Channel Emulation of Satellite-to-Ground APD-based FSO Link in the Presence of Atmospheric Turbulence Fading

Free Space Optics (FSO) is emerging frontier technology in the field of ground-space communication that offers significant benefits in direction of expanding the information bandwidth. Wireless optical links are challenged by atmospheric weather processes and especially atmospheric turbulence, which is solely addressed in the current work. Considering atmospheric channel prototyping and turbulence simulations, laboratory characterization of FSO feeder links allowing tests of high-end components and technologies is carried out. In order to evaluate satellite-to-ground optical downlinks using a state-of-the-art APD receiver with Trans-Impedance Amplifier (TIA), self-developed FSO channel emulator implementing optical-fiber-based variable attenuator is utilized. Furthermore, the input scintillation data are modelled based on vast atmospheric radiosonde observation databases together with applying Log-normal and Gamma-Gamma FSO channel modelling. This leads to precise characterization of the used APD-TIA photodetector under test whose performance is measured with a high resolution oscilloscope and a bit error rate tester. Consequently, by means of this proof of concept, atmospheric scintillations and their negative influence over satellite-to-ground laser communication scenarios are evaluated without involving real near-Earth test campaigns.