OFDM系统中基于功率延时谱的信道估计算法  

Power delay profile based estimation algorithm in OFDM system

作　　者：王钢[1] 刘晓明[1] 于迎新[1] 

机构地区：[1]哈尔滨工业大学电子与信息工程学院,黑龙江哈尔滨150080

出　　处：《华中科技大学学报（自然科学版）》2014年第2期91-95,共5页Journal of Huazhong University of Science and Technology(Natural Science Edition)

基　　金：总装备部'十二五'装备预研项目(513060502)

摘　　要：在多径时变信道环境下,以IEEE802.11a物理层规范为背景,根据多径延时对最小均方误差(MMSE)估计得到的频率响应进行最小二乘估计,从而得到更加精确的信道估计值.接收机首先通过对训练序列和导频符号做MMSE估计得到初步信道估计结果,再对其做快速反傅里叶变换(IFFT)并求解线性方程组,得到信道冲击响应;然后由接收机根据信道功率延时谱来对冲击响应进行最小二乘估计(LSE),从而消除残留白噪声对冲击响应估计值的影响;最后对结果进行傅里叶变换(FFT)后得到各子载波的频率响应.仿真结果表明:在所采用的典型的二径瑞利时变信道模型下,相较于MMSE算法,最小二乘估计能够更精确地估计信道频率响应,当最大多普勒频移增加时,其抗误码性能明显优于MMSE算法.Based on IEEE802 .11a physical standard and multipath time-varying channel , a novel method by using LSE （least-squares estimation ） on the result of frequency response which gets from the MMSE（minimum mean square error） estimation to yield a much more accurate frequency response was proposed .First ,the receiver taken MMSE estimation on training symbols and pilot ,and then taken FFT （fast Fourier transformation）on the MMSE estimation value and solved a system of linear equations to obtain the impulse response of channel .According to the power delay profile ,a LSE was performed on impulse response to eliminate the effect of remaining w hite noise .Finally ,frequency re-sponse on subcarriers was attained using FFT .Simulation results show that for the typical two-path time-varying channel this paper adopted ,LSE method can obtain a more accurate estimation on chan-nel frequency response .When max Doppler-shift is rising ,LSE can gain a significant performance than MMSE method .

关 键 词：多径时变信道 信道估计 最小均方误差 最小二乘估计 导频分布 minimum mean square error (MMSE) LEAST-SQUARES estimation (LSE) 

分 类 号：TN911[电子电信—通信与信息系统]