In Situ Assessment of 5G NR Massive MIMO Base Station Exposure in a Commercial Network in Bern, Switzerland
2. Materials and Methods
2.1. Commercial 5G NR Network
2.2. Measurement Positions
2.3. Measurement Method
- Step 1 ‘Spectrum overview’—A spectrum overview measurement in the frequency range between 700 MHz and 6 GHz to identify the RF environment in general and the NR signals in particular at the measurement site.
- Step 2 ‘Identification of the Synchronization Signal Block (SSB) (or Synchronization Signal (SS) burst)’—For each present NR signal, an in-band measurement to detect the bandwidth (and therefore the numerology or subcarrier spacing (SCS)) and frequency position () of the channel’s SSB or SS burst, as well as the channel bandwidth.
- Step 3 ‘Assessment of the electric-field level per resource element (RE) of the (dominant) SSB and PDSCH’—For each present NR signal, a measurement of the electric-field strength per resource element of the (dominant) SSB (of the SS burst) as well as of the PDSCH was taken.
- Step 4 ‘Assessment of the time-averaged electric-field level’—For each present NR signal, the time-averaged electric-field strength over the channel bandwidth was measured. The applicable averaging time is specified by the exposure standards (e.g., 6 min or 30 min for localized and whole-body exposure, respectively, according to ). However, for convenience, in this work, an averaging time in the order of 30 s was used since it was found that this provided an accurate estimate of exposure when time-averaged over 6 min or 30 min. Time averaging over periods different than what was given by the relevant exposure standards can be used provided that this results in a reliable estimate of exposure [3,18].
- Step 5 ‘Post-processing’—Post-processing of data and calculation of the maximum theoretical electric-field level , using either
- the maximum number of resource blocks used in the channel bandwidth (depends on the bandwidth and the numerology),
- the electric-field level per RE in the dominant SSB of the SS burst, i.e., the SS beam with the highest gain in the direction of the evaluation point (hence resulting in the maximum ),
- the (maximum) gain of the PDSCH-allocated resources transmitted by the BS radio in the direction of the evaluation point,
- the gain of the SS beam in the direction of the evaluation point,
2.4. Measurement Setup
3.1. Characterization of the 5G NR Signal
3.2. Maximum Exposure
3.2.1. Electric-Field Strength per Resource Element
3.2.2. Extrapolation to the Maximum Electric-Field Strength
3.3. Average Exposure
3.4. Impact of the NR Network on the Environmental RF-EMF Exposure
Conflicts of Interest
|AAS||Advanced Antenna Systems|
|GSCN||Global Synchronization Channel Number|
|GSM||Global System for Mobile Communications|
|ICNIRP||International Commission on Non-Ionizing Radiation Protection|
|IEC||International Electrotechnical Commission|
|OFDM||Orthogonal Frequency Duplexing Multiplexing|
|PDSCH||Physical Downlink Shared Channel|
|TDD||time division duplexing|
|UDP||User Datagram Protocol|
|UMTS||Universal Mobile Telecommunications System|
|WHO||World Health Organization|
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Aerts, S.; Deprez, K.; Colombi, D.; Van den Bossche, M.; Verloock, L.; Martens, L.; Törnevik, C.; Joseph, W. In Situ Assessment of 5G NR Massive MIMO Base Station Exposure in a Commercial Network in Bern, Switzerland. Appl. Sci. 2021, 11, 3592. https://doi.org/10.3390/app11083592
Aerts S, Deprez K, Colombi D, Van den Bossche M, Verloock L, Martens L, Törnevik C, Joseph W. In Situ Assessment of 5G NR Massive MIMO Base Station Exposure in a Commercial Network in Bern, Switzerland. Applied Sciences. 2021; 11(8):3592. https://doi.org/10.3390/app11083592Chicago/Turabian Style
Aerts, Sam, Kenneth Deprez, Davide Colombi, Matthias Van den Bossche, Leen Verloock, Luc Martens, Christer Törnevik, and Wout Joseph. 2021. "In Situ Assessment of 5G NR Massive MIMO Base Station Exposure in a Commercial Network in Bern, Switzerland" Applied Sciences 11, no. 8: 3592. https://doi.org/10.3390/app11083592