958 research outputs found
Advanced Trends in Wireless Communications
Physical limitations on wireless communication channels impose huge challenges to reliable communication. Bandwidth limitations, propagation loss, noise and interference make the wireless channel a narrow pipe that does not readily accommodate rapid flow of data. Thus, researches aim to design systems that are suitable to operate in such channels, in order to have high performance quality of service. Also, the mobility of the communication systems requires further investigations to reduce the complexity and the power consumption of the receiver. This book aims to provide highlights of the current research in the field of wireless communications. The subjects discussed are very valuable to communication researchers rather than researchers in the wireless related areas. The book chapters cover a wide range of wireless communication topics
Interaction of antenna systems with human body
The research investigates the influence on the human body on a communication system. To understand this, the effect of hands free kit (HFK) on energy absorption in the body was investigated when operating a smart phone at 2G. Findings on the research are given in the thesis report. Also, the influence of the way in which a phone is held on a phone s received power was investigated. The result was compared to that obtained using a hand phantom acquired from SPEAG. This was to check if the hand phantom best represents the human hand when using it in experiments. The setup for the experiment was in an anechoic chamber at Loughborough University. The mobile phone transmitted in the 2G system. In further experiments carried out on the body, two antennas were attached to the body in six different orientations to receive power from a source creating a Single Input Multiple Output (SIMO) system. The antennas used were monopoles mounted on a circular ground plane. These antennas were designed and constructed with the influence of the body taken into consideration. The use of diversity techniques to improve transmission to an on-body system is investigated with the antennas on the body. For each alignment, the transmission to the on-body was compared with the transmission to the corresponding off-body (free space). Experiments for this work were carried out in three environments
Cooperative Radio Communications for Green Smart Environments
The demand for mobile connectivity is continuously increasing, and by 2020 Mobile and Wireless Communications will serve not only very dense populations of mobile phones and nomadic computers, but also the expected multiplicity of devices and sensors located in machines, vehicles, health systems and city infrastructures. Future Mobile Networks are then faced with many new scenarios and use cases, which will load the networks with different data traffic patterns, in new or shared spectrum bands, creating new specific requirements. This book addresses both the techniques to model, analyse and optimise the radio links and transmission systems in such scenarios, together with the most advanced radio access, resource management and mobile networking technologies. This text summarises the work performed by more than 500 researchers from more than 120 institutions in Europe, America and Asia, from both academia and industries, within the framework of the COST IC1004 Action on "Cooperative Radio Communications for Green and Smart Environments". The book will have appeal to graduates and researchers in the Radio Communications area, and also to engineers working in the Wireless industry. Topics discussed in this book include: âą Radio waves propagation phenomena in diverse urban, indoor, vehicular and body environmentsâą Measurements, characterization, and modelling of radio channels beyond 4G networksâą Key issues in Vehicle (V2X) communicationâą Wireless Body Area Networks, including specific Radio Channel Models for WBANsâą Energy efficiency and resource management enhancements in Radio Access Networksâą Definitions and models for the virtualised and cloud RAN architecturesâą Advances on feasible indoor localization and tracking techniquesâą Recent findings and innovations in antenna systems for communicationsâą Physical Layer Network Coding for next generation wireless systemsâą Methods and techniques for MIMO Over the Air (OTA) testin
New Radio Small Cell Propagation Environment
The characterization of the wireless medium in indoor small cell networks is essential to obtain appropriate modelling of the propagation environment. This dissertation on âMeasurementBased Characterization of the 5G New Radio Small Cell Propagation Environmentâ has been
developed in an experimental environment. The underlying tasks are divided into three
phases. The first phase took place in the laboratory of the Instituto de TelecomunicaçÔes
â CovilhĂŁ, located in the Departamento de Engenharia ElectromecĂąnica of Universidade da
Beira Interior. During this part of the research, spectrum measurements and the characterization of the S11 parameter (response in the first port for the signal incident in the first port)
have been made experimentally through the printed circuit board antennas in the 2.6 GHz
and 3.5 GHz frequency bands operating in the 2.625 GHz and 3.590 GHz center frequency,
manufactured by us. The fabrication of the antennas was preceded by the simulation in the
student version CST STUDIO software. In this phase, the spectrum measurements and the
characterization of Smith Chart have been made to measure gain and impedance using the
Rohde & Schwarz Vector Network Analyzer (VNA) from IT laboratory. Based on mathematical calculations and considerations on the conductivity and permeability of the environment,
the antennas were built for use in indoor and outdoor environments. The developed antennas are characterized by their bandwidth and their radiation characteristics.
