Rain Fade on Satellite Transmission in Warri, Benin, and Abuja, Nigeria

Abstract

Rain-induced attenuation (rain fade) is one of the most significant atmospheric propagation impairments affecting the performance and reliability of satellite communication systems operating at frequencies above 10 GHz, particularly in tropical regions characterized by intense precipitation. This study investigates the impact of rainfall on satellite signal propagation in three representative Nigerian locations, Warri, Benin, and Abuja, to evaluate spatial and temporal rainfall variability and its implications for satellite communication link performance. Rainfall data for the period 2020–2021 were obtained from the Nigerian Meteorological Agency (NiMet) and analyzed using rainfall classification based on rain-rate intensity. Rain events were categorized as drizzle, widespread rain, showers, thunderstorms, and monthly rainfall accumulation; rainfall-type distribution, and frequency of occurrence were statistically analyzed in Microsoft Excel. The study further assessed the suitability of established rain attenuation prediction models, including the ITU-R P.618 model, for tropical propagation environments.
The results reveal pronounced geographical variations in rainfall characteristics, with the coastal cities of Warri and Benin recording significantly higher annual rainfall accumulations (2,670–2,842 mm and 2,018–2,313 mm, respectively) than Abuja (1,326–1,380 mm). Peak rainfall occurred during the wet season, with exceptionally high precipitation recorded in August 2021, contrary to the traditionally expected August break. Stratiform rainfall constituted the dominant rainfall type across all locations, accounting for approximately 65–85% of total rainfall by volume and frequency, thereby producing prolonged periods of background attenuation that reduce satellite link availability and Quality of Service (QoS). Although convective rainfall events (showers and thunderstorms) occurred less frequently, they generated higher rain rates that produced severe, short-duration signal fading capable of exceeding conventional fade margins, particularly in the coastal regions.
The findings demonstrate that rain fade over Nigeria exhibits strong spatial and interannual variability, making generalized global prediction models insufficient without local calibration. The study establishes that coastal satellite earth stations are considerably more vulnerable to rain-induced signal degradation than inland stations due to higher rainfall intensity and more frequent convective events. Consequently, reliable satellite communication system design in tropical environments requires location-specific rainfall statistics, adaptive fade mitigation techniques, increased fade margins for coastal regions, and site diversity strategies. The outcomes of this research provide valuable localized propagation data that can improve rain attenuation prediction, satellite link budgeting, and the overall reliability of high-frequency satellite communication systems operating in Nigeria and similar tropical climates