Analysis of optical attenuation from measured visibility data in islamabad, pakistan

FSOL (Free-Space Optical Links) are becoming very popular due to the inherent advantages of high data rates, rapid deployment, portability, cost effective and immunity to electromagnetic interference. FSOL is a line-of-sight technology that uses a modulated beam of light to transmit and receive the data of multiple of Giga Bit per second. FSOL uses the free space or atmosphere as a communication channel. Optical signal launched at transmitter end, travels through the atmosphere and reaches to the receiver, is severely affected by the local atmospheric conditions. Atmosphere contains different atmospheric particulates like fog, rain, snow, smog, clouds and haze. These atmospheric particulates, particularly fog, effect the propagation of optical signal passing through the atmosphere and cause significant amount of optical attenuation. In order to deploy FSO system, a detailed analysis of local weather condition is much more important. Here, we present the measured visibility data for analysis of optical attenuation. Visibility data was measured at COMSATS Institute of Information Technology from 2009-2012. Percentage CDF (Cumulative Distribution Function) is used to find out the detailed insight about the optical attenuation of FSOL. Yearly based CDFs is compared with each other which clearly suggest that almost 99% of time optical attenuation remains within the range of 2 dB/km. (author)