Analysis of Actual Transmitted Power from Hundreds of 5G FR2 Radio Base Stations over One Month in Urban Areas in Japan

Abstract

Overview

This study analyzes the actual transmitted power from 5G beamforming radio base stations (BF-RBSs) to clarify the effectiveness and issues of an actual maximum approach specified in the International Electrotechnical Commission 62232:2025. The actual maximum approach is a new compliance assessment method for electromagnetic field exposure levels from BF-RBSs based on time-averaged transmitted power.

• Actual maximum transmitted power every 5 or 30 min from more than 400 BF-RBSs using millimeter waves in urban areas in Japan was collected using a network management system over one month.
• For each BF-RBS, normalized actual transmitted power was derived as the ratio of actual to configured maximum transmitted power.

As a result of this measurement, the maximum value of normalized actual transmitted power was approximately -3 dB when the number of sets of user equipment (UEs) in the BF-RBS was less than two with high data traffic. Statistical analysis showed that the actual maximum approach may underestimate the electromagnetic field (EMF) exposure levels from a BF-RBS with three or fewer UEs if transmitted power is not monitored and controlled to maintain a level below the threshold.

Findings

• All the actual transmitted powers for each BF-RBS were below the configured maximum transmitted power.
• The maximum value of the normalized actual transmitted power averaged for 30 min was less than -8 dB.
• When the average time of compliance assessment exceeds 30 min, the actual maximum approach is effective in avoiding overestimation.
• The maximum value of normalized actual transmitted power averaged for 5 min was approximately -3 dB when the number of UEs was less than three, indicating a power reduction factor for beamforming technologies of approximately 0.19.
• The influence of adjacent beams (sidelobes) was not considered in the power reduction factor definition and should be addressed in future compliance assessments for RBS installations.
• Theoretical statistical analysis using multinomial distribution confirms that the actual maximum approach underestimates EMF exposure levels if transmitted power is not closely monitored and controlled, particularly with three or fewer UEs.

Conclusion

The study highlights the necessity of monitoring and controlling actual transmitted power from 5G base stations to avoid underestimating EMF exposure levels. This is crucial for accurately assessing the health risks associated with environmental electromagnetic fields (EMF), especially when compliance with safety guidelines depends on averaging intervals and the dynamic use of beamforming technology.