OFDM信号过采样率盲估计的新方法  

Novel blind estimation method for OFDM over-sampling rate

作　　者：刘明骞[1] 李兵兵[1] 唐宁洁[1] 

机构地区：[1]西安电子科技大学综合业务网理论及关键技术国家重点实验室,陕西西安710071

出　　处：《江苏大学学报（自然科学版）》2012年第1期55-59,共5页Journal of Jiangsu University：Natural Science Edition

基　　金：国家自然科学基金资助项目(60772138);国家"863"计划项目(2007AA01Z288);高等学校学科创新引智计划项目(B08038)

摘　　要：针对低信噪比多径信道下过采样率估计性能低的问题,根据正交频分复用(OFDM)基带采样信号的频谱特性,提出了基于采样信号频谱逼近的过采样率盲估计方法.该方法首先利用改进的移动协方差方法估计信号的载波频率,采用修正的周期图平均法估计信号的功率谱;然后通过选择最佳的滚降系数,设计一个最佳余弦滚降滤波器,使余弦滚降滤波器的截止频率逼近信号的截止频率;最后根据过采样信号的频谱特性原理估计出接收信号的过采样率,实现了不同类型OFDM信号的过采样率的盲估计.仿真结果表明,在信噪比为-2 dB,多径信道条件下OFDM信号的过采样率估计的均方误差不超过0.2.可见该方法无需任何先验知识,在低信噪比多径信道下具有良好的估计性能.To solve the poor performance of traditional blind orthogonal frequency division multiplexing（OFDM） over-sampling rate estimation method at low signal to noise ratio（SNR） and multi-path channel conditions,a novel blind OFDM over-sampling rate estimation method was proposed based on the spectrum characteristics of OFDM baseband sampling signals.The improved moving covariance method was adopted to estimate the carrier frequency,and to establish the power spectrum of received signal by Welch method.An optimal cosine roll-off filter was designed with an optimal roll-off factor to make the cut-off frequency of the designed filter approach that of sampling signal.The over-sampling rate was estimated based on the spectrum characteristics of over-sampling signals to realize blind estimation for different OFDM signals over-sampling rate.The simulation results show that the mean square error（MSE） of OFDM signals over-sampling rate is less than 0.2 at the conditions of-2 dB SNR and multi-path channel.The proposed method has good estimation performance at the conditions of low SNR and multi-path channel without any prior knowledge.

关 键 词：OFDM 参数估计 功率谱 载波频率 过采样率 

分 类 号：TN911.7[电子电信—通信与信息系统]