Rain Drop Size Distribution and Variability of Specific Rain Attenuation for Indian Climate

The demand of cellular data is expanding its capacity multifold due to exponential growth of traffic in the cellular network, which requires to achieve the very high data rate and large bandwidth by shifting from current frequency spectrum (below 10 GHz) to mm wave range (30 GHz to 300 GHz) spectrum. Rain plays a very important role in attenuation and depolarization of radio signals at mm wave frequencies due to rain drop size distribution. The rain drop size distribution in tropical climate follows the log-normal rain drop size distribution (RDSD) compared to the exponential RDSD in temperate climate. In this paper, the variability of rain drop size spectra based on the log-normal RDSD model of Indian climate have been described and compared with other tropical climatic region. The variability of the specific rain attenuation at mm wave range has been estimated based on log-normal RDSD model from 10 GHz to 100 GHz. In this paper, the variability of specific rain attenuation in mm wave region is described for Indian tropical climate, which shows less attenuation of radio signals at 100 GHz compared to 60 GHz during heavy rainfall event beyond 30 mm/hrs.