P Draft revision of Recommendation ITU-R P – Propagation data and prediction methods required for the design of terrestrial. ITU-R WP3M Contribution Title: On the development of Recommendation ITU-R P – Prediction of autage intensity for digital line-of-sight systems. ITU-R P 4. 1. 0. – B. D. Ad. – 1. 0. 1. – – GHz 2. % ke.. (dB) h/F1. B.: D.: GHz 6,5. 4/3 = ke. Ad.: (2) h.
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The results can be summarized as follows. The attenuation by hydrometeors is speci? 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 p.53013 rate is introduced.
K factor as function of dN1 P. This represents a shortcoming of the method, as in two regions with different distributions of point rainfall rate but similar values of R 0. Likewise for equipments, radio signature and antenna cross-polarization discrimination highly reduce the overall performance in terms of link availability. The performance of each method is measured by the average value and the standard deviation of the values of test variable calculated for all links, at all percentages of time for which measured data are available.
This p5.30-13 addresses the recent evolution of this method and presents some experimental validation examples. Fully automatic generation of path profile with terrain. The basic assumption in the method is that an equivalent cell of uniform rainfall rate and length d 0randomly positioned in the great circle plane, can represent the effect of the non-uniform rainfall along the propagation path.
The values of R eff were obtained from the measured distribution of attenuation and rainfall rate by The dependence of the effective rainfall rate with the point rainfall rate, the slant path length the elevation angle and the rain iti-r found in the experimental data is shown in Figs. S, Da Silva Mello L. Finally, our own measurements con? The rainfall rate exceeded at 0.
The presence of hydrometeors, particularly rain, in the propagation path causes scattering and absorption of the propagating wave. From 12 to 13, there is a radical change in the expression of the geoclimatic K factor and the worst month probability of unavailability.
To avoid inconsistencies and retain the general expression for d eff given by 1the concept of an effective rainfall p.530-113 was introduced. The validation of each new revision is confronted to measurements data collected over the world and available in SG3 database. For the terrestrial case, the data used to test the itu-d methods includes concurrent measurements of rainfall rate, analyzed with one-minute integration time, and rain attenuation available in the ITU-R databank , a total of 74 year-stations from 64 links in 15 countries.
Another important limitation is that, when tested against the experimental data now available, the terrestrial prediction method shows significant underestimation of the measured attenuations. Spartial temporal structure of rain, 2nd Edition, Propagation of Radio Waves.
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The model for the effective path length can be extended for the slant path case by considering the rain height. It was found that rp decreases with the path length and the point rainfall rate, as depicted in Figs. The main difference in the various methods developed for predicting rain attenuation statistics from rainfall rate measurements is in the models used to describe the time-space structure of rainfall rate.
As a starting point, the dependence of the reduction factor on link parameters was investigated, using experimental data from concurrent long-term measurements of point rainfall rate and rain attenuation in terrestrial links available in the ITU-R databanks . Download free trial mlinkplanner is allinone software for microwave point to point link planning. Pdf the effect of terrain roughness in the microwave.
The new method proposed for the prediction of rain attenuation in terrestrial and slant path is. An improved itu r rain attenuation prediction model over. Test results indicate that the proposed method provides a large improvement over the one currently recommended by the ITU-R for prediction of rain attenuation in terrestrial links.
Itu r p 530 13 pdf file
For example a high roughness can reduce the K factor and consequently the outage probability. If the rainfall rate variation along ittu-r given path is known, the attenuation due to rainfall along the path may be calculated by integrating the specific attenuation over the path length. The effective path length is the average length of the intersection between the cell and path, given by: The dependence of the effective rainfall rate with the point rainfall rate, the slant path length the elevation angle and the rain height found in the experimental data is shown in Figs.
This method assumes that an equivalent rain cell of uniform rainfall rate and length d 0 can model nonuniform rainfall rate along the propagation path.
The proposed method was tested against the ITU-R itu- and other methods proposed in the technical literature, using the test variable recommended by the ITU-R . Vilar, “The spatial distribution of rain and its implications for wide area communications systems”, ICAPExeter.
Finally, the analysis of diversity improvement factors show a good agreement between measurements and prediction for frequency and space diversity using 2 receivers but the improvement factor when 4 receivers are applied is low compared to ITU prediction.
The results of this work show that three climatic parameters, namely rain intensity, refractivity gradient and annual mean temperature are critical. For the equivalent cell diameter d 0it was found that a power-law could provide better results than the exponential law used in iut-r current ITU-R method.
The diameter d 0 of the equivalent cell is empirically derived from experimental data, depending on the long-term point rainfall rate measured in the region. International telecommunication union, propagation data and prediction methods required for the design of terrestrial lineofsight systems, itu r p.