“ASSESSMENT OF RAIN-INDUCED DEGRADATION ON TERRESTRIAL LINE-OF-SIGHT LINKS IN LAGOS AND GOMBE STATES”

In this work, rainfall data of thirty (30) years (1994-2023) for Lagos and Gombe states were used for the prediction of point rainfall rate and rain attenuation for terrestrial line-of-sight links. The prediction of rainfall rates for both locations was achieved using the Chebil rain rate model, while the ITU-R P.530-17 model was used for predicting rain attenuation. There was a significant difference in the rainfall rate because both locations are situated in different regions of Nigeria. For Lagos State, the point rainfall rate was computed to be 108.74 mm/hr at 0.01% of the time, while for Gombe, the point rainfall rate was computed to be 97.01 mm/hr at 0.01% of the time. The specific attenuation at 26 GHz for Lagos was observed to be 17.75 dB/km for horizontal polarization and 13.83 dB/km for vertical polarization, and that of Gombe was observed to be 15.86 dB/km for horizontal polarization and 12.42 dB/km for vertical polarization. At 38 GHz, the specific attenuation for Lagos was observed to be 24.97 dB/km for horizontal polarization and 21.19 dB/km and 12.42 dB/km for vertical be. The horizontal polarisation was observed to be 22.58 dB/km and the vertical polarisation to be 19.23 dB/km. The rain induced attenuation computed using the ITU-R P.530-17 model for frequencies between the range of 10 GHz and 40 GHz and path length of 1 km to 20 km yielded the following results: In Lagos, the rain attenuation for horizontal polarisation at 1km path length was computed to be between 6.11 dB and 36.03 dB, while for Gombe, it was computed to be between 5.37 dB and 32.09 dB. At 10km path length, the rain attenuation for horizontal polarisation was computed to be 22.95 dB and 124.17 dB for Lagos State, while for Gombe State, it was computed to be between 20.34 dB and 114.18 dB. At 20 km path length, the rain attenuation for horizontal polarisation was computed to be between 36.02 dB and 191.73 dB for Lagos State, while for Gombe State, it was computed to be between 32.09 dB and 176.83 dB. The results obtained in this work will aid communication engineers when designing terrestrial line-of-sight systems to have a more efficient communication system and will also provide an idea for microwave engineers on the effect of rain attenuation on high frequency band 5G networks.