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
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
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
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.
Open Access
A comprehensive survey of 'metamaterial transmission-line based antennas: design, challenges, and applications'
(IEEE, 2020) Alibakhshikenari, Mohammad; Virdee, Bal S.; Azpilicueta Fernández de las Heras, Leyre; Naser Moghadasi, Mohammad; Falcone Lanas, Francisco; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren
In this review paper, a comprehensive study on the concept, theory, and applications of composite right/left-handed transmission lines (CRLH-TLs) by considering their use in antenna system designs have been provided. It is shown that CRLH-TLs with negative permittivity (< 0) and negative permeability (μ < 0) have unique properties that do not occur naturally. Therefore, they are referred to as artificial structures called 'metamaterials'. These artificial structures include series left-handed (LH) capacitances (CL), shunt LH inductances (LL), series right-handed (RH) inductances (LR), and shunt RH capacitances (CR) that are realized by slots or interdigital capacitors, stubs or via-holes, unwanted current flowing on the surface, and gap distance between the surface and ground-plane, respectively. In the most cases, it is also shown that structures based on CRLH metamaterial-TLs are superior than their conventional alternatives, since they have smaller dimensions, lower-profile, wider bandwidth, better radiation patterns, higher gain and efficiency, which make them easier and more cost-effective to manufacture and mass produce. Hence, a broad range of metamaterial-based design possibilities are introduced to highlight the improvement of the performance parameters that are rare and not often discussed in available literature. Therefore, this survey provides a wide overview of key early-stage concepts of metematerial-based designs as a thorough reference for specialist antennas and microwave circuits designers. To analyze the critical features of metamaterial theory and concept, several examples are used. Comparisons on the basis of physical size, bandwidth, materials, gain, efficiency, and radiation patterns are made for all the examples that are based on CRLH metamaterial-TLs. As revealed in all the metematerial design examples, foot-print area decrement is an important issue of study that have a strong impact for the enlargement of the next generation wireless communication systems.
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
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.
Open Access
Design, implementation, and empirical validation of an IoT smart irrigation system for fog computing applications based on Lora and Lorawan sensor nodes
(MDPI, 2020) Froiz Míguez, Iván; López Iturri, Peio; Fraga Lamas, Paula; Celaya Echarri, Mikel; Blanco Novoa, Óscar; Azpilicueta Fernández de las Heras, Leyre; Falcone Lanas, Francisco; Fernández Caramés, Tiago M.; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren; Institute of Smart Cities - ISC; Ingeniería Eléctrica, Electrónica y de Comunicación
Climate change is driving new solutions to manage water more efficiently. Such solutions involve the development of smart irrigation systems where Internet of Things (IoT) nodes are deployed throughout large areas. In addition, in the mentioned areas, wireless communications can be difficult due to the presence of obstacles and metallic objects that block electromagnetic wave propagation totally or partially. This article details the development of a smart irrigation system able to cover large urban areas thanks to the use of Low-Power Wide-Area Network (LPWAN) sensor nodes based on LoRa and LoRaWAN. IoT nodes collect soil temperature/moisture and air temperature data, and control water supply autonomously, either by making use of fog computing gateways or by relying on remote commands sent from a cloud. Since the selection of IoT node and gateway locations is essential to have good connectivity and to reduce energy consumption, this article uses an in-house 3D-ray launching radio-planning tool to determine the best locations in real scenarios. Specifically, this paper provides details on the modeling of a university campus, which includes elements like buildings, roads, green areas, or vehicles. In such a scenario, simulations and empirical measurements were performed for two different testbeds: a LoRaWAN testbed that operates at 868 MHz and a testbed based on LoRa with 433 MHz transceivers. All the measurements agree with the simulation results, showing the impact of shadowing effects and material features (e.g., permittivity, conductivity) in the electromagnetic propagation of near-ground and underground LoRaWAN communications. Higher RF power levels are observed for 433 MHz due to the higher transmitted power level and the lower radio propagation losses, and even in the worst gateway location, the received power level is higher than the sensitivity threshold (–148 dBm). Regarding water consumption, the provided estimations indicate that the proposed smart irrigation system is able to reduce roughly 23% of the amount of used water just by considering weather forecasts. The obtained results provide useful guidelines for future smart irrigation developers and show the radio planning tool accuracy, which allows for optimizing the sensor network topology and the overall performance of the network in terms of coverage, cost, and energy consumption.