Open Access
Spatial characterization of personal RF-EMF exposure in public transportation buses
(IEEE, 2019) Celaya Echarri, Mikel; Azpilicueta Fernández de las Heras, Leyre; López Iturri, Peio; Aguirre Gallego, Erik; Miguel Bilbao, Silvia de; Ramos, Victoria; Falcone Lanas, Francisco; Ingeniería Eléctrica, Electrónica y de Comunicación; Institute of Smart Cities - ISC; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren
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 work, 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 of 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.
Open Access
Spatial MIMO channel characterization under different vehicular distributions
(IEEE, 2024) Rodríguez Corbo, Fidel Alejandro; Celaya Echarri, Mikel; Shubair, Raed M.; Falcone Lanas, Francisco; Azpilicueta Fernández de las Heras, Leyre; Estadística, Informática y Matemáticas; Estatistika, Informatika eta Matematika; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Institute of Smart Cities - ISC
Considering the large benefits brought by multipleinput- multiple-output (MIMO) technologies in vehicular communications, the analysis of MIMO channel characteristics using accurate and efficient channel models for these scenarios has become crucial. In this work, an intensive analysis of the MIMO channel characteristics in a mmWave vehicle-to-infrastructure (V2I) communication link with different vehicular distributions is performed. For that purpose, an in-house deterministic simulation channel model with an embedded MIMO channel approach has been developed. Experimental measurements in the same vehicular scenario have been performed to validate the proposed channel simulation technique. Variations in the capacity of the MIMO system have been analyzed in relation to different channel metrics, obtaining that the main contributors are the Signal-to- Noise Ratio (SNR) and the Angular Spread (AS).
Open Access
Deterministic wireless channel characterization towards the integration of communication capabilities to enable context aware industrial internet of thing environments
(Springer, 2022) Picallo Guembe, Imanol; López Iturri, Peio; Celaya Echarri, Mikel; Azpilicueta Fernández de las Heras, Leyre; Falcone Lanas, Francisco; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren; Institute of Smart Cities - ISC; Ingeniería Eléctrica, Electrónica y de Comunicación
In order to provide interactive capabilities within the context of Internet of Thing (IoT) applications, wireless communication systems play a key role, owing to in-herent mobility, ubiquity and ease of deployment. However, to comply with Quality of Service (QoS) and Quality of Experience (QoE) metrics, coverage/capacity analysis must be performed, to account for the impact of signal blockage as well as multiple interference sources. This analysis is especially complex in the case of indoor scenarios, such as those derived from Industrial Internet of Things (IIoT). In this work, a fully volumetric approach based on hybrid deterministic 3D Ray Launching is employed providing precise wireless channel characterization and hence, system level analysis of indoor scenarios. Coverage/capacity, interference mapping and time domain characterization estimations will be derived, considering different frequencies of operation below 6 GHz. The proposed methodology will be tested against a real measurement scenario, providing full flexibility and scalability for adoption in a wide range of IIoT capable environments.
Open Access
Analysis of interaction mechanisms and intercomparison of raytracing tools for optimizing THz simulations
(IEEE, 2025-03-11) Aksoy, Enes; Schultze, Alper; Fazli, Abdolvakil; Raschkowski, Leszek; Azpilicueta Fernández de las Heras, Leyre; Celaya Echarri, Mikel; Navarro Cía, Miguel; Stanczak, Slawomir; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Estadística, Informática y Matemáticas; Estatistika, Informatika eta Matematika; Institute of Smart Cities - ISC
This paper quantifies the weight of the different physical mechanisms (reflection, diffraction, and scattering) in a typical indoor THz wireless communication environment and provides an intercomparison of raytracing tools. Two state-of-the-art raytracing tools - Wireless InSite and Sionna - are utilized to analyze the capabilities of currently available open-source and commercial raytracing engines for THz simulations. A channel sounder measurement campaign at 300 GHz was conducted in a conference room at Fraunhofer HHI, which is used to validate the raytracing simulations. Additionally, the measurements are compared to a proprietary raytracer, optimized for THz simulations. This paper presents a guideline to increase the capabilities of state-of-the-art raytracing tools, to obtain good results for high frequency simulations. The comparisons show, that currently used raytracing tools are not sufficiently accurate for THz simulations. However, these inaccuracies can be mitigated by the implementation of new features, such as the inclusion of different scattering mechanisms and the incorporation of atmospheric attenuation, while utilizing precise geometry and accurate material parameter models.
