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

Pontes, M.S.; Mello, Luiz da Silva; Souza, R. S. L.; Miranda, Emilio

doi:10.1109/icics.2005.1689223

Cited by 21 publications

(14 citation statements)

References 5 publications

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“…The rainfall rate and rain attenuation data for the Brazilian tropical climate were sourced from [12]. The measured point rainfall rate CD of Rio de Janeiro, Brazil, is reproduced in Figure 6a, while the characteristics of the five terrestrial links over which rain attenuation was measured are shown in Table 2.…”

Section: R a I N A T T E N U A T I O N ( D B ) P E N A N G J O H O R mentioning

confidence: 99%

An improved ITU-R rain attenuation prediction model over terrestrial microwave links in tropical region

Islam

Abdulrahman

Rahman

2012

J Wireless Com Network

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An improved approach of predicting rain attenuation cumulative distribution (CD) over terrestrial microwave links operating in tropical regions is presented in this article. The proposed method offers a better extrapolation approach for determining the values of rain attenuation at different exceedance probability from the measured attenuation at 0.01% of the time. The experimental data consist of measured rainfall rates and rain attenuation over six geographically spread DIGI MINI-LINKs operating at 15 GHz in Malaysia. A new set of numerical coefficients was derived for improved rain attenuation CD predictions in the Malaysian tropical climate. In order to test the applicability of the proposed extrapolation method, a validation was performed using rain rate and rain attenuation measurements from five Brazilian and seven Nigerian tropical locations. When tested against measurements, the proposed method seems to provide a significant improvement over the current extrapolation method adopted by ITU-R Recommendations P.530-14, for the prediction of rain attenuation CD over tropical regions.

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Section: R a I N A T T E N U A T I O N ( D B ) P E N A N G J O H O R mentioning

confidence: 99%

An improved ITU-R rain attenuation prediction model over terrestrial microwave links in tropical region

Islam

Abdulrahman

Rahman

2012

J Wireless Com Network

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“…Noted that the remarkably low year to year variability of the annual cumulative distributions for the two years over the 0.1% exceedance range detected in Malaysia. The data measured in Abakaliki, Nigeria (Omotosho and Oluwafemi, 2009) and in Rio de Janeiro, Brazil (Pontes et al, 2005), both in equatorial region, show considerably more fading than Malaysia. With the variety of rain climates to be characterized, considerably more data are thus required for the development of satisfactory physically based models for prediction.…”

Section: Cumulative Distribution For Diurnal Variabilitymentioning

confidence: 99%

V-Band Fade Dynamics Characteristics Analysis in Tropical Region

Badron¹

2010

American Journal of Applied Sciences

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Problem statement: Satellite operations at V-band in tropical and equatorial regions are constrained as a result of attenuation from rain. Approach: Statistics for 20 consecutive months of V-band terrestrial link signal attenuation measurements in Malaysia were presented in this analysis. Such information was considered very pertinent for Earth-space communication link design and can be used for initial groundwork plan for the engineers as well as researchers. Results: The measured statistics were then fittingly scaled up to fit Earth-satellite link. The statistics were then broken down to examine diurnal variations. Characteristics of rain events such as fade duration and inter-fade interval were presented. Conclusion/Recommendations: It is essential to identify such characteristics for the design and implementation of future fade countermeasure techniques on satellite links.

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“…Generally, the required inputs in most attenuation prediction models for terrestrial point-to-point microwave links are the rainfall rate exceeded at p % of time, the effective propagation path length and the link's operating frequency [7], [16]. Thus p…”

Section: Theoretical Background Of Rain Attenuation Prediction Momentioning

confidence: 99%

“…An overview of Lin model [7], revised Moupfouma model [8], revised Silva Mello model [9] and the newly released ITU-R model [10] is briefly presented in the following subsections.…”

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confidence: 99%

“…Lin Model According to Lin [7], the reduction factor can be expressed as: The factor accounts for the partially correlated rain rate ) / ( h mm R variations along the propagation path of length L such that the non linear factor in Equation (4) equals one half when ) (R L L  is related to the diameter of rain cell. So that the overall rain attenuation is calculated by substituting the empirical value of path reduction factor into Equation (1), as follows:…”

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confidence: 99%

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Statistical Evaluation of Measured Rain Attenuation in Tropical Climate and Comparison with Prediction Models

Yusuf

Falade

Olufeagba

et al. 2016

J. Microw. Optoelectron. Electromagn. Appl.

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Abstract-Substantial modifications have been made to the expressions for calculating distance factor and extrapolation techniques in the latest ITU-R P.530-14. However, its performance has not been rigorously evaluated in the tropical and equatorial climates. In this article, the new ITU-R method and three prediction models are validated using measurement data from tropical Malaysian climate. The data were collected on six geographically spread terrestrial microwave DIGI MINI-LINKs operating at 15 GHz. When tested against measurements, the Da Silva Mello model yields a significant improvement for the prediction of rain attenuation distributions. The prediction errors observed in the ITU-R model suggest the need for more data campaign in the afore-mentioned climates. I. INTRODUCTIONTraditionally frequencies above 10 GHz are commonly employed in the current microwave point-topoint networks, due to large bandwidth and freedom from traffic congestion. However, in these frequency bands, the performance of the fixed service (FS) is predominantly controlled by rain in 2012; however, its performance has not been largely evaluated using data collected from tropical climates. Therefore, the main aim of this article is to evaluate the performance of the newly released ITU-R model and the three afore-mentioned models, using measurement data from six locations in a tropical climate. The data used are the rain rate and rain attenuation data banks available from six geographically spread terrestrial microwave DIGI MINI-LINKs operating at 15 GHz as described in[13]. It should be mentioned here that the ITU-R P.530-14 was not yet in force when our previous works were reported. II. THEORETICAL BACKGROUND OF RAIN ATTENUATION PREDICTION MODELSRain attenuation can be conveniently defined as the product of specific attenuation (dB/km) corresponding to the point rain rate (typically measured at one end of the link) and the effective propagation path length (km) [1]. The path correction factor is defined as the ratio of effective path length to the physical path length of a microwave link, and its value is usually less than unity, except in rear cases [14].The concept of effective path length is thus a way of 'averaging out' the spatial inhomegeneity of rain rate and thus specific attenuation [15]. Note that the degree of spatial inhomogeneity in rain rate generally varies with rainfall intensity. Therefore the variation of path length reduction factor can be expressed as a function of rain rate or the corresponding time exceedance [16].Attenuation p A exceeded at p % of time can either be obtained from direct measurements, or predicted from the knowledge of long-term rainfall rate. Generally, the required inputs in most attenuation prediction models for terrestrial point-to-point microwave links are the rainfall rate exceeded at p % of time, the effective propagation path length and the link's operating frequency [7], [16]. Thus p

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

Cited by 21 publications

References 5 publications

An improved ITU-R rain attenuation prediction model over terrestrial microwave links in tropical region

An improved ITU-R rain attenuation prediction model over terrestrial microwave links in tropical region

V-Band Fade Dynamics Characteristics Analysis in Tropical Region

Statistical Evaluation of Measured Rain Attenuation in Tropical Climate and Comparison with Prediction Models

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