Estimation of Rain Fade Durations on Communication Links at Ka-band in Equatorial and Tropical Regions
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Date
2020
Authors
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Publisher
Begellhaouse
Abstract
Duration of rain fade events is a major parameter to be considered when designing a
communication link. Fading is a phenomenon responsible for intermittent fluctuations of radio
signals observed in the tropical region. The prevalence of rain in the tropics accounts for the
frequency of fading observed in this region. Despite, the efforts of researchers to help systems
designers give due consideration to fade mitigation techniques in other parts of the world, there
is still a dearth of fade duration data from the African equatorial and tropical regions. Hence,
this study estimates the number of fade events per fade duration interval exceeding attenuation
thresholds ranging from 1 dB to 18 dB at ka-Band (26.5 GHz−40 GHz), leading to
nonavailability of satellite systems during raining events in the African equatorial regions. The
range of fade durations is from 10 s to 5000 s. The International Telecommunication Union
(ITU-RP) propagation model and data from the Tropospheric Data Acquisition Network
(TRODAN) were used for the analysis. The eight TRODAN observatories, under the Centre for
Atmospheric Research (CAR), cover the major climatic regions in the sub-Saharan region,
namely equatorial, humid tropical and tropical zones (Geo. 4.82єN to 9.58єN). Fade duration
decreases latitudinally as the attenuation threshold increases from low to higher latitudes. The
equatorial region suffers the highest frequency of fade events while the tropical zones recorded
the lowest. In addition, the 10 s fade duration recorded the highest occurrence of fade events. The
implication is that heavy rains, causing higher attenuation, occur for a shorter time duration.
Similarly, higher attenuation depends on raindrops size and rain intensity. Consequently, the
number of fade events exceeding 1 dB threshold is higher than other thresholds with respect to
the fade duration.
Description
Keywords
Fade durations, Rain fade, Radio propagation, Rain attenuation, Tropical regions, Satellite communications, Communication links, Sub-Saharan climate