The second phase took place in the three rooms adjacent to the laboratory, in which the
srsLTE emulation software was applied to the 4G indoor scenario. The experimental setup
includes three elements, namely a base station (BS or 4G eNodeB), which transmits the communication signal and which served as a signal source, a user equipment (UE), and an interfering eNodeB. The size of each room is 7.32 Ă 7.32 square meters. While room 1 is the room
of interest, where theoretical and practical measurements took place, BSs that act as wireless
interfering nodes are also separately considered either in room 2 or room 3. By varying the
UE positions within room 1, it was possible to verify that the highest values of the received
power occur close to the central BS. However, the received power does not decrease suddenly
because of the reduced gain in the radiation pattern in the back part of the antenna. In addition, it was demonstrated that there is an effect of âwall lossâproven by the path loss increase
between room 1 and room 2 (or between room 2 and 3). If we consider an attenuation for
each wall of circa 7-9 dB the trend of the WINNER II at 2.625 GHz model for the interference coming across different walls is verified. Future work includes to investigate the 3.5
GHz frequency band.
The third phase is being carried out at the facilities of the old aerodrome of CovilhĂŁ which,
using a temporary license assigned to us by Instituto de ComunicaçÔes PortuguĂȘs (ICP-ANACOM)
as the two first phases. The aim of this phase is to investigate the two-slope behaviour in the
UMi scenario. Very initial LTE-Advanced tests have been performed to verify the propagation of the two ray (with a reflection in the asphalt) from BS implemented with USRP B210
and srsLTE system by considering an urban cell with a length of 80 m and an interfering base
station at 320 m, at 2500 - 2510 MHz (DL - Downlink) by now, mainly due to the current
availability of a directional antenna in this specific band.A investigação de sinais rådio em comunicaçÔes sem fios continua a gerar consideråvel interesse em todo mundo, devido ao seu amplo leque de aplicaçÔes, que inclui a troca de dados
entre dois ou mais dispositivos, comunicaçÔes móveis e via Wi-Fi, infravermelho, transmissão de canais de televisão, monitorização de campos, proteção e vigilùncia costeira e observação ambiental para exploração. A tecnologia de ondas de rådio é o um dos vårios recursos
que viabilizam as comunicaçÔes de alta velocidade e encurta distùncias entre dois pontos em
comunicação. Na realidade, caracterização da comunicação em redes com pequenas células é essencial para obter uma modelização apropriada de ambiente de propagação. Esta
dissertação sob o tema âMeasurement-Based Characterization of the 5G New Radio Small
Cells Propagation Envioronmentâ foi desenvolvida num ambiente experimental, cujas tarefas foram divididas em fases. A primeira fase teve lugar no laboratĂłrio do Instituto de
TelecomunicaçÔes da Covilhã (IT), afeto ao Departamento de Engenharia Eletromecùnica.
Nela foram feitas as simulaçÔes das antenas no software CST STUDIO, versão do estudante
que foram utilizadas nos equipamentos durante as mediçÔes. Seguiu-se a padronização das
mesmas nas faixas dos 2.6 GHz e 3.5 GHz, nas frequĂȘncias centrais de 2.625 GHz e 3.590
GHZ, usando placas de circuitos impressos. Em seguida, foram feitas as mediçÔes do espectro e a caraterização do S11 e da carta de Smith para medir a impedùncia de entrada e
o ganho. As mediçÔes foram feitas com recurso ao Vector Network Analyzer (VNA). Com
base em cålculos matemåticos e consideraçÔes sobre a condutividade e permeabilidade do
ambiente, as antenas foram construĂdas para uso em ambientes internos e externos e com
ou sem interferentes. As antenas desenvolvidas sĂŁo caracterizadas por sua largura de banda
e suas caracterĂsticas de radiação.
