Thesis (Ph.D.) - Carleton University, 2006. / Includes bibliographical references (p. 139-144). Also available in electronic format on the Internet.

Orientador: Paulo Cardieri / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação / Made available in DSpace on 2018-08-13T00:30:17Z (GMT). No. of bitstreams: 1 Figueiredo_FabricioLira_D.pdf: 5083177 bytes, checksum: 498c831a8d9546502e8c14d3a4ac4ad4 (MD5) Previous issue date: 2008 / Resumo: As redes metropolitanas sem fio (Wireless Metropolitan Area Networks - WMAN) modernas representam uma tendência tecnológica que viabiliza a ampliação da disponibilidade de acesso a serviços banda larga em todo o mundo. Estas redes se baseiam principalmente nas tecnologias WiMAX e Wi-Fi ad hoc e mesh, que apresentam características complementares e ermitem, a partir de sua integração, construir uma rede metropolitana sem fio híbrida com suporte a múltiplos serviços, mais flexível e de custo otimizado. Esta é a solução de rede investigada nesta tese, que exige o tratamento de diversos desafios tecnológicos, principalmente com o intuito de maximizar cobertura e desempenho da rede. Para tanto, é proposta uma abordagem que consiste em adotar, ao mesmo tempo, metodologias de planejamento e protocolos eficientes para redes WMAN híbridas. Neste contexto, dois aspectos de grande relevância são tratados: esquemas de roteamento de pacotes eficientes para redes Wi-Fi ad hoc e mesh e o planejamento de redes WMAN híbridas. Os resultados obtidos nesta tese representam contribuições significativas para o tratamento destes aspectos, e podem ser adotados para aumentar a eficiência de soluções de redes WMAN híbridas. / Abstract: Modern wireless metropolitan area networks (WMAN) correspond to technological tendency that has contributed to the growth of broadband services availability all over the world. These networks are currently based on technologies WiMAX, Wi-Fi ad hoc e mesh, which support complimentary features, thus allowing the design of multi- service hybrid WMANs, which correspond to a more flexible and cost-effective solution. This approach is the key research subject of this thesis, which requires that several technological challenges are handled, aiming at maximizing network coverage and performance. In this thesis, this problem is addressed by adopting network planning techniques and protocols that jointly contribute to increase coverage and efficiency of hybrid WMAN. In this context, two major aspects are considered: routing in Wi-Fi ad hoc and mesh and planning of hybrid WMAN. The results from this work correspond to significant contributions for each subject and can be adopted for increasing efficiency of hybrid WMAN solutions. / Doutorado / Telecomunicações e Telemática / Doutor em Engenharia Elétrica

Orientadores: Nelson Luis Saldanha da Fonseca, Juliana Freitag Borin / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Computação / Made available in DSpace on 2018-08-23T23:57:58Z (GMT). No. of bitstreams: 1 Kubota_FlavioAdalberto_M.pdf: 1781271 bytes, checksum: 8b229f3a6899591d9307497c320a37f9 (MD5) Previous issue date: 2013 / Resumo: O padrão IEEE 802.16, também conhecido como WiMAX (Worldwide Interoperability for Microwave Access) e seu adendo, o IEEE 802.16-2005, apresentam uma solução de baixo custo para o acesso à Internet. A tecnologia é capaz de prover altas taxas de transferências de dados para amplas áreas geográficas, alto nível de escalabilidade e baixo custo de instalação e manutenção. Além disso, a tecnologia inclui uma arquitetura para provisão de Qualidade de Serviço (QoS) para aplicações de tempo real e aplicações que demandam altas taxas de transferências. Para garantir os requisitos de QoS, o padrão define um mecanismo de sinalização entre a estação base (BS) e a estação cliente (SS), cinco classes de serviço, um mecanismo de escalonamento e um mecanismo de controle de admissão de novas conexões. Entretanto, as políticas que devem ser utilizadas na implementação dos mecanismos de escalonamento e controle de admissão não foram especificadas no padrão. O mecanismo de escalonamento é responsável principalmente por garantir os requisitos de banda mínima das conexões, enquanto que o controle de admissão restringe o número de conexões para evitar a sobrecarga do enlace sem fio. Esta dissertação propõe dois mecanismos de escalonamento e um mecanismo de controle de admissão para redes baseadas no padrão IEEE 802.16. Os mecanismos propostos são totalmente compatíveis com o padrão IEEE 802.16 e são capazes de atender os requisitos de QoS das cinco classes de serviço. Devido a alta variabilidade do sinal do canal sem fio, os mecanismos de escalonamento para redes cabeadas não são adequados para dispositivos sem fio. Dessa forma, as duas políticas de escalonamento e o mecanismo de controle de admissão propostos utilizam informações sobre a qualidade do sinal, através de uma abordagem cross-layer, para promover um uso eficiente do enlace sem fio. As três soluções foram avaliadas através de experimentos de simulação utilizando um módulo para simulação de redes IEEE 802.16 / Abstract: The IEEE 802.16 standard, also known as WiMAX (Worldwide Interoperability for Microwave Access) and its amendment, IEEE 802.16-2005, are a low cost solution for Internet access. The technology is capable of providing high data transfer rates for large geographic areas, high level of scalability and low cost of installation and maintenance. Furthermore, the technology includes an architecture for Quality of Service (QoS) provision for real-time applications and applications that require high transfer rates. To garantee the QoS requirements, the standard defines a signaling mechanism between Base Station (BS) and Subscriber Station (SS), five classes of service, a scheduling mechanism and an admission control mechanism for new connections. However, policies that must be used in the implementation of scheduling mechanisms and admission control mechanisms were not defined by the standard. The scheduling mechanism is responsible for guaranteeing the minimum reserved rate requirements for the connections, while the admission control mechanism restricts the number of connections in the network to avoid the wireless link saturation. This dissertation proposes two scheduling mechanisms and one admission control mechanism for IEEE 802.16 networks. The proposed mechanisms are fully-standard compliant and capable of meeting the QoS requirements of the five classes of service. Due to the high variability of wireless channel signal, the scheduling mechanisms for wired networks are not suitable for wireless networks. Thus, the two scheduling policies and admission control mechanism proposed use information about the quality of the signal, through a cross-layer approach, to promote an efficient use of the wireless link. The three solutions were evaluated through simulation experiments using a simulation module for IEEE 802.16 networks / Mestrado / Ciência da Computação / Mestre em Ciência da Computação

