OFDM系统改进的训练序列结构及时频同步算法

Improved training sequence structure and timing and frequency synchronization algorithm for OFDM system

提出了一种改进的基于Zadoff-Chu(ZC)序列的正交频分复用(Orthogonal Frequency Division Multiplexing,OFDM)系统时频同步算法。该算法构造了一个具有共轭重复关系结构的训练序列,首先利用时域训练序列前后的共轭特性完成定时同步,同时得到整数倍频偏估计,使定时结果不受频率同步性能影响,然后在获取精确的定时同步之后利用训练序列的重复性完成小数频偏估计。理论分析和仿真结果表明,在高斯信道和多径信道下,改进算法的定时估计和频偏估计均方误差较低,同时扩大了整数和小数频偏估计范围,降低了系统计算复杂度。

An improved timing and frequency synchronization algorithm based on Zadoff-Chu(ZC)sequence for OFDM system is proposed.The algorithm constructs a training sequence with conjugate repetition relationship.Firstly,the timing synchronization is completed by utilizing the conjugate characteristics of the training sequence in time domain,and the integer frequency offset(IFO)estimation is obtained directly,not affected by the frequency synchronization performance.Then the fractional frequency offset(FFO)estimation is done using the repeatability of the training sequence after timing synchronization.Theoretical analysis and simulation results show that the improved algorithm′s timing and frequency offset estimation mean square error is lower,the integer and fractional frequency offset estimation range is expanded,and computational complexity is reduced.