Optimal Rain Attenuation Prediction Models for Earth-Space Communication at Ku-Band in North Central Nigeria

Abstract

Precipitation adversely affects satellite-earth links operating at frequen cies ≥ 10 GHz. This paper evaluates five of the best performing rain attenuation models for earth-space links so as to obtain the optimal models for North Central Nigeria. The models considered are ITU-R P.618-9, Bryant, Simple attenuation, Garcia-Lopez and Svjatogor. Also, three elevation angles were considered: 55° (the look angle of most satellite receivers over the Atlantic Ocean Region (AOR) in Nigeria), 23° (the look angle of receivers over the Indian Ocean Region (IOR)) and 42.5° (the look angle of Nigeria’s communication satellite (NIGCOMSAT-1R) over the AOR). 2–4 years of 5-min integration time rainfall data was obtained from the Centre for atmospheric research (CAR), Anyigba, Nigeria. The cumulative distri bution of rain attenuation at Ku-band was predicted for circularly polarised signals at different percentages of time of the year. Results obtained showed that the ITU R P.618, Garcia-Lopez and Bryant models performed optimally in this region with attenuation values ranging from 6 to 19 dB at exceedance time percentage of 0.01% in all the stations.