As the number of people using wireless networks is increasing, the need to reduce the vulnerability of wireless networks from node or link failures that cause loss of data is becoming a priority. Also the present techniques and topologies used for wireless networking are not sufficient to handle the traffic load even if we solve the issues of reliability and resilience. Packet loss or delay is increasingly likely due to the increase in the number of packets as technology is evolving and more video and voice packets along with the data packets are being transmitted. Only the efficient and intelligent use of the shared medium can solve the problem and help in avoiding the collision or delay among the packets using a newly proposed intelligent topology. Wireless technology offers the potential to replace wires from many applications, particularly for the rapid deployment of networks for permanent or temporary use. Fiber_ optic metropolitan area networks (WAN) provide security and resilience. A target of the research was to match this in the wireless environment. This research investigates the suitability if using wireless technology for the establishment of a MAN by adding features to enhance resilience. We proposed a mechanism that may be rapidly deployed and provide automatic configuration. Research work and simulation design has been used to develop a new wireless network topology for an efficient and intelligent packet transmission by identifying reliable routes. This novel idea will help give wireless as well as mobile technology a clear edge over wired technology, not only in the case of mobility but also in the case of security of data and other services. A decision based routing tree mechanism has been developed, that can establish routes in an ad-hoc network which may than be configured into a logical dual ring. At the same time the proposed system proposes to embed the quality of service mechanisms, resilience, and reliability features from RPR. The simulations were created using Microsoft Visual Studio.Net for the Decision based routing algorithm. The results were compared with an existing LAR algorithm. We have obtained 95% confidence intervals on all the performance analysis results to indicate accuracy.

<p> Cooperative haptics enables multiple users to manipulate computer simulated objects in a shared virtual environment and to feel the presence of other users. Prior research in the literature has mainly addressed single user haptic interaction. This thesis is concerned with haptic simulation in multi-user virtual environments in which the users can interact in a shared virtual world from separate workstations over Ethernet-based Local Area Networks (LANs) or Metropolitan Area Networks (MANs). In practice, the achievable real-time communication rate using a typical implementation of network protocols such as the UDP and TCP/IP can be well below the 1kHz update rate that is suggested in the literature for high fidelity haptic rendering. However by adopting a multi-rate control strategy as proposed in this work, the local control loops can be executed at 1kHz while the data packet transmission between the user workstations occur at a lower rate. Within such a framework, two control architectures, namely centralized and distributed are presented. In the centralized controller a central workstation simulates the virtual environment, whereas in the distributed controller each user workstation simulates its own copy of the virtual environment. Two different approaches have been proposed for mathematical modeling of the controllers and have been used in a comparative analysis of their stability and performance. The results of such analysis demonstrate that the distributed control architecture has greater stability margins and outperforms the centralized controller. They also reveal that the limited network transmission rate can degrade the haptic fidelity by introducing viscous damping into the virtual object perceived impedance. This extra damping is compensated by active control based on the damping values obtained from the analytical results. Experimental results conducted with a dual-user/dual-finger haptic platform are presented for each of the proposed controller under various scenarios in which the user workstations communicate with UDP protocol subjected to a limited transmission rate. The results demonstrate the effectiveness of the proposed distributed architecture in providing a stable and transparent haptic simulation in free motion and in contact with rigid environments.</p> / Thesis / Master of Applied Science (MASc)

Thesis (M.App.Sc.) - Carleton University, 2002. / Includes bibliographical references (p. 59-63). Also available in electronic format on the Internet.

This Master’s thesis analizes technologies suitable for metropolitan area networks. In this thesis there are mentioned technologies used for wireless transfer with speeds above 1 Gbps. There are described basic features and parameters of microwave radio relay links in 70/80GHz range and free space optic links. These technologies are compared with classic optical networks. Practical part of thesis was focused on development of application which calculates signal attenuation caused by the passage of the atmosphere for both technologies. Results gained from this application are mentioned in this Master’s thesis.