We have taken measurements in 3 separate categories to assess a range of ways carriers should comply with EME standards.
Categories of 5G EME measurement activity
- Environmental EME measurements
This category seeks to establish whether the measured EME power density at a base station is within the limits set by the ARPANSA standard.
- Comparisons to carriers’ predicted EME
For each base station facility, carriers publish a calculated prediction of the maximum level of EME and a distance from the base station where that maximum occurs. This category seeks to determine the integrity of the carriers’ EME predictions, by comparing them with field-based measurements taken at, or as close as practically possible to, the predicted distance from the base station provided by the carriers.
- Investigating 5G beamforming technology
The purpose of this category is to use alternative measurement techniques to indicate the maximum level of EME that may be contained within a 5G beamformed transmission from base stations installed with beamforming-capable antennas. This more accurately reflects the way 5G technology works.
Due to various travel restrictions and lockdowns resulting from the COVID-19 pandemic during 2020 to 2022, a nationwide measurement program was not feasible. We chose to conduct measurements only in states where ACMA field staff were located.
In February 2021, ARPANSA released a new standard, the Standard for Limiting Exposure to Radiofrequency Fields – 100 KHz to 300 GHz (the ARPANSA RPS S-1 standard). This new standard updates the Radiation Protection Standard for Maximum Exposure Levels to Radiofrequency Fields - 3 kHz to 300 GHz (2002) (the ARPANSA RPS3 standard).
The new ARPANSA RPS S-1 standard specifies a change to the average time for whole of body exposure to RF fields from 6 minutes to 30 minutes. This change was made to better match the time taken for body core temperature to rise. The EME power density exposure limits for frequencies we measured between 420 MHz and 6 GHz remain the same for both the ARPANSA RPS3 and RPS S-1 standards.
The ACMA updated its legislative instruments in November 2021 to reflect the new standard, specifically the Radiocommunications Licence Conditions (Apparatus Licence) Determination 2015 which, among other things, sets out the licence conditions for mobile network operator licensees.
We conducted environmental EME measurements using the ARPANSA RPS3 standard referenced in our legislative instruments when we began the measurements in early 2021. However, we chose to depart from that standard and use the increased whole-of-body exposure measurement time of 30 minutes specified in the new ARPANSA RPS S-1 standard.
The increased exposure measurement time was adopted to apply a best practice approach. The adoption of the 30-minute measurement period has enabled us to make comparisons between results collected prior to November 2021 with results collected currently and in future programs using the ARPANSA RPS S-1 standard.
Base station site selection
A sample of 5G-enabled mobile telecommunication sites for measurement was selected from the Radio Frequency National Site Archive (RFNSA), a public database of all Australian mobile phone base stations hosted by the Australian Mobile Telecommunications Association (AMTA).
For our 2020–21 and 2021–22 measurement programs, we selected an equal number of Telstra, Optus and TPG Telecom Ltd sites in Victoria, New South Wales and Queensland, a total of 129 sites in each state.
In late 2022, we moved to a business-as-usual measurement program, and aim to measure 130 sites nationally each year. The sites we measure will be a mixture of new sites as well as sites previously measured.
The sites selected for measurement during our business-as-usual program will be informed by the movements of our Field Operations teams as they move around the country as part of their regular work activity.
Selecting a suitable measurement location
A suitable location for conducting measurements at each base station was selected based the following criteria:
- at a distance from the base station accessible to the general public that is as close as possible to where the highest level of predicted EME is specified in the ARPANSA/environmental EME report
- has a clear and uninterrupted line-of-sight view to the base station antennas
- in a direction not more than ±30 degrees from the centre line of the azimuth of one of the base station’s antenna sectors.
Conducting the measurements
Before conducting each EME measurement, ACMA staff identified known characteristics of the transmitters installed at each site, including the likely propagation and physical environment characteristics.
Physical site characteristics were visually inspected, photographed and compared with corresponding information for each base station in the ARPANSA/environmental EME report and the EME guide. Observations made at each site were recorded and used to inform both the EME records and base station deployment code audit programs.
Measurements in all 3 categories were conducted using a selective field strength measuring device – a Narda SRM-3006 selective radiation meter, along with an isotropic electric field probe – a Narda 3-axis antennae (420 MHz to 6 GHz). The radiation meter was mounted on a tripod at a height of 1.5 metres above ground level.
Measurement data was then collected and loaded into the ACMA’s EME measurement database for analysis using a Power BI analytics tool.
Environmental EME measurements – measuring the average cumulative EME at a site
Cumulative EME is all the EME at a site. It includes all of the carriers’ phone services such as 3G, 4G and 5G, as well as any other emissions in the environment at the time.
For the measurement process, EME measurements were conducted in accordance with the Standards Australia document, Radiofrequency fields, Part 2: Principles and methods of measurement and computation - 3 kHz to 300 GHz—AS/NZS 2772.2 Standard (the AS/NZS 2772.2 Standard).
