12 research outputs found

    Multicast for ubiquitos streaming of multimedia content to mobile terminals : Network architecture and protocols

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    The Universal Mobile Telecommunication Services (UMTS) network was envisioned to carry a wide range of new services; however, the first UMTS release was not designed to efficiently support multimedia content. In this thesis we analyse several mechanisms, and suggest architectural changes to improve UMTS’s capacity for a subset of the multimedia services; high-bandwidth group services. In our initial work we have suggested how IP multicast protocols can be used in the UMTS network to reduce the required network capacity for group services. This proposal was one of many suggestions for the evolving Multimedia Broadcast/Multicast Service (MBMS) architecture for UMTS. The next technique we have suggested and analysed is a new wireless channel type named the "sticky-channel"; this channel is intended for sparsely populated multicast groups. The sticky-channel is able to stick to mobile multicast members in the boarder area of neighbouring radio cells, thus some base stations does not need to broadcast the multicast data. Consequently, the total number of broadcast channels needed to cover a given area is reduced. There is a marginal reduction of required resources with this technique. In the main part of our work we have studied heterogeneous multihop wireless access for multicast traffic in the UMTS network. In a heterogeneous wireless access network, the wireless resources needed to distribute high-bandwidth group services, can be shared among cooperating network technologies. Mobile terminals with a UMTS interface and an IEEE 802.11 interface are readily available, consequently a heterogeneous network with UMTS and 802.11 links will be easy to deploy. We have described a heterogeneous architecture based on those wireless technologies. In this architecture, the range of a UMTS radio channel is reduced, and local IEEE 802.11-based Mobile Ad Hoc Networks (MANETs) forward the data to users located outside the coverage of the reduced UMTS channel. The wireless resources required to transmit a data packet are proportional to (at least) the square of the distance the packet must travel, thus a reduction in the channel range releases a significant amount of UMTS radio resources. Detailed simulation results showed acceptable service quality when the UMTS broadcast channel range is more than halved. Finally we have studied whether Forward Error Correction (FEC) at the packet-level on multicast flows could improve the performance of the heterogeneous wireless access network. There is a marginal improvement. Most of the protection brought by the FEC code has been used to repair the increased packet-loss introduced by the FEC overhead

    IEEE 802.11 parameters adaptation for Performance enhancement in high density Wireless networks

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    Tribunal : Ramón Agüero, Álvaro Martín, Federico LarrocaNowadays, it is common to find wireless networks that are based on the IEEE 802.11 standard deployed in an unplanned and unmanaged manner. Moreover, because of the low hardware cost and, trying to obtain optimal coverage and performance, a large number of devices are usually installed in reduced spaces generating high-density deployments. This kind of networks experiment a myriad of problems (e.g., interference, medium access control, etc.) related with the shared nature of the transmission medium. In recent years, different physical-layer- and link-layer-adaptation mechanisms have been proposed to palliate those problems, however, their feedback-loop-based behaviour in a highly complex RF medium makes their performance hard to assess. In this work, we study the problems of high-density networks, experimentally evaluate some existing solutions and propose a new adaptation mechanism, PRCS, that tackles some common weakness of those solutions. PRCS control the transmit power, the data rate, and the carrier sense threshold of APs of a wireless network so as to mitigate the effects of interference in high-density deployments without causing unfairness between links. In simulation-based experiments, PRCS outperforms similar existing mechanisms in various scenarios and in a particular scenario, where most mechanisms fail, duplicates global network throughput.En la actualidad, es muy común encontrar redes inalámbricas basadas en el estándar IEEE 802.11 desplegadas de manera no planificada ni gestionada. Además, debido al bajo costo de los dispositivos y con la intención de obtener una cobertura y rendimiento óptimos, un gran número de dispositivos son instalados en espacios reducidos, generado despliegues de alta densidad. Este tipo de redes experimentan una gran variedad de problemas (por ej., interferencia, control de acceso al medio, etc.) relacionados con el hecho de que utilizan un medio de transmisión compartido. En los últimos años, diferentes mecanismos de adaptación de parámetros de la capa física y de enlace han sido propuestos con el objetivo de mitigar estos problemas. Estas soluciones adaptan parámetros tales como la potencia de transmisión o la tasa de transmisión. En este trabajo, estudiamos los problemas de las redes inalámbricas de alta densidad, evaluamos mediante experimentos algunas de las soluciones existentes y proponemos un nuevo mecanismo de adaptación, PRCS, que aborda algunas de las debilidades de estas soluciones. PRCS controla la potencia de transmisión, la tasa de transmisión y el umbral del mecanismo de sensado de portadora de los puntos de acceso de una red inalámbrica. El objetivo de este mecanismo es mitigar los efectos de la interferencia en despliegues de alta densidad sin causar asimetrías entre los enlaces. En experimentos basados en simulaciones, mostramos que PRCS supera a los mecanismos existentes en varios escenarios y, en un escenario en particular donde la mayoría de los mecanismos fallan, duplica el rendimiento global de la red

