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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Acesso seguro a redes moveis IP / Secure access to mobile IP networks

Barboza, Daniel Henrique 07 July 2008 (has links)
Orientador: Eleri Cardozo / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação / Made available in DSpace on 2018-08-11T19:00:21Z (GMT). No. of bitstreams: 1 Barboza_DanielHenrique_M.pdf: 1643461 bytes, checksum: 54208ec1e9074c404ed862b0134b81b0 (MD5) Previous issue date: 2008 / Resumo: Os dispositivos de rede sem fio estão cada vez mais populares. Quase todos os dispositivos portáteis atuais possuem uma interface de rede sem fio e pontos de acesso estão acessíveis a baixo custo para uso corporativo e doméstico. No entanto, este aumento no uso de redes sem fio gera novos desafios. O mais crítico deles é com relação à segurança no acesso à rede sem fio. A natureza da comunicação sem fio dificulta a confidencialidade da informação que viaja livremente em forma de ondas eletromagnéticas. Deste modo, as redes sem fio apresentam novas brechas de segurança que não existem em redes cabeadas. Outro desafio em redes sem fio é preservar as conexões da rede de transporte durante o handover. Handover é o processo pelo qual um dispositivo móvel substitui seu ponto de acesso atual por um outro que possui melhor relação sinal-ruído. Durante o handover, as conexões da rede de transporte mantidas pelo dispositivo móvel são comprometidas. Isto ocorre devido aos procedimentos de desassociação e re-associação entre os pontos de acesso e a atualização dos parâmetros de camada três do nó móvel para sua nova localização. Este trabalho tem como objetivo avaliar o impacto da segurança no overhead de handover e propor mecanismos pelos quais as camadas superiores sejam notificadas quando um handover ocorrer. / Abstract: Wireless devices are becoming more popular. Almost any portable device nowadays has a wireless network interface and wireless access points are available at low cost for commercial or domestic use. However, the widespread of wireless networks is creating new challenges. The most critical challenge is related to the security in the access of wireless networks. The nature of wireless communications makes harder to guarantee privacy as data travels freely in electromagnetic waves. As such, wireless networks present many security breaches not found in cabled networks. Another challenge in wireless networks is to preserve the transport connections during handover. Handover is the process by which a mobile device replaces its current access point by a new one that presents a better signal to noise ratio. During handover the transport connections kept by the mobile device are compromised due to the procedures of disassociation and re-association among the access points and the updating of the mobile node's layer three parameters for its new location. This work has the objective of evaluating the impact of security in the handover overheads and to propose mechanisms by which the upper layers are notified when a handover occurs. / Mestrado / Engenharia de Computação / Mestre em Engenharia Elétrica
2

Metodika měření kvality služeb ve Wi-Fi sítích / Methods for Quality of Service measurement in Wi-Fi networks

Bachan, Jiří January 2008 (has links)
This work deals with the wireless Wi-Fi networks, that used unlicenced ISM frequency band 2,4 GHz. These wireless networks are very extended in these days and used mainly for the Internet connection. With the multimedia data transfers expanding it’s necessary to ensure the specific quality of service QoS in wireless networks mainly for applications, which are sensitive to delay or packets lost. The main aim of this work is to describe Wi-Fi networks based on IEEE 802.11b/g/n standards, description of QoS techniques according to IEEE 802.11e standard and description of parameters describing QoS for the VoIP services. The practical part is divided on a two parts. The problems of measuring the radio link quality and the creation of simple program for quality of wireless connection analysis are solved in the first part. The second part incluledes measuring of the lost packets number in Wi-Fi network with the commercial application AirMagnet Laptop Wireless LAN Analyzer and measuring of the signal noise influence with the help of spectrum analyzer and vector signal generator.

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