Ka-band satellite beacon attenuation and rain rate measurements in Singapore - comparison with ITU-R models

IEEE Trans. Antennas Propagat.

Ong³

2010

A model that is less sensitive to errors in the extreme small and large drop diameters, the gamma model with central moments (3, 4 and 6), is proposed to model the rain drop size distribution of Singapore. This is because, the rain rate estimated using measured drop size distribution shows that the contributions of lower drop diameters are small as compared to the central drop diameters. This is expected since the sensitivity of the Joss distrometer degrades for small drop diameters. The lower drop diameters are therefore removed from the drop size data and the gamma model is redesigned for its moments. The effects of the removal of a particular rain drop size diameter on the specific rain attenuation (in dB) and the slant-path rain attenuation calculations with forward scattering coefficients for vertical polarization are analyzed at Ku-band, Ka-band and Q-band frequencies. It is concluded that the sensitivity of the Joss distrometer although affects the rain rate estimation at low rain rates, does not affect the slant path rain attenuation on microwave links. Therefore, the small drop diameters can be ignored completely for slant path rain attenuation calculations in the tropical region of Singapore.Index Terms-dead-time problem, drop diameters, gamma distributions, rain, rain attenuation, rain drop size distribution.

Section: Methodsmentioning

confidence: 99%

Truncated Gamma Drop Size Distribution Models for Rain Attenuation in Singapore

Kumar

IEEE Trans. Antennas Propagat.

Ong³

2010

“…Finally, in order to calculate the rain attenuation along the slant path between the earth stations to the WINDS satellite, the path attenuation associated with each Cartesian pixel is calculated and then integrated over the length of the path in (2).…”

Section: Theoretical Formulation and Modelsmentioning

confidence: 99%

“…These heavy rainfalls can cause outage of signals and therefore, the interruption of satellite services. At a common tropical rain rate of 100 mm/hr, an attenuation of up to 10 dB per km is observed over 10 minutes in the Ka-band frequency of 20 GHz [1], [2]. In such situations, common mitigation techniques such as power control cannot be used to counteract the large signal fade.…”

Section: Introductionmentioning

confidence: 99%

Performance of Site Diversity Investigated Through RADAR Derived Results

Yeo

IEEE Trans. Antennas Propagat.

Ong

2011

Site diversity is an effective rain attenuation mitigation technique, especially in the tropical region with high rainfall rate. The impact of different factors such as site separation distance, frequency, elevation angle, polarization angle, baseline orientation and wind direction is assessed. Results are compared to those reported in existing literature and also compared to the commonly used ITU-R site diversity prediction models. The effect of the wind direction on site diversity is also presented. It can be observed that diversity gain is highly dependent on the site separation distance, elevation angle and wind direction but independent of the frequency, baseline angle and polarization angle of the signal. This study is useful for the implementation of site diversity as a rain attenuation mitigation technique.

“…Once the point rain rate, R i , is obtained, the slant path attenuation can then be derived using (2). In order to calculate the rain attenuation along the slant path between the earth stations to the satellites, the path attenuation associated with each pixel is calculated and then integrated over the length of the slant path using (2). The earth-space path attenuation A is calculated through the numerically summation of…”

Section: Theoretical Formulation and Modelsmentioning

confidence: 99%

“…To derive the site diversity model, the slant path attenuation for any path within the scanning volume of the radar is simulated using (2). In our analysis, the 45 sites labeled in Figure 1 are selected as earth stations.…”

Section: Site Diversity Gain Prediction Modelmentioning

confidence: 99%

Site diversity gain at the equator: radar‐derived results modeling in Singapore

Yeo

Ong

2014

Satell Commun Network

SUMMARYSite diversity is an effective rain attenuation mitigation technique, especially in the tropical region where high rainfall rates are common. According to our previous study, site diversity gain is found to be dependent on the site separation distance and path elevation angle while it is independent of signal frequency, baseline angle and polarization angle. Therefore, using 28 months of radar data, a simple site diversity gain prediction model is proposed. The proposed model is compared with the existing ITU-R models. The seasonal wind direction, another factor that might affect the site diversity gain prediction model, is shown to have negligible effect on site diversity gain. Triple-site diversity is also investigated, and although it is found to provide gain improvement over dual-site diversity, this gain improvement is too little to justify for the cost of setting up an additional site. This study is useful for the implementation of site diversity as a rain attenuation mitigation technique in the tropical region.