Modelling Rain Attenuation Prediction for Terrestrial Links at Centimeter and Millimeter Bands Over Kenya

Abstract

The wireless sector of telecommunications networks has seen the development of more data-hungry products and services due to the industry's ongoing growth. The radio network's constrained bandwidth must support these services and products. However, radio network systems still under-utilize the frequency spectrum, particularly in the higher frequency bands, because rain substantially attenuates high-frequency signals through methods of absorption and dispersion. Prediction of rain attenuation has remained an active research problem for implementing radio links. The International Telecommunications Union Radio Sector Recommendation (ITU-R) periodically updates its model based on new research approaches that lead to better rain rate prediction models. Based on two years' worth of rainfall data, this thesis presents the cumulative distributions of rain intensity for 87 locations across various areas of Kenya. According to ITU-R standards, the rain rate with a 60-minute integration time is changed to an integration period of 1 minute. The resultant cumulative rain intensities and their relationships are evaluated against the global data published in ITU-R Recommendation P.837 and against the work in other African nations. Given that raindrops are not spherical and are flattened at the base, the results demonstrate that the specific rain attenuation for horizontal polarization is more significant than for vertical polarization. As a result, the horizontally polarized waves are attenuated more than the vertically polarized waves. Additionally, it is also determined that the ITU-R mapping of Kenya as 50𝑚𝑚/ℎ𝑟 underestimates rain attenuation in certain parts of the country and over estimates in other parts. Contour plots of specific attenuation are modeled based on the collected data and the outcomes, which reflect the true rain rate for the various locations in Kenya where these values should be used by Mobile Network Operators for link designs.