Path Reduction Factor Research Articles

The Path Reduction Factor for the Prediction of Rain Attenuation Affecting Short EHF Terrestrial Links

The Path Reduction Factor for the Prediction of Rain Attenuation Affecting Short EHF Terrestrial Links

A Long‐Term Experimental Investigation on the Impact of Rainfall on Short 6G D‐Band Links

AbstractResults from a long‐term propagation campaign are presented, whose main goal is to investigate the impact of rainfall on short terrestrial links operating at frequencies in the D‐band, to be possibly exploited for backhaul links in future 6G mobile networks. To this aim, data are collected at two sites with different climatic conditions (Milan, Italy; Athens, Greece) for 24 and 20 months, respectively, using two links (path length of 325 and 100 m, respectively), operating at 156 GHz carrier frequency. At the same sites, disdrometers are also installed to concurrently collect information on precipitation, not only in terms of rain rate but also of its microphysical properties. The received power data are carefully pre‐processed to exclude outliers and further elaborated to derive the rain attenuation. The data are afterward used to evaluate the accuracy of different prediction models, both on an event basis and on a statistical basis. Results indicate that the information delivered by the Drop Size Distribution allows a more accurate estimation of the rain attenuation and that the model currently adopted by the ITU‐R to predict rain attenuation statistics on terrestrial links (recommendation ITU‐R P.530‐18) yields a significant overestimation for such short links, due to the unrealistic value of its path reduction factor. On the contrary, the statistical prediction model proposed by Lin turns out to offer a very satisfactory prediction accuracy.

Evaluation of Some Path Reduction Factor Models Performance i n Tropical Location

Performance evaluation of the ITU-R. P.530-17, Ghiani and Budalal model are considered for this work. It is found that the predicted values from the ITU-R and Ghiani distance factor models are seen to gradually decrease with an increase in path length for distances below 1km. Results further suggest that for a link length of 300 m, the Ghiani model predicts a 0.2499 dB (1.059 w) to 0.3273 dB (1.078 w) precipitation loss across all four (4) stations. For the ITU-R. P.530-17 model, a 3.4741 dB (2.225 w) to 5.329 dB (3.411 w) precipitation loss is estimated across all stations while the Budalal model estimated a 2.8608 dB (1.932 w) to 4.6250 dB (2.901 w) precipitation loss across all stations. The ITU-R. P.530-17, Ghiani and Budalal model further suggest a precipitation loss in the Received Signal Strength (RSS) of a typical 5G base station operating in the four (4) stations considered to be at least -9.4733 dBm, -8.8601 dBm, and -6.2489 dBm respectively. Generally, all models are found to predict rain attenuation and distance factor values with disparities especially for link lengths above 300 m. Further research is recommended on the models for accurate prediction and improve agreement with measured values.

Effects of reduction factor on rain attenuation predictions over millimeter-wave links for 5G applications

Millimeter-wave will be the strong contender for the terrestrial link using for 5G networks. So it is imperative to examine these frequency bands to ensure the uninterrupted services when 5G network is connected in tropical regions. A critical challenge of link-budgeting in mm-wave 5G networks is the precise estimation of rain attenuation for short-path links. The difficulties are further intensified in the tropical areas where the rainfall rate is very high. Different models are proposed to predict rain attenuation, however recent measurements show huge discrepancies with predictions for shorter links at mm-wave. The path reduction factor is the main parameter in the prediction model for predicting total attenuation from specific rain attenuation. This study investigates four path reduction factor models for the prediction of rain attenuation. A comparison was made between these models based on rain attenuation data measured at 26 GHz at 300 m and 1.3 km links in Malaysia. All models are found to predict rain attenuation at a 1.3 km link with minimum errors, while tremendous discrepancies are observed for 300 m link. Hence it is highly recommended to further investigate the reduction factor model for shorter links less than 1 km

A physically based rain attenuation model for terrestrial links

AbstractThis contribution presents a novel physically based approach to modeling the rain attenuation affecting terrestrial links. The model is devised by investigating the path reduction factor (PF) on terrestrial links, a typical element of rain attenuation prediction models introduced to take into due account the spatial inhomogeneity of rainfall. To this aim, a large number of PF values are analyzed by simulating the interaction of a hypothetical terrestrial link with a set of realistic synthetic rain fields. The dependence of PF on different parameters such as the path length, the operational frequency, and the rain rate measured at the transmitter is addressed, and the results are exploited to devise analytical expressions aiming to provide an accurate yet simple approach to predicting rain attenuation on terrestrial links. Finally, the prediction accuracy of the proposed method is discussed (and compared to the one of other two models) by considering experimental data collected worldwide.

Empirically Derived Path Reduction Factor for Terrestrial Microwave Links Operating at 15 Ghz in Peninsula Malaysia

This paper describes the technique of deriving path reduction factor from experimental rain rate and rain attenuation data over seven DIGI MINI-LINKs operating at 15 GHz in Malaysia (Lat.: 1.45°N and Long.: 103.75°E). The relationship between experimental path reduction factors with different link lengths has been studied, using multiple non-linear curve-fitting techniques. Based on these studies, an empirical path reduction factor model has been proposed and compared with the ITU-R model. The test results have shown that the ITU-R prediction model may not be appropriate for predicting rain-induced attenuation for the tropical Malaysian climate.

Vertical path reduction factor for high elevationcommunication systems

The prediction of rain attenuation along slant paths can be improved by taking into account the vertical variation of rain specific attenuation. The authors describe how data from the 3 GHz Chilbolton Advanced Meteorological Radar (CAMRa) have been used to derive a vertical path reduction factor in the rain region.