一种逼近零抖动的Gardner定时误差检测算法

摘要

随着无线通信容量的提升，在频率资源紧张的情况下，为了提高整个系统的频带利用率，实现高速率传输，必须采用高阶调制，低滚降系数成型。但是高阶调制和低滚降系数成型会增大自噪声，造成定时抖动过大，容易引起失步。针对该问题研究了一种适用于高阶调制（ MQAM）和低滚降系数成型下的定时同步算法———基于预滤波的Gardner算法，仿真得到加预滤波前后的波形时域图和小数间隔收敛的抖动图，通过仿真可以清晰看到预滤波前后波形的变化及定时抖动的减小。%With the increase of wireless communication rate and the decrease of frequency resources,the high order modulation and shaping with low rolloff factor should be used to improve the spectrum utilization of the whole system and achieve high⁃rate trans⁃mission.But the high order modulation and shaping with low rolloff factor may increase the self⁃noise and timing jitting,making the sys⁃tem out of synchronization.To solve the problem,a Gardner timing⁃error detection algorithm with zero jitting is studied for high order modulation(MQAM)and shaping with low rolloff factor.The algorithm is based on pre⁃filter.By simulation,the waveform in time domain before and after pre⁃filtering and the fraction interval jitting are obtained.In these figures,the change in the waveform before and after the pre⁃filtering is shown clearly and the timing jitter is decreased significantly.