NICT undertakes measurement of radio exposure around 5G base stations

The National Institute of Information and Communications Technology (NICT) announced on July 5 that it has measured the strength of radio waves emitted from cell phone base stations for commercial 5G services. Although there have been cases where cell phone operators themselves have conducted measurements, NICT claims to be the first public research organization in the world to have performed such measurements.

According to the report, the radio wave strength (radio wave exposure level) from 5G cell phone base stations was measured at several locations and found to be approximately equal to or lower than the exposure levels of conventional 4G cell phone systems. Radio waves emitted from wireless devices are used to the extent that they do not adversely affect the human body in accordance with radio wave protection guidelines. However, since invisible radio waves, including those emitted by cell phones, exist around us on a daily basis, there has long been concerns that this may be harmful to human health. There have been cases overseas where health concerns pertaining to radio waves emitted from 5G cell phone base stations have become an obstacle toward 5G deployment. Some people in Japan have also voiced their concerns. One of the reasons for these concerns is that radio waves are almost always present around us and invisible; hence, we do not know how strong they are. Therefore, there is a need to comprehensively understand the environments around various sources of radio waves, accumulate related data, and widely share information on exposure levels.

NICT is the first public research institute in Japan with the relevant measurement technology for radio environments to perform large-scale, long-term measurements of radio exposure levels, beginning in 2019. By combining fixed-point measurements, spot measurements, measurements based on portable instruments, and wide-area measurements based on electro-measurement vehicles with mounted measuring instruments, data bias is minimized and large-scale, detailed data on radio exposure levels were obtained. For this purpose, they performed measurements in the two frequency bands used in 5G communications.

One of them is called FR1 (below 6 GHz). The bands in FR1 mainly used in Japan are 3.7 GHz and 4.5 GHz bands. The band below 6 GHz is also called the sub-6-GHz band. The other is called FR2, which uses a wavelength of 28 GHz; it is also known as the quasi-millimeter waveband.

The measurements were performed at 51 locations (51 points) in and around Tokyo for the FR1 band and at 3 locations (15 points) in central Tokyo for the FR2 band. A spectrum analyzer and an electric field probe were used to measure FR1 signals, and a 28-GHz-band-compatible antenna was used instead of an electric field probe to measure FR2 signals. In addition, electric field strength measurements were performed while data was downloaded in a cell phone terminal (smartphone). In particular, 6 GB of data was downloaded using FR1 signals and 10 GB of data was downloaded using FR2 signals for approximately 1 minute.

Since the data were transmitted from the cell phone terminal to the base station during data downloading, the conditions were studied in advance to minimize the influence of radio waves emitted from the cell phone terminal during transmission on the measurement results. The data obtained from the measurements were statistically processed and compared with the results of previous measurements.

A comparison with and without data downloading showed that exposure levels were about 70 times greater when using the FR1 band and about 1000 times greater when using the FR2 band during data downloading compared with exposure levels in the case of no downloading. Comparison of these results with previous measurement results for base stations of conventional 4G cellular systems showed that exposure levels were approximately equal or lower even when data was downloaded. In all cases, the exposure levels were lower (median value of less than about 1/10,000) compared to those specified in the radio frequency protection guidelines. The radio frequency exposure levels determined in this study were also 12% of those determined in recent measurements of 5G FR1 base stations overseas.

These research results were published in the electronic edition of the international academic journal Bioelectromagnetics in April and presented at EMC Japan/APEMC, Okinawa, in May. Moreover, these measurement results are the first ones since the introduction of 5G communication in Japan. They will serve as reference data for clarifying how radio wave exposure levels will change with the further spread of 5G communication in the future. Hence, NICT will continue performing measurements over a long period, at least until 2040, and publish the results in conference presentations and other media. In addition, NICT will work to acquire, accumulate, and utilize internationally comparable data on radio wave exposure level measurements in cooperation with overseas research initiatives on radio wave exposure level measurements.

Journal Information
Publication: Bioelectromagnetics
Title: Electromagnetic field exposure monitoring of commercial 28-GHz band 5G base stations in Tokyo, Japan
DOI: 10.1002/bem.22505