Cumulative Distribution Of Rain Attenuation Research Articles

COMPUTATION OF RAIN-INDUCED ATTENUATION AT CENTIMETRIC WAVE BAND FOR SLANT PATH COMMUNICATION IN NORTH CENTRAL NIGERIA

In this paper, five globally recognised rain attenuation models for slant path communication are considered in order to compute the amount of attenuation and obtain the optimal rain attenuation models for North Central region of Nigeria. The models are Bryant, Garcia-Lopez, ITU-R P.618-9, Simple Attenuation and Svjatogor. These models were evaluated at Ku and Ka-bands and at three elevation angles of 55o, 42.5o and 23o. 5-minute integration time rainfall data obtained from the Tropospheric Data Acquisition Network (TRODAN), Anyigba, Nigeria was converted to 1-minute integration time using Lavergnat and Gole rain rate model. Predictions were made for circularly polarised signals at different percentages of time of the year. The cumulative distribution of rain attenuation computed showed that attenuation values generally ranged between 9 and 19 dB at time percentage exceedance of 0.01% for the Ku-band, while it ranged between 21 and 41 dB at 0.01% for the Ka-band. Also, computations by the Garcia-Lopez and Bryant models were in agreement with the ITU-R P.618-9 model, while the Simple Attenuation and Svjatogor models underestimated the computed rain attenuation values at every percentage of time in all the stations considered

Development of software for Ku-Band signal availability due to rain attenuation

<span>Ku-Band signal is often used for satellite communication mainly for direct to home (DTH) broadcasting. One of the major issues using this band is that the signal will be affected by raindrops. Raindrops absorb and scatter signal that operates at a frequency of more than 10 GHz. However, studies have been done to predict and measure the rainfall rate and rain attenuation. The rain attenuation in Ku-Band range and the rain rate were measured at satellite receiving dish, pointed towards the orbital slot 91.5 E over a one-year period in 2013. The cumulative distribution of rain rate obtained as well as a cumulative distribution of rain attenuation obtained are presented and compared with the rain prediction models. The aim is to get the best model to be used for the purpose of software development. It was found out that the DAH prediction model is fairly equitable when compared to direct satellite dish receiving measurements in Malaysia. The model provided a suitable baseline in developing a user interface software for weather prediction.</span>

Rain Attenuation Prediction Model for Satellite Communications in Tropical Regions

This paper proposes a model for predicting rain attenuation in the tropical region. Slant path rain attenuation measurements were carried out in Singapore by analyzing the beacon signals from two satellites, namely WINDS and GE23, operating at frequencies of 18.9 and 12.75 GHz, respectively. Rainfall rates at the location of the beacon receivers were recorded. The cumulative distributions of the rainfall rate and the corresponding rain attenuation are presented and analyzed. It is found that the cumulative distribution of the measured rainfall rate is close to that predicted by the ITU-R model. Measurement data from a total of nine countries are compared with four existing rain attenuation prediction models, namely the Yamada, DAH, Karasawa, and Ramachandran models. Results show that although three of these models have relatively good prediction capability for the tropical region, they could be improved. Therefore, in this paper, a slant path rain attenuation model suitable for the tropical region is proposed. This is done by using the complementary cumulative distributions of rain attenuation for satellite links measured in Singapore and five other tropical countries. The proposed model is found to outperform exisitng models.

Analysis of rain attenuation prediction models at Ku-band in Thailand

The performance of the existing rain attenuation models in tropical zones is still a debated issue due to the lack of measurements reported from these areas of the world to develop and validate prediction models. A three-year (2003–2005) campaign of rainfall rate and rain attenuation measurements was conducted on a satellite beacon link located in a tropical region of Thailand. The cumulative distributions of rain attenuation derived from the measured data are presented and compared with those obtained with existing prediction models.

Terrestrial rain attenuation time series synthesizers for tropical regions

The aim of this paper is to present and validate rain attenuation time series synthesizers relying on the Maseng-Bakken principle for terrestrial links in tropical areas. Data obtained in experimental measurements at four links operating at 15 GHz in São Paulo, Brazil, are used to parameterize the synthesizers. Two models are tested with respect to long-term statistics including cumulative distributions of rain attenuation, fade durations and fade slope.

