Adaptive antennas
Requirements met for operating adaptive antennas
Mobile network operators' adaptive 5G antennas fulfil the implementing guidelines to the Ordinance on Protection against Non-Ionising Radiation (NIRO). This was the result of an in-depth examination of network operators by OFCOM. Both the automatic power lock and the quality assurance systems of the antennas meet the legal requirements. This means that the cantons can approve the use of adaptive antennas in mobile networks.
Adaptive antennas play an important role in expanding the 5G network. To provide the licensing authorities with clarity when assessing these antennas, the Federal Office for the Environment (FOEN) published guidelines on 23 February 2021. The guidelines specify that adaptive antennas must have an automatic power lock to ensure compliance with the authorised transmission power and that the operators' quality assurance system for monitoring adaptive antennas must be upgraded with additional parameters. To examine compliance with these requirements, OFCOM and the FOEN carried out validation tests on site at Salt, Sunrise and Swisscom and reviewed their quality assurance systems.
Power of antennas automatically limited
The tests carried out by OFCOM showed that the operators apply the automatic power lock in such a way that the transmission power of adaptive antennas is automatically reduced in line with the FOEN guidelines. The tested systems reliably fulfil their function and therefore meet the technical requirements for using automatic power locks.
Quality assurance requirements met
The mobile network operators upgraded the mandatory quality assurance systems with the parameters necessary for adaptive antennas, as specified by the guidelines. Since testing showed that the systems monitor adaptive antenna activity accurately, OFCOM has issued the appropriate validation certificates.
Now that all the requirements have been met, the cantons can approve the use of new adaptive antennas for mobile networks. Adaptive antennas that were licensed before the guidelines came into force may continue operating using a so-called correction factor, provided that the authorised transmission power is not exceeded. Operators must notify the authorising body of the correction factor. The cantons are responsible for the procedure.
Tests and measurements by OFCOM on adaptive antennas
In March 2020, the Federal Department of the Environment, Transport, Energy and Communications (DETEC) tasked OFCOM with conducting tests on adaptive antennas. The measurements and simulations conducted in the course of this task revealed that :
- the average level of exposure from adaptive antennas is significantly lower than from classic antennas;
- Conventional antennas transmit mainly to the centre of their coverage area. The further the user is from this central part, the lower the transmission quality. Adaptive antennas, on the other hand, send data specifically to the end device, regardless of its position in the coverage area. The communication maintains the same quality and speed, even at the edge of the area.
- the "power-lock" function (automatic power limiter), which has to be integrated into each adaptive antenna, ensure that emission limit values are respected by limiting transmission power to a mean value.
The report on "Testkonzession und Messungen adaptive Antennen" dated 24.09.2020 brings together the results of measurements carried out in the summer of 2020 on two base stations equipped with 5G technology and computer simulations carried out to validate these measurements. Complementary simulations were used to visualise the exposure to non-ionising radiation (NIR) when the same antenna serves one or more users, taking into account the many possible configurations.
The supplementary report on "Testkonzession und Messungen adaptive Antennen Nachtrag" dated 8.2.2021 confirms the measurements and simulations of the first report and attests to the reliability of the power-lock function, which is used as an automatic mechanism to limit the transmission power of adaptive antennas to a mean value.
These two reports show that the method used to assess the exposure level generated by a conventional antenna cannot be applied in the same manner as it is to adaptive antennas. Indeed, this method of calculation clearly overestimates the real average exposure generated by adaptive antennas. The guidance on adaptive antennas therefore introduces a correction factor that ensures that both types of antenna are treated equally while guaranteeing compliance with the emission limit values specified in the Ordinance on Protection against Non-Ionising Radiation (ORNI, RS 814.710). The results of the tests and measurements carried out by OFCOM made an important contribution to the development of guidance on adaptive antennas issued by the Federal Office for the Environment.
Further information
Qualitätssicherung zur Einhaltung der Grenzwerte der NISV bei Mobilfunkanlagen (in German)
The validation measurements were carried out according to the following document: