In Situ Assessment of 5G NR Massive MIMO Base Station Exposure in a Commercial Network in Bern, Switzerland

Aerts S, Deprez K, Colombi D, Van den Bossche M, Verloock L, Martens L, Törnevik C, Joseph W (2021): In Situ Assessment of 5G NR Massive MIMO Base Station Exposure in a Commercial Network in Bern, Switzerland. Appl Sci. 2021; 11(8):3592.

Summary and assessment

Dosimetrical study
Exposure assessment in a commercial 5G network in Bern, Switzerland (Aerts et al. 2021)

In an initial in situ measurement campaign, an assessment of the exposure from fifth-generation base station antennas (New Radio (NR) massive multiple-input-multiple-output (MaMIMO)) was carried out in a commercial mobile network (Swisscom) in Bern, which is also equipped with 5G. In a 5G-NRnetwork within reach of four base station sites, measurements were performed at a total of 22 lineof-sight positions and at distances between 30 and 410 m from the NR antennas. 20 of the measurement positions were at 1.5 m height from the ground and two were on roofs at a height of 20.5 m. Field strengths were determined for two scenarios. The first scenario comprised the field strength in the currently running network operation. The second scenario additionally comprised the exposure due to an experimentally induced connection between the NR antenna and a mobile phone, with a maximal utilization of the traffic channels. The mobile phone was placed in the extension of the line-of-sight to the antenna. The NR antennas of the four base stations under investigation operated in the n78 band (3.3 – 3.8 GHz) with input powers ranging from 1.5 to 8 W, and used codebook-based beamforming, i.e. predefined and preset beam distributions of the adaptive antennas, whose radiated transmission power at the time of the measurement campaign is limited in Switzerland in such a way that the maximum exposure of places of sensitive use1 may not exceed 10% of the exposure limit values. Without actively induced traffic data, the emissions of the NR antennas operated with 1.6 to 8W input power generated field strengths of less than 0.05 V/m at the selected measurement sites. When operating with the additional experimentally induced traffic channel load, the field strengths reached a maximum value of 0.6 V/m at the selected measurement points. This maximum value corresponds to the highest value measured within a so-called “resource element” within a transmission packet of 20ms duration. Extrapolated to the maximum antenna input power of 200 W allowed by the manufacturer, this leads to maximum field strengths of 4.9 V/m at the selected measurement points. This approximately corresponds with the Swiss installation limit values, and 0.5 – 0.6% of the ICNIRP limits with regard to power density (10 W/m2 at 3.5 GHz). At the time of the measurement in Bern, the average contribution of NR antenna exposure to the total electromagnetic field immission was 2%.

Based on this first in situ measurement campaign in a commercial network on currently generated and extrapolated field strengths by 5G-NR-antennas, the authors conclude that the EMF contribution of the new antennas to the already existing EMF immissions is small. Even in the case of 100% occupancy of the traffic channel, the levels remained well below the international limits.

It has to be noted that the spatial and temporal validity of such measurements is limited. Further comprehensive measurement campaigns are needed to confirm these conclusions, especially when 5G is more widely used in Switzerland. The study was supported by Mobile & Wireless Forum (international association of companies with an interest in mobile and wireless communications).

places of sensitive use = places where humans can stay for a prolonged time. For more information please see–omen-.html.

Source: Newsletter Nr. 27 / December 2021 of the Swiss expert group on electromagnetic fields and non-ionising radiation (BERENIS)

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