Outdoor wireless communication is subject to several outdoor environment conditions. Among them, atmospheric turbulence which happens on a daily basis, introduces signal fading and degrades the system performance. Many channel models have been proposed in the literature to model the turbulence fading in free space optic (FSO) communication systems. In this work, we aim to evaluate the performance of some key proposed channel models for FSO systems under weak turbulence condition. First, an outdoor experimental setup is utilized to measure the turbulence fading and build a dataset. The setup is all-optical, which gives us the advantage of isolating the solar radiation noise during measurements. Second, the obtained dataset is used to investigate the performance of five key FSO channel models claimed to perform well under weak turbulence conditions. The results show that for very weak turbulence with scintillation index (SI) $<10^{-3}$, four models that claim to work well under such condition failed to fit the dataset. For weak turbulence with SI$>10^{-3}$, all the models fit the dataset except I-K model. Third, we exploited the obtained dataset to propose a new empirical channel model that has good performance under weak turbulence conditions. Using this model, we studied the outage probability of FSO system under the joint effect of weak turbulence and fog attenuation.

室外无线通信受多种室外环境条件的影响。其中，每天都会发生的大气湍流会引入信号衰减并降低系统性能。在文献中已经提出了许多信道模型来对自由空间光学（FSO）通信系统中的湍流衰落进行建模。在这项工作中，我们旨在评估在弱湍流条件下FSO系统的一些关键建议通道模型的性能。首先，利用室外实验装置测量湍流衰落并建立数据集。该设置是全光学的，这为我们提供了在测量过程中隔离太阳辐射噪声的优势。其次，获得的数据集用于研究声称在弱湍流条件下表现良好的五个关键FSO通道模型的性能。$<\mathrm{1个}{0}^{-3}$，声称在这种条件下可以正常工作的四个模型无法拟合数据集。使用SI用于弱湍流$>\mathrm{1个}{0}^{-3}$，除IK模型外，所有模型均适合数据集。第三，我们利用获得的数据集提出了一个新的经验通道模型，该模型在弱湍流条件下具有良好的性能。使用此模型，我们研究了在弱湍流和雾气衰减共同作用下的FSO系统的停机概率。