多径信道下ZP-OFDM信号的时域参数盲估计

摘要

针对低信噪比多径信道下,零前缀正交频分复用(zero prefix orthogonal frequency division multiplexing,ZP-OFDM)信号时域参数估计精度低的问题,提出了一种改进的ZP-OFDM信号时域参数盲估计方法.该方法首先计算信号的功率自相关函数,并利用小波消噪及平滑滤波对其进行预处理,通过检测峰峰值距离的方法完成符号总长度的估计.然后计算单位符号总长度数据的幅度平方值并对其进行小波分解与重构,设定门限提取一个零前缀估计值.最后通过多段数据联合估计确定最终的零前缀估计长度.仿真实验结果表明,在低信噪比多径信道条件下,提出ZP-OFDM信号的时域参数盲估计方法具有良好的估计性能.%In view of poor performance of traditional blind estimation methods for zero prefix orthogonal frequency division multiplexing (ZP-OFDM) time-parameters, especially in low signal-to-noise ratio (SNR) and multipath channels, a novel blind estimation method is proposed. Firstly, the power autocorrelation function is calculated and then the pretreatments of wavelet de-noising and smoothing filtering are operated, the symbol duration is estimated by detecting of the distance between two peaks. Secondly, the amplitude square values for the received data length of unit symbol duration are calculated and then the wavelet decomposition and reconstruction are operated. The adaptive threshold is set to extract the estimated zero prefix (ZP) length. Finally, the final ZP length is decided by joint estimation of multiple segment data. Simulation results show that the proposed methods have the superior performance in low SNR and multipath channel conditions.