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 in-house 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 simulation-based analysis methodology for dosimetry estimation is provided, aiding in the assessment of current and future cellular deployments in complex heterogeneous vehicular environments.
Highlights
Tram systems are a popular public transportation service widely used in medium and large cities around the world [1]–[5]
From a general approach, when discussing electromagnetic threats within the tram wagon cars, the low frequency component of exposure, which is created by the supplying network and electric engines, can be considered, as well as the high frequency components created by devices used inside the tram cars or entering from the sources used along the tram lines
By means of an in-house developed deterministic 3D Ray-Launching (3D-RL) algorithm, E-field exposure estimations have been obtained for the complete volume of the tram wagon car
Summary
Tram systems are a popular public transportation service widely used in medium and large cities around the world [1]–[5]. Flexibility, as tramlines need fixed railways and overhead supplying cables supported by dedicated towers or mesh of lines fixed between nearby buildings They have several advantages when compared with other transportation vehicles such as small building cost, high passenger transport capacity, timeliness of service, safety, quiet, comfort and low environmental impact. Radio Frequency electromagnetic fields (RF-EMF) exposure assessments in urban tram transportation systems is challenging due to the presence of multiple EMF sources with their specific features, affectations and interrelations. In this context, realistic case studies are pivotal in order to achieve RF-EMF dosimetry impact evaluations of general public exposure in these complex heterogeneous environments. From a general approach, when discussing electromagnetic threats within the tram wagon cars, the low frequency component of exposure, which is created by the supplying network and electric engines, can be considered, as well as the high frequency components created by devices used inside the tram cars or entering from the sources used along the tram lines
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