Atmospheric Impairments and Mitigation Techniques for High-Frequency Earth-Space Communication System in Heavy Rain Region: A Brief Review

This work surveys the atmospheric impairments that affect a satellite link operating in a high-frequency band, such as Ka and Q/V bands, particularly in heavy rain regions. The impacts of hydrometeors and cloud attenuation are emphasised and discussed along with the contribution of gases and scintillation to signal fade. Also, propagation impairment mitigation techniques are reviewed from the perspective of satellite operators in heavy rain areas

Clear sky diurnal behavior of tropospheric scintillation at ku-band satellite communication in equatorial Malaysia

Tropospheric scintillation is referred to rapid fluctuation of received signal amplitude. It can cause propagation impairments that affect satellite communication systems operating at above 10 GHz of frequency. In this work, we have exploited 1 year of measured broadcasting signal data collected in Johor, Malaysia to investigate the effects of scintillation intensity on a SatCom system operating at 11.075 GHz with its links pointed towards the MEASAT-1 satellite (an elevation angle of 75.61°). We have investigated the behavior of this scintillation amplitude through the classification and analysis of a timeseries satellite broadcasting signal and have then compared the statistical results with existing scintillation prediction models. The comparison results indicate that there is a significant discrepancy between measured data and those models and that the performance of these prediction models does not appear to be satisfactory, with the exception of the ITU-R and the Ortgies Refractivity model. In addition, we have investigated the diurnal behavior of the scintillation intensity at four different periods of the day and proposed a modified Marzano model to accommodate local meteorological input parameters. The models performances are assessed against the available measurement dataset. The proposed models provide system operators and radio communication engineers with critical information on the fluctuations of tropospheric scintillation variance on the satellite signal during a typical day taken into the account of local meteorological peculiarities

Statistical and Physical Descriptions of Raindrop Size Distributions in Equatorial Malaysia from Disdrometer Observations

This work investigates the physical characteristics of raindrop size distribution (DSD) in an equatorial heavy rain region based on three years of disdrometer observations carried out at Universiti Teknologi Malaysia’s (UTM’s) campus in Kuala Lumpur, Malaysia. The natural characteristics of DSD are deduced, and the statistical results are found to be in accordance with the findings obtained from others disdrometer measurements. Moreover, the parameters of the Gamma distribution and the normalized Gamma model are also derived by means of method of moment (MoM) and maximum likelihood estimation (MLE). Their performances are subsequently validated using the rain rate estimation accuracy: the normalized Gamma model with the MLE-generated shape parameter µ was found to provide better accuracy in terms of long-term rainfall rate statistics, which reflects the peculiarities of the local climatology in this heavy rain region. These results not only offer a better understanding of the microphysical nature of precipitation in this heavy rain region but also provide essential information that may be useful for the scientific community regarding remote sensing and radio propagation

Turbulent structure of hole gas-liquid flows

The experimental investigation of medium and pulsation components of local hydrodynamic characteristics of ascending and descending vertical hole flows is the aim of the paper. As a result the base of experimental data for the method creation of the gas-liquid flow calculation has been obtained. The decrease of the slip speed in the ascending flow has been detected for the first time. The data obtained may be the base for new models of the hole flow calculation. The paper results may find their field of application in the creation of technological devices for energetics, chemical industryAvailable from VNTIC / VNTIC - Scientific & Technical Information Centre of RussiaSIGLERURussian Federatio

The relationship between ground wind direction and seasonal variation of rain attenuation at Ku band satellite broadcasting services

This study is aimed to investigate the relationship between ground wind direction and the seasonal variation of rain attenuation based on one year of weather station data recorded in Universiti Teknologi Malaysia (UTM), Johor, Malaysia. Preliminary analysis of wind direction based on monsoon seasonal and their impact on rain field advection are carried out to clarify the characteristics of rain attenuation in monsoon season. It is found that rain attenuation is not only affected by the monsoon seasonal variation but it also depends on rain field advection which can be preliminary identified from the wind direction. Such information is useful for the system operators to apply appropriate site diversity techniques during heavy rain events to reduce the system outage in this particular equatorial region

Slant Path Ka-Band Rain Attenuation Statistics In Equatorial Malaysia Obtained Using Stratiform Convective-Synthetic Storm Technique

In the design of satellite communication link,rain attenuation statistics is essential information for system designer to realistically determine link availability and provide means to combat system degradation.Due to the limitation of available measured data in equatorial regions especially for high frequencies (Ka-band and above),the prediction model is the best way to obtain rain attenuation statistics.This paper presents statistical analysis of rain attenuation at Ka-band by applying the Stratiform Convective-synthetic Storm Technique (SC-SST) model taking advantage from local weather features from rain rate time series. The study on seasonal and diurnal variability is also presented in this paper to provide good insight in the design and implementation of fade margin

Fade slope analysis for Ku-band earth-space communication links in Malaysia

Heavy precipitation severely degrades the performance of satellite communication systems operating at frequencies higher than 10 GHz. For the implementation of effective countermeasures, rain attenuation statistics are needed, second order statistics in particular. Here, the characteristics of rain fade slope are extensively investigated, exploiting one year of Ku-band attenuation measurements collected in Malaysia

Impact of link elevation angles on rain attenuation statistics in heavy rain region predicted using the synthetic storm technique

In the absence of measured rain attenuation, prediction models are the best way to estimate statistics of rain attenuation. Synthetic Storm Technique (SST) model is one of the solutions to obtain time series of rain attenuation. By using SST, we will investigate the impact of link elevation angle on the prediction models; in particular, the results show that time series of rain attenuation at low elevation angles deviate significantly from those at high elevation angles. In addition, higher frequencies show considerably higher attenuation than lower frequencies. This is particularly severe in a tropical and equatorial region where the rainfall rate is higher with respect to the temperate region

Performance of synthetic storm technique in estimating fade dynamics in equatorial Malaysia

In this paper, the synthetic storm technique (SST) is applied to 1‐minute rainfall rate collected from a rain gauge to predict the fade dynamics of the signal in an earth‐to‐satellite link in an equatorial climate location without the needs of satellite beacon measurements. The obtained results are compared with the statistics calculated from measured rain attenuation and with the ITU recommendation model. As for fade duration, a good agreement with measurements has been found together with a significant improvement in terms of prediction errors with respect to the ITU‐R model. Synthetic storm technique is also able to predict fade slope statistics fairly well and has equivalent performance of ITU‐R model