非编码MPSK-OFDM系统判决指导的相位估计研究

Decision-directed phase estimation for uncoded M-PSK modulated OFDM carrier tracing

本文论及非编码MPSK-OFDM系统载波跟踪中的重要部件?判决指导的相位估计器(PED)的研究。多载波系统的相位估计可以表示为各子载波相位估计的加权和。文中在分析单载波的基础上考察了符号判决错误对多载波相位估计的影响,并提出了两种改进方案,一是给出一组新的加权系数,改善了PED在较低信噪比的性能;二是由导频子载波相位估计指导其它数据子载波相位估计,获得了(?π/Mπ/M)区间上的线性无偏估计器。文中对两种改进算法进行了分析比较和仿真验证。

The important component–decision-directed phase error detector (PED) used in carrier tracing for un-coded MPSK-OFDM system is discussed. Phase of multi-carrier system can be expressed by weighted sum of phase estimation obtained from all sub-carriers. Based on the analysis of how decision error affects on the PED in case of single carrier, two improved schemes are presented. One is presenting a new set of coefficients to combine results of PED of all sub-carriers, which can improve performance at low and moderate SNR compared to original coefficients obtained in case of no decision error. The other is using estimated phase error from pilot sub-carrier to guide the estimation of other data sub-carriers that are decision-directed, which can obtain linear unbiased estimation in range of ?π/M to π/M. Analysis, comparison and computer simulations have been conducted to show the performance of two proposed schemes.