Open Access
Spatial V2X traffic density channel characterization for urban environments
(IEEE, 2021) Granda, Fausto; Azpilicueta Fernández de las Heras, Leyre; Celaya Echarri, Mikel; López Iturri, Peio; Vargas Rosales, César; Falcone Lanas, Francisco; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren
In this work, Vehicle-to-everything (V2X) wireless communications performance is analyzed, in order to account for inherent scenario complexity, in the deployment phase of wireless systems towards the implementation of a Context Aware environment. An urban environment has been simulated by means of an in-house three-dimensional (3D) Ray Launching algorithm, coupled with a microscopic vehicular movement simulator, accounting for embedded urban elements as well as variable traffic densities within the complex environment. Large-scale and small-scale results are presented, as well as statistical analysis of the impact of different traffic densities. A campaign of measurements in the same real scenario has been performed, showing good agreement with wireless channel estimations for the considered frequency. These results can aid in V2X deployment configurations in urban environments, in order to minimize power consumption, optimize interference levels and increase overall system performance.
Open Access
Tuning selection impact on kriging-aided in-building path loss modeling
(IEEE, 2022) Diago Mosquera, Melissa; Aragón Zavala, Alejandro; Rodríguez Corbo, Fidel Alejandro; Celaya Echarri, Mikel; Shubair, Raed M.; Azpilicueta Fernández de las Heras, Leyre; Estadística, Informática y Matemáticas; Ingeniería Eléctrica, Electrónica y de Comunicación; Estatistika, Informatika eta Matematika; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren
How do you know you select enough tuning dataset from measurements to guarantee model prediction accuracy? Tuning datasets are often selected based on simple random sampling with predefined rates. Usually, these rates are determined as a/b, where a% of the data goes to training and the remaining b% goes to testing. But it is not clear to what extent tuning dataset in order to minimize the estimation path loss errors. It is, thus, required to analyze the performance of channel modeling by selecting—among all measurement samples—appropriate tuning dataset. Using radio measurements and deterministic Ray Launching techniques to collect enough reliable samples, this letter analyzes the impact of tuning dataset selection—expressed in terms of the mean absolute error and cost—on a novel Kriging-aided in-building measurement-based path loss prediction model.
Open Access
Deterministic and empirical approach for millimeter-wave complex outdoor smart parking solution deployments
(MDPI, 2021) Rodríguez Corbo, Fidel Alejandro; Azpilicueta Fernández de las Heras, Leyre; Celaya Echarri, Mikel; López Iturri, Peio; Alejos, Ana V.; Shubair, Raed M.; Falcone Lanas, Francisco; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren; Institute of Smart Cities - ISC; Ingeniería Eléctrica, Electrónica y de Comunicación
The characterization of different vegetation/vehicle densities and their corresponding effects on large-scale channel parameters such as path loss can provide important information during the deployment of wireless communications systems under outdoor conditions. In this work, a deterministic analysis based on ray-launching (RL) simulation and empirical measurements for vehicle-to-infrastructure (V2I) communications for outdoor parking environments and smart parking solutions is presented. The study was carried out at a frequency of 28 GHz using directional antennas, with the transmitter raised above ground level under realistic use case conditions. Different radio channel impairments were weighed in, considering the progressive effect of first, the density of an incremental obstructed barrier of trees, and the effect of different parked vehicle densities within the parking lot. On the basis of these scenarios, large-scale parameters and temporal dispersion characteristics were obtained, and the effect of vegetation/vehicle density changes was assessed. The characterization of propagation impairments that different vegetation/vehicle densities can impose onto the wireless radio channel in the millimeter frequency range was performed. Finally, the results obtained in this research can aid communication deployment in outdoor parking conditions.
