一种适用于多径衰落信道的OFDM定时同步算法

A Novel OFDM Timing Synchronization Algorithm in Multipath Fading Channel

提出一种新的正交频分复用定时同步算法,该算法深入研究了在多径衰落信道中第1径不是最强径的情况下,滞后的离散傅里叶变换(DFT)窗定时导致的符号间干扰影响系统性能的问题,通过采用本地产生伪随机噪声(PN)序列与接收信号进行求相关的方法,很容易分离出每条径并搜索到最强径.同时考虑到通常第1径处于深衰落的时间不会持续很长,采用Alpha滤波器,对定时度量函数起到平滑平均的作用,并且进一步引入前向搜索窗以及门限的概念,能准确定位出第1径的位置,大大提高了定时算法的准确概率,因而该新定时算法非常适用于多径衰落信道.

This paper proposes a novel training symbol-based orthogonal fraquency division multiplexing (OFDM) timing synchronization algorithm. This algorithm analyzes the problem of discrete fourier transform (DFT) window timing with error away from cyclic prefix in multipath fading channel where the first path is not the strongest one. In this case the intersymbol interference (ISI) is resulted by the multipaths arriving at the receiver ahead of the strongest path. This new timing algorithm can easily separate different paths and find the strongest one. Considering the fact that the duration of the first path in deep fading will not last for a long time, Alpha filter is applied in timing metric to achieve averaging effect. Moreover search window and threshold are introduced to easily find out the first path at any situation with low complexity and high timing correct probability. This novel timing algorithm is very suitable for wireless multipath environments.