Radio frequency electromagnetic dosimetry in complex heterogeneous environments
Celaya Echarri, Mikel
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The expansion of new wireless services and applications within contextual environments in a large-scale worldwide, requires a heterogeneous network framework with multiple wireless communication systems operating simultaneously. Considering the popularity and widespread use of cellular communication systems and the emerge of the new Fifth Generation (5G) communication technology, this huge wireless development will increase in a near future. At the same time, general public has started to show concern about the possible adverse effects of electromagnetic fields (EMF) radiation exposure on human health. In fact, administrations and governments have involved human health entities and scientific organizations to work together in order to release guidelines and regulations to provide clear EMF safety insight. In this context, electromagnetic dosimetry has become a relevant research topic and hence, the evaluation of health and safety issues concerning environmental EMF exposure of occupational and general public has acquired special attention, in order to reduce or even mitigate general population concern. In this thesis, a novel EMF safety simulation tool for occupational and general public environmental radio frequency electromagnetic fields (RF-EMF) exposure assessment and dosimetric characterization in complex heterogeneous environments is presented. This full integrated general solution is derived from an in-house deterministic three-dimensional ray-launching (3D-RL) algorithm with an embedded dosimetric framework, enabling precise volumetric exposure results, as a function of user distribution and transceiver location within the scenarios under evaluation. By using this deterministic approach, the impact of topology, dimensions and morphology as well as materials, body shielding and user distributions and densities, are considered with an effective and efficient balance between accuracy and computational cost. In addition, the EMF behavior and influence of next generation wireless communications systems operating in complex context-aware dense challenging environments on the millimeter wave (mmWave) frequency range has been addressed, even in worst-case operation conditions, where brief or irregular local exposure assessment will be required due to massive directive communication links, generated by 5G Multiple Input Multiple Output (MIMO) antennas and beamforming techniques. Therefore, the proposed simulation methodology can be a useful and suitable technique to satisfactorily assess and verify EMF exposure recommendations and limits and therefore implement safe, efficient, and reliable wireless systems deployments in complex heterogeneous sensible environments. Moreover, intensive and comprehensive in-depth occupational and general public environmental RF-EMF exposure assessment studies and dosimetric characterization analyses have been provided in realistic challenging sensible environments, from an empirical and modelling approach (with a mean error of ±" dB), considering current as well as future, wireless communication systems deployments. In general, the obtained environmental EMF exposure results verify compliance with current international adopted guidelines and standards as well as established regulation limits, even in worst-case operation conditions. These results could become a starting point to stablish the RF-EMF assessment reference basis of future wireless deployments (5G, beyond 5G (B5G) or even the Sixth Generation (6G)), where complex context-aware scenarios with massive high-node density heterogenous networks are expected at mmWave frequency bands, or even at terahertz (THz) frequency bands. In consequence, the obtained EMF results, the presented methodology and the proposed simulation tool, can aid in an adequate assessment of human exposure to non-ionizing RF-EMF radiation in complex heterogeneous environments for current as well as future wireless technologies and exposure limits.