中文摘要：

在高速移动正交频分复用系统（OFDM）中,信道的快速变化引起载波间干扰,降低系统性能,且使信道的准确估计变得更为困难.由于在接收端待估计的信道参数多于接收信号样点数,信道估计方程无确定解.为了解决这一问题,通常将快变信道展开为基函数叠加的近似表达形式,信道估计问题变成对展开系数的估计,待估计的参数大大减少.本文分析并比较了常用的基展开模型的特点,指出了它们的不足,并在此基础上提出一种改进的快变信道展开模型,该模型的核心思想是在过采样基础上通过基线补偿减小吉布斯效应的影响,从而减小展开误差.该模型性能与信道的统计性质无关,且在展开基的变化赶不上实际信道变化速度时,展开误差不会明显增大,优于CE-BEM,GCE-BEM,KL-MEM等模型,可用于高速移动OFDM系统的快变信道估计.

英文摘要：

In orthogonal frequency division modulation（OFDM）,channel′s variation introduces intercarrier interference,making the accurate estimation of time-varying channel more complicated.For the number of channel parametres to be estimated at the receiver is greater than that of the received signal,the equation of channel estimation has no definite solution.To solve this problem,Basis Expansion Models（BEM） are usually used to approximate the channel′s variation.The problem of channel estimation is reduced to estimate the expansion coefficients,making the number of parameters to be estimated significantly reduced.The performance of widely used BEMs are analyzed.Based on oversampling and baseline tilting,an improved BEM is proposed to reduce the effects of Gibbs phenomenon and therefore increase the expansion accuracy.The performance of the proposed BEM is independent from the channel statistics and can be used for time-varying channel estimation in OFDM systems.