频率选择性衰落信道下的同步参数联合盲估计算法

Blind Estimation Algorithm of Synchronization Parameters in Frequency-Selective Fading Channels

对于多径频率选择性衰落信道以及低信噪比环境下线性调制信号的同步参数盲估计问题,提出基于循环累积量的载波频偏、初始相偏和符号定时误差前向联合盲估计算法。通过理论推导得出多径频率选择性衰落信道下信号的循环累积量与初始相偏和符号定时误差的数学关系。在此基础上先以较大频率间隔进行粗估计确定频偏范围,再以较高精度遍历检测信号特定循环频率,提高载波频偏估计精度,进而由累积量值估计出初始相偏和符号定时误差,不依赖于信道衰落和加性噪声的分布特性,尤其适用于频偏、相偏、定时误差和信道衰落同时存在的复杂情况。仿真结果表明,该算法能有效实现低信噪比和多径频率选择性衰落信道下对线性调制信号同步参数的联合盲估计。

To realize blind estimation of synchronization parameters of linearly digitally modulated signals in multipath fading channels and low signal-to-noise ratio（SNR）,ajoint algorithm for the estimation of carrier frequency offset,phase offset and symbol timing error based on cyclic cumulation is proposed.The mathematical relationships of cyclic cumulation and phase offset,symbol timing error are obtained through theoretical derivation.Based on this,the carrier frequency offset is roughly estimated firstly,then the quite precise estimation is obtained from the test of certain cycle frequency.Flinally,the phase offset and symbol timing error are estimated from the value of some certain cyclic cumulation.The algorithm do not rely on the color and distribution characteristics of the fading distortion or additive noise and is quite appropriate for complex condition that frequency offset,phase offset,time error and fading exist at the same time.Experimental results demonstrate the good performance of blind estimation of synchronization parameters in frequency selective fading channels under low SNR.