Theoretical and empirical based extinction coefficients for fog attenuation in terms of visibility at 850 nm

Free space optics (FSO) is the transmission of Infrared (IR) signals through LASER in free space with point to point link and receiving through photo diode. Now a days FSO is most preferable last mile solution. In last 15 years researchers focused for designing fog model which convert the visibility value in fog attenuation factor. In the literature two approaches, theoretical and empirical, were used for estimating fog attenuation factor. In theoretical approach fog attenuation formula were derived by using rigorous Mie scattering theory, six fog models based on theoretical approach were selected these are Kruse, Kim, Al Naboulsi advection and convection, Ferdinandov and Grabner models. These models convert the visibility statistics available on meteorological sites into predict specific optical attenuation. In empirical approaches, fog models were derived by a hardware setup form which visibility and optical power at both transmitting and receiving sides were measured statistically and a relation is obtained by applying regression analysis. Three different empirical based models were selected from the literature on the basis of their practical deployment such as continental fog, dense maritime fog and under controlled laboratory condition setup. Selected nine models including theoretical and empirical were simulated in Matlab and comparison results is discussed in this paper.