A segunda fase decorreu nas trĂȘs salas adjacentes ao laboratĂłrio de TelecomunicaçÔes, na
qual foi montada a topologia com o sistema srsLTE associado aos USRP B210 ligados aos
computadores com o sistema operativo Linux com trĂȘs componentes, nomeadamente uma
estação base (BS), que serviu de fonte do sinal de comunicação com um equipamento de
utilizador (UE) que o recebe, e dois interferentes. Importa realçar que esta segunda fase
foi dividida em duas etapas, das quais uma sem interferente para medir a potĂȘncia recebida
da própria estação base e outra com os interferentes mais próximo e mais afastado da sala
do sinal da própria célula. O objetivo desta fase foi o de verificar o modelo de propagação
do sinal de comunicação da tecnologia LTE e medir a potĂȘncia recebida pelo utilizador com
recurso ao Analisador de Espectro portĂĄtil FSH8 da Rohde & Schwarz capaz de medir de 10
kHz a 8 GHz, feita na frequĂȘncia central de 2.625 GHz.
Nas mediçÔes feitas em ambiente interior, o tamanho de cada uma das trĂȘs salas Ă© 7.32 Ă
7.32 metros quadrados. Embora a sala 1 seja a sala de interesse, onde ocorreram as mediçÔes
teĂłricas e prĂĄticas, as BSs que atuam como nĂłs interferentes tambĂ©m sĂŁo consideradas separadamente na sala 2 ou na sala 3. Ao variar as posiçÔes de UE dentro da sala 1, foi possĂvel
verificar que os valores superiores da potĂȘncia recebida ocorrem prĂłximos Ă BS central. No
entanto, a potĂȘncia recebida nĂŁo diminui repentinamente por causa do efeito do ganho reduzido no diagrama de radiação na parte traseira da antena. AlĂ©m disso, foi demonstrado que existe um efeito de âatenuação da paredeâ comprovado pelo aumento da atenuação de
trajeto entre a sala 1 e a sala 2 (ou entre a sala 2 e 3). Se considerarmos uma atenuação para
cada parede de cerca de 7-9 dB, verifica-se a tendĂȘncia do modelo WINNER II a 2.625 GHz
para a interferĂȘncia que atravessa as diversas paredes. Trabalhos futuros incluem a investigação da banda de frequĂȘncia de 3.5 GHz.
Jå a terceira fase foi realizada nas instalaçÔes do antigo aeródromo da Covilhã, e em todas
as fases servimo-nos de uma licença concedida pela Entidade Reguladora do Espectro (ICPANACOM), que permitiu realizar testes de verificação da propagação do sinal no ambiente
livre na faixa de frequĂȘncia dos 2.6 GHz com 2500 â 2510 MHz (UL - Uplink) e 2620 â 2630
MHz (DL - Downlink). A terceira fase ainda estĂĄ a decorrer nas instalaçÔes do antigo aerĂłdromo da CovilhĂŁ, mediante a mesma licença temporĂĄria que nos foi atribuĂda pelo Instituto
de ComunicaçÔes de Portugal ou Autoridade Nacional de ComunicaçÔes (ICP-ANACOM)
sendo esta reguladora do espectro. O objetivo Ă© continuar a investigar o comportamento
de duas inclinaçÔes no cenårio UMi. Testes muito iniciais LTE-Advanced foram realizados
para verificar a propagação dos dois raios (direto e refletido, com uma reflexão no asfalto)
do BS implementado com o sistema USRP B210 e srsLTE, considerando uma célula urbana
com um comprimento de 80 metros uma estação base interferente em 320 metros, a operar, provisoriamente, a 2500 - 2510 MHz (na ligação descendente, DL - Downlink, devido
Ă disponibilidade de uma antena direcional especĂfica para esta banda).
