Wednesday, March 18, 2020

Worry versus reality: Low EMF levels from telecom infrastructure

With the rollout of new network infrastructure, questions often arise about what this means for general levels of electromagnetic fields (EMF) in the community. This was the case with earlier generations as it is now with 5G.

Several countries have published the results of national measurement and monitoring campaigns that assessed the current public exposure levels from telecommunications network infrastructure. Each of the reports have found that overall EMF levels remain far below the safety limits, with most results being around 1% of the international limits.

Ofcom, the United Kingdom Office of Communications, for example released a set of testing carried out in 2020 that found EMF levels around Britain to be between 0.0052% and 1.4960% of the ICNIRP reference levels for general public exposure. This is in line with the results obtained by French regulator ANFR as part of their yearly measurement program.

Will exposure levels rise with 5G? 

With the introduction of new technologies, there may be a small increase in the overall level of EMF due to the fact that new transmitters are active. In some countries, deployment of 5G may occur as part of closure of earlier wireless networks. Based on the transition from previous wireless technologies we can expect that the overall exposure levels will remain relatively constant and a small fraction of the international exposure guidelines (1).

For example, EMF measurements carried out by Australian network provider Telstra within their commercial 5G network with 5G devices found that EMF levels remained at around 1000 times below the safety limits and were similar in exposure levels to those of 3G, 4G or Wi-Fi.

This is consistent with the results from several studies (2) that have looked at measurements of base station RF emissions over time, and they found that irrespective of the country, the year and the mobile technology, RF fields at a ground level were only a small fraction of the international human RF exposure recommendations. Importantly, environmental levels have remained essentially constant despite the increasing number of base stations and deployment of additional mobile technologies.

Further information: 

Ofcom 2020 set of measurements:
https://www.ofcom.org.uk/spectrum/information/mobile-operational-enquiries/mobile-base-station-audits/2020

ICNIRP RF EMF Guidelines 2020
https://www.icnirp.org/en/activities/news/news-article/rf-guidelines-2020-published.html

5 surveys of 5G show EME levels well below safety limits:
https://exchange.telstra.com.au/5-surveys-of-5g-show-eme-levels-well-below-safety-limits/

(1) See 5G and EMF Explained: http://www.mwfai.org/docs/eng/2018_05_MWF_5G-EMF%20Explained%20final.pdf

(2) Rowley and Joyner, Comparative international analysis of radiofrequency exposure surveys of mobile communication radio base stations, Journal of Exposure Science and Environmental Epidemiology (2012) 1 – 12., Joyner, Van Wyk and Rowley National Surveys of Radiofrequency Field Strengths from Radio Base Stations in Africa, Radiation Protection Dosimetry (2013) 1–12 and Rowley JT, Joyner KH, Observations from national Italian fixed radiofrequency monitoring network, Bioelectromagnetics. 2016 Feb;37(2):136-9.

Thursday, February 27, 2020

MWF Research Outcomes: In-Situ Measurement Methodology for 5G Base Stations

Deployment  of 5G networks is already well underway around the world and one of the areas that the MWF identified for further research work was the need for updated exposure assessment methodologies to demonstrate compliance of the base stations. 5G base stations make use of beam forming and massive MIMO (Multiple-Input Multiple-Output) to direct the signal where is needed rather than spreading the energy over a large angular beam. Beam forming and massive MIMO result in greater efficiency and better use of spectrum, but using traditional compliance assessment methodologies results in unrealistic overestimation of EMF exposure. This overestimation comes about since it assumes all the power of the base station is allocated within the same beam for several minutes.

This project therefore had two objectives:

  • to develop a measurement method to assess exposure from 5G NR base stations on-site; and 
  • to develop a measurement methodology applicable to assess exposure for massive MIMO products. 

Measurements being undertaken on a base station with a number of different services. The small 5G antennas are located in the middle of the head of the tower.

Measurements being undertaken on a base station with a number of different services. The small 5G antennas are located in the middle of the head of the tower. The MWF supported a research project at the University of Ghent to undertake the identified work. The results involve a five-step methodology consisting of: (1) a spectrum overview to identify the 5G NR channels; (2) the identification of the synchronization signal block (SSB) which contains the ‘always on’ signals; (3) the measurement of electric field strength per resource element of the SSB; (4) the measurement of the of the time-averaged instantaneous exposure level; and (5) the extrapolation of the resource element electric-field strength to the theoretical maximum level as well as the actual maximum level taking into account a variety of factors outlined in existing standards.

The methodology has now been presented to the International Electrotechnical Commission (IEC) standards committee overseeing work on a new standard in this area and has been published in the journal IEEE Access.

The publication details are as follows: