Wireless Channel Models for Indoor Environments

Wireless networks have made significant advancement in recent times by adding a new dimension to theway people communicate. Development of wireless standards have constantly aimed at providing higher datarates even under complex environments using smart antennas, multiple-input, and multiple-output systems.This has necessitated an understanding of the indoor propagation channel. Channel models describe acommunication channel and are essential in developing efficient wireless communication networks. This papersurveys different channel models used to characterise wireless indoor environment. This survey may be usefulfor the army, where the communication over wide areas during wargames that they hold periodically, isnecessary. Moreover, it may also be useful for communication near the border areas for surveillance operations.Defence Science Journal, 2008, 58(6), pp.771-777, DOI:http://dx.doi.org/10.14429/dsj.58.170

Modelling of radio wave propagation using Finite Element Analysis.

Fourth generation (4G) wireless communication systems are intended to support high data rates which requires careful and accurate modelling of the radio environment. In this thesis, for the first time finite clement based accurate and computationally efficient models of wave propagation in different outdoor and indoor environments has been developed. Three different environments were considered: the troposphere, vegetation and tunnels and wave propagation in these environments were modelled using finite element analysis. Use of finite elements in wave propagation modelling is a novel idea although many propagation models and approaches were used in past. Coverage diagrams, path loss contours and power levels were calculated using developed models in the troposphere, vegetation and tunnels. Results obtained were compared with commercially available software Advanced Refractive Effects Prediction Software (AREPS) to validate the accuracy of the developed approach and it is shown that results were accurate with an accuracy of 3dB. The developed models were very flexible in handling complex geometries and similar analysis can be easily extended to other environments. A fully vectored finite element base propagation model was developed for straight and curved tunnels. An optimum range of values of different electrical parameters for tunnels of different shapes has been derived. The thesis delivered a novel approach to modelling radio channels that provided a fast and accurate solution of radio wave propagation in realistic environments. The results of this thesis will have a great impact in modelling and characterisation of future wireless communication systems

Radio Network Planning and Propagation Models for Urban and Indoor Wireless Communication Networks

As the growing demand for mobile communications is constantly increasing, the need for better coverage, improved capacity, and higher transmission quality rises. Thus, a more efficient use of the radio spectrum and communication systems availability are required. This chapter presents EM propagation models most commonly used for the design of wireless communication systems, computer networks WLAN and WPAN for urban and/or in indoor environments. The review of commercial or University computer codes to assist design of WLAN and WPAN networks were done. An example of computer design and simulation of indoor Bluetooth and WLAN communication systems, in the building of Wroclaw University of Science and Technology, Wroclaw, Poland is shown in Chapter 8

Research of the acoustic phenomenon produced by isolated scatterers and its applicability as a noise reducing device in transport infrastructures. Search for an optimised and sustainable design.

