Decoder-Based Extrapolation Techniques for Human Exposure Assessment From 4G/LTE Base Stations: Experimental Challenges and Procedures for Reliable Estimations

Nowadays, the accurate assessment of human exposure to electromagnetic fields (EMFs) radiated by mobile communication systems is fundamental, not only for safety reasons but also for assuring the proper operation and coexistence of such systems. As an alternative to classical exposure assessment methods, the extrapolation-based approach relies on the power consistency of the expected time-constant reference signal for estimating the maximum electric field. Nevertheless, several studies have shown that the hypothesis of constancy of the reference signal level cannot always be kept in practical situations, thus creating possible misleading estimations when comparing the measurement results with the applicable limits. To overcome such an issue, we propose a suitable approach to estimate a comparator offset (COF) value to robustly compare the extrapolated value with the reference applicable limits, to meet the requirements of the IEC 62232 (the standard in force for cellular base station (BS) EMF human exposure assessment). Through a wide experimental campaign, conducted at different test sites, this article also highlights some practical issues that could arise in estimating maximum E-field levels, based on dedicated decoder measurements, for different operators (OPs) and frequency bands in 4G networks. Such findings can be useful for technical standard committees, and practitioners and technicians involved in the EMF exposure assessment.