Degradation of free space optical communication performance caused by atmospheric turbulence

In the paper the influence of turbulent atmosphere on optical power loss in transmission channel of free space optical communication link is presented. Compared to the other, previously published works, the paper presents simulations based on very complex link model containing all important parts of an optical wireless communication system. The link model allows setting of the basic parameters of laser diode, transmitting lens, laser beam, receiver lens, and parameters of photodiode and front-end amplifier of an optical receiver and also allows selection of the modulation format and many other electrical parameters. For modeling the turbulence effect on the link performance the modified Rytov scintillation theory have been used. The paper extends already published analysis of scintillation loss performed for a plane wave to a spherical wave which includes, in addition, the propagation loss. Communication link performances are calculated not only in dependence on general quantities such as scintillation index or signal to noise ratio, but they are evaluated for real link model parameters such as transmission range or power link margin.