Rain profile characterization and rain effect analysis of land mobile satellite based on measurement in Malaysia
Precipitation affects modern satellite communication operating above 10 GHz frequencies causing deep signal fades, particularly in equatorial regions. Many studies had considered the Fixed Satellite Services (FSS), however recent studies show that the same conditions in FSS cannot be applied for Lan...
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| Main Author: | |
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| Format: | Thesis |
| Language: | English |
| Published: |
2022
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| Subjects: | |
| Online Access: | http://eprints.utm.my/id/eprint/101708/1/MohammadIbrahiemAboPSKE2022.pdf |
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| Summary: | Precipitation affects modern satellite communication operating above 10 GHz frequencies causing deep signal fades, particularly in equatorial regions. Many studies had considered the Fixed Satellite Services (FSS), however recent studies show that the same conditions in FSS cannot be applied for Land Mobile Satellite (LMS) systems, as the LMS has completely different characteristics. The receiver of LMS is moving in complex environments where optimal propagation conditions are rarely fulfilled. Past studies on the LMS channel at Ku band and above considered exclusively the attenuation coming from the multi-path effect along the route. Nevertheless, limited attention has been considered to model tropospheric effects on the LMS. Thus, the present study aims to explore the LMS propagation channel operating at Ku and Ka bands, by addressing the problem of rain attenuation for mobile receivers in equatorial Malaysia. Investigated utilizing two years of meteorological radar observation in Kluang, Johor to obtain the rain rate time series for the area. Then the attenuation time series at Ku and Ka band frequencies are calculated. The attenuation results are then verified with link operating at Ku band at 12 GHz of a beacon experimental data to the satellite MEASAT-1, and a Ka band link data operating at 20 GHz, to the satellite Syracuse 3A. A statistical approach has been chosen and a modelling approach has been presented and detailed. The proposed approach builds upon well-established research on rain attenuation time series. Fixed and mobile cases are then simulated to assess the model effectiveness in estimating strong signal fades in equatorial regions. Additionally, we have reported a method to scale the cumulative distribution function, for a given attenuation exceeded in fixed terminals, to that for a given attenuation exceeded in mobile terminals, using simulated city patterns and simulated freeways. the scaling factor for different speeds and probability of directions was presented, ranging between 0.36-0.8 and is 20 percent higher in comparison with temperate regions. The speed of the mobile receiver was modelled as a lognormal random variable. In all cases, the results can be considered frequency-independent. We found that in inner-city roads results depending on movement speed modelling and starting conditions. While in freeways attenuation can change significantly in different straight lines and opposite directions. The movement of rain cells was also considered and a simulation over the radar coverage area was carried with multiple mobile terminals within it. More than three hundred thousand different rain intensity values are generated during the simulation. It was observed that the terminals' disconnection ratio increases with rain intensity almost monotonically. However, for high rain intensities (above 50 mm/h) the exceedance probability is low (around 10−4). Nonetheless, 10 percent of the terminals become disconnected even at relatively low rain intensities (around 20 mm/h). It is shown that this propagation study may provide significant aid, in LMS system simulations and the design and optimization of fade mitigation techniques (FMTs). This work also shows that the LMS system requires unique treatment when designing such systems, taking into account that the channel modelling should study the mobility and the rainfall effects concurrently. |
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