequency Division Multiplexing（OFDM）, channel estimation, Discrete Fourier Transform（DFT）, iterative estimation, Doppler shift