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 and description of HOLTIN service provision for AECG monitoring in complex indoor environments
(MDPI, 2013) Led Ramos, Santiago; Azpilicueta Fernández de las Heras, Leyre; Aguirre Gallego, Erik; Martínez de Espronceda Cámara, Miguel; Serrano Arriezu, Luis Javier; Falcone Lanas, Francisco; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
In this work, a novel ambulatory ECG monitoring device developed in-house called HOLTIN is analyzed when operating in complex indoor scenarios. The HOLTIN system is described, from the technological platform level to its functional model. In addition, by using in-house 3D ray launching simulation code, the wireless channel behavior, which enables ubiquitous operation, is performed. The effect of human body presence is taken into account by a novel simplified model embedded within the 3D Ray Launching code. Simulation as well as measurement results are presented, showing good agreement. These results may aid in the adequate deployment of this novel device to automate conventional medical processes, increasing the coverage radius and optimizing energy consumption.
Open Access
Impedance bandwidth improvement of a planar antenna based on metamaterial-inspired T-matching network
(IEEE, 2021) Alibakhshikenari, Mohammad; Virdee, Bal S.; Shukla, Panchamkumar; Wang, Yan; Azpilicueta Fernández de las Heras, Leyre; Naser Moghadasi, Mohammad; See, Chan H.; Elfergani, Issa; Zebiri, Chemseddine; Abd-Alhameed, Raed; Huynen, Isabelle; Rodriguez, Jonathan; Denidni, Tayeb A.; Falcone Lanas, Francisco; Limiti, Ernesto; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren; Institute of Smart Cities - ISC; Ingeniería Eléctrica, Electrónica y de Comunicación
In this paper a metamaterial-inspired T-matching network is directly imbedded inside the feedline of a microstrip antenna to realize optimum power transfer between the front-end of an RF Wireless transceiver and the antenna. The proposed T-matching network, which is composed of an arrangement of series capacitor, shunt inductor, series capacitor, exhibits left-handed metamaterial characteristics. The matching network is first theoretically modelled to gain insight of its limitations. It was then implemented directly in the 50-Ω feedline to a standard circular patch antenna, which is an unconventional methodology. The antenna’s performance was verified through measurements. With the proposed technique there is 2.7 dBi improvement in the antenna’s radiation gain and 12% increase in the efficiency at the center frequency,and this is achieved over a significantly wider frequency range by a factor of approximately twenty. Moreover, there is good correlation between the theoretical model, method of moments simulation, and the measurement results.
Open Access
Evaluation of electromagnetic dosimetry of wireless systems in complex indoor scenarios with human body interaction
(EMW Publishing, 2012) Aguirre Gallego, Erik; Arpón Díaz-Aldagalán, Javier; Azpilicueta Fernández de las Heras, Leyre; Ramos González, Victoria; Falcone Lanas, Francisco; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa; Gobierno de Navarra / Nafarroako Gobernua
In this work, the influence of human body within the estimation of dosimetric values is analyzed. A simplified human body model, including the dispersive nature of material parameters of internal organs, skin, muscle, bones and other elements has been implemented. Such a model has been included within an indoor scenario in which an in-house 3D ray launching code has been applied to estimate received power levels within the complete scenario. The results enhance previous dosimetric estimations, while giving insight on influence of human body model in power level distribution and enabling to analyze the impact in the complete volume of the scenario.
Open Access
A ray launching-neural network approach for radio wave propagation analysis in complex indoor environments
(IEEE, 2014) Azpilicueta Fernández de las Heras, Leyre; Rawat, Meenakshi; Rawat, Karun; Ghannouchi, Fadhel; Falcone Lanas, Francisco; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
A novel deterministic approach to model the radio wave propagation channels in complex indoor environments reducing computational complexity is proposed. This technique combines a neural network and a 3D ray launching algorithm in order to compute wireless channel performance in indoor scenarios. An example of applying the method for studying indoor radio wave propagation is presented and the results are compared with a very high resolution fully three dimensional ray launching simulation as the reference solution. The new method allows the use of a lower number of launched rays in the simulation scenario whereas intermediate points can be predicted using neural network. Therefore a high gain in terms of computational efficiency (approximately 80% saving in simulation time) is achieved.
Open Access
Implementation of context aware e-health environments based on social sensor networks
(MDPI, 2016) Aguirre Gallego, Erik; Led Ramos, Santiago; López Iturri, Peio; Azpilicueta Fernández de las Heras, Leyre; Serrano Arriezu, Luis Javier; Falcone Lanas, Francisco; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa; Gobierno de Navarra / Nafarroako Gobernua
In this work, context aware scenarios applied to e-Health and m-Health in the framework of typical households (urban and rural) by means of deploying Social Sensors will be described. Interaction with end-users and social/medical staff is achieved using a multi-signal input/output device, capable of sensing and transmitting environmental, biomedical or activity signals and information with the aid of a combined Bluetooth and Mobile system platform. The devices, which play the role of Social Sensors, are implemented and tested in order to guarantee adequate service levels in terms of multiple signal processing tasks as well as robustness in relation with the use wireless transceivers and channel variability. Initial tests within a Living Lab environment have been performed in order to validate overall system operation. The results obtained show good acceptance of the proposed system both by end users as well as by medical and social staff, increasing interaction, reducing overall response time and social inclusion levels, with a compact and moderate cost solution that can readily be largely deployed.
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
Optimum power transfer in RF front end systems using adaptive impedance matching technique
(Nature Research, 2021) Alibakhshikenari, Mohammad; Virdee, Bal S.; Azpilicueta Fernández de las Heras, Leyre; See, Chan H.; Abd-Alhameed, Raed; Althuwayb, Ayman Abdulhadi; Falcone Lanas, Francisco; Huynen, Isabelle; Denidni, Tayeb A.; Limiti, Ernesto; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren; Institute of Smart Cities - ISC; Ingeniería Eléctrica, Electrónica y de Comunicación
Matching the antenna’s impedance to the RF-front-end of a wireless communications system is challenging as the impedance varies with its surround environment. Autonomously matching the antenna to the RF-front-end is therefore essential to optimize power transfer and thereby maintain the antenna’s radiation efficiency. This paper presents a theoretical technique for automatically tuning an LC impedance matching network that compensates antenna mismatch presented to the RF-front-end. The proposed technique converges to a matching point without the need of complex mathematical modelling of the system comprising of non-linear control elements. Digital circuitry is used to implement the required matching circuit. Reliable convergence is achieved within the tuning range of the LC-network using control-loops that can independently control the LC impedance. An algorithm based on the proposed technique was used to verify its effectiveness with various antenna loads. Mismatch error of the technique is less than 0.2%. The technique enables speedy convergence (< 5 µs) and is highly accurate for autonomous adaptive antenna matching networks.
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
From 2G to 5G spatial modeling of personal RF-EMF exposure within urban public trams
(IEEE, 2020) Celaya Echarri, Mikel; Azpilicueta Fernández de las Heras, Leyre; Karpowicz, Jolanta; López Iturri, Peio; Falcone Lanas, Francisco; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren; Institute of Smart Cities - ISC; Ingeniería Eléctrica, Electrónica y de Comunicación
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.