From 2G to 5G Spatial Modeling of Personal RF-EMF Exposure Within Urban Public Trams

Abstract

The upcoming design and implementation of the new generation of 5G cellular systems, jointly with the multiple wireless communication systems that nowadays coexist within vehicular environments, leads to Heterogeneous Network challenging urban scenarios. In this framework, user's Radiofrequency Electromagnetic Fields (RF-EMF) radiation exposure assessment is pivotal, to verify compliance with current legislation thresholds. In this work, an in-depth study of the E-field characterization of the personal mobile communications within urban public trams is presented, considering different cellular technologies (from 2G to 5G). Specifically, frequency bands in the range of 5G NR frequency range 1 (FR1) and millimeter wave (mm-wave) bands within frequency range 2 (FR2) have been analyzed for 5G scenarios, considering their dispersive material properties. A simulation approach is presented to assess user mobile phone base station up-link radiation exposure, considering all the significant features of urban transportation trams in terms of structure morphology and topology or the materials employed. In addition, different user densities have been considered at different frequency bands, from 2G to 5G (FR1 and FR2), by means of an inhouse developed deterministic 3D Ray-Launching (3D-RL) technique in order to provide clear insight spatial E-field distribution, including the impact in the use of directive antennas and beamforming techniques, within realistic operation conditions. Discussion in relation with current exposure limits have been presented, showing that for all cases, E-Field results are far below the maximum reference levels established by the ICNIRP guidelines. By means of a complete E-field campaign of measurements, performed with both, a personal exposimeter (PEM) and a spectrum analyzer within a real tram wagon car, the proposed methodology has been validated showing good agreement with the experimental measurements. In consequence, a simulationbased analysis methodology for dosimetry estimation is provided, aiding in the assessment of current and future cellular deployments in complex heterogeneous vehicular environments.

Empirical and Modeling Approach for Environmental Indoor RF-EMF Assessment in Complex High-Node Density Scenarios: Public Shopping Malls Case Study

“…As in the previous research works, similar conclusions have been obtained: generally, RF-EMF exposure levels over a broad frequency range are very low in a general life context (with exposure levels well below 1 V/m) when compared with current established international RF-EMF exposure limits [33,48,[63][64][65] presenting higher mean exposure levels for public transportation systems environments (considered complex heterogeneous environments in terms of radio wave propagation) [59][60][66][67]. In this sense, worst exposure average levels are obtained for rail transportation wagon cars scenarios, where the metal structure influence, the supplying electric lines and towers and particularly their huge passenger affluence (high density cellular use environments), involves much more challenging propagation phenomena [60,[68][69][70]. From the results, it must be pointed out that there is lack of clear evidence when analyzing the relative contribution of UL and DL signals in the total cumulative exposure [18,48,63].…”

“…context aware or heterogeneous network environments), among others. In general, it can be stated that the new aforementioned EMF exposure limits are now expressed as a function of the frequency range, the exposure duration and also the spatial characterization [60]. From a worldwide perspective, RF-EMF regulatory frameworks differences have motivated a lack of harmonized RF-EMF exposure limits adoption due to mainly the following concern factors: precautionary principle application [84][85][86] and specific and local socio-political contexts.…”

“…In this work, EMF safety analysis has been implemented as a new module providing full support for non-ionizing radiation exposure results in complex heterogeneous environments with high-node user density. In this library, precise E-field exposure evaluation for the complete volume of the scenario under analysis can be achieved applying conversion EMF equations to the matrix of power level results, obtained in the previous simulation phase [59][60]. It must be clearly remarked that RL simulation techniques provide uncertain near field results in the vicinity of the transmitter antenna.…”

Measurements and Analysis of Personal Exposure to Radiofrequency Electromagnetic Fields at Outdoor and Indoor School Buildings: A Case Study at a Spanish School

“…Other studies have compared levels of RF-EMF exposure in different areas and moments of the day [21], [22] and have compared those levels with maximum levels allowed by international guidelines [23]. Several studies have also measured exposure levels and determined contributions from different sources [5], [9], [24]- [26], through monitoring of exposure levels in microenvironments with the participation of volunteers [13], [27]- [31], or specific measurements carried out by a researcher [10], [14], [32]- [37].…”

Personal Exposure Assessment to Wi-Fi Radiofrequency Electromagnetic Fields in Mexican Microenvironments

“…A revised version of these limits appeared in 2019 for IEEE C95.1-2019 Standard [ 64 ], and a new version of the ICNIRP guidelines was published in March 2020 [ 61 ]. The ICNIRP establishes that the maximum legal exposure level between 2 and 300 GHz is 50 W/m 2 for occupational exposure and 10 W/m 2 for the general public [ 52 , 61 , 65 ]. Exposure guidelines are not legal documents, but they are recommendations that legislative bodies can use for different purposes.…”