Analysis/Simulation of Unavailability of FSO Link Due to FOG in Karachi & Lahore

Abstract –– Now a day’s transmission of data using infrared light in free space through laser is keen interest of researchers as compared to traditional fiber optics and RF transmission due to its inherent advantages, such as low cost, easy to install and maintain high bandwidth in license free spectrum, Like other unguided media the local climate degrades the system performance of FSO system. The effect of fog on narrowband (780 nm to 850nm & 1529 nm to 1600 nm) transmission of FSO system is maximum due to the smaller size of particle of water as compared to rain where the size of particle is large. In our proposal of current work the two highly populated metropolitan cities of Pakistan ((i) Karachi-the city with less dense fog & (ii) Lahore-the city with more dense fog) are selected for calculation of signal attenuation due to fog. The statistical measurement of the fog for the whole year is obtained in terms of the Visibility from the secondary data available with civil aviation. On the availability of the statistical measurements the four well known fog attenuation models (i) Krus model, (ii) Kim model, (iii) Al-Naublsi advection model and (iv) Al-Naublsi convection model have been used for calculation of unavailability/ absence of the FSO link. These models have been simulated in Matlab 2011Rb for calculation of fog attenuation. Result shows that FSO is good choice for Karachi city instead of Lahore city because its climate does not degrade the signal power at long distance and availability of link is maximum. This measurement will helpful for implementation of FSO system in Climate of Pakistan.