Determination of rain attenuation from electromagnetic scattering by spherical raindrops: Theory and experiment

[1] The forward scattering amplitudes for the spherical raindrops are determined for all raindrop sizes at different frequencies by using the Mie scattering theory. The real parts of the extinction cross sections are used to generate power law models at different frequencies. These are integrated over different established raindrop-size distribution models to formulate rain attenuation models. Using the developed rain attenuation models with 5 year rain rate statistics at R0.01 determined in previous work, the specific rain attenuation is computed. The experimental results obtained from the horizontally polarized signal level measurements recorded in Durban for different rain attenuation bounds are compared with the theoretical results. Finally, the best theoretical model is used to estimate the seasonal cumulative distribution of rain attenuation for Durban, South Africa.

Calculation of the Dynamic Input Parameter for a Stochastic Model Simulating Rain Attenuation: A Novel Mathematical Approach

The Maseng-Bakken model simulates rain attenuation induced on a microwave link, and it accepts as input three parameters: the first two coincide with the parameters belonging to the conditional lognormal cumulative distribution of rain attenuation while the third one-called the dynamic parameter hereafter-should be assigned appropriately so that the model reflects some particular dynamic properties of rain attenuation. Thus far, the dynamic parameter has been calculated with emphasis on the simulation of the spectral density function of rain attenuation. This in turn, does not necessarily imply that the Maseng-Bakken model also simulates other crucial statistical features of rain attenuation such as Fade/Inter-Fade Duration Statistics. In this paper, we demonstrate a novel mathematical algorithm that gives the optimum value for the dynamic parameter so that the Maseng-Bakken model approximates simultaneously both second-order and hitting time statistics, with the latter being quite similar to Fade/Interfade durations. The algorithm is exemplified through the simulation of rain attenuation affecting a satellite channel which operates at 20 GHz and connects Athens with Hellas-Sat 2. The results show that the optimum value for the dynamic parameter is much more "sensitive" to hitting time statistics-and probably to fade durations statistics as well-than it is to the spectral density function of rain attenuation.

Rain Attenuation at 58 GHz: Prediction versus Long-Term Trial Results

Electromagnetic wave propagation research in frequency band 58 GHz was started at TESTCOM in Praha due to lack of experimentally obtained results needed for a realistic calculation of quality and availability of point-to-point fixed systems. Rain attenuation data obtained from a path at 58 GHz with V polarization located in Praha was processed over a 5-year period. Rainfall intensities have been measured by means of a heated siphon rain gauge. In parallel, rainfall intensity data from rain gauge records was statistically processed over the same year periods as the rain attenuation data. Cumulative distributions of rainfall intensities obtained as well as cumulative distributions of rain attenuation obtained are compared with the calculated ones in accordance with relevant ITU-R recommendations. The results obtained can be used as the primary basis for the possible extension of the ITU-R recommendation for calculating rain attenuation distributions up to 60 GHz. The obtained dependence of percentages of time of the average year on the percentages of time of the average worst month is also compared with the relevant ITU-R recommendation. The results obtained are discussed.

RAIN ATTENUATION PREDICTIONS AT KU-BAND IN SOUTH EAST ASIA COUNTRIES

The rain attenuation in the 12-GHz band and one-minute- rain rate were measured at four satellite beacons located in South East Asia countries over a three-year period (2002-2004). The cumulative distribution of rain rate obtained as well as cumulative distribution of rain attenuation obtained are presented and compared with the rain prediction models. Most of the rain prediction models showed noticeable deviation to the measured values above the existence of the breakpoint (the point at which the slope changes). The results can be employed to guide the design and application of slant-path communication systems, especially in South East Asia countries.

Slant-path rain attenuation predictions in tropical regions

A two-year campaign of rain-induced slant-path attenuation measurement was conducted on three satellite beacons located in the equatorial and tropical region. The cumulative distribution of rain attenuation obtained from the measured data are presented and compared with the predefined rain attenuation prediction models.

Analysis of rain attenuation models for slant path

Several methods for computing the cumulative distribution of rain attenuation for slant paths have been tested at three different locations in Italy. The results have been compared with the measured attenuation at 11.6 GHz through the Sirio satellite beacon, and the behaviour of each model has been investigated.