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 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
An acceleration approach for channel deterministic approaches based on quasi-stationary regions in V2X communications
(IEEE, 2024) Rodríguez Corbo, Fidel Alejandro; Celaya Echarri, Mikel; Shubair, Raed M.; Falcone Lanas, Francisco; Azpilicueta Fernández de las Heras, Leyre; 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
Vehicular environments are characterized by a high mobility, which alongside with the presence of abundant dynamic scatterers, lead to vehicular communication channels to be intrinsically non-stationary. In this sense, the quasi-stationary regions (QSRs) can assess the degree of non-stationarity within a determined scenario, and ultimately assist geometrical models to increase channel sampling intervals or to develop more efficient hybrid stochastic-geometric channel models. In this work, the channel QSRs in a vehicular communication (V2X) generic highdense urban environment at millimeter wave (mmWave) frequencies (28 GHz) have been analyzed using different approaches, such as the extended channel response into a Doppler-delay domain or the shadow fading spatial auto-correlation function (SF ACF) methodology. Then, the QSRs have been used as sampling distance in an in-house developed three-dimensional ray-launching (3D-RL) algorithm as an acceleration approach. The time variant channel features have been extracted and compared with the full resolution approach, obtaining consistent results when considering the QSR sampling distances, while decreasing by 83.30% the simulation computational time for the Doppler-delay approach, and 92.86% for the SF ACF method.
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
Propagation models in vehicular communications
(IEEE, 2021) Rodríguez Corbo, Fidel Alejandro; Azpilicueta Fernández de las Heras, Leyre; Celaya Echarri, Mikel; Falcone Lanas, Francisco; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren; Institute of Smart Cities - ISC; Ingeniería Eléctrica, Electrónica y de Comunicación
In the advent of becoming reality, the era of autonomous vehicles is closer than ever, and with it, the need for faster and reliable wireless connections. The propagation channel determines the performance limits of wireless communications, and with the aid of empirical measurements, channel modeling is the best approach to predict and recreate how signal propagation conditions may perform. To this end, many different approaches and techniques have been implemented, from specific applications to general models, considering the characteristics of the environment (geometry-based or non-geometry-based) as well as seeking high performance algorithms in order to achieve good balance between accuracy and computational cost. This paper provides an updated overview of propagation channel models for vehicular communications, beginning with some specific propagation characteristics of these complex heterogeneous environments in terms of diverse communication scenarios, different combinations of link types, antenna placement/diversity, potentially high Doppler shifts, or non-stationarity, among others. The presented channel models are classified in four categories: empirical, non-geometry-based stochastic, geometry-based stochastic, and deterministic models, following the classical approach. The features and key concepts of the different vehicular communications channel models are presented, from sub 6 GHz to millimeter wave (mmWave) frequency bands. The advantages and disadvantages of the main works in the area are discussed and compared in a comprehensive way, outlining their contributions. Finally, future critical challenges and research directions for modeling reliable vehicular communications are introduced, such as the effects of vegetation, pedestrians, common scatterers, micro-mobility or spherical wavefront, which in the context of the near future are presented as research opportunities.