Performance analysis of rain fades on terrestrial optical and microwave earth - to satellite links

Abstract

Rain is a dominant source of attenuation at higher frequencies and consequently it degrades the system performance of microwave satellite and terrestrial links in tropical and subtropical regions. Bangladesh has a subtropical monsoon climate characterized by wide seasonal variations in rainfall and most parts of the country receive at least 2000 mm of rainfall per year. The knowledge of rain fade and its performance is essential in order to optimize system capacity and meet quality and reliability. The rain intensity data for Bangladesh is not available since it has not been measured so far. In this thesis, investigations have been carried out to find the rain fade and intensity data and their effect on the performance of terrestrial and satellite microwave links in Bangladesh. In this regard, long term rainfall data are collected from 34 meteorological stations of Bangladesh for thirteen years. The collected data are converted to 1-minute integration time rain intensity which can be used to design microwave systems in any parts of Bangladesh. The converted rain intensity data are used to estimate rain fades at C, Ku and Ka bands for both terrestrial and earth to satellite microwave links. The converted rain intensity data and ITU-R recommended rain intensity are used to estimate the deviation of rain fades at C, Ku and Ka-bands for comparison. The deviations are found to be small at lower frequency bands and are significantly higher at higher frequency bands. Performance of terrestrial and earth-to-satellite links in terms of Carrier-to- Noise (CNR) are also evaluated considering the predicted rain fades at different frequency bands operating in Bangladesh.