FastM: Design and Evaluation of a Fast Mobility Mechanism for Wireless Mesh Networks

Although there is a large volume of work in the literature in terms of mobility approaches for Wireless Mesh Networks, usually these approaches introduce high latency in the handover process and do not support realtime services and applications. Moreover, mobility is decoupled from routing, which leads to inefficiency to both mobility and routing approaches with respect to mobility. In this paper we present a new extension to proactive routing protocols using a fast mobility extension, FastM, with the purpose of increasing handover performance in Wireless Mesh Networks. With this new extension, a new concept is created to integrate information between neighbor wireless mesh routers, managing locations of clients associated to wireless mesh routers in a certain neighborhood, and avoiding packet loss during handover. The proposed mobility approach is able to optimize the handover process without imposing any modifications to the current IEE 802.11 MAC protocol and use unmodified clients. Results show the improved efficiency of the proposed scheme: metrics such as disconnection time, throughput, packet loss and control overhead are largely improved when compared to previous approaches. Moreover, these conclusions apply to mobility scenarios, although mobility decreases the performance of the handover approach, as expected

AMazING - Advanced Mobile wireless playGrouND

We describe a wireless testbed composed of 24 wireless nodes that can be used to perform a broad range of studies in the area of next generation networks. This paper addresses the difficulties and constrains faced by the authors throughout the deployment process of such testbed. Flexibility and controllability were key concerns driving the testbed design. The testbed can be remotely managed through a series of remotely accessible web services performing low level management. Validation results are presented, showing the interference levels of the testbed as well as its maximum throughput capabilities

Integration of the Captive Portal paradigm with the 802.1X architecture

In a scenario where hotspot wireless networks are increasingly being used, and given the amount of sensitive information exchanged on Internet interactions, there is the need to implement security mechanisms that guarantee data confidentiality and integrity in such networks, as well as the authenticity of the hotspot providers. However, many hotspots today use Captive Portals, which rely on authentication through Web pages (thus, an application-level authentication approach) instead of a link-layer approach. The consequence of this is that there is no security in the wireless link to the hotspot (it has to be provided at upper protocol layers), and is cumbersome to manage wireless access profiles (we need special applications or browsers' add-ons to do that). This work exposes the weaknesses of the Captive Portals' paradigm, which does not follow a unique nor standard approach, and describes a solution that intends to suppress them, based on the 802.1X architecture. This solution uses a new EAP-compliant protocol that is able to integrate an HTTP-based registration or authentication with a Captive Portal within the 802.1X authentication framework

Sistema de apoio a organização e gestão de conferências cientificas (CoW – Conference on the Web)

Este artigo pretende divulgar o software de organização e gestão de conferências científicas Conference on the Web (CoW). Software este desenvolvido por alunos finalistas de Eng. Computadores e Telemática na cadeira de opção de 5º ano, de Ferramentas e Aplicacionais Multimédia.This article intends to divulge software developed to help in the organization and management of Scientific Conferences on the Web (CoW). This Software package was developed by last year students of Eng. Computadores and Telemática in 5º year optional subject Ferramentas and Aplicacionais Multimédia

Demonstrating the AMazING panel

Experimental testbeds for evaluating solutions in computer net- works, are today required as a complement to simulation and emu- lation. As these testbeds become larger, and accessible to a broader universe of the research community, dedicated management tools become mandatory. These tools ease the complex management of the testbed specific resources, while providing an environment for researchers to define their experiments with large flexibility. While there are currently several management tools, the research commu- nity is still lacking tools that smooth the experimentation workflow. These were key aspects that we considered when developing the management infrastructure for our wireless testbed[4] (AMazING). We developed a experimentation support framework supported by an attractive GUI, automation and scripting capabilities, as well as experiment versioning and integrated result gathering and analysis

