Assessment of Mobile Radio Exposure With Digital Twins

The advancement of mobile communication technologies necessitates the assessment of RF exposure in view of coexistence, interference, and radiation protection. As a complement to real-world measurements, numerical field simulations based on ray tracing in digital environment twins enable a virtual assessment and thus advance this field of studies. The fidelity of the simulation results depends on the accuracy of the environmental model in terms of its geometrical and electromagnetic features. Beside the propagation modeling, it is crucial to model the field sources as well, namely the base station antennas. To reproduce the behavior of the antennas as mounted, the installed-performance radiation patterns need to be considered, which may differ from the manufacturer's data. We performed a systematic exposure assessment study of a 4G/5G mobile system on the campus of the TU Ilmenau, for which high-precision map data are available. The simulated field data were compared with analytical free-space calculations and measurements at two frequencies around 800 MHz and 2100 MHz. Overall, we found promising agreement between all three assessment methods. One instance revealed higher synthetic field values compared to the measured data, indicating deviations of the installed-performance antenna pattern from the manufacturer specifications. Our results prove the feasibility of virtual field exposure assessment and indicate ways for further improvement.