A modified time domain interpolation method for LS channel estimation in OFDM systems  

OFDM通信系统LS信道估计的改进时域插值法

作　　者：Zhang Yenan Xu Feiyun Jia Minping 张烨楠;许飞云;贾民平(东南大学机械工程学院,南京211189)

机构地区：[1]School of Mechanical Engineering,Southeast University,Nanjing 211189,China

出　　处：《Journal of Southeast University(English Edition)》2022年第3期219-226,共8页东南大学学报（英文版）

基　　金：The National Natural Science Foundation of China(No.51975117)。

摘　　要：A modified time domain interpolation method is proposed for orthogonal frequency division multiplexing(OFDM)systems to address the problem that time domain interpolation in the least square(LS)channel estimation method based on comb-type pilots cannot choose the pilot spacing flexibly.Firstly,the estimated channel frequency response(CFR)at pilot positions in the frequency domain is obtained by LS channel estimation based on comb-type pilots,and the estimated channel impulse response(CIR)in the time domain is obtained by linear interpolation and inverse fast Fourier transform(IFFT).Secondly,the error of the estimated CIR obtained by linear interpolation is analyzed by theoretical deduction,and a method for correcting it is proposed.Finally,an estimated CFR at all subcarrier positions in the frequency domain is obtained by performing zero padding in the time domain and fast Fourier transform(FFT)on the modified CIR.The simulation results suggest that the proposed method gives similar performance to time domain interpolation,yet it does not need to meet the condition of time domain interpolation that the number of subcarriers must be an integral multiple of pilot spacing to use it.The proposed method allows for flexible pilot spacing,reducing the number of pilots and the consumption of subcarriers used for channel estimation.对于正交频分复用(OFDM)系统,针对基于梳状导频的最小二乘信道估计算法中时域插值法无法灵活选择导频间隔的问题,提出了一种改进的时域插值法.首先,使用梳状导频和最小二乘法信道估计算法得到频域的导频处信道估计值,通过线性插值和反快速傅里叶变换得到时域的信道冲击响应估计值;其次,通过理论推导分析线性插值得到的信道冲击响应估计值的误差,并提出对其进行修正的方法;最后,通过对修正后的信道冲击响应进行时域补零和快速傅里叶变换,得到频域所有子载波处的信道估计值.仿真结果表明,所提方法与时域插值法性能相似,且不必满足时域插值法子载波数为导频间隔整数倍的要求.所提方法能灵活选择导频间隔,减少导频数目和信道估计对子载波资源的消耗.

关 键 词：orthogonal frequency division multiplexing(OFDM) channel estimation linear interpolation time domain interpolation 

分 类 号：TN922.2[电子电信—通信与信息系统]