Improved ITU Model for Rainfall Attenuation Prediction of in Terrestrial Links

Rain attenuation is one of the main detrimental effects on the performance of wireless telecommunications systems operating in frequencies above 10 GHz. Mitigation of its impacts requires, among other things, the use of rain attenuation models adequate to local climatic characteristics in which the communications systems will be implemented. In this paper, a modified version of the ITU-R Recommendation ITU-R.P.530-17 prediction method is proposed. The model maintains the concept of the distance correction factor used in the ITU-R model, but considers the full rainfall rate distribution. To derive the model, a nonlinear regression adjustment is performed based on results from measurements carried out in temperate and tropical climate. Subsequently, a fine-tuning of the model parameters is carried out using the computational intelligence technique, Particle Swarm Optimization (PSO). The accuracy of the proposed model, evaluated by the root mean square error (RMSE), is higher than that of several tested models for unavailability percentages of time in the range from 0.001% to 0.1%.