Investigation of Rain Attenuation Effect on 5G Millimeter Wave Short-Range Fixed Links

Abstract

The evolution of wireless communication has been driven by the limitations of spectrum
availability below 6 GHz. As a solution, Fifth Generation (5G) networks have embraced
Millimeter Wave (mmWave) frequency bands to meet the demand for higher data through-
put across diverse applications. Implementing mmWave frequencies for short-range fixed
links, specifically in 5G Fixed Wireless Access (FWA), holds the potential for better user
experiences through high data rates, low latency, and cost-effective deployment.

However, the promising potential of mmWave frequencies is accompanied by a significant
challenge – rain attenuation. Rain-induced signal degradation poses a substantial threat
to signal quality in mmWave short-range fixed links. In response, this thesis undertakes
an extensive measurement campaign utilizing experimental fixed link setups operating
at distinct frequencies: 25.84 GHz, 77.54 GHz, and 77.125 GHz. These setups span
two short-range fixed links, measuring 36 m and 200 m. Augmented by a sophisticated
weather station, which facilitates a comprehensive assessment of rain-induced attenuation
and scattering effects. The incorporation of various weather parameters, such as rain intensity, drop size distribution, temperature, and refractive index, enhances the accuracy of
attenuation measurement and prediction models.

The thesis delves into the investigation of the obtained measurement results, meticulously
analyzing rain attenuation across the two short-range links and mmWave frequencies. Key
parameters influencing attenuation behaviour, including drop diameter, velocity, and antenna wetness, are examined. A pivotal contribution of this research is the establishment
of correlations between measured radio links and weather data. This correlation enhances
ITU-R guidelines and guides optimization for FWA 5G networks, particularly impactful
in weather-variable regions.