Evaluation of EMF Exposure From Distributed MIMO Antennas for 6G in an Industrial Indoor Environment

Abstract

Distributed multi-input multioutput (D-MIMO) is one of the promising technology components for the 6G mobile communication systems. In this article, electromagnetic field (EMF) exposure from D-MIMO deployment scenarios in an industrial indoor environment is evaluated using a hybrid simulation approach, based on ray-tracing and full-wave simulations, for downlink transmission at 3.5 GHz. For comparison, EMF exposure from a massive MIMO (mMIMO) deployment scenario is also assessed in the same environment. Both single-user equal gain transmission precoding and multiuser centralized zero forcing precoding schemes are considered. EMF exposure is assessed with the metrics of incident power density, local specific absorption rate (SAR), and whole-body average SAR. The dependence of the exposure on the number of simultaneously served users and number of distributed radio units is investigated. The simulated exposure at the ground level is well below the limits specified in the international EMF exposure guidelines considering realistic output power levels for both D-MIMO and mMIMO scenarios. It is observed that the 95th and 99th percentiles of the assessed EMF exposure levels from D-MIMO are lower than those from the mMIMO deployment under the same condition. However, a trend is not observed for the median exposure levels.