Open Access
3D-RL MIMO capacity estimations under vegetation blockage
(IEEE, 2023-09-07) Rodríguez Corbo, Fidel Alejandro; Celaya Echarri, Mikel; Shubair, Raed M.; Falcone Lanas, Francisco; Azpilicueta Fernández de las Heras, Leyre; Institute of Smart Cities - ISC
Multiplexing gains are one of the many promises for increasing throughput in multiple-input-multiple-output (MIMO) systems. In this sense, a rich scattered environment may be beneficial for the multiplexing capabilities of the MIMO channel. However, mm Wave frequency bands tend to have less effective multipath contributions than sub-6 GHz bands. In this work, an in-deep analysis of the multiplexing capabilities in a mm Wave vehicular-to-infrastructure (V2I) channel is performed. Metrics that may impact the channel capacity like received power and angle-of-arrival (AoA) Spread are fully analyzed as well.
Open Access
Deterministic propagation approach for millimeter-wave outdoor smart parking solution deployment
(MDPI, 2020) Rodríguez Corbo, Fidel Alejandro; Azpilicueta Fernández de las Heras, Leyre; Celaya Echarri, Mikel; López Iturri, Peio; Alejos, Ana V.; Falcone Lanas, Francisco; Ingeniería Eléctrica, Electrónica y de Comunicación; Institute of Smart Cities - ISC; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren
Impact factor as an indicator of efficiency or sustainability is entirely correlated with the continuous development of the smart city concept technology application. Intelligent transportation systems (ITSs) and particularly autonomous vehicles are expected to play an important role in this challenging environment. Fast and secure connections will be pivotal in order to achieve this new vehicular communications’ application era. The use of millimeter-wave (mmWave) frequency range is the most promising approach to allow these real-time, high-demand applications that require higher bandwidth with the minimum possible latency. However, an in-depth mmWave-channel characterization of the environment is required for a proper mmWave-based solution deployment. In this work, a complete radio wave propagation channel characterization for a mmWave smart parking solution deployment in a complex outdoor environment was assessed at a 28 GHz frequency band. The considered scenario is a parking lot placed in an open free university campus area surrounded by inhomogeneous vegetation. The vehicle and vegetation density within the scenario, in terms of inherent transceivers density and communication impairments, leads to overall system operation challenges, given by multiple communication links operation at line-of-sight (LOS) and non-line-of-sight (NLOS) conditions. By means of an in-house developed 3D ray launching (3D-RL) algorithm, the impact of variable vegetation density is addressed, providing precise modelling estimations of large-scale multipath propagation effects in terms of received power levels and path loss. The obtained results along with the proposed simulation methodology can aid in an adequate characterization of an mmWave communication channel for new vehicular communications networks, applications, and deployments, considering the outdoor conditions as well as the impact of different vegetation densities, for current as well as for future wireless technologies.
Open Access
Design and empirical validation of a Bluetooth 5 fog computing based industrial CPS architecture for intelligent industry 4.0 shipyard workshops
(IEEE, 2020) Fraga Lamas, Paula; López Iturri, Peio; Celaya Echarri, Mikel; Blanco Novoa, Óscar; Azpilicueta Fernández de las Heras, Leyre; Varela Barbeito, José; Falcone Lanas, Francisco; Fernández Caramés, Tiago M.; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren; Institute of Smart Cities - ISC; Ingeniería Eléctrica, Electrónica y de Comunicación
Navantia, one of largest European shipbuilders, is creating a fog computing based Industrial Cyber-Physical System (ICPS) for monitoring in real-time its pipe workshops in order to track pipes and keep their traceability. The deployment of the ICPS is a unique industrial challenge in terms of communications, since in a pipe workshop there is a significant number of metallic objects with heterogeneous typologies. There are multiple technologies that can be used to track pipes, but this article focuses on Bluetooth 5, which is a relatively new technology that represents a cost-effective solution to cope with harsh environments, since it has been significantly enhanced in terms of low power consumption, range, speed and broadcasting capacity. Thus, it is proposed a Bluetooth 5 fog computing based ICPS architecture that is designed to support physically-distributed and low-latency Industry 4.0 applications that off-load network traffic and computational resources from the cloud. In order to validate the proposed ICPS design, one of the Navantia's pipe workshops was modeled through an in-house developed 3D-ray launching radio planning simulator that allows for estimating the coverage provided by the deployed Bluetooth 5 fog computing nodes and Bluetooth 5 tags. The experiments described in this article show that the radio propagation results obtained by the simulation tool are really close to the ones obtained through empirical measurements. As a consequence, the simulation tool is able to reduce ICPS design and deployment time and provide guidelines to future developers when deploying Bluetooth 5 fog computing nodes and tags in complex industrial scenarios.