Modelling of rain drop size distribution for microwave and millimiter wave in Central Africa

The rapid expansion of the global telecommunication has led to an exponential growth in the demand of wireless services. This has led to the migration to higher frequency bands in the microwave and millimeter wave spectrum. Research has shown that rainfall is the most dominant factor affecting the qualitative provision of network services in these bands. In this paper, the equatorial Butare-Rwanda in Central Africa (2°35' 53.88"S and 29°44' 31.5"E) characterized with voluminous levels of rainfall is investigated based on its cyclical rainfall pattern. Measurements of rain drop size distributions (DSD), have been carried out using a Joss-Waldvogel RD-80 disdrometer for a period of 32 months between 2012 and 2015 to develop a suitable model on drop size distribution in the region. Rainfall data were classified into four different regimes: drizzle, widespread, shower and thunderstorm. Different DSD models such as Lognormal, Gamma, Marshall-Palmer and Weibull distributions are selected and the method of moment technique is applied for estimating input DSD fit-parameters for those different DSD models. From results, the proposed model compare well with our rainfall measurement for different rainfall regimes.