At each measurement location, measurements were conducted between 420 MHz and 6 GHz, which includes all public mobile telecommunication service bands currently used in Australia.
The equipment provided an overall exposure level made up of individual contributions from the mobile base station and other sources in the vicinity transmitting between 420 MHz and 6 GHz. The average EME expressed as a percentage of the ARPANSA RPS3 limit was measured for 30 minutes.
Comparisons to carriers’ predicted EME
For this assessment, at each location we measured the maximum cumulative EME between 420 MHz and 6 GHz, as well as the maximum EME contained within all individual public mobile telecommunications service bands, including other defined service bands between 420 MHz and 6 GHz. These bands include:
- UHF LMRS
- UHF TV
- 700 MHz 4G
- 800 MHz TRUNK
- 800 MHz 3G/4G
- 915 MHz LIPD
- 900 MHz 3G/4G
- 1800 MHz 4G
- 2100 MHz 3G/4G
- 2300 MHz 4G
- 2400 MHz LIPD
- 2600 MHz 4G
- 3500 MHz 5G
- 5800 MHz LIPD
The maximum level of cumulative EME, expressed as a percentage of the ARPANSA RPS3 limit, was measured over a period of 30 minutes between 420 MHz to 6 GHz, as well as the maximum EME within each of the defined service bands.
The results compare predicted maximums from each site’s environmental EME report with the measured maximum of all emissions between 420 MHz and 6 GHz, as well as the measured maximum of the 3500 MHz 5G service band.
The environmental EME report provides calculations of the maximum levels of radiofrequency (RF) electromagnetic energy (EME) around an existing and/or proposed wireless base station that may include mobile telephony, broadband and data services. The report is generally produced by a network operator (such as a mobile phone company) or consultants working on their behalf.
All deployment of public mobile telecommunications service infrastructure in Australia, which includes wireless base stations, small cells and antennas, must be carried out according to the Industry Code C564:2020 Mobile Phone Base Station Deployment. The code requires the supply of certain information as part of the consultative process with the local community and local government authority. The environmental EME report is part of this process and is produced according to a methodology developed by the ARPANSA. It provides objective estimates of the maximum levels of EME from a wireless base station or small cell for both existing and proposed upgrades to telecommunications systems at the site.
While the environmental EME report provides a calculated prediction of the maximum cumulative EME for all active and proposed transmitters at an individual site, because EME measurements conducted in the field are made up of all components from all transmitter sources at the measurement location at the time of measurement we have not compared our results against this figure. Additionally, the environmental EME report provides for proposed transmitters, which may not have been active at the time we conducted the measurement. To address this, we use the ‘Maximum level EME for proposed change’ figure calculated in the environmental EME report as opposed to the current calculated EME figure when referencing the predicted EME calculation data.
The maximum predicted EME figure referenced in our measurement studies also reflects the information in the environmental EME report for each RFNSA site on the day our measurement was undertaken. As mobile network operators are continuing to roll-out new 5G services across their networks the environmental EME report on the RFNSA may have been updated, and the figures may differ from those we have reported.
Investigating 5G beamforming technology
For 3G and 4G networks, downlink power control is activated based on the received signal strength of the base station at the user’s mobile handset. As the received signal strength increases, the downlink power of the base station is throttled back to such a point that an acceptable signal is received. The closer the handset is to the base station, the stronger the signal is, and more transmitter power reduction can be applied.
This scenario does not apply to 5G beamforming. 5G mobile base station transmitters adjust their power up and down to be just sufficient to manage user demand. Transmitter power is determined by data demand, so to attract as much of the transmitter power resource available at any point in time, it is necessary to provide as much traffic load as possible on the 5G transmitter.
To achieve a high traffic-load scenario, a 5G capable smart phone handset utilising the Ookla speed-test application was used to activate the 5G transmitter. Maximum base station transmitter demand from the mobile handset occurs during the download part of the speed test transaction, and EME is measured during this short interval of time during the download.
As shown in Figure 1, to avoid measuring EME from the smartphone as much as possible, the phone is positioned no less than 3 metres behind the measurement probe to create a direct path for the beamform that intersects with the measurement probe. It should also be noted that the smartphone transmitter is least active during the Ookla speed-test download transaction, further reducing its contribution to the EME measured result.
Figure 1: Positioning of the measurement probe, base station and smartphone
For the selected carrier at each site, 6 individual measurements were taken of the active beamformed transmission for 10 seconds each, corresponding to the duration of the Ookla speed-test download transaction. Six idle measurements of 10 seconds each were also taken, in between active measurements, to measure the non-activated level of EME from the base station.
The highest of the 6 active and idle measurements was recorded and expressed as a percentage of the ARPANSA RPS3 limit.
The ACMA’s 5G beamforming methodology is specified and validated in IEC-62232: Revision 3, October 2022 - Determination of RF field strength, power density and SAR in the vicinity of base stations for the purpose of evaluating human exposure.