基于傅里叶系数插值的短波信道迭代频偏估计  

Iterative Frequency Offset Estimation for High-Frequency Channel Based on Interpolation Using Fourier Coefficients

作　　者：游行远 杨平[2] 徐彬彬[2] 

机构地区：[1]哈尔滨工程大学信息与通信工程学院,黑龙江哈尔滨150001 [2]武汉船舶通信研究所,湖北武汉430079

出　　处：《华南理工大学学报（自然科学版）》2015年第1期53-58,共6页Journal of South China University of Technology(Natural Science Edition)

基　　金：船舶工业国防科技预研基金资助项目(11J3.4.2)~~

摘　　要：针对短波突发通信中存在的频偏问题,结合短波调解器的波形格式以及低信噪比的信道条件,提出了一种基于傅里叶系数插值的迭代频偏估计算法.该算法首先利用离散傅里叶变换(DFT)确定频谱峰值;然后对其结果进行Jacobsen插值,通过对插值结果进行误差分析,得出其方差与训练序列长度及信噪比的函数关系,并依此自适应调节其置信度为0.99999时的置信区间,将其作为精频偏估计的搜索区间;最后在搜索区间内进行迭代,并利用抛物线插值获取更精确的结果.仿真结果表明:对于长度为128、256、512的训练序列,在低信噪比条件下,文中算法均可逼近Cramer-Rao下界(CRLB),特别是在信噪比为0 d B时,两次迭代即可使算法的均方误差与CRLB的比值达到1.005左右.In order to overcome the frequency offset existing in short-wave （namely high-frequency, HF） burst-mode communication, an iterative frequency offset estimation algorithm on the basis of interpolation using Fourier coefficients is proposed, which takes into consideration the waveform of HF modem under low signal-to-noise ratio （SNR）. The proposed estimator is tackled in several stages. Firstly, a coarse estimation of peak frequency is made by the application of discrete Fourier transform （DFT）. Secondly, Jacobsen＇ s method is used to interpolate DFT sam- ples, and a bias analysis of the interpolating results is carried out. Then, variance as a function of SNR and training sequence length is obtained, and a confidence interval with a confidence coefficient of 0.999 99, which is used as the searching interval of frequency offset estimation, is adaptively adjusted. Finally, a combination of parabolic interpolation is made with the iterative method to obtain an accurate result through the interval. Simulated results show that the proposed algorithm helps achieve Cramer-Rao low bound （CRLB） at low SNR with the training sequences equal to 128, 256 and 512. Especially, at 0 dB, the estimator＇s mean square error is about 1.005 times that of CRLB only with two iterations.

关 键 词：迭代频偏估计 误差分析 置信区间 离散傅里叶变换 抛物线插值 

分 类 号：TN911.23[电子电信—通信与信息系统]