Estimation of Maximum RF-EMF Exposure by Single-User MIMO mmWave 5G Systems

The assessment of maximum exposure levels generated by 5G base stations (BSs) via the maximum-power extrapolation (MPE) procedure defined in international standards is challenged by the technical traits of next-generation signals. Dynamic resource allocation to multiple users produces highly nonuniform signal frames in both frequency and time, complicating worst case exposure evaluation. Furthermore, massive multiple-input multiple-output (mMIMO) beamforming reduces the reliability of control channel-based measurements, motivating traffic-forcing techniques. The wide frequency span of 5G necessitates measurement protocols applicable to both FR1 and FR2 bands. In this article, we compare conventional methods–namely, channel power (CP) and zero span (ZS)–against vector-based techniques like vector CP (VCP) and physical downlink shared channel power (PDSCHP), based on the demodulation of the received signal. Unlike most studies focused on FR1, our measurements target a 5G millimeter-wave MIMO signal under realistic network conditions, including multiuser setups and diverse traffic-forcing scenarios. The results show that decoding-based procedures analyzing the PDSCH traffic channel reliably estimate maximum exposure, even when network operation deviates from ideal scenarios. These findings support integrating PDSCH-based methodologies into future revisions of standards such as International Electrotechnical Committee (IEC) 62232.