Finalmente este trabalho de investigação pode ser resumidamente dividido em trĂȘs categorias, nomeadamente investigação de anĂĄlises teĂłricas e matemĂĄticas relevantes da propagação de ondas de rĂĄdio em meios com e sem interferĂȘncia significativa. MediçÔes para verificar o comportamento do sinal de propagação da tecnologia LTE-Advanced com recursos ao
analisador de espectro, simulação das antenas, fabricação e medição das caracterĂsticas de
radiação das mesmas. Assim, as antenas concebidas com bons resultados foram fabricadas
nas instalaçÔes da Faculdade de CiĂȘncias no Departamento de FĂsica da Universidade da
Beira Interior, sendo de seguidas testadas e caracterizadas com o auxĂlio do Vector Nettwork
Analyzer disponĂvel no LaboratĂłrio de TelecomunicaçÔes do Departamento de Engenharia
EletromecĂąnica da Universidade da Beira Interior. E, finalmente, os cĂĄlculos estatĂsticos que
incluem o teste de normalidade de Kolmogorov-Smirnov com recurso ao software estatĂstico
SPSS para validar os resultados obtidos seguida da construção dos gråficos no Matlab em
3D, conforme a superfĂcie da sala
Cooperative Radio Communications for Green Smart Environments
The demand for mobile connectivity is continuously increasing, and by 2020 Mobile and Wireless Communications will serve not only very dense populations of mobile phones and nomadic computers, but also the expected multiplicity of devices and sensors located in machines, vehicles, health systems and city infrastructures. Future Mobile Networks are then faced with many new scenarios and use cases, which will load the networks with different data traffic patterns, in new or shared spectrum bands, creating new specific requirements. This book addresses both the techniques to model, analyse and optimise the radio links and transmission systems in such scenarios, together with the most advanced radio access, resource management and mobile networking technologies. This text summarises the work performed by more than 500 researchers from more than 120 institutions in Europe, America and Asia, from both academia and industries, within the framework of the COST IC1004 Action on "Cooperative Radio Communications for Green and Smart Environments". The book will have appeal to graduates and researchers in the Radio Communications area, and also to engineers working in the Wireless industry. Topics discussed in this book include: âą Radio waves propagation phenomena in diverse urban, indoor, vehicular and body environmentsâą Measurements, characterization, and modelling of radio channels beyond 4G networksâą Key issues in Vehicle (V2X) communicationâą Wireless Body Area Networks, including specific Radio Channel Models for WBANsâą Energy efficiency and resource management enhancements in Radio Access Networksâą Definitions and models for the virtualised and cloud RAN architecturesâą Advances on feasible indoor localization and tracking techniquesâą Recent findings and innovations in antenna systems for communicationsâą Physical Layer Network Coding for next generation wireless systemsâą Methods and techniques for MIMO Over the Air (OTA) testin
Microwave measurement techniques for wearable antennas
This research is germane to the area of on-body antennas and the characterisation of antennas in close proximity to biological matter. The ranges of frequencies discussed are currently popular for mobile communications, namely 0.9GHz to 6GHz with spot frequencies of GSM900, GSM1800 and WiFi2.5GHz. Particular attention is given to the elimination of errors in measurement. This is achieved by the characterisation of an anechoic chamber; a study of the effects of cables; a study of the interaction of surface currents and the human body; a study of tissue simulating liquid; the design of a simple body phantom; the characterisation of the on-body channel for human males in wet and dry clothing and a comparison of perturbation on antennas close to humans and a phantom.EThOS - Electronic Theses Online ServiceGBUnited Kingdo
Fully Integrated Biochip Platforms for Advanced Healthcare
