Long-term rain attenuation probability and site diversity gain prediction formulas

Simple models for long-term induced rain attenuation on a slant path and site diversity gain are presented in this work. As verified by numerous tests against the ITU-R databank and other data from the literature, the proposed models exhibit a very good performance. The novel slant path rain attenuation prediction model compared to the ITU-R one exhibits a similar behavior at low time percentages and a better root-mean-square error performance for probability levels above 0.02%. Moreover, comparing the proposed site diversity gain model with other widely accepted models from the literature, an improved performance is observed for distances less than 15 km, while the model performs equally well for greater distances. Furthermore, a sensitivity test between the proposed and Hodge´s formula with respect to the separation distance D is also carried out. While the lower limit of the proposed model is found to be D=1.7 km, its extension covering large-scale site diversity is successfully compared with experimental data coming from Japan. The set of presented models exhibits the advantage of easy implementation with little complexity and is considered useful for educational and back of the envelope computations.