本文研究快于奈奎斯特信令(FTN)系统中的无数据辅助的QPSK信号频偏估计方法.相较于奈奎斯特系统,FTN系统的脉冲会叠加的更紧密以此来提高数据速率.据此,将FTN理论应用在卫星通信系统中吸引着众多研究者的目光.然而,由于FTN系统中码间干扰是不可避免的,在接收端准确的估计出频偏变得愈加困难.为了提高估计性能,本文基于接收信号同相与正交分量交叉项与二阶差分项信息,提出一种利用快速傅里叶变换(FFT)估计频偏的方法.仿真结果证明,本文提出的方法可以准确地估计出频偏值.%In this paper,we study a non -data aided frequency -offset estimation scheme of QPSK signal for faster -than -Nyquist(FTN)signaling system.The FTN transmission would increase the data rate by overlapping the pulse closer than the Nyquist pulse.For this reason,there have been some efforts to apply FTN theory to satellite communication.However,because the FTN produces inter symbol interference(ISI),it is difficult to estimate the frequency-offset accurately at the receiver.In order to improve the estimation performance,a new frequency-offset estimation scheme is proposed,which is based on the cross term and the second order difference term information of received signal's in-phase and quadrature component and uses Fast Fourier trans-form(FFT).Simulation results show that the scheme can estimate the frequency-offset accurately.
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