Effects Of Foggy Weather On Free Space Optical(FSO) Communication

The Free Space Optical(FSO)Communication is a high-speed wireless communication technology with high data rates and extremely secure over several kilometers.FSO system works within line-of-sight from source to destination,transmitting modulated optical(light)signals over the atmosphere to obtain broadband communications.FSO communications are attracting attention as this modern technology solves the last mile bottleneck problem of local area access networks with high bandwidth,rural broadband Internet access,low cost implementation in unlicensed spectrum,and relatively low power consumption.The performance of the FSO system is degraded by internal and external parameters.Internal parameters are wavelength,optical power,frequency,etc.,and external parameters are meteorological effects such as Fog,Rain,Snow,Haze etc.In all weather conditions Fog produces very high attenuation,which reduces the availability of FSO links at higher levels.Fog can be measured in visibility(km-1),and the fog attenuation models:Kim,Kruse,and AlNaboulsi(advection,convection)are used to convert visibility statistics into attenuation factor for performance analysis of FSO.The aim of this work is to provide information on the losses caused by the foggy weather in the FSO links.FSO links are simulated with different fog visibilities.The performance of FSO systems is analyzed at different fog visibilities using different optical wavelength windows.Opti-System software is used to simulate the effects of fog on FSO links and results are obtained by using MATLAB software.In addition,attenuation is observed in the various most commonly used optical wavelength windows:850 nm,1310 nm,and 1550 nm.We examined case studies of fog affected major cities of Pakistan:Islamabad,Lahore,Sukkur and Peshawar,and considered visibility of 1,2,3 and 7 km.The performance of FSO links in different fog visibility is analyzed by bit error rate(BER)and quality factor(Q-factor)finally concluded that as distance increases,BER increases and quality factor decreases with increasing distance.