We provide a tutorial on how to create link budgets and bit error rate (BER) and probability of fade calculations for optical communications systems designed to operate in the turbulent channel. It reviews the characterization models necessary for either incoherent or coherent free space optical communications uplink, downlink, and horizontal system analyses in the turbulent channel. Beam wander, scintillation, and receiver noise variance as well as pointing and tracking effects were included in this paper. Comparisons among these models, computer simulations and field measurements are provided throughout the paper. Good agreement is shown among all. An example analysis was provided using this information. The conclusion is that no matter whether the system is incoherent or coherent and/or which signaling format is used, the scintillation index will peg the BER to constant value at high signal-to-noise ratio well above the desired value. Other turbulence mitigation techniques must be employed to get the desired system performance.

中文翻译：

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湍流中的光通信：教程

我们提供了有关如何为设计用于在湍流信道中运行的光通信系统创建链路预算和误码率 (BER) 以及衰落概率计算的教程。它回顾了湍流信道中非相​​干或相干自由空间光通信上行链路、下行链路和水平系统分析所需的表征模型。本文涵盖了光束漂移、闪烁、接收器噪声方差以及指向和跟踪效应。整篇论文提供了这些模型、计算机模拟和现场测量之间的比较。所有人之间表现出良好的一致性。使用此信息提供了示例分析。结论是，无论系统是不相干的还是相干的和/或使用哪种信令格式，闪烁指数都会在远高于所需值的高信噪比下将 BER 固定为恒定值。必须采用其他湍流缓解技术才能获得所需的系统性能。