Recent advances in microelectronics and biosensors are enabling developments of innovative biochips for advanced healthcare by providing fully integrated platforms for continuous monitoring of a large set of human disease biomarkers. Continuous monitoring of several human metabolites can be addressed by using fully integrated and minimally invasive devices located in the sub-cutis, typically in the peritoneal region. This extends the techniques of continuous monitoring of glucose currently being pursued with diabetic patients. However, several issues have to be considered in order to succeed in developing fully integrated and minimally invasive implantable devices. These innovative devices require a high-degree of integration, minimal invasive surgery, long-term biocompatibility, security and privacy in data transmission, high reliability, high reproducibility, high specificity, low detection limit and high sensitivity. Recent advances in the field have already proposed possible solutions for several of these issues. The aim of the present paper is to present a broad spectrum of recent results and to propose future directions of development in order to obtain fully implantable systems for the continuous monitoring of the human metabolism in advanced healthcare applications
Study, Measurements and Characterisation of a 5G system using a Mobile Network Operator Testbed
The goals for 5G are aggressive. It promises to deliver enhanced end-user experience
by offering new applications and services through gigabit speeds, and significantly
improved performance and reliability. The enhanced mobile broadband (eMBB) 5G use
case, for instance, targets peak data rates as high as 20 Gbps in the downlink (DL) and
10 Gbps in the uplink (UL).
While there are different ways to improve data rates, spectrum is at the core of enabling
higher mobile broadband data rates. 5G New Radio (NR) specifies new frequency
bands below 6 GHz and also extends into mmWave frequencies where more
contiguous bandwidth is available for sending lots of data. However, at mmWave
frequencies, signals are more susceptible to impairments. Hence, extra consideration is
needed to determine test approaches that provide the precision required to accurately
evaluate 5G components and devices.
Therefore, the aim of the thesis is to provide a deep dive into 5G technology, explore its
testing and validation, and thereafter present the OTE (Hellenic Telecommunications
Organisation) 5G testbed, including measurement results obtained and its characterisation based on key performance indicators (KPIs)
Microwave Photonic Applications - From Chip Level to System Level
Die Vermischung von Mikrowellen- und optischen Technologien â Mikrowellenphotonik â ist ein neu aufkommendes Feld mit hohem Potential. Durch die Nutzung der VorzĂŒge beider Welten hat die Mikrowellenphotonik viele AnwendungsfĂ€lle und ist gerade erst am Beginn ihrer Erfolgsgeschichte. Der Weg fĂŒr neue Konzepte, neue Komponenten und neue Anwendungen wird dadurch geebnet, dass ein höherer Grad an Integration sowie neue Technologien wie Silicon Photonics verfĂŒgbar sind. In diesem Werk werden zuerst die notwendigen grundlegenden Basiskomponenten â optische Quelle, elektro-optische Wandlung, Ăbertragungsmedium und opto-elektrische Wandlung â eingefĂŒhrt. Mithilfe spezifischer Anwendungsbeispiele, die von Chipebene bis hin zur Systemebene reichen, wird der elektrooptische Codesign-Prozess veranschaulicht. SchlieĂlich werden zukĂŒnftige Ausrichtungen wie die UnterstĂŒtzung von elektrischen TrĂ€gern im Millimeterwellen- und THz-Bereich sowie Realisierungsoptionen in integrierter Optik und Nanophotonik diskutiert.The hybridization between microwave and optical technologies â microwave photonics â is an emerging field with high potential. Benefitting from the best of both worlds, microwave photonics has many use cases and is just at the beginning of its success story. The availability of a higher degree of integration and new technologies such as silicon photonics paves the way for new concepts, new components and new applications. In this work, first, the necessary basic building blocks â optical source, electro-optical conversion, transmission medium and opto-electrical conversion â are introduced. With the help of specific application examples ranging from chip level to system level, the electro-optical co-design process for microwave photonic systems is illustrated. Finally, future directions such as the support of electrical carriers in the millimeter wave and THz range and realization options in integrated optics and nanophotonics are discussed
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