Estimation of link range and bit rate for 16 channel WDM-FSO considering atmospheric turbulence and pointing error under various weather conditions

To meet the increasing demand of bandwidth and speed, Free Space Optics (FSO) has been emerged as a promising wireless communication technique leading behind the conventional copper wire and fiber optic communications. The capacity of this cost-effective and rapidly deployable FSO system can be increased using Wavelength Division Multiplexing (WDM) technique. Atmospheric turbulence and pointing error are two constant phenomena in FSO that affect transmitted signal strength along with different critical weather like haze, rain, snow and fog. This paper presents a complete overview of WDM-FSO system in terms of link range and bit rate considering all the impediments of Free-Space channel i.e. how long the signal can propagate and how much bit rate the WDM-FSO system can support maintaining the acceptable value of Bit Error Rate (BER) of 10−9 and Quality factor of 6 in an atmospheric turbulent channel with pointing error under various weather conditions like haze, moderate rain and foggy weather. It is found that using 5 × 10−15 m−2/3 as the value of the index of refraction structure for atmospheric turbulence and respective maximum allowable pointing error, the maximum attainable link range is 5.4km, 3.1km and 1.1km for haze, moderate rain and fog respectively at a constant bit rate of 2.5Gbps and the maximum attainable bit rate is 9Gbps, 6.5Gbps and 2.5Gbps for haze, moderate rain and foggy weather respectively at a constant link range of 2.2km for haze and moderate rain and 1.1km for fog.