Rain Statistics Investigation and Rain Attenuation Modeling for Millimeter Wave Short-Range Fixed Links

Abstract

Millimeter wave (mmWave) communication is a key technology for fifth generation (5G) and beyond communication networks. However, the communication quality of the radio link can be largely affected by rain attenuation, which should be carefully taken into consideration when calculating the link budget. In this paper, we present results of weather data collected with a PWS100 disdrometer and mmWave channel measurements at 25.84 GHz (K band) and 77.52 GHz (E band) using a custom-designed channel sounder. The rain statistics, including rain intensity, rain events, and rain drop size distribution (DSD) are investigated for one year. The rain attenuation is predicted using the DSD model with Mie scattering and from the model in ITU-R P.838-3. The distance factor in ITU-R P.530-17 is found to be inappropriate for a short-range link. The wet antenna effect is investigated and additional protection of the antenna radomes is demonstrated to reduce the wet antenna effect on the measured attenuation.

Statistical Analysis of Rain at Millimeter Waves in Tropical Area

“…This makes the study of rain effects in the E-band crucial. A few studies have investigated the rain attenuation at the E-band, but mostly for short distances [5], [73]- [76]. In [5], the rainfall rate statistics and rain attenuation were investigated based on a one-year measurement data for a short 35 m link at 25.84 and 77.52 GHz in the UK.…”

“…A few studies have investigated the rain attenuation at the E-band, but mostly for short distances [5], [73]- [76]. In [5], the rainfall rate statistics and rain attenuation were investigated based on a one-year measurement data for a short 35 m link at 25.84 and 77.52 GHz in the UK. The rain attenuation at different rainfall rates for short measurement periods was studied at 77 and 300 GHz over 160 m terrestrial radars link in Birmingham, UK [73].…”

“…The rain attenuation based on (3) may cause overestimation due to the wet antenna effect after rain occurrence. To overcome the wet antenna effect, the antenna radome can be covered with an additional hydrophobic material [5], [124]. The wet antenna attenuation can also be calculated and excluded from the rain attenuation of (3).…”

“…The ITU-R P.530-17 [81] is the latest ITU-R recommendation for terrestrial LOS link propagation and prediction methods. It recommends calculating the rain attenuation (A 0.01 ) for the rainfall rate using (5). Next, the rain attenuation (A p ) for other rainfall rates is computed by scaling A 0.01 to other percentages of time p%.…”

“…With Release 17, 3GPP would like to extend that across 52.6 GHz all the way up to 114 GHz [4]. However, the quality of the radio link at high frequencies can be potentially affected by weather conditions such as rain, snow and fog, which should be considered in the link budget [5], [6]. Due to absorption and scattering at frequencies above 10 GHz, the precipitations cause significant attenuation at these frequencies, especially at the E-band [1].…”