Evaluation of Rain Attenuation Models in Satellite Links under Tropical and Equatorial Climates

Attenuation induced by rain is the most relevant propagation effect in satellite communications at frequencies above 10 GHz. Recent research suggests that classical and widely accepted prediction models, such as ITU-R P.618-11 and Crane, do not perform well at intense rain regime found in tropical regions. Over the last decade, several models formulated specifically for equatorial and tropical climate were proposed. This paper summarizes some of the new rain attenuation models, describing its parameters and applications. The models were tested comparing predicted attenuation values to measurements available at the ITU propagation data bank (ITU DBSG3), taken from 10 locations over the Brazilian territory. The prediction error evaluation was carried out according to the ITU Recommendation P.311. The evaluation results show that some of those prediction methods can provide better accuracy than ITU-R P.618-11 for climates found in Brazil. The use of these models satellite link budget planning can lead to a target reliability while avoiding the over dimensioned systems.