M.S. Pontes

Unified method for the prediction of rain attenuation in satellite and terrestrial links

In this paper, a semi-empirical method for the prediction of rain attenuation in slant paths and terrestrial links is proposed. The method uses the same simplified model of equivalent rain cell that is the basis for the ITU-R rain attenuation prediction methods but, additionally, the concept of an effective rain rate is introduced. This allows the use of the full rainfall rate distribution for the prediction of the rain attenuation distribution and the unification of the slant path and terrestrial links prediction algorithms. The numerical coefficients in the method’s expressions were derived by multiple non-linear regressions using the experimental data currently available in the ITU-R data banks. Test results indicate that the proposed method provides significant improvement over the current ITU-R methods.

Review of Rain Attenuation Studies in Tropical and Equatorial Regions in Brazil

This paper presents a review of rain attenuation studies based on measurements performed since 1987 in tropical and equatorial regions of Brazil. The terrestrial measurements include long term measurements for frequencies between 11 and 38 GHz at 20 links. The satellite measurements have been performed in the Ku band using radiometers and beacon receivers at 10 sites

Rainfall induced satellite beacon attenuation on three 12 GHz links in equatorial and tropical Brazil

This paper presents the results for the statistical analysis of rainfall induced attenuation on three satellite beacon links located in the equatorial and tropical regions of Brazil. The results and database obtained during the course of this study may be of help in the design of cost-effective satellite communication systems in regions subjected to heavy rainfall regimes.

Fade slope statistics for three 12-GHz satellite beacon links in Brazil

The fade slope is defined as the rate of increase or decrease of attenuation over time. The possible correlation between the statistics of fade slope values and attenuation levels is investigated. Results show a direct positive correlation between the mean values of fade slope and the attenuation levels. The distributions of fade slope values present a degree of skewness toward the negative values that makes the curves depart from the Gaussian distribution observed by other authors.

Slant path rain attenuation synthesizers for tropical and equatorial regions

In tropical and equatorial areas, the terrestrial telecommunications infrastructure is less developed than in temperate regions and there is a strong need to implement satellite communication systems in the next few years. These systems have the advantage of serving wide regions with a short deployment time and the possibility to reach a large market size for economic profitability. For new consumer applications, C-band is unattractive because the deployment of new systems with small terminals is incompatible with the large antennas required to protect the existing systems.

Modeling of effective rainfall rate based on attenuation measurements in converging terrestrial links

In this paper, the statistical characterization of the effective rainfall rate parameter is investigated based on the cumulative distribution of measured signal attenuation in converging links with different path lengths, spatial orientations and operation frequencies. Results indicate that the lognormal distribution provides the best fit for the effective rainfall rate. Also, an empirical expression for the effective rainfall rate as a function of path length and link orientation was obtained.

Modified rain attenuation prediction method considering the effect of wind direction

The method currently recommended by the ITU-R for the prediction of rain attenuation in terrestrial line-of sight links considers an equivalent path length over which the rain intensity is assumed to be constant. In other methods, the spatial and temporal variations of the rainfall rate along the path are characterized by an effective rainfall rate that is dependent on the actual path length. Based on experimental measurements, this paper presents a modified effective rainfall rate method that includes the prevailing wind direction during rainy conditions as an additional parameter for the prediction of rain attenuation. The wind direction, which can be obtained from meteorological databases with global coverage, is shown to significantly improve prediction accuracy.

New method for the prediction of rain attenuation in terrestrial links using the concept of effective rainfall rate

A semi-empirical method for the prediction of rain attenuation in terrestrial links is presented in this paper. The proposed method is simple to apply and uses the concept of an effective rainfall rate and the full rainfall rate cumulative probability distribution to predict the attenuation distribution. Test results indicate that the proposed method provides significant improvement over the current ITU-R method and other methods available in the literature.

Influence of wind direction on rain attenuation in terrestrial line-of-sight links

In this paper, the influence of wind direction on rain attenuation is investigated based on concurrent measurements of rainfall rate and signal attenuation in converging links with different path lengths, spatial orientations and operation frequencies. A simple but efficient method for predicting the cumulative distribution of rain attenuation in terrestrial line-of-sight links is derived.

An Improlved Method For Slant Path Rain Attenuation Prediction

This paper presents a rain attenuation prediction method that uses the complete point rainfall rate cumulative probability distribution as !input data to calculate the attenuation distribution, in an equi-probability basis. The motivation foir this effort was the recognition that the most commonly used prediction method, the one currently recommended by the CCIR, was developed with basis on a limited amount of data measured in temperate climates and offers poor results when applied to sites in tropical and equatorial regions. It was found that some improvement can also be obtained for temperate climates, taking advantage of the larger set of experimental results now available in the CCIR data bank.