Tesis por compendio[ES] El control de ruido ambiental es una preocupación de primera magnitud para las sociedades avanzadas, debido a los problemas derivados que ocasionan en la salud de los ciudadanos. Una de las soluciones más extendidas para el control del ruido en su fase de transmisión en la utilización de pantallas acústicas. La aparición de nuevos materiales formados por redes de dispersores acústicos aislados, denominados cristales de sonido, está revolucionando el campo del apantallamiento acústico, posibilitando el avance tecnológico de esta área. Así, en los últimos años, las pantallas acústicas basadas en cristales de sonido se han posicionado como una alternativa viable a las pantallas acústicas tradicionales, puesto que ofrecen múltiples ventajas frente a las soluciones actuales. En el presente trabajo se muestra primeramente una recopilación de los avances realizados en el campo del apantallamiento acústico mediante esta tipología de pantallas. No obstante, aún existen líneas de investigación abiertas en esta área, que es necesario abordar para conseguir el objetivo de aplicar esta tecnología como atenuadores de sonido en las infraestructuras de transporte. Durante el periodo de formación de la doctoranda, se ha trabajado en algunas de las líneas de investigación activas en este campo del apantallamiento acústico. Una de estas investigaciones condujo al descubrimiento de interferencias entre los efectos de la resonancia y la dispersión múltiple de los cristales de sonido cuando estos efectos se producen en rangos de frecuencia cercanos. También hemos diseñado un nuevo dispositivo de reducción de ruido basado en cristales de sonido, utilizando herramientas de optimización multiobjetivo, que permitan apantallar y reflejar de forma difusa el ruido. El empleo de esta nueva herramienta de diseño identificó la necesidad de realizar un estudio comparativo de los métodos de simulación más utilizados para estimar el rendimiento de los dispositivos basados en cristales de sonido. Por último, hemos realizado un estudio psicoacústico para determinar la percepción de la reducción de molestia que proporcionan las pantallas acústicas basadas en cristales sonido y las barreras tradicionales, determinando si los parámetros objetivos que evalúan su rendimiento coinciden con la respuesta subjetiva de los usuarios.[CA] El control de soroll ambiental és una preocupació de primera magnitud per a les societats avançades, a causa dels problemes derivats que ocasionen en la salut dels ciutadans. Una de les solucions més esteses per al control del soroll en la seua fase de transmissió en la utilització de pantalles acústiques. L'aparició de nous materials formats per xarxes de dispersors acústics aïllats, denominats cristals de so, està revolucionant el camp de l'apantallament acústic, possibilitant l'avanç tecnològic d'esta àrea. Així, en els últims anys, les pantalles acústiques basades en cristals de so s'han posicionat com una alternativa viable a les pantalles acústiques tradicionals, ja que oferixen múltiples avantatges enfront de les solucions actuals. En el present treball es mostra primerament una recopilació dels avanços realitzats en el camp de l'apantallament acústic per mitjà d'esta tipologia de pantalles. No obstant això, encara hi ha línies d'investigació obertes en esta àrea, que és necessari abordar per a aconseguir l'objectiu d'aplicar esta tecnologia com a atenuadors de so en les infraestructures de transport. Durant el període de formació de la doctoranda, s'ha treballat en algunes de les línies d'investigació actives en este camp de l'apantallament acústic. Una d'estes investigacions va conduir al descobriment d'interferències entre els efectes de la ressonància i la dispersió múltiple dels cristals de so quan estos efectes es produïxen en rangs de freqüència pròxims. També hem dissenyat un nou dispositiu de reducció de soroll basat en cristals de so, utilitzant ferramentes d'optimització multiobjectiu, que permeten apantallar i reflectir de forma difusa el soroll. L'ús d'esta nova ferramenta de disseny va identificar la necessitat de realitzar un estudi comparatiu dels mètodes de simulació més utilitzats per a estimar el rendiment dels dispositius basats en cristals de so. Finalment, hem realitzat un estudi psicoacústic per a determinar la percepció de la reducció de molèstia que proporcionen les pantalles acústiques basades en cristals so i les barreres tradicionals, determinant si els paràmetres objectius que avaluen el seu rendiment coincidixen amb la resposta subjectiva dels usuaris.[EN] Control of environmental noise is a major concern for advanced societies because of the resulting problems for citizens' health. One of the most widespread solutions for controlling noise in its transmission phase is the use of acoustic screens. The emergence of new materials made up of arrays of isolated acoustic scatterers, called sonic crystals, is revolutionizing the field of acoustic screening. In recent years, acoustic screens based on sonic crystals have positioned themselves as a viable alternative to traditional acoustic screens, as they offer multiple advantages over current traditional solutions. This Doctoral dissertation compiles the advances in the field of acoustic screening using this type of sonic crystals. However, there is still active research in this area which needs to be addressed and studied in order to apply this technology as noise reduction devices in transport infrastructures. Therefore, during the PhD student's training period, we have researched the acoustic phenomena produced by isolated scatterers in order to better understand the physical phenomena behind the lasts designs of this type of screen. One of these researches led to the discovery of interferences between the effects of resonance and multiple scattering of sonic crystals when occurring in nearby frequency ranges. Also we have designed a new noise reduction device based on sonic crystals, using multi-objective optimization tools, which would block and diffuse the noise. This new designing tool identified the need for a comparative study of the most commonly used simulation methods to estimate the performance of devices based on sonic crystals. Finally, we have carried out a psychoacoustic study that determined the perception of the annoyance reduction provided by acoustic screens based on sonic crystals and traditional barriers, determining whether the objective parameters that evaluate their performance match to the subjective response of the users.Agradezco al Ministerio de Ciencia e Innovación por la ayuda concedida dentro del programa Doctores Industriales. Asimismo, a mi tutor en empresa Dr. Juan José Martín Pino, por posibilitar la realización de esta investigación dentro de la empresa BECSA. Al Departamento de Física Aplicada de la Universitat Politècnica de València, a la Comisión Académica del Programa de Doctorado de Matemáticas y al Centro de Tecnologías Físicas: Acústica, Materiales y Astrofísica.Peiró Torres, MDP. (2021). Research of the acoustic phenomenon produced by isolated scatterers and its applicability as a noise reducing device in transport infrastructures. Search for an optimised and sustainable design [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/164903TESISCompendi