Mecanismos de facturação segura em redes auto-organizadas

Mestrado em Engenharia Electrónica e TelecomunicaçõesAs redes ad-hoc e as redes auto-organizadas constituem uma área de investigação com grande interesse. Estas redes são uteis em cenários onde seja necessária uma rede de baixo custo, elevada adaptabilidade e reduzido tempo de criação. As redes infra-estruturadas, tendo uma gestão centralizada, estão agora a começar a adoptar os conceitos de redes autoorganizadas nas suas arquitecturas. Ao contrário dos sistemas centralizados, redes auto-organizadas requerem que todos os terminais participantes operem de acordo com o melhor interesse da rede. O facto de, em redes ad-hoc, os equipamentos possuírem recursos limitados, pôe em causa este requisito levando a comportamentos egoístas. Este comportamento é espectavel criando problemas nas redes auto-organizativas, ameaçando o funcionamento de uma rede inteira. Algumas propostas foram ja criadas de modo a motivar a sua utilização correcta. Destas, algumas são baseadas em trocas de credito entre utilizadores, outras preveêm a existência de entidades gestoras de creditos. Estas ultimas propostas, que irão ser o foco desta dissertação, permitem a facil integração de redes ad-hoc com redes infra-estruturadas e geridas por um operador. Este trabalho descreve o estado da arte actual e, com algum detalhe, os métodos utilizados e as solucões relevantes para esta area. São propostas duas novas soluções de taxação para estas redes. Ambas as soluções possibilitam a integração das redes com metodos de taxação habituais em redes geridas por operadores. Para além disto, a motivação à participaçãao é aumentada através de incentivos ao encaminhamento de pacotes. Todos os processos são criptograficamente seguros através da utilização de métodos standard como DSA sobre Curvas Elípticas e funções de síntese robustas. As soluções propostas são descritas analiticamente e analisadas, sendo os os resultados obtidos comparados com outra proposta do estado da arte. Um exaustivo trabalho de simulação é igualmente descrito de forma a avaliar as soluções em cenários mais complexos. Os resultados obtidos em simulação são avaliados tendo em conta a variação de várias métricas como mobilidade, carga na rede, protocolo de encaminhamento e protocolo de transporte. No final, a arquitectura, implementação e resultados obtidos com uma implementação real de uma das propostas e os seus resultados analisados.Self-organised and ad-hoc networks are an area with an existing large research community. These networks are much useful in scenarios requiring a rapidly deployed, low cost and highly adaptable network. Recently, infrastructure networks, which are managed in a much centralised form, are starting to introduce concepts of self-organised networks in its architecture. In opposition to centralised systems, self-organisation creates the necessity for all nodes to behave according to the best interest of the network. The fact that in many ad-hoc networks nodes have scarce resources poses some threats to this requirement. As resources decreases, such as battery or wireless bandwidth, nodes can start acting selfishly. This behaviour is known to bring damage to self-organised networks and threatens the entire network. Several proposals were made in order to promote the correct usage of the network. Some proposals are based on local information and direct credit exchange while others envision the existence of a central bank. The later solutions are further elaborated in this thesis, as they make possible integration of ad-hoc network with operator driven infrastructures. This work presents the current state-of-the-art on the area providing a detailed insight on the methods adopted by each solution presented. Two novel solutions are proposed providing charging support for integrated ad-hoc networks. Both solutions provide means of integration with standard management methods found in operator networks. Also, node´s motivation is increased through the reward of nodes forwarding data packets. The entire process is cryptographically secure, making use of standard methods such as Elliptic Curve DSA and strong digest functions. The solutions proposed are described and analysed analytically, comparing the results with other state-of-the-art proposals. Extensive simulation work is also presented which furthers evaluates the solutions in complex scenarios. Results are obtained from these scenarios and several metrics are evaluated taking in consideration mobility, network load, routing protocol and transport protocol. The architecture and results obtained with a real implementation are finally presented and analysed

QoS-aware service continuity in the virtualized edge

5G systems are envisioned to support numerous delay-sensitive applications such as the tactile Internet, mobile gaming, and augmented reality. Such applications impose new demands on service providers in terms of the quality of service (QoS) provided to the end-users. Achieving these demands in mobile 5G-enabled networks represent a technical and administrative challenge. One of the solutions proposed is to provide cloud computing capabilities at the edge of the network. In such vision, services are cloudified and encapsulated within the virtual machines or containers placed in cloud hosts at the network access layer. To enable ultrashort processing times and immediate service response, fast instantiation, and migration of service instances between edge nodes are mandatory to cope with the consequences of user’s mobility. This paper surveys the techniques proposed for service migration at the edge of the network. We focus on QoS-aware service instantiation and migration approaches, comparing the mechanisms followed and emphasizing their advantages and disadvantages. Then, we highlight the open research challenges still left unhandled.publishe

