An enhanced approach to virtually increase quasi-stationarity regions within geometric channel models for vehicular communications

Vehicular communication channels are intrinsically non-stationary, as they present high mobility and abundant dynamic scatterers. Quasi-stationary regions can assess the degree of non-stationarity within a determined scenario and time variant observation of the channel can be extracted. These regions can aid geometrical models as to increase channel sampling intervals or to develop hybrid stochastic-geometric channel models. In this work, a new methodology for the use of virtual quasi-stationary regions within geometric channel models is proposed, in order to leverage the inherent location information to virtually increase their size. Overall, the use of delay-shifted channel responses improves the mean correlation coefficient between consecutive locations, ultimately reducing computation time for time-variant geometric channel models.The authors wish to acknowledge the support received under Grant RYC2021-031949-I, funded by MCIN/AEI/10.13039/501100011033 and NextGenerationEU/PRTR; and under Grant PID2021-127409OB-C31, funded by MCIU/AEI/FEDER, UE

5G spatial modeling of personal RF-EMF assessment within aircrafts cabin environments

Recently, new wireless communication systems within aircrafts cabins have drawn higher attention due to the growing demand of passenger services and applications and their corresponding requirements and constraints. In this regard, the fifth generation (5G) of wireless communication becomes an attractive and promising alternative to enable aircraft passengers' comfort and entertainment along the flight, considering its potential benefits in term of high data transfers and low latencies. Nevertheless, general population concern about radio frequency electromagnetic fields (RF-EMF) safety in general and, in particular to the environmental exposure at which we are all exposed in these flights, increases at the same time. Thus, in this work, we present an experimental campaign of measurements for current passengers' environmental exposure assessment, performed in different real generalizable type of flights and aircrafts' cabins, in order to provide current RF-EMF exposure insight within these complex heterogeneous environments. In addition, worst-case uplink 5G scenarios, where all 5G cellular handsets of the passengers operate at the same time, have been simulated by means of an in-house developed 3D Ray Launching (3D-RL) deterministic technique. Before takeoff and after landing, critical scenarios with the aircrafts' doors closed have been selected and assessed considering different types of modeled aircrafts full of passengers, considering 5G frequency range 2 (5G-FR2) operating links. The obtained results show that the operation frequency and the morphology and topology of the aircraft cabin have a great influence in the environmental RF-EMF passengers' spatial distribution and overall exposure, but not exceeding, even in worst case conditions, the international established regulatory limits. © 2022 IEEE.This work was supported by the Ministerio de Ciencia, Innovación y Universidades, Gobierno de España (MCIU/AEI/FEDER, UE) under Project RTI2018-095499-B-C31

Towards environmental RF-EMF assessment of mmwave high-node density complex heterogeneous environments

The densification of multiple wireless communication systems that coexist nowadays, as well as the 5G new generation cellular systems advent towards the millimeter wave (mmWave) frequency range, give rise to complex context-aware scenarios with high-node density heterogeneous networks. In this work, a radiofrequency electromagnetic field (RF-EMF) exposure assessment from an empirical and modeling approach for a large, complex indoor setting with high node density and traffic is presented. For that purpose, an intensive and comprehensive in-depth RF-EMF E-field characterization study is provided in a public library study case, considering dense personal mobile communications (5G FR2 @28 GHz) and wireless 802.11ay (@60 GHz) data access services on the mmWave frequency range. By means of an enhanced in-house deterministic 3D ray launching (3D-RL) simulation tool for RF-EMF exposure assessment, different complex heterogenous scenarios of high complexity are assessed in realistic operation conditions, considering different user distributions and densities. The use of directive antennas and MIMO beamforming techniques, as well as all the corresponding features in terms of radio wave propagation, such as the body shielding effect, dispersive material properties of obstacles, the impact of the distribution of scatterers and the associated electromagnetic propagation phenomena, are considered for simulation. Discussion regarding the contribution and impact of the coexistence of multiple heterogeneous networks and services is presented, verifying compliance with the current established international regulation limits with exposure levels far below the aforementioned limits. Finally, the proposed simulation technique is validated with a complete empirical campaign of measurements, showing good agreement. In consequence, the obtained datasets and simulation estimations, along with the proposed RF-EMF simulation tool, could be a reference approach for the design, deployment and exposure assessment of the current and future wireless communication technologies on the mmWave spectrum, where massive high-node density heterogeneous networks are expected.Project RTI2018-095499-B-C31 was funded by the Ministerio de Ciencia, Innovación y Universidades, Gobierno de España (MCIU/AEI/FEDER, UE). This project received funding from Universidad Carlos III de Madrid and the European Union's Horizon 2020 research and innovation programme under Marie Sklodowska-Curie Grant 801538

Adquisición de datos analógicos con alta precisión usando una Computadora de Placa Única

The use of single-board computers in the field of continuous analog data acquisition leads to the reduction of manufacturing times, easy implementation and more compact and portable systems. Disadvantages include data loss and temporary errors between samples. Real-time Operating Systems and components external to the system can reduce these errors, but tend to make the project more complex and increase its cost. This work proposes the implementation of a high precision system for continuous analog data acquisition using the BeagleBone Black. The Programmable Real-Time Subsystem, also inside the BeagleBone Black, guarantees the reduction of external components and a high temporal precision, by imposing the sampling frequency of the internal digital to analog converter. In the practical tests carried out, an error of 38 ppm of samples was obtained when using the Programmable Real-Time Subsystem, improving the data losses that occur when managing the sampling frequency from a timer or from software.La utilización de las computadoras de placa única en el campo de la adquisición continua de datos analógicos conduce a la reducción de tiempos de fabricación, fácil implementación y a sistemas más compactos y portables. Como desventajas tienen las pérdidas de datos y errores temporales entre muestras. Sistemas Operativos de Tiempo Real y componentes externos al sistema pueden reducir estos errores, pero tienden a complejizar el proyecto y aumentar su costo. Este trabajo se propone la implementación de un sistema de alta precisión para la adquisición continua de valores analógicos utilizando el BeagleBone Black. La gestión de la frecuencia de muestreo del convertidor analógico digital interno se realiza a través del Subsistema Programable de Tiempo Real, también al interior del BeagleBone Black, garantizando la reducción de componentes externos y una alta precisión temporal. En las pruebas prácticas realizadas se obtuvo un error de 38 ppm de muestras al usar el Subsistema Programable de Tiempo Real mejorando las pérdidas de datos que se producen al gestionar la frecuencia de muestreo desde un temporizador o desde software