Open Access
Spatial characterization of radio propagation channel in urban vehicle-to-infrastructure environments to support WSNs deployment
(MDPI, 2017) Granda, Fausto; Azpilicueta Fernández de las Heras, Leyre; Vargas Rosales, César; López Iturri, Peio; Aguirre Gallego, Erik; Astrain Escola, José Javier; Villadangos Alonso, Jesús; Falcone Lanas, Francisco; Ingeniaritza Elektrikoa eta Elektronikoa; Matematika eta Informatika Ingeniaritza; Institute of Smart Cities - ISC; Ingeniería Eléctrica y Electrónica; Ingeniería Matemática e Informática
Vehicular ad hoc Networks (VANETs) enable vehicles to communicate with each other as well as with roadside units (RSUs). Although there is a significant research effort in radio channel modeling focused on vehicle-to-vehicle (V2V), not much work has been done for vehicle-to-infrastructure (V2I) using 3D ray-tracing tools. This work evaluates some important parameters of a V2I wireless channel link such as large-scale path loss and multipath metrics in a typical urban scenario using a deterministic simulation model based on an in-house 3D Ray-Launching (3D-RL) algorithm at 5.9 GHz. Results show the high impact that the spatial distance; link frequency; placement of RSUs; and factors such as roundabout, geometry and relative position of the obstacles have in V2I propagation channel. A detailed spatial path loss characterization of the V2I channel along the streets and avenues is presented. The 3D-RL results show high accuracy when compared with measurements, and represent more reliably the propagation phenomena when compared with analytical path loss models. Performance metrics for a real test scenario implemented with a VANET wireless sensor network implemented ad-hoc are also described. These results constitute a starting point in the design phase of Wireless Sensor Networks (WSNs) radio-planning in the urban V2I deployment in terms of coverage.
Open Access
A 3D ray launching time-frequency channel modeling approach for UWB ranging applications
(IEEE, 2020) Otim, Timothy; López Iturri, Peio; Azpilicueta Fernández de las Heras, Leyre; Bahillo, Alfonso; Falcone Lanas, Francisco; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren; Institute of Smart Cities - ISC; Ingeniería Eléctrica, Electrónica y de Comunicación
Ultrawideband (UWB) has the ability to achieve decimetre level of ranging accuracy, hence, its wider usage nowadays in the field of positioning. In spite of the attractiveness of UWB, its performance is strongly dependent on the propagation channel. In this paper, an analysis of the the UWB channel for ranging applications using an inhouse developed 3D Ray launching (3D RL) algorithm is presented. A parametric study has been performed considering variations of cuboid size resolution of the simulation mesh, in order to analyze convergence impact on estimation accuracy, focusing on Radio frequency (RF) power levels as well as time domain characterization. The RF power results have been used to model the path-loss, small scale fading, and the power delay profile so as to obtain the statistics of the multipath channel as well as time of flight (TOF) estimation values. The results show that the 3D RL is a valuable tool to test UWB systems for ranging applications with a mean accuracy of up to 10 cm in multipath conditions considering complex scatterer distributions within the complete volume of the scenarios under test.
Open Access
Metamaterial-inspired antenna array for application in microwave breast imaging systems for tumor detection
(IEEE, 2020) Alibakhshikenari, Mohammad; Virdee, Bal S.; Shukla, Panchamkumar; Ojaroudi Parchin, Naser; Azpilicueta Fernández de las Heras, Leyre; See, Chan H.; Abd-Alhameed, Raed; 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
This paper presents a study of a planar antenna-array inspired by the metamaterial concept where the resonant elements have sub-wavelength dimensions for application in microwave medical imaging systems for detecting tumors in biological tissues. The proposed antenna consists of square-shaped concentric-rings which are connected to a central patch through a common feedline. The array structure comprises several antennas that are arranged to surround the sample breast model. One antenna at a time in the array is used in transmission-mode while others are in receive-mode. The antenna array operates over 2-12 GHz amply covering the frequency range of existing microwave imaging systems. Measured results show that compared to a standard patch antenna array the proposed array with identical dimensions exhibits an average radiation gain and efficiency improvement of 4.8 dBi and 18%, respectively. The average refiection-coefficient of the array over its operating range is better than S11 = -20 dB making it highly receptive to weak signals and minimizing the distortion encountered with the transmission of short duration pulse-trains. Moreover, the proposed antenna-array exhibits high-isolation on average of 30dB between radiators. This means that antennas in the array (i) can be closely spaced to accommodate more radiators to achieve higher-resolution imaging scans, and (ii) the imagining scans can be done over a wider frequency range to ascertain better contrast in electrical parameters between malignant tumor-tissue and the surrounding normal breast-tissue to facilitate the detection of breast-tumor. It is found that short wavelength gives better resolution. In this experimental study a standard biomedical breast model that mimics a real-human breast in terms of dielectric and optical properties was used to demonstrate the viability of the proposed antenna over a standard patch antenna in the detection and the localization of tumor. These results are encouraging for clinical trials and further refinement of the antenna-array.
