Abstract: Based on summing up traditional Discrete Fourier Transform（DFT） for channel estimation in OFDM systems，a new channel estimation algorithm for OFDM systems based on Windowed the fourth Discrete Cosine Transform（WDCT-Ⅳ） is proposed.The algorithm eliminates edge effect using the DCT transform’s symmetrical characteristic，and restrains the spectral leakage of the channel impulse response through adding the frequency domain windowing，and then a low pass filter is used to reduce the AWEN interference.Simulation result shows that the technique is effective and the system performance is improved more significantly than estimation based on DFT under the multipath fading channels.Therefore，this algorithm is practical and powerful for channel estimation.

Key words: Discrete Fourier Transform（DFT）, the fourth discrete cosine transform, channel estimation, Orthogonal Frequency Division Multiplexing（OFDM）

摘要： 在总结传统的基于离散傅里叶变换（DFT）的正交频分复用（OFDM）系统的信道估计算法的基础上，提出了一种新的基于加窗型的第四类离散余弦变换（DCT-Ⅳ）的OFDM系统的信道估计算法。该算法利用DCT变换的对称特性消除边缘效应，并且使用加窗抑制信道冲激响应的频谱泄露，然后用低通滤波器消除信道高斯白噪声的干扰。仿真结果表明：在多径衰落信道下，该算法优于基于DFT的信道估计算法，是一种可行而且有效的信道估计算法。

关键词: 离散傅里叶变换, 第四类离散余弦变换, 信道估计, 正交频分复用