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

2021 · No effect · Moderate evidence

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No effectModerate evidencePaper 1147

Study snapshot

Publicationmanual · 2021

Study typeexposure_assessment

Reported directionNo effect

Evidence ratingModerate

Abstract

In Situ Assessment of 5G NR Massive MIMO Base Station Exposure in a Commercial Network in Bern, Switzerland Sam Aerts, Kenneth Deprez, Davide Colombi, Matthias Van den Bossche, Leen Verloock, Luc Martens, Christer Törnevik, Wout Joseph. In Situ Assessment of 5G NR Massive MIMO Base Station Exposure in a Commercial Network in Bern, Switzerland. Appl. Sci. 11(8): 3592. 2021. doi.org. Abstract This paper describes the assessment of radiofrequency (RF) electromagnetic field (EMF) exposure from fifth generation (5G) new radio (NR) base stations in a commercial NR network in Bern, Switzerland. During the measurement campaign, four base station sites were investigated and the exposure induced by the NR massive multiple-input-multiple-output (MaMIMO) antennas was assessed at 22 positions, at distances from the base station between 30 m and 410 m. The NR base stations operated at 3.6 GHz and used codebook-based beamforming. While the actual field levels without inducing downlink traffic were very low (<0.05 V/m) due to a low traffic load and low antenna input powers of up to 8 W, setting up a maximum downlink traffic stream towards user equipment resulted in a time-averaged exposure level of up to 0.4 V/m, whereas the maximum extrapolated exposure level reached 0.6 V/m. Extrapolated to an antenna input power of 200 W, values of 4.3 V/m and 4.9 V/m, respectively, were obtained, which amount to 0.5–0.6% of the reference level recommended by the International Commission on Non-Ionizing Radiation Protection (ICNIRP). In Bern, it was found that the impact of the NR network on the total environmental RF exposure was very limited; with maximum downlink, it contributed 2% on average. Finally, it was also concluded that extrapolation to the maximum exposure level can be done without prior knowledge of the radiation patterns, directly based on the measurement of the Physical Downlink Shared Channel (PDSCH) resource elements. Conclusions To the authors’ knowledge, this study provides the first assessment of the range of actual and maximum exposure levels in a 5G NR commercial network. It was found that the impact of the investigated network on the total environmental RF-EMF exposure was small, only a few percent of the total RF-EMF exposure even in the case of 100% induced traffic. Moreover, an extrapolation method was demonstrated for which no prior information from the network provider or radio equipment manufacturer is necessary, validated using the actual antenna radiation patterns. In the (near) future, as 5G technologies evolves (e.g., when introducing reciprocity-based beamforming and other advanced MaMIMO techniques), some aspects of the presented methodology, such as the position of the UE relative to the base station and measurement probe, the averaging time to assess Eavg, and the use of the UE to stimulate the maximum exposure scenario may also have to be amended. In addition, we are confident that the described procedure is valid also at frequencies in Frequency Range 2 (FR2), above 24 GHz (‘mmWaves’), provided that the measurement settings are adjusted to account for wider channel bandwidths as well as larger SCS. However, a comprehensive in situ validation study remains essential. Open access paper: mdpi.com

Machine Enhanced Logic

AI evidence extraction

Structured fields below were generated from the paper’s abstract and metadata to make the evidence easier to inspect. Automated extraction may be incomplete or incorrect; verify important details against the original paper.

Study typeexposure_assessment

Effect directionno_effect

PopulationNot supplied

Sample sizeNot supplied

ExposureRF · 3600 MHz

Evidence strengthModerateConfidence: 78% · Peer reviewed: yes

Main findings

Four 5G NR base station sites in Bern (3.6 GHz, codebook-based beamforming) were measured at 22 positions (30–410 m). Measured field levels were <0.05 V/m without induced downlink traffic; with a maximum downlink traffic stream, time-averaged exposure was up to 0.4 V/m and maximum extrapolated exposure reached 0.6 V/m. Extrapolated to 200 W antenna input power, values of 4.3–4.9 V/m were reported, corresponding to 0.5–0.6% of the ICNIRP reference level; the NR network contribution to total environmental RF exposure was limited (2% on average with maximum downlink).

