Atmospheric Turbulence and Fog Attenuation Effects in Controlled Environment FSO Communication Links

Free-space optical (FSO) communication can be seen as a promising technology for point-to-point and back-hauling links in the next generation wireless networks (5G and beyond) where cell size may shrink to a few hundred meters. In this work, we have experimentally investigated the laser beam propagation for FSO link under atmospheric turbulence and fog conditions. A controlled atmospheric environment chamber is designed to perform experiments under varying channel conditions. For fog attenuation, we have proposed an empirical model as a function of visibility against the measured average values, for visibility range of <inline-formula> <tex-math notation="LaTeX">$0\leq V \leq1000$ </tex-math></inline-formula> m. For atmospheric turbulence, we report the measured values of the refractive index structure parameter <inline-formula> <tex-math notation="LaTeX">$C_{n}^{2}$ </tex-math></inline-formula>. The measured <inline-formula> <tex-math notation="LaTeX">$C_{n}^{2}$ </tex-math></inline-formula> is used to calculate the atmospheric coherence width along the propagation distance. This work would help in the design optimization of practical FSO links under adverse conditions like fog and atmospheric turbulence.