ASSESSMENT OF THE SCATTERING EFFECTS ON TERRESTRIAL FSO LINK IN A TROPICAL WEATHER CONDITION, WITH LAGOS
Abstract
Abstract
The increasing demand for high-speed and reliable communication systems has necessitated the exploration of alternative technologies beyond conventional radio frequency (RF) systems. Free Space Optics (FSO) has emerged as a promising solution due to its high bandwidth capacity, cost-effectiveness, ease of deployment, and immunity to electromagnetic interference. However, the performance of FSO systems is significantly affected by atmospheric conditions, particularly in tropical regions where rainfall is prevalent. This study investigates the effect of rainfall-induced scattering on terrestrial FSO links, using selected locations in Lagos State, Nigeria (Badagry, Eko, Epe, Ikeja, and Ikorodu) as case studies.
Rainfall data spanning ten years (2011–2020) with 30-minute integration intervals were obtained from the GIOVANNI database and converted to 1-minute integration time using the Burgueno model. Statistical analysis of rainfall rates was conducted to determine cumulative distribution and specific attenuation across the study areas. The results indicate that rainfall intensity plays a critical role in signal degradation, with most rainfall events falling within the 0–10 mm/hr range, although higher intensities contribute significantly to attenuation.
The study revealed that Ikorodu experienced the highest specific attenuation (29.7 dB/km), followed by Epe (29.1 dB/km), Eko (27.4 dB/km), and both Badagry and Ikeja (27.1 dB/km). Furthermore, attenuation levels at link distances of 0.5 km and 1 km exceeded acceptable thresholds, reaching up to 138 dB in some locations at 0.01% exceedance probability. These findings demonstrate that heavy rainfall in tropical environments can severely degrade FSO link performance and even cause signal outages.
The study concludes that rainfall-induced attenuation is a major limiting factor for FSO deployment in tropical regions. It recommends that network designers incorporate sufficient link margins and adaptive techniques to mitigate weather-related impairments. The findings provide valuable insights for telecommunications engineers and policymakers, particularly in optimizing broadband deployment strategies in regions with high rainfall intensity.
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