5 research outputs found
Descoberta de serviços independentes do acesso para redes heterogéneas
Mestrado em Engenharia de Computadores e TelemáticaA recente proliferação de nós móveis com múltiplas interfaces sem fios e a constituição de ambientes heterogéneos possibilitaram a criação de cenários complexos onde os operadores de rede necessitam de disponibilizar conectividade para diferentes tipos de redes de acesso. Assim, a norma IEEE 802.21 foi especificada de forma a facilitar e optimizar os procedimentos de handover entre diferentes tecnologias de acesso sem perda de conectividade.
Para cumprir o seu propósito, a norma disponibiliza serviços chamados Media Independent Handover e que permitem o controlo e a obtenção de informação de diferentes ligações. A configuração estática destes serviços por parte do nó móvel torna-se ineficiente devido aos múltiplos cenários possíveis. Desta forma, o nó móvel deve descobrir nós da rede
que providenciem serviços de mobilidade e as suas capacidade de uma forma dinâmica. Nesta dissertação, um conjunto de mecanismos para descoberta de serviços de handover independentes do acesso são analisados, implementados e avaliados em termos de duração e quantidade de informação trocada. Um novo mecanismo de descoberta de entidades locais
é também proposto e avaliado, demonstrando que a sua utilização aumenta o desempenho e requer a troca de menos quantidade de informação.The recent proliferation of mobile nodes with multiple wireless interfaces,
in addition to the creation of heterogeneous environments, created complex
scenarios where network operators need to provide connectivity for di erent
kinds of access networks. Therefore, the IEEE 802.21 standard has been
speci ed to facilitate and optimize handover procedures between di erent
access technologies in a seamless way. To ful l its purpose, it provides Media
Independent Handover services which allow the control and gathering of
information from di erent links. The static con guration of these services by
the MN becomes ine cient due to the amount of possible scenarios. Thus,
the MN must discover the network-supporting nodes and their capabilities
in a dynamic way. In this work, a series of proposed Media Independent
Handover discovery procedures are analyzed, implemented and evaluated
in terms of duration and amount of exchanged information. In addition,
a novel discovery procedure for local entities is proposed and evaluated,
showing that its deployment increases the performance and requires less
information exchanged
Towards Seamless Mobility: An IEEE 802.21 Practical Approach
In the recent years, mobile devices such as cell phones, notebook or ultra mobile computers and videogame
consoles are experiencing an impressive evolution in terms of hardware and software possibilities. Elements
such a wideband Internet connection allows a broad range of possibilities for creative developers. Many of
these possibilities can include applications requiring continuity of service when the user moves form a coverage
area to another.
Nowadays, mobile devices are equipped with one or more radio interfaces such as GSM, UMTS, WiMax or Wi‐
Fi. Many of these technologies are ready to allow transparent roaming within their own coverage areas, but
they are not ready to handle a service transfer between different technologies. In order to find a solution to this
issue, the IEEE has developed a standard known as Media Independent Handover (MIH) Services with the aim
of easing seamless mobility between these technologies.
The present work has been centered in developing a system capable to enable a service of mobility under the
terms specified in the stated standard. The development of a platform aiming to provide service continuity is
mandatory, being a cross‐layer solution based in elements from link and network layers supplying a transparent
roaming mechanism from user’s point of view.
Two applications have been implemented in C/C++ language under a Linux environment. One application is
designed to work within a mobile device, and the other one in the network access point. The mobile device
basically consists in a notebook equipped with two Wi‐Fi interfaces, which is not a common feature in
commercial devices, allowing seamless communication transfers aided by the application. Network access
points are computers equipped with a Wi‐Fi interface and configured to provide Internet wireless access and
services of mobility.
In order to test the operation, a test‐bed has been implemented. It consists on a pair of access points
connected through a network and placed within partially overlapped coverage areas, and a mobile device, all of
them properly set. The mobile detects the networks that are compatible and gets attached to the one that
provides better conditions for the demanded service. When the service degrades up to certain level, the mobile
transfers the communication to the other access point, which offers better service conditions. Finally, in order
to check if the changes have been done properly, the duration of the required actions has been measured, as
well as the data that can have been lost or buffered meanwhile.
