Siat Ling Jong

Analysis of Fade Dynamic at Ku-Band in Malaysia

This work investigates fade dynamics of satellite communication systems in equatorial heavy rain region based on a one year of Ku-band propagation measurement campaign carried out in Universiti Teknologi Malaysia (UTM), Johor, Malaysia. First order statistics of rain attenuation are deduced and the results are found to be in good agreement with those obtained from other beacon measurements gathered within the same area (Kuala Lumpur). Moreover, the fade duration and slope statistics of the satellite signal variations are also carefully derived and subsequently compared with the ITU-R recommendation model. Such information is useful for the system operator and radio communication engineer for the design of appropriate fade mitigation techniques as well as the quality of service that could be offered to the user (according to the time interval for a typical day). Further evaluation on the performances of several ITU-R models in the heavy rain region are needed based on the measurement database available of this climatic region.

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.

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.

Performance of time diversity technique in heavy rain region

Satellite communication systems operating at frequencies above 10 GHz are often subject to deep fades due to rain attenuation. One of the cost-effective countermeasures that can be used to counteract severe rain attenuation is time diversity. In this paper, performance of time diversity is investigated based on a one-year, Ku-band propagation measurement campaign carried out in heavy rain region. The results found show that the diversity gain increases as a function of time delay. The performance of time diversity is compared with prediction obtained by applying the Stratiform Convective-Synthetic Storm Technique (SC-SST) and a good agreement with measured statistics has been found.

Analysis of precipitation characteristics over Southern peninsular Malaysia for satellite propagation application

This contribution investigates precipitation characteristics in Southern peninsular Malaysia, by exploiting local meteorological measurements. Several peculiar characteristics of precipitation are derived from one year of tipping bucket rain gauge in Universiti Teknologi Malaysia (UTM), Johor Bahru. Stratiform and convective types of precipitation are investigated based on monthly distribution, and several rain rate distributions are compared for few locations; moreover, we present the statistics of seasonal and diurnal variations of rainfall rate as well as rainfall intensity. Furthermore, combined effects of both, seasonal and diurnal variations of rain rate are also presented for better representation of local precipitation characteristics. In addition, the measured rain attenuation statistics show that higher attenuation is most likely to occur during the afternoon hours from 12 pm to 6 pm. These results provide a significant information to service provider who needs to guarantee the Quality of Service (QoS) of the link service during a typical month or day by implements an appropriate PIMTs during severe rain period.

Estimation of interfade duration for Ku- and Ka-band satellite communication system in equatorial Malaysia

Knowledge of the dynamics characteristics of rain fade is important for satellite communication (SatCom) system designs since it determines the system availability as well as provides essential information for the implementation of Propagation Impairment Mitigation Techniques (PIMTs). In particular, the interfade duration due to rain - appear as one of the crucial parameter to provide estimation for the system requirements to recover in time before the next outage. In fact, this is even much more critical in tropical/equatorial region and at high frequencies (Ku-band and above). In this paper, we present an estimation of interfade duration in Ku- and Ka-band by applying the Stratiform-Convective Synthetic Storm Techniques (SC-SST) and a good agreement with measured statistic has been found. The performance of the prediction model in estimating interfade duration characteristic is evaluated quantitatively by means of figure of merit, and the result show RMS error of 0.91 for prediction at Ku-band. In addition, comparison of the SC-SST in equatorial region with the measurement results in temperate area for Ka-band clearly point out significant differences among two regions and also the needs of the measurement results for further validation activities in equatorial area.

Analysis of inter-fade intervals at Ku-band in heavy rain region

This paper aims to present a statistical analysis on inter-fade interval in equatorial heavy rain region based on one year of Ku-band propagation measurement campaign carried out in Universiti Teknologi Malaysia (UTM), Johor, Malaysia. We first present the rain attenuation statistic from both temperate and tropical region (equatorial) followed by analysis on inter-fade intervals for different thresholds as well as their diurnal variation. Statistical knowledge of inter-fade interval has significant impact in designing earth-to-satellite communication system.

Interpretation procedure of meteorological radar data for propagation application in heavy rain region

Advanced satellite communication or modern wireless systems operate at high frequencies will suffer from deep signal fades caused by rain particularly in equatorial region. Meteorological radar operates by MET department is one of the valuable resources to provide the peculiarities of the local precipitation information oriented to the analysis of radio propagation impairments. In this paper, the processing methodology and the interpretation procedure of operational weather radar data are presented from the perspective of such application. The applicability of the processed meteorological radar data is preliminary assessed against Stratiform Convective-Synthetic Storm Technique (SC-SST) in terms of first order rain attenuation statistics. The radar data simulated statistic is found to agree well with the one obtained through SC-SST. This procedure can be useful as a reference methodology for the employment of operational meteorological radar particularly focus on the propagation applications.

Evaluation of small-scale spatial distribution of rain cells in equatorial Malaysia for rain attenuation modeling

This work evaluates the spatial features of the synthetic rain cell profile based on two years of real rain cells database extracted from weather radar observation located in Kluang, Johor, Malaysia. Single rain cells modeled by an analytical exponential and Gaussian profile are evaluated and investigated based on certain features of real rain cells such as maximum rain rate and root mean square rain rate inside a single rain cell. Preliminary results indicate the Gaussian profile with a shape factor k of 1 best represents real single-peaked rain structures in this particularly heavy rain area. However, the validity of results rely highly on the resolution limitation of the database used in this work, where the commercial operating meteorological radar consists of coarse quantization resolution of rain-rate, which might misinterpret the real rain cell profile at a lower rain rate. Nevertheless, this work still provides radio engineers with useful information for the design of wireless communication systems in this particular area (heavy rain region).