    Teoria de jogos para utilização efetiva dos recursos em aplicações para 5G

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    Doutoramento em Engenharia Eletrotécnica - TelecomunicaçõesEsta tese tem como objetivo fornecer afirmações conclusivas em relação a utilização eficiente de recursos para redes e aplicações de 5G (5a geração) com recurso a teoria dos jogos. Neste contexto, investigamos dois cenários principais, um relativo a comunicações móveis e um outro relativo a redes inteligentes. Uma métrica importante para o desenho das redes móveis emergentes é a eficiência energética, com particular ênfase no lado do dispositivo móvel, onde as tecnologias das baterias são ainda limitadas. Alguns trabalhos de investigação relacionados têm demonstrado que a cooperação pode ser um paradigma útil no sentido de resolver o problema do défice energético. Contudo, pretendemos ir mais além, ao definir a cooperação e os utilizadores móveis como um grupo de jogadores racionais, que podem atuar sobre estratégias e utilidades, por forma a escolher a retransmissão mais apropriada para poupança de energia. Esta interpretação presta-se à aplicação da teoria dos jogos, e recorremos assim aos jogos coalicionais para solucionar conflitos de interesse entre dispositivos cooperantes, empregando Programação Linear (LP) para resolver o problema da selecção da retransmissão e derivar a principal solução do jogo. Os resultados mostram que a escolha do jogo de retransmissão coalicional proposto pode potencialmente duplicar a duração da bateria, numa era em que a próxima geração de dispositivos móveis necessitará de cada vez mais energia para suportar serviços e aplicações cada vez mais sofisticados. O segundo cenário investiga a resposta da procura em aplicações smart grid, que está a ganhar interesse sob a égide do 5G e que é considerada uma abordagem promissora, incentivando os utilizadores a consumir electricidade de forma mais uniforme em horas de vazio. Recorremos novamente à teoria dos jogos, imaginando as interacções estratégicas entre a empresa fornecedora de energia eléctrica e os potenciais utilizadores finais como um jogo de forma extensiva. São abordados dois programas em tempo real de resposta à procura: Day-Ahead Pricing (DAP) e Convex Pricing Tariffs. A resposta dos consumidores residenciais conscientes dos preços destas tarifas, é formulada como um problema de Mixed Integer Linear Programming (MILP) ou Quadratic Programming (QP), nos quais as soluções potenciais são o agendamento dos seus electrodomésticos inteligentes de modo a minimizar os seus gastos diários de electricidade, satisfazendo as suas necessidades diárias de energia e níveis de conforto. Os resultados demonstram que implementar o programa DAP pode reduzir a razão Peak-to-Average (PAR) at e 71% e as faturas de consumo das casas inteligentes at e 32%. Para além disso, a aplicação de tarifas convexas em tempo real pode melhorar ainda mais estas métricas de desempenho, alcançando uma redução de 80% do PAR e uma economia de mais de 50% na faturação da energia residencial.This research thesis aims to provide conclusive statements towards effective resource utilization for 5G (5th Generation) mobile networks and applications using game theory. In this context, we investigate two key scenarios pertaining to mobile communications and smart grids. A pivotal design driver for the upcoming era of mobile communications is energy efficiency, with particular emphasis on the mobile side where battery technology is still limited. Related works have shown that cooperation can be a useful engineering paradigm to take a step towards solving the energy deficit. However, we go beyond by envisaging cooperation and mobile users as a game of rational players, that can act on strategies and utilities in order to choose the most appropriate relay for energy saving. This interpretation lends itself to the application of game theory, and we look at coalitional games to settle conflicts of interest among cooperating user equipments, and employ Linear Programming (LP) to solve the relay selection problem and to derive the core solution of the game. The results reveal that adopting the proposed coalitional relaying game can potentially double battery lifetime, in an era where the next wave of next generation handsets will be more energy demanding supporting sophisticated services and applications. The second scenario investigates demand response in smart grid applications, which is also gaining momentum under the umbrella of 5G, which is a promising approach urging end-users to consume electricity more evenly during nonpeak hours of the day. Again, we resort to game theory and picture the strategic interactions between the electric utility company and the potential end-users as an extensive form game. Two real-time demand response programmes are addressed, namely Day-Ahead Pricing (DAP) and convex pricing tariffs. The response of price-aware residential consumers to these programmes is formulated as Mixed Integer Linear Programming (MILP) or Quadratic Programming (QP) problem, which optimally schedule their smart home appliances so as to minimise their daily electricity expenses while satisfying their daily energy needs and comfort levels. The results demonstrate that implementing the DAP programme can reduce the Peakto- Average Ratio (PAR) of demand by up to 71% and cut smart households bill by 32%. Moreover, applying real-time convex pricing tariffs can push these performance metrics even further, achieving 80% PAR reduction and more than 50% saving on the household electricity bill

    Mobile Ad-Hoc Networks

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    Being infrastructure-less and without central administration control, wireless ad-hoc networking is playing a more and more important role in extending the coverage of traditional wireless infrastructure (cellular networks, wireless LAN, etc). This book includes state-of-the-art techniques and solutions for wireless ad-hoc networks. It focuses on the following topics in ad-hoc networks: quality-of-service and video communication, routing protocol and cross-layer design. A few interesting problems about security and delay-tolerant networks are also discussed. This book is targeted to provide network engineers and researchers with design guidelines for large scale wireless ad hoc networks

