Cloud attenuation

Severe tropical weather dynamics impairments on the earth-sky signal quality at the Ku-band relative to temperate weather increase the demand for land mobile satellite (LMS) channel characterization and modeling specific to tropical regions. Variation in weather dynamics decreases the accuracy of the existing LMS channel models if applied to the tropics. This paper presents a tropical weather-aware LMS channel model that can be applied at areas with diverse atmospheric (rain, clouds, and tropospheric scintillation) and mobility impairments. The proposed tropical-LMS channel (TRO-LMSC) model is designed based on actual experimental measurements conducted in a tropical area. The TRO-LMSC model involves multipath design, mobility model, rain impairment model, cloud impairment model, tropospheric scintillation model, and link budget module (LBM). The proposed model shows improved channel modeling accuracy and comprehensiveness with relatively less root mean square error (rmse), compared with existing models. Consequently, this improvement enhances the identification of the type and performance of the fade mitigation technique, the management of available communication resources, and the reliability and efficiency of the communication services.

—Cloud impairments have significant effect on signal propagated in the satellite to land stationary terminals channel at frequencies above 10 GHz. With the recent satellite to land mobile terminals network technologies and services that use these frequencies, there is a lack of channel impairments modeling and analysis for such type of link. This study presents a reliable channel model of satellite-to-land mobile terminals that consider dynamic cloudy weather impairments. The cloud's dynamic parameters and their effect on the Rician factor are modeled. The model involves modules that design multipath signals, direct clear line-of-sight (LOS) normalized signals, and cloud impairments. Results show that a considerable change occurs in the performance of the signal propagated through the cloud. The change appears as deviations in the fade depth and the variance of the propagated signal in the link between the satellite and the land mobile terminals. The channel model is a realistic approach to the link characteristics, which satellite systems designers should consider when designing high data rate satellite systems.

As the scarcity of the radio spectrum implies difficulties in the earth-space communication link (ESCL) especially in satellite communication, it is necessary to estimate the amount of attenuation to ensure efficient utilization of the spectrum. By the scarcity in the frequency spectrum, the coming era will demand more data to be transferred at certainly more speed. And, this will demand for the higher frequencies. Keeping in mind the end goal to exploit present day space communications innovation, acknowledgment of a household correspondence satellite systems with impressive communication link at Ku-band is attainable. Climate is exceptionally unverifiable and labile hydrometeor activities make issue in a satellite communication. The real issue connected with the communication links at these high frequency radio waves is the rain attenuation estimation. In this thesis, a productive approach to gauge rain and cloud attenuation is discussed especially to give better execution at 12--40 GHz band. A comparative analysis of rain attenuation estimation models at 12--40 GHz band over ESCL have been carried out at real urban communities of India by considering information of NSS-6 satellite. The conclusion is made at last considering different rain and cloud attenuation models, and the most reliable model has been considered for the satellite link budget computation.

At frequencies above 10 GHz, cloud attenuation in equatorial climate is one of the components that need to be characterized for low-availability satellite links. In addition to annual and worst month cumulative cloud attenuation, the statistics of seasonal and diurnal variations are required for providing detailed insights
into system design. The authors present the cloud occurrences observed during different months, seasons and cloud attenuation results obtained from Penang, Malaysia, for a period of 5 years. A comparison of the present results with the results obtained from the existing models is also presented.

This paper presents the impact of cloud on free space optical signal in the guinea savannah region of Nigeria. The study was based on the total columnar content of cloud, liquid water density in the cloud and the average surface temperature obtained at three locations: Jos (9.896 0 N, 8.858 0 E), Lafia (8.506 0 N, 8.522 0 E), and Markurdi (7.732 0 N, 8.539 0 E) within the guinea savannah region using the ITU-R (2009) recommendation on cloud attenuation. Results on cloud attenuation were determined at a frequency of 12GHz at different elevation angles (5 0 , 15 0 , 25 0 , 50 0 , 75 0 , and 90 0). At 5 0 elevation angle, cloud attenuation was determined to be 3.97dB while at 90 0 , elevation angle, cloud attenuation was found to be 0.358dB using the same specific attenuation coefficient (0.231(dB/km)/(g/m 3)) and total columnar content of cloud (1.5 kg/m 2) for 1% of the year. From the results obtained, it was discovered that signal and power losses due to cloud on the free space optical signal is more pronounce when the elevation angle is low (below 45 0) at high frequency. This study will enable satellite communication operators to determine the optimum satellite transmission frequency and elevation angle at which there will be the least effect of cloud within the study area.