Rainfall rate and attenuation performance analysis at microwave and millimeter bands for the design of terrestrial line-of-sight radio links in Ethiopia

Rainfall is a major cause of propagation degradation in wireless communication systems at microwave and millimetre bands. While the International Telecommunications Union (ITU-R) recommends rain attenuation models based on measured rainfall and radio propagation data, the propagation model in Ethiopian context remains unstudied - with one-minute rainfall rate measurement recommended by ITU-R also unavailable. This paper thus addresses the following: the estimation of the cumulative probability distribution, giving the rainfall rate versus the percentage of time the indicated rainfall was exceeded in a year; derivation of one-minute rain rate distribution using the Rice-Holmberg (R-H) model, and then proposing the rainfall rate conversion factors for Ethiopian sites from 15-minute to one-minute integration time; developing rain rate and fade margin contour maps for Ethiopia; and modelling rain attenuation using the ITU-R method.