Outcomes measured

In situ RF-EMF field strength (V/m) from 5G NR MaMIMO base stations
Time-averaged exposure level under low traffic and induced maximum downlink traffic
Extrapolated maximum exposure levels (including extrapolation to 200 W antenna input power)
Contribution of 5G NR to total environmental RF exposure
Validation/demonstration of extrapolation method based on PDSCH resource elements without prior radiation pattern knowledge

Limitations

Only four base station sites were investigated
Measurements were conducted at 22 positions and distances of 30–410 m (limited spatial sampling)
Actual field levels were influenced by low traffic load and low antenna input powers (up to 8 W) during measurements
Maximum exposure scenarios relied on induced downlink traffic towards user equipment
Authors note methodology may need amendments as 5G evolves (e.g., reciprocity-based beamforming) and that comprehensive in situ validation remains essential for FR2/mmWave

View raw extracted JSON

{
  "study_type": "exposure_assessment",
  "exposure": {
    "band": "RF",
    "source": "5G NR base station (massive MIMO)",
    "frequency_mhz": 3600,
    "sar_wkg": null,
    "duration": null
  },
  "population": null,
  "sample_size": null,
  "outcomes": [
    "In situ RF-EMF field strength (V/m) from 5G NR MaMIMO base stations",
    "Time-averaged exposure level under low traffic and induced maximum downlink traffic",
    "Extrapolated maximum exposure levels (including extrapolation to 200 W antenna input power)",
    "Contribution of 5G NR to total environmental RF exposure",
    "Validation/demonstration of extrapolation method based on PDSCH resource elements without prior radiation pattern knowledge"
  ],
  "main_findings": "Four 5G NR base station sites in Bern (3.6 GHz, codebook-based beamforming) were measured at 22 positions (30–410 m). Measured field levels were <0.05 V/m without induced downlink traffic; with a maximum downlink traffic stream, time-averaged exposure was up to 0.4 V/m and maximum extrapolated exposure reached 0.6 V/m. Extrapolated to 200 W antenna input power, values of 4.3–4.9 V/m were reported, corresponding to 0.5–0.6% of the ICNIRP reference level; the NR network contribution to total environmental RF exposure was limited (2% on average with maximum downlink).",
  "effect_direction": "no_effect",
  "limitations": [
    "Only four base station sites were investigated",
    "Measurements were conducted at 22 positions and distances of 30–410 m (limited spatial sampling)",
    "Actual field levels were influenced by low traffic load and low antenna input powers (up to 8 W) during measurements",
    "Maximum exposure scenarios relied on induced downlink traffic towards user equipment",
    "Authors note methodology may need amendments as 5G evolves (e.g., reciprocity-based beamforming) and that comprehensive in situ validation remains essential for FR2/mmWave"
  ],
  "evidence_strength": "moderate",
  "confidence": 0.78,
  "peer_reviewed_likely": "yes",
  "keywords": [
    "5G NR",
    "massive MIMO",
    "MaMIMO",
    "base station",
    "RF-EMF",
    "in situ measurements",
    "beamforming",
    "PDSCH",
    "environmental exposure",
    "ICNIRP",
    "Bern",
    "Switzerland",
    "3.6 GHz"
  ],
  "suggested_hubs": [
    {
      "slug": "who-icnirp",
      "weight": 0.7,
      "reason": "Exposure levels are explicitly compared to ICNIRP reference levels."
    },
    {
      "slug": "5g-policy",
      "weight": 0.55,
      "reason": "In situ assessment of 5G NR base station exposure in a commercial network, relevant to 5G exposure/policy discussions."
    }
  ]
}

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AI-extracted fields are generated from the abstract and metadata and may be incomplete or incorrect. This material is for informational purposes and is not medical advice.

Identifiers and source

DOI: 10.3390/app11083592
PubMed: Not supplied

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