Spatial Characterization of Personal RF-EMF Exposure in Public Transportation Buses

Abstract

New services and applications within vehicular environments employ multiple wireless communication systems, within a heterogeneous network framework. In this context, evaluation of electromagnetic field impact is compulsory in order to warrant compliance with current exposure limits. In this paper, E-field strength distribution within urban transportation buses is studied, in which different types of buses, as well as network configurations, are considered. E-field estimations are obtained within the complete interior volume of the urban buses, considering all the characteristics in terms of bus structure and materials employed, by means of an in-house-developed deterministic 3D ray-launching (3D-RL) code. In this way, relevant phenomena in terms of electromagnetic propagation and interaction are considered, such as multipath propagation and shadowing, which determine exposure levels as a function of transceiver location within the bus scenarios. The behavior in terms of E-field distribution of wireless public land mobile communication systems within transportation buses have been analyzed by means of measurement campaigns employing personal exposimeter devices. In addition, E-field volumetric distributions by means of 3D-RL simulations have been obtained as a function of user distribution within the buses, with the aim of analyzing the impact of user presence within complex intra-vehicular indoor scenarios, such as urban transportation buses. A comparison with current exposure limits given by currently adopted standards is obtained, showing that E-field levels were below the aforementioned limits. The use of deterministic simulation techniques based on 3D-RL enables E-field exposure analysis in complex indoor scenarios, offering an optimized balance between accuracy and computational cost. These results and the proposed simulation methodology can aid in an adequate assessment of human exposure to non-ionizing radiofrequency fields in public transportation buses, considering the impact of the morphology and the topology of vehicles, for current as well as for future wireless technologies and exposure limits. INDEX TERMS Radiofrequency electromagnetic fields (RF-EMF), personal exposimeter (PEM), electromagnetic safety, E-field strength distribution, 3D ray launching (3D-RL), urban transportation buses.

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

“…Two different methodologies have been followed during the measurement campaign in order to provide clear insight in terms of use, performance and accuracy [13], [33]. For that purpose, a dynamic approach using a PEM device and a static procedure using a spectrum analyzer have been simultaneously performed to enable comparison.…”

“…The EME Spy Evolution personal dosimeter, from Microwave Vision SA -MVG (https://www.mvg-world. com/en), the newest released version of the EME Spy 121 previously used in [13], have been selected for the study, which is shown within the considered tram wagon car in Fig. 3.…”

“…In another study by the same authors [12], the RF-EMF exposure due to the radiation originated by other people's devices within a train is assessed in a simulation study, showing that passive exposure from other passengers' mobile phones is not negligible and a femtocell within the train infrastructure could drastically reduce the total absorption for other users. Finally, the spatial characterization of personal RF-EMF exposure in public transportation buses is presented in [13], where worst-case studies considering different user densities and distributions for GSM, UMTS and LTE cellular communication systems were evaluated in terms of legislation compliance, showing that E-field levels were below the current established limits.…”

“…In contrast with the previous analysis, the aim of this work is to provide a comprehensive and intensive in-depth realistic case study of the personal mobile communications E-field spatial modeling considering different cellular technologies with special emphasis into future 5G up-link connections within complex heterogenous indoor environments, as urban transportation trams. For that purpose, and distinguishing itself from its predecessor [13], multiple factors must be carefully analyzed in order to provide RF-EMF assessment clear insight. Although both scenarios, the bus and the tram wagon car can be considered as complex indoor heterogeneous scenarios in terms of radio wave propagation, the metal structure influence of the tram as well as the supplying lines and towers, and specifically its presence in the city central urban districts with huge passenger affluence, involves much more challenging propagation phenomena and thus presents higher exposure average levels.…”

Deterministic 3D Ray-Launching Millimeter Wave Channel Characterization for Vehicular Communications in Urban Environments

“…On the other hand, in [ 54 ], with the aid of the 3D-RL tool, the radio wave characterization for ISM 2.4 GHz and 5 GHz Wireless Sensor Networks (WSNs) deployed within a smart city scenario has been assessed and validated. It has also been validated for wireless propagation in closed environments [ 55 ], interference analysis [ 56 ] or electromagnetic dosimetry evaluation in wireless systems [ 57 ]. A detailed description of the algorithm and its convergence analysis can be found in [ 58 ].…”