复杂多径信道下的OFDM抗干扰同步算法

An Antijaming OFDM Synchronization Algorithm under Complicated Multipath Fading Channels

时间、频率同步是正交频分复用(Orthogonal Frequency Division Multiplexing,OFDM)系统的关键技术之一。针对存在干扰的复杂多径信道场景,本文提出了在一个OFDM符号内利用两个重复的恒包络零自相关序列进行时间频率同步的新方法。该方法通过在频域生成训练序列并进行时域加窗,减小干扰的影响;通过设置相对门限值和多个相关峰联合判决,提高定时同步性能;利用相关值进行频偏估计,减小干扰对频率同步的影响。仿真表明,该方法能够有效地提高系统的同步精度与抗干扰能力,适用于存在干扰的复杂多径信道环境。

Time and frequency synchronization is one of the key technologies of OFDM（ Orthogonal Frequency Division Multiplexing） systems. In order to achieve desirable synchronization performance under complicated multipath fading channels with jamming,we propose a new antijamming OFDM synchronization method,for which the training sequence is composed of two repetitive Constant Amplitude Zero Auto Correlation（ CAZAC） sequences within one OFDM symbol. For this proposed method,the training sequence is generated in frequency domain,and windowing is perfomed in time domain to reduce the influence of jamming. The relative threshold and several correlation peaks are jointly used to improve the performance of timing synchronization. Meanwhile,the carrier frequency offset is estimated based on the correlation value to reduce the influence of jamming on the frequency synchronization. Simulation results show that this proposed novel method can improve the synchronization accuracy and the antijaming capability. Therefore,it can work well in complicated multipath channel environments with jamming.