| Summary: | Rain Attenuation can cause significant degradation of signal strength in satellite communication links operating at higher frequency bands such as Ku and Ka. The extent of degradation can be severe in the tropical regions which experience frequent heavy rainfall. While there exist models that predict rain attenuation for satellite communication links at these frequencies, many of these models are based on rainfall statistics for non-tropical regions and therefore do not provide accurate prediction for the tropical regions such as Singapore.
This thesis attempts to develop a rain attenuation model which is suitable for Singapore and, to some extent, to the tropical regions in general. This has been done by collecting rainfall data for several years, monitoring of signal strength through beacon signals received from geostationary satellites, and by developing a rainfall rate map of Singapore based on Radar reflectivity data. These inputs are used to compare the predictions of rainfall rate and slant path attenuation obtained from the existing models are then suggested and are shown to better match the measured signal attenuation values.
To mitigate the effect of rain attenuation, site diversity has also been examined in this thesis. Extensive simulations are carried out to predict diversity gain as a function of a number of parameters and a diversity gain prediction model has been evolved for Singapore. This model is shown to be simpler and more accurate than the existing models in tropical regions.
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