    Cooperative Internet access using heterogeneous wireless networks

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    Ph.DDOCTOR OF PHILOSOPH

    Facilitating Flexible Link Layer Protocols for Future Wireless Communication Systems

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    This dissertation addresses the problem of designing link layer protocols which are flexible enough to accommodate the demands offuture wireless communication systems (FWCS).We show that entire link layer protocols with diverse requirements and responsibilities can be composed out of reconfigurable and reusable components.We demonstrate this by designing and implementinga novel concept termed Flexible Link Layer (FLL) architecture.Through extensive simulations and practical experiments, we evaluate a prototype of the suggested architecture in both fixed-spectrumand dynamic spectrum access (DSA) networks. FWCS are expected to overcome diverse challenges including the continual growthin traffic volume and number of connected devices.Furthermore, they are envisioned to support a widerange of new application requirements and operating conditions.Technology trends, including smart homes, communicating machines, and vehicularnetworks, will not only grow on a scale that once was unimaginable, they will also become the predominant communication paradigm, eventually surpassing today's human-produced network traffic. In order for this to become reality, today's systems have to evolve in many ways.They have to exploit allocated resources in a more efficient and energy-conscious manner.In addition to that, new methods for spectrum access and resource sharingneed to be deployed.Having the diversification of applications and network conditions in mind, flexibility at all layers of a communication system is of paramount importance in order to meet the desired goals. However, traditional communication systems are often designed with specific and distinct applications in mind. Therefore, system designers can tailor communication systems according to fixedrequirements and operating conditions, often resulting in highly optimized but inflexible systems.Among the core problems of such design is the mix of data transfer and management aspects.Such a combination of concerns clearly hinders the reuse and extension of existing protocols. To overcome this problem, the key idea explored in this dissertation is a component-based design to facilitate the development of more flexible and versatile link layer protocols.Specifically, the FLL architecture, suggested in this dissertation, employs a generic, reconfigurable data transfer protocol around which one or more complementary protocols, called link layer applications, are responsible for management-related aspects of the layer. To demonstrate the feasibility of the proposed approach, we have designed andimplemented a prototype of the FLL architecture on the basis ofa reconfigurable software defined radio (SDR) testbed.Employing the SDR prototype as well as computer simulations, thisdissertation describes various experiments used to examine a range of link layerprotocols for both fixed-spectrum and DSA networks. This dissertation firstly outlines the challenges faced by FWCSand describes DSA as a possible technology component for their construction.It then specifies the requirements for future DSA systemsthat provide the basis for our further considerations.We then review the background on link layer protocols, surveyrelated work on the construction of flexible protocol frameworks,and compare a range of actual link layer protocols and algorithms.Based on the results of this analysis, we design, implement, and evaluatethe FLL architecture and a selection of actual link layer protocols. We believe the findings of this dissertation add substantively to the existing literature on link layer protocol design and are valuable for theoreticians and experimentalists alike

    5G Outlook – Innovations and Applications

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    5G Outlook - Innovations and Applications is a collection of the recent research and development in the area of the Fifth Generation Mobile Technology (5G), the future of wireless communications. Plenty of novel ideas and knowledge of the 5G are presented in this book as well as divers applications from health science to business modeling. The authors of different chapters contributed from various countries and organizations. The chapters have also been presented at the 5th IEEE 5G Summit held in Aalborg on July 1, 2016. The book starts with a comprehensive introduction on 5G and its need and requirement. Then millimeter waves as a promising spectrum to 5G technology is discussed. The book continues with the novel and inspiring ideas for the future wireless communication usage and network. Further, some technical issues in signal processing and network design for 5G are presented. Finally, the book ends up with different applications of 5G in distinct areas. Topics widely covered in this book are: • 5G technology from past to present to the future• Millimeter- waves and their characteristics• Signal processing and network design issues for 5G• Applications, business modeling and several novel ideas for the future of 5

    5G Outlook – Innovations and Applications

    Get PDF
    5G Outlook - Innovations and Applications is a collection of the recent research and development in the area of the Fifth Generation Mobile Technology (5G), the future of wireless communications. Plenty of novel ideas and knowledge of the 5G are presented in this book as well as divers applications from health science to business modeling. The authors of different chapters contributed from various countries and organizations. The chapters have also been presented at the 5th IEEE 5G Summit held in Aalborg on July 1, 2016. The book starts with a comprehensive introduction on 5G and its need and requirement. Then millimeter waves as a promising spectrum to 5G technology is discussed. The book continues with the novel and inspiring ideas for the future wireless communication usage and network. Further, some technical issues in signal processing and network design for 5G are presented. Finally, the book ends up with different applications of 5G in distinct areas. Topics widely covered in this book are: • 5G technology from past to present to the future• Millimeter- waves and their characteristics• Signal processing and network design issues for 5G• Applications, business modeling and several novel ideas for the future of 5
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