DESIGN OF A PRECISE FSO NETWORK INCLUDING IMPROVED MODIFIED REFRACTIVE INDEX STRUCTURE PROFILING FOR SHIMLA CITY, INDIA

Abstract

The most commonly used altitude-dependent Hufnagel-Valley (HV) model for Refractive-Index Structure Parameter (C_n²) calculation has limited accuracy due to the reason of not considering various meteorological parameters for mountainous locations which have negative influence on optical signals. Although altitude and turbulent winds (due to temperature and pressure variations) are significant parameters giving rise to atmospheric turbulences intensity but the presence of water droplets and snowflakes in humid climate of mountainous locations play major role in reducing optical visibility, so should not be ignored. We have included the effect of snowfall in existing HV model while calculating path loss due to atmospheric turbulences to estimate these effects in Shimla city. The computed results show considerable decrement in Q-factor due to the additional losses imposed by snowflakes to the laser beam. Enlargement in effects of absorption and scattering is also observed in bit error rate (BER) results. So, the proposed modified model presents more accurate estimation of the refractive index profile as it takes more parameters into consideration responsible for atmospheric turbulence.