Open Access
Radio characterization for ISM 2.4 GHz wireless sensor networks for judo monitoring applications
(MDPI, 2014) López Iturri, Peio; Aguirre Gallego, Erik; Azpilicueta Fernández de las Heras, Leyre; Astrain Escola, José Javier; Villadangos Alonso, Jesús; Falcone Lanas, Francisco; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa; Ingeniería Matemática e Informática; Matematika eta Informatika Ingeniaritza
In this work, the characterization of the radio channel for ISM 2.4GHz Wireless Sensor Networks (WSNs) for judo applications is presented. The environments where judo activity is held are usually complex indoor scenarios in terms of radiopropagation due to their morphology, the presence of humans and the electromagnetic interference generated by personal portable devices, wireless microphones and other wireless systems used by the media. For the assessment of the impact that the topology and the morphology of these environments have on electromagnetic propagation, an in-house developed 3D ray-launching software has been used in this study. Time domain results as well as estimations of received power level have been obtained for the complete volume of a training venue of a local judo club’s facilities with a contest area with the dimensions specified by the International Judo Federation (IJF) for international competitions. The obtained simulation results have been compared with measurements, which have been carried out deploying ZigBee-compliant XBee Pro modules at presented scenario, using approved Judogis (jacket, trousers and belt). The analysis is completed with the inclusion of an in-house human body computational model. Such analysis has allowed the design and development of an in house application devoted to monitor the practice of judo, in order to aid referee activities, training routines and to enhance spectator experience.
Open Access
A hybrid ray launching-diffusion equation approach for propagation prediction in complex indoor environments
(IEEE, 2017) Azpilicueta Fernández de las Heras, Leyre; Falcone Lanas, Francisco; Janaswamy, Ramakrishna; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
A novel and efficient deterministic approach to model radio wave propagation channels in complex indoor environments improving prediction accuracy is proposed. This technique combines a 3-D Ray Launching algorithm based on Geometrical Optics with a Diffusion Equation method based on the equation of transfer. A comparison between the Geometrical Optics only approach and the new method considering the Diffusion Equation has been presented for studying indoor radio wave propagation. The Geometrical Optics-Diffusion Equation method achieves better agreement with measurements, while resulting in high computational efficiency, with approximately 40% savings in simulation time.
Open Access
Analysis of radio wave propagation for ISM 2.4GHz wireless sensor networks in inhomogeneous vegetation environments
(2014) Azpilicueta Fernández de las Heras, Leyre; López Iturri, Peio; Aguirre Gallego, Erik; Astrain Escola, José Javier; Villadangos Alonso, Jesús; Falcone Lanas, Francisco; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa; Ingeniería Matemática e Informática; Matematika eta Informatika Ingeniaritza
The use of wireless networks has been extended in an exponential growing due to the improvement in terms of battery life and low consumption of the devices. However, it is highly important to conduct previous radio propagation analysis when deploying a wireless sensor network. These studies are necessary to perform an estimation of the range coverage, in order to optimize the distance between devices in an actual network deployment. In this work, the radio channel characterization for ISM 2.4GHz Wireless Sensor Networks (WSN) in an inhomogeneous vegetation environment has been analyzed. The impact of topology as well as morphology of the environment is assessed by means of an in-house developed 3D Ray Launching code, to emulate the realistic operation in the framework of the scenario. Experimental results gathered from a measurements campaign conducted by deploying a ZigBee Wireless Sensor Network, are analyzed and compared with simulations in this paper. The scenario where this network is intended to operate is a combination of buildings and diverse vegetation species. To gain insight in the effects of radio propagation, a simplified vegetation model has been developed, considering the material parameters and simplified geometry embedded in the simulation scenario. The use of deterministic tools can aid to know the impact of the topological influence in the deployment of the optimal Wireless Sensor Network in terms of capacity, coverage and energy consumption, making the use of these systems attractive for multiple applications in inhomogeneous vegetation environments.
