Abstract: In terms of the deficiencies of channel estimation algorithm based on the Complex Exponential Basis Expansion Model（CE-BEM） in Orthogonal Frequency Division Multiplexing（OFDM） systems under doubly-selective fading channels, this paper proposes a new channel estimation algorithm based on windowed basis expansion model. The algorithm can be applied to reduce spectrum leakage which exists in CE-BEM through the time domain windowing and de-windowing processing, and suppress the influence of doppler shift to estimation performance. The mathematical model is simplified by using the designed pilot scheme；and then the estimated coefficients of CE-BEM are converted by orthogonal projection, and further improve the channel estimation accuracy. Besides, the Normalized Mean Square Error（NMSE） and Bit Error Rate（BER） are used to measure the channel estimation performance. Experimental simulation results demonstrate that the proposed algorithm can effectively improve the channel estimation performance in mobile environment with high speed.

Key words: Orthogonal Frequency Division Multiplexing（OFDM）, Doubly -Selective Fading Channels, channel estimation, Basis Expansion Model（BEM）, spectrum leakage

摘要： 针对双选择衰落信道下OFDM系统中基于复指数基扩展模型（CE-BEM）的信道估计算法存在的不足，提出了一种基于加窗的基扩展模型信道估计算法。该算法通过时域加窗和去窗处理来减少CE-BEM存在的频谱泄露，并抑制多普勒频移对估计性能的影响；利用设计的导频方案，简化数学模型；再通过正交映射对估计的基扩展模型系数进行转换，从而进一步提高信道估计的精确度。同时采用归一化均方误差和误码率来衡量信道的估计性能，实验仿真表明，提出的算法在高速的移动环境下能有效提高估计性能。

关键词: 正交频分复用, 双选择衰落信道, 信道估计, 基扩展模型, 频谱泄露