A personal, distributed exposimeter: procedure for design, calibration, validation, and application

This paper describes, for the first time, the procedure for the full design, calibration, uncertainty analysis, and practical application of a personal, distributed exposimeter (PDE) for the detection of personal exposure in the Global System for Mobile Communications (GSM) downlink (DL) band around 900 MHz (GSM 900 DL). The PDE is a sensor that consists of several body-worn antennas. The on-body location of these antennas is investigated using numerical simulations and calibration measurements in an anechoic chamber. The calibration measurements and the simulations result in a design (or on-body setup) of the PDE. This is used for validation measurements and indoor radio frequency (RF) exposure measurements in Ghent, Belgium. The main achievements of this paper are: first, the demonstration, using both measurements and simulations, that a PDE consisting of multiple on-body textile antennas will have a lower measurement uncertainty for personal RF exposure than existing on-body sensors; second, a validation of the PDE, which proves that the device correctly estimates the incident power densities; and third, a demonstration of the usability of the PDE for real exposure assessment measurements. To this aim, the validated PDE is used for indoor measurements in a residential building in Ghent, Belgium, which yield an average incident power density of 0.018 mW/m(2)

The characterisation and modelling of the wireless propagation channel in small cells scenarios

“A thesis submitted to the University of Bedfordshire, in partial fulfilment of the requirements for the degree of Doctor of Philosophy”.The rapid growth in wireless data traffic in recent years has placed a great strain on the wireless spectrum and the capacity of current wireless networks. In addition, the makeup of the typical wireless propagation environment is rapidly changing as a greater percentage of data traffic moves indoors, where the coverage of radio signals is poor. This dual fronted assault on coverage and capacity has meant that the tradition cellular model is no longer sustainable, as the gains from constructing new macrocells falls short of the increasing cost. The key emerging concept that can solve the aforementioned challenges is smaller base stations such as micro-, pico- and femto-cells collectively known as small cells. However with this solution come new challenges: while small cells are efficient at improving the indoor coverage and capacity; they compound the lack of spectrum even more and cause high levels of interference. Current channel models are not suited to characterise this interference as the small cells propagation environment is vast different. The result is that overall efficiency of the networks suffers. This thesis presents an investigation into the characteristics of the wireless propagation channel in small cell environments, including measurement, analysis, modelling, validation and extraction of channel data. Two comprehensive data collection campaigns were carried out, one of them employed a RUSK channel sounder and featured dual-polarised MIMO antennas. From the first dataset an empirical path loss model, adapted to typical indoor and outdoor scenarios found in small cell environments, was constructed using regression analysis and was validated using the second dataset. The model shows good accuracy for small cell environments and can be implemented in system level simulations quickly without much requirements

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

Dosimetric study of the radiolectric influence of humans into complex environments through determistic simulations and the implementation of a simplified model

The research presented in this thesis falls under the framework of dosimetry and deterministic estimations. A dosimetric study is carried out with the aid of a 3D Ray Launching simulation technique, by means of an in-house developed code at UPNA. Dosimetry is defined as the calculation of the absorbed dose when a tissue is exposed to electromagnetic radiation, in this case, non-ionizing radiation. It has reached a great importance since a part of the society starts to show concern about the exposure of people to artificial exposures caused by mobile phones or Wi-Fi networks. In fact, some entities (administrations and health bodies) are involved in the regulation and the release of guidelines about this subject. The objective of this thesis is to study dosimetry through 3D Ray Launching simulation technique, calibrating it by the implementation of several scenarios where the simulation tool is tested throughout the comparison of theoretical and measurement results. A simplified human body has been also developed with the aim of employing it in different scenarios, performing dosimetric estimations and providing insight on its influence in the electromagnetic power distribution inside an indoor scenario. Finally, obtained results are compared with different guideline thresholds giving an idea of the compliance of the law when usual wireless communication systems are emitting.Programa Oficial de Doctorado en Tecnologías de las Comunicaciones (RD 1393/2007)Komunikazioen Teknologietako Doktoretza Programa Ofiziala (ED 1393/2007