Wednesday, March 30, 2022

mmWaves, 5G network measurements, cumulative exposure from IoT…. MWF research in 2021

In 2021, the MWF carried out research projects with the Universities of Ghent, l’Aquila and Aalborg, as well as Rohde & Schwarz and Telstra, investigating exposure in 5G networks, simulation of reverberation chambers for animal exposure studies, exploring the behaviour of incident and absorbed power densities in different frequency ranges, and cumulative exposure of IoT devices. 

Since its creation in 1998, the funding and promotion of research in view of science-based standards for safety and compliance testing has been one of the core activities of the Mobile & Wireless Forum (MWF). Since then, we have moved on to 5G and the practical implementation of this new generation of mobile technology has required data as the basis for safety and compliance standards. 

For this reason, the MWF worked in 2021 with three universities and two companies on five research projects. These include, a project with the Ghent University on “EMF exposure measurements of a 5G commercial network”. In a previous MWF project, the team developed a new method to assess exposure to radiofrequency (RF) electromagnetic fields (EMF) emitted by 5G New Radio (NR) base stations (published in December 2019). The objective of the 2021 project was the validation of the measurement procedure in commercial networks and gathering of actual EMF exposure levels in a 5G commercial network. One week of measurements in a commercial 5G network in Switzerland showed that the highest average field value measured was only 0.46 V/m, which corresponds to 0.006% of the ICNIRP exposure limits. Overall, the 5G network was found to have only very limited impact on the environmental RF-EMF exposure levels. The findings were published in a scientific paper: In Situ Assessment of 5G NR Massive MIMO Base Station Exposure in a Commercial Network in Bern, Switzerland (Ghent/IMEC):

With the University of l’Aquila the MWF has a research project on “Simulation of a reverberation chamber exposure with Sim4Life”. The goal is to simulate a large group of animals (96 animals) and to compare the results with those of the NTP Study (120 animals). The team looked at the correlation between the electric field, magnetic field and SAR. It seems that the whole-body SAR is more correlated with the magnetic field than the electric field. This is a new insight. The analysis also looked at different rat models over a whole day of exposure to verify the standard deviation, and reproduced a number of simulations with different positioning and different rat models to investigate possible bias through positioning of the animal cages. The research outcomes were presented at the BioEM Conference 2021 and two research papers are under preparation for publication in scientific journals. 

With Aalborg University, the MWF has started a research project looking at new restriction above 6 GHz for localized exposure as outlined in the ICNIRP 2020 guidelines. This project compares the matrix of the incident power density and absorbed power density and how they behave in different frequency ranges. Insights from this work will feed into the development of simulation and measurement standers for absorbed power density. 

In conjunction with Australian network operator Telstra, the MWF undertook a project on the compliance of Internet of Things (IoT) systems made up of many different devices, which mirror typical use cases. The study focused on EMF measurements of a range of smart home IoT wireless devices with Wi-Fi and Bluetooth connections with the aim to determine the time-averaged exposure form the IoT devices under typical conditions of use. A wide range of devices was selected, including security and doorbell cameras, kitchen scales, smart Wi-Fi LED globes, smart Wi-Fi power strips, Smart Home hubs, hot spot routers etc. Wi-Fi tended to be the main way of connection between the devices. Based on the outcomes of this work, the MWF is currently developing a “Smart Home Walkthrough” tool, which will allow consumers to understand what kind of exposure they might have in their own homes with multiple RF devices emitting at the same time. The data will also be used as basis for a research paper. 

Finally, the MWF worked with Rohde & Schwarz GmbH & Co. KG to manufacture antennas according to the specification of IEC 63195-1, to validate the reference values for incident power density and to identify gaps in the antenna design specifications. In future projects, these antennas might also be used to do measurements of absorbed power density. One of the papers coming out of this research: Zhekov et al. “Test Reduction for Power Density Emitted by Handset mmWave Antenna Arrrays”, IEEE Access, Jan 28, 2021 

Throughout the years, the MWF has developed and worked through a comprehensive research agenda, which resulted in many peer-reviewed publications and contributed substantial data as basis for the technical discussions in the standardisation committees. 

For its 20th anniversary, the MWF summarised these research efforts in a 56-page document: