Behaviour of Lognormally-Distributed Differential Functions of Rain Drop Profiles over Radio Links

摘要

Rainfall attenuation is undoubtedly one of the factors to be considered in the deployment of outdoor 5G services as the system rollout becomes inevitable. In this paper, the rainfall subject is approached from the microstructure of rain drop sizes, by utilizing derivatives of the Type II Lognormal Drop Size Distribution (DSD) model. DSD measurements from three African locations - Durban, South Africa (29°52'S, 30°58'E), Butare, Rwanda (2°36'S, 29°44'E) and Ile-Ife, Nigeria (7°31'N, 4°31'E) - are investigated as first order and second order Differential Equations (DEs). General expressions representing these DEs are developed and applied to derivative scenarios for different rainfall rate categories: 20 mm/h, 60 mm/h and 110 mm/h. These scenarios represent shower events, thunderstorm events and severe thunderstorm events. Results obtained show that a good overview of DSD variations is realized from these derivatives, when compared with the measured diameter spectrum. The compared DSD characteristics at these selected locations offer an interesting perspective on the behaviour of lognormal distributions at these selected locations.