The result is a MIH‐alike system working in a proper way. The discovery and selection of a destination network
is correct and is done before the old connection gets too degraded, providing seamless mobility. The measured
latencies and packet losses are affordable in terms of MIH protocol, but require future work improvements in
terms of network protocols that have not been considered under the scope of this work
Middleware de comunicações para a internet móvel futura
Doutoramento em Informática (MAP-I)A evolução constante em novas tecnologias que providenciam suporte à forma como os nossos dispositivos se ligam, bem como a forma como utilizamos diferentes capacidades e serviços on-line, criou um conjunto sem precedentes de novos desafios que motivam o desenvolvimento de uma recente área de investigação, denominada de Internet Futura. Nesta nova área de investigação, novos aspectos arquiteturais estão ser desenvolvidos, os quais, através da re-estruturação de componentes nucleares subjacentesa que compõem a Internet, progride-a de uma forma capaz de não são fazer face a estes novos desafios, mas também de a preparar para os desafios de amanhã. Aspectos chave pertencendo a este conjunto de desafios são os ambientes de rede heterogéneos compostos por diferentes tipos de redes de acesso, a cada vez maior mudança do tráfego peer-to-peer (P2P) como o tipo de tráfego mais utilizado na Internet, a orquestração de cenários da Internet das Coisas (IoT) que exploram mecanismos de interação Maquinaa-Maquina (M2M), e a utilização de mechanismos centrados na informação
(ICN). Esta tese apresenta uma nova arquitetura capaz de simultaneamente
fazer face a estes desafios, evoluindo os procedimentos de conectividade e
entidades envolvidas, através da adição de uma camada de middleware, que
age como um mecanismo de gestão de controlo avançado. Este mecanismo
de gestão de controlo aproxima as entidades de alto nível (tais como
serviços, aplicações, entidades de gestão de mobilidade, operações de encaminhamento, etc.) com as componentes das camadas de baixo nível
(por exemplo, camadas de ligação, sensores e atuadores), permitindo uma
otimização conjunta dos procedimentos de ligação subjacentes. Os resultados
obtidos não só sublinham a flexibilidade dos mecanismos que compoem
a arquitetura, mas também a sua capacidade de providenciar aumentos de
performance quando comparados com outras soluÇÕes de funcionamento
especÍfico, enquanto permite um maior leque de cenáios e aplicações.The constant evolution in new technologies that support the way our devices
are able to connect, as well the way we use available on-line services and capabilities, has created a set of unprecedented new challenges that motivated
the development of a recent research trend known as the Future Internet.
In this research trend, new architectural aspects are being developed which,
through the restructure of underlying core aspects composing the Internet,
reshapes it in a way capable of not only facing these new challenges,
but also preparing it to tackle tomorrow’s new set of complex issues. Key
aspects belonging to this set of challenges are heterogeneous networking
environments composed by di↵erent kinds of wireless access networks, the
evergrowing change from peer-to-peer (P2P) to video as the most used kind
of traffic in the Internet, the orchestration of Internet of Things (IoT) scenarios exploiting Machine-to-Machine (M2M) interactions, and the usage of
Information-Centric Networking (ICN). This thesis presents a novel framework
able to simultaneous tackle these challenges, empowering connectivity
procedures and entities with a middleware acting as an advanced control
management mechanism. This control management mechanism brings together
both high-level entities (such as application services, mobility management
entities, routing operations, etc.) with the lower layer components
(e.g., link layers, sensor devices, actuators), allowing for a joint optimization of the underlying connectivity and operational procedures. Results highlight not only the flexibility of the mechanisms composing the framework, but also their ability in providing performance increases when compared with other specific purpose solutions, while allowing a wider range of scenarios and deployment possibilities