Demonstration of Safe Electromagnetic Radiation Emitted by 5G Active Antenna Systems

TL;DR

The paper addresses public EMF concerns for 5G-NR with Active Antenna Systems by examining how beamforming and dynamic TDD affect radiation exposure. It combines software simulations and over-the-air field measurements to compare downlink beamformed transmissions against traditional wide-beam transmissions and to analyze uplink exposure, highlighting gaps in conventional EMF metrics. Key findings show that UE-specific beamforming can maintain or improve SNR while reducing EMF near the intended user, whereas uplink transmissions can generate significant EMF near the user under weak reception; the authors propose guidelines and measurement methodologies that account for spatio-temporal beam dynamics, especially for mmWave and dynamic-TDD operation. Overall, the work provides data-driven insights to inform EMF standards, network planning, and public communication, and offers practical measurement strategies to better assess safe 5G deployments.

Abstract

The careful planning and safe deployment of 5G technologies will bring enormous benefits to society and the economy. Higher frequency, beamforming, and small-cells are key technologies that will provide unmatched throughput and seamless connectivity to 5G users. Superficial knowledge of these technologies has raised concerns among the general public about the harmful effects of radiation. Several standardization bodies are active to put limits on the emissions which are based on a defined set of radiation measurement methodologies. However, due to the peculiarity of 5G such as dynamicity of the beams, network densification, Time Division Duplexing mode of operation, etc, using existing EMF measurement methods may provide inaccurate results. In this context, we discuss our experimental studies aimed towards the measurement of radiation caused by beam-based transmissions from a 5G base station equipped with an Active Antenna System(AAS). We elaborate on the shortcomings of current measurement methodologies and address several open questions. Next, we demonstrate that using user-specific downlink beamforming, not only better performance is achieved compared to non-beamformed downlink, but also the radiation in the vicinity of the intended user is significantly decreased. Further, we show that under weak reception conditions, an uplink transmission can cause significantly high radiation in the vicinity of the user equipment. We believe that our work will help in clearing several misleading concepts about the 5G EMF radiation effects. We conclude the work by providing guidelines to improve the methodology of EMF measurement by considering the spatiotemporal dynamicity of the 5G transmission.

Figures (9)

• Figure 1: 5G-NR Synchronization Signal Block (PSS< SSS and PBCH) and PDSCH. SSB is restricted only to 240 subcarriersin frequency domain and only 4 OFDM symbols in the time domain.
• Figure 2: (a) A fully loaded cell where traffic channel power is the same as SSB power; (b) A partially loaded cell where traffic channel power is less than SSB power (c) A fully loaded cell where traffic channel power is more than SSB power
• Figure 3: Beam sweeping of SSBs in a gNB and user-specific beamforming. It is important to have apriori information about the gNB antenna pattern for placing the isotropic antenna at an appropriate location in order to minimize the EMF measurement error. While measuring the EMF caused by traffic channel (user-specific beam) Position-B is desirable to get the accurate EMF.
• Figure 4: (a)Power and direction of traffic and SSB beam are same -- linear extrapolation on the power of SSB beam provides correct result (b),(c) Power and direction of traffic beam are different than SSB beam -- linear extrapolation on the power of SSB beam may provide incorrect result.
• Figure 5: In the TDD mode of operation, it is important to perform a gated measurement to measure DL specific EMF.