Open Access
Basketball player on-body biophysical and environmental parameter monitoring based on wireless sensor network integration
(IEEE, 2021) Picallo Guembe, Imanol; López Iturri, Peio; Astrain Escola, José Javier; Aguirre Gallego, Erik; Azpilicueta Fernández de las Heras, Leyre; Celaya Echarri, Mikel; Villadangos Alonso, Jesús; Falcone Lanas, Francisco; Matematika eta Informatika Ingeniaritza; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren; Institute of Smart Cities - ISC; Ingeniería Matemática e Informática; Ingeniería Eléctrica, Electrónica y de Comunicación
Sport activities have benefited in recent years from the progressive adoption of different technological assets in order to improve individual as well as group training, collect different statistics or enhance the spectator experiences. The progressive adoption of Internet of Things paradigms can also be considered within the scope of sport activities, providing high levels of user interactivity as well as enabling cloud-based data storage and processing. In this work, a system for monitoring biophysical, kinematic and environmental parameters within the development of basketball training is presented. A set of on-body nodes with multiple sensors and wireless body area network capabilities have been designed, implemented and tested under real training conditions during a match. Wireless channel analysis results have been obtained with the aid of in house implemented deterministic 3D ray launching algorithm, providing accurate coverage/capacity estimations in relation with human body consideration in the field as well as in the stadium. Measurement results give relevant information in relation with individual player characteristics as well as with team characteristics, providing a flexible tool to improve training development of basketball.
Open Access
Implementation and operational analysis of an interactive intensive care unit within a smart health context
(MDPI, 2018) López Iturri, Peio; Aguirre Gallego, Erik; Trigo Vilaseca, Jesús Daniel; Astrain Escola, José Javier; Azpilicueta Fernández de las Heras, Leyre; Serrano Arriezu, Luis Javier; Villadangos Alonso, Jesús; Falcone Lanas, Francisco; Ingeniaritza Elektrikoa eta Elektronikoa; Matematika eta Informatika Ingeniaritza; Institute of Smart Cities - ISC; Ingeniería Eléctrica y Electrónica; Ingeniería Matemática e Informática
In the context of hospital management and operation, Intensive Care Units (ICU) are one of the most challenging in terms of time responsiveness and criticality, in which adequate resource management and signal processing play a key role in overall system performance. In this work, a context aware Intensive Care Unit is implemented and analyzed to provide scalable signal acquisition capabilities, as well as to provide tracking and access control. Wireless channel analysis is performed by means of hybrid optimized 3D Ray Launching deterministic simulation to assess potential interference impact as well as to provide required coverage/capacity thresholds for employed transceivers. Wireless system operation within the ICU scenario, considering conventional transceiver operation, is feasible in terms of quality of service for the complete scenario. Extensive measurements of overall interference levels have also been carried out, enabling subsequent adequate coverage/capacity estimations, for a set of Zigbee based nodes. Real system operation has been tested, with ad-hoc designed Zigbee wireless motes, employing lightweight communication protocols to minimize energy and bandwidth usage. An ICU information gathering application and software architecture for Visitor Access Control has been implemented, providing monitoring of the Boxes external doors and the identification of visitors via a RFID system. The results enable a solution to provide ICU access control and tracking capabilities previously not exploited, providing a step forward in the implementation of a Smart Health framework.
