Statistical Modeling of the Climatic Influence on a 5 GHz Microwave Link: A Tropical Weather Case Empirical Study

Abstract

The 5 GHz band is crucial for telecom services; however, unexpectedly high attenuation levels in outdoor wireless systems under varying weather conditions pose significant challenges that traditional models cannot explain. This unexplained attenuation may be due to antenna losses from rain, and there is no standardized method for estimating it. While some studies have explored the impact of climatic variables on signal strength for 5 GHz microwave links, there is a lack of research on quantifying climatic influence on attenuation through mathematical modeling and the prediction of attenuation values using simulations simultaneously. Our research, conducted in the tropical city of Guayaquil, Ecuador, during the rainy season of 2017, aims to bridge this gap by studying the relationship between the climatic variables and signal attenuation for a 5.645 GHz microwave link and modeling these variables’ influence to predict signal attenuation accurately. We aim to provide a unique approach presenting a Poisson model that accurately predicts the signal attenuation of a radio link operating under specific tropical weather conditions, showing the influence level of the main climatic variables that cause this electromagnetic fading. Our proposed model has been validated using different metrics and considers a scenario where it always rains at the transmitter site and any other segment in the radio link trajectory. This provides a very good fit between the observed and predicted attenuation values, reaching pseudo R-squared and correlation values of 51.65% and 75%, respectively. We found that the most critical factor driving the signal attenuation was the wet antenna effect, which occurs when it rains at the transmitter site, simultaneously reducing the environmental temperature. This effect was influenced by three climatic variables: temperature and rain rate at the transmitter site and solar radiation, which complementarily affects the ambient temperature. Our proposed model can accurately estimate the maximum signal fading caused by rain at the microwave link antennas. This enables precise determination of the minimum quality of service parameters of a radio link and enhances the system’s capability to recover from signal attenuation by adjusting the transmitted power appropriately.

Keywords

• 5 GHz
• attenuation
• climatic variables
• Poisson model
• prediction model
• rainfall