Estabelecimento de redes de comunidades sobreponíveis

Doutoramento em Engenharia InformáticaUma das áreas de investigação em Telecomunicações de interesse crescente prende-se com os futuros sistemas de comunicações móveis de 4a geração e além destes. Nos últimos anos tem sido desenvolvido o conceito de redes comunitárias, no qual os utilizadores se agregam de acordo com interesses comuns. Estes conceitos têm sido explorados de uma forma horizontal em diferentes camadas da comunicação, desde as redes comunitárias de comunicação (Seattle Wireless ou Personal Telco, p.ex.) até às redes de interesses peer-to-peer. No entanto, estas redes são usualmente vistas como redes de overlay, ou simplesmente redes de associação livre. Na prática, a noção de uma rede auto-organizada, completamente orientada ao serviço/comunidade, integralmente suportada em termos de arquitetura, não existe. Assim este trabalho apresenta uma realização original nesta área de criação de redes comunitárias, com uma arquitetura subjacente orientada a serviço, e que suporta integralmente múltiplas redes comunitárias no mesmo dispositivo, com todas as características de segurança, confiança e disponibilização de serviço necessárias neste tipo de cenários (um nó pode pertencer simultaneamente a mais do que uma rede comunitária). Devido à sua importância para os sistemas de redes comunitárias, foi dado particular atenção a aspetos de gestão de recursos e controlo de acessos. Ambos realizados de uma forma descentralizada e considerando mecanismos dotados de grande escalabilidade. Para isso, é apresentada uma linguagem de políticas que suporta a criação de comunidades virtuais. Esta linguagem não é apenas utilizada para o mapeamento da estrutura social dos membros da comunidade, como para, gerir dispositivos, recursos e serviços detidos pelos membros, de uma forma controlada e distribuída.One of the research areas with increasing interest in the field of telecommunications, are the ones related to future telecommunication systems, both 4th generation and beyond. In parallel, during the last years, several concepts have been developed related to clustering of users according to their interested, in the form of community networks. Solutions proposed for these concepts tackle the challenges horizontally, for each layer of the communication stack, ranging from community based communication networks (e.g. Seattle Wireless, or Personal Telco), to interest networks based on peer-to-peer protocols. However, these networks are presented either as free joining, or overlay networks. In practice, the notion of a self-organized, service and community oriented network, with these principles embedded in its design principles, is yet to be developed. This work presents an novel instantiation of a solution in the area of community networks, with a underlying architecture which is fully service oriented, and envisions the support for multiple community networks in the same device. Considerations regarding security, trust and service availability for this type of environments are also taken. Due to the importance of resource management and access control, in the context of community driven communication networks, a special focus was given to the support of scalable and decentralized management and access control methods. For this purpose, it is presented a policy language which supports the creation and management of virtual communities. The language is not only used for mapping the social structure of the community members, but also to, following a distributed approach, manage devices, resources and services owned by each community member

Cooperative performance bounds of Wireless Local Area Networks

In a Wireless Local Area Network (WLAN), capacity gain and delay reduction play a crucial role in system performance. In this paper, we focus on performance improvements when WLANs exploit the concept of cooperation among nodes. We propose a geometrical model to determine the potential location area of relay nodes. The analytical results are validated by simulation. Performance bounds and average of capacity gain and delay ratio are studied for different IEEE 802.11 standards

User centric community clouds

With the evolution in cloud technologies, users are becoming acquainted with seamless service provision. Nevertheless, clouds are not a user centric technology, and users become completely dependent on service providers. We propose a novel concept for clouds, where users self-organize to create their clouds. We present such an architecture for user-centric clouds, which relies on self-managed clouds based on doctrine and on identity management concepts