Seasonal investigation on prediction accuracy of atmospheric turbulence strength with a new model at Punalkulam, Tamil Nadu

Abstract

Atmospheric parameters strongly affect the performance of free space optical communication systems when an optical wave is propagating through an inhomogeneous turbulence transmission medium. Developing models to get an accurate prediction of the turbulence strength (Cn2) according to meteorological parameters becomes significant to understand the behavior of the channel in different seasons. A dedicated free space optics link for the range of 0.5 km at an altitude of 15.25 m is established and explained. The power level and beam centroid information of the received signal with meteorological parameters at the same time are continuously measured using the optoelectronic assembly and developed weather station, respectively, and stored in a data logging computer. The existing models selected, based on exhibiting relatively less prediction error, for comparative analysis are briefed. Measured meteorological parameters (as input factors) and Cn2 (as a response factor) of size [2000×4] are used for linear regression analysis and to design the empirical models more suitable at the test field. Along with the model formulation methodologies, the contributions of the input factors’ individual and combined effects on the response surface and coefficient of determination (R2) estimated using Analysis of Variance tools are presented. Model equation-V (R2=98.93%) is finalized for predicting Cn2. In addition, the prediction accuracy of the proposed and selected models for different seasons in a one year period are investigated and validated in terms of the sum of absolute error (SAE). The average SAE of 0.000641×10−9 m−2/3 for Cn2 is achieved using the new model in a longer range dynamic of meteorological parameters during different local seasons.