335 research outputs found
Avaliação de desempenho e mobilidade em redes auto-organizadas
Mestrado em Engenharia de Computadores e TelemáticaAs redes móveis ad hoc (ou auto-organizadas) são um assunto que nos últimos
anos tem ganho muita atenção da comunidade cientĂfica. Os problemas associados
a este tipo de redes foram amplamente estudados e expostos, foram
propostas soluções, e algumas até foram tornadas um padrão da indústria.
No entanto, a grande maioria do trabalho realizado, Ă© dedicado a resolver sĂł
um problema de cada vez. Da mesma forma, as soluções que são testadas
por forma a verificar a sua validade, muitas das vezes, sĂŁo testadas recorrendo
a trabalho de simulação. Uma parte do trabalho que é apresentado
nesta dissertação de mestrado, junta uma série de protocolos desenvolvidos
para redes ad hoc, os quais providenciam funcionalidades como: auto configuração,
encaminhamento unicast e multicast, qualidade de serviço e taxação
com incentivos numa única solução integrada que interliga as redes ad hoc
a redes infra-estruturadas funcionando como uma extensĂŁo das mesmas. O
demonstrador criado Ă© avaliado de forma experimental, e os resultados obtidos
sĂŁo apresentados e discutidos. Uma vez que a rede ad hoc está interligada Ă
rede infra-estruturada, num ambiente de quarta geração, é também apresentada
uma arquitectura que suporta mobilidade de nĂłs entre redes ad hoc e as
redes infra-estuturadas que fazem parte do ambiente heterogéneo