Open Access
Enhanced wireless channel estimation through parametric optimization of hybrid ray launching-collaborative filtering technique
(IEEE, 2020) Casino, Fran; López Iturri, Peio; Aguirre Gallego, Erik; Azpilicueta Fernández de las Heras, Leyre; Falcone Lanas, Francisco; Solanas, Agustí; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren; Institute of Smart Cities - ISC; Ingeniería Eléctrica, Electrónica y de Comunicación
In this paper, an enhancement of a hybrid simulation technique based on combining collaborative filtering with deterministic 3D ray launching algorithm is proposed. Our approach implements a new methodology of data depuration from low definition simulations to reduce noisy simulation cells. This is achieved by processing the maximum number of permitted reflections, applying memory based collaborative filtering, using a nearest neighbors' approach. The depuration of the low definition ray launching simulation results consists on discarding the estimated values of the cells reached by a number of rays lower than a set value. Discarded cell values are considered noise due to the high error that they provide comparing them to high definition ray launching simulation results. Thus, applying the collaborative filtering technique both to empty and noisy cells, the overall accuracy of the proposed methodology is improved. Specifically, the size of the data collected from the scenarios was reduced by more than 40% after identifying and extracting noisy/erroneous values. In addition, despite the reduced amount of training samples, the new methodology provides an accuracy gain above 8% when applied to the real-world scenario under test, compared with the original approach. Therefore, the proposed methodology provides more precise results from a low definition dataset, increasing accuracy while exhibiting lower complexity in terms of computation and data storage. The enhanced hybrid method enables the analysis of larger complex scenarios with high transceiver density, providing coverage/capacity estimations in the design of heterogeneous IoT network applications.
Open Access
Design and experimental validation of a LoRaWAN fog computing based architecture for IoT enabled smart campus applications
(MDPI, 2019) Fraga Lamas, Paula; Celaya Echarri, Mikel; López Iturri, Peio; Castedo, Luis; Azpilicueta Fernández de las Heras, Leyre; Aguirre Gallego, Erik; Suárez Albela, Manuel; Falcone Lanas, Francisco; Fernández Caramés, Tiago M.; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren; Institute of Smart Cities - ISC; Ingeniería Eléctrica, Electrónica y de Comunicación
A smart campus is an intelligent infrastructure where smart sensors and actuators collaborate to collect information and interact with the machines, tools, and users of a university campus. As in a smart city, a smart campus represents a challenging scenario for Internet of Things (IoT) networks, especially in terms of cost, coverage, availability, latency, power consumption, and scalability. The technologies employed so far to cope with such a scenario are not yet able to manage simultaneously all the previously mentioned demanding requirements. Nevertheless, recent paradigms such as fog computing, which extends cloud computing to the edge of a network, make possible low-latency and location-aware IoT applications. Moreover, technologies such as Low-Power Wide-Area Networks (LPWANs) have emerged as a promising solution to provide low-cost and low-power consumption connectivity to nodes spread throughout a wide area. Specifically, the Long-Range Wide-Area Network (LoRaWAN) standard is one of the most recent developments, receiving attention both from industry and academia. In this article, the use of a LoRaWAN fog computing-based architecture is proposed for providing connectivity to IoT nodes deployed in a campus of the University of A Coruña (UDC), Spain. To validate the proposed system, the smart campus has been recreated realistically through an in-house developed 3D Ray-Launching radio-planning simulator that is able to take into consideration even small details, such as traffic lights, vehicles, people, buildings, urban furniture, or vegetation. The developed tool can provide accurate radio propagation estimations within the smart campus scenario in terms of coverage, capacity, and energy efficiency of the network. The results obtained with the planning simulator can then be compared with empirical measurements to assess the operating conditions and the system accuracy. Specifically, this article presents experiments that show the accurate results obtained by the planning simulator in the largest scenario ever built for it (a campus that covers an area of 26,000 m2), which are corroborated with empirical measurements. Then, how the tool can be used to design the deployment of LoRaWAN infrastructure for three smart campus outdoor applications is explained: a mobility pattern detection system, a smart irrigation solution, and a smart traffic-monitoring deployment. Consequently, the presented results provide guidelines to smart campus designers and developers, and for easing LoRaWAN network deployment and research in other smart campuses and large environments such as smart cities.