基于Pilot的OFDM系统定时和频率同步算法

An Improved Timing and Frequency Synchronization Algorithm for OFDM Systems Based on Pilot

为改善系统性能,提出一种将近似最大似然法与导频相结合的方法。首先对近似最大似然法的定时函数,设定门限,以此确定一个粗时偏估计范围,再利用导频的定时函数,按一定规则,在该范围内搜索出精确的时偏,同时FFT之前记录下的对应于该时刻的频偏即为估计出的系统频偏。仿真表明,该算法能改进多径环境下的同步性能,尤其是在首径非能量最大径的环境下,提高系统的性能。

A joint approximate maximum likelihood （ML） and pilot algorithm is proposed in this paper. First, the threshold of the approximate ML timing metric is supposed to confirm a timing offset range. Second, we search the precise timing offset in the range utilizing the pilot timing metric. At the same time, the frequency offset which is registered of this time is the frequency offset in the system. Simulation results show that the proposed algorithm can improve the synchronization performance in the multi-path fading channel, especially in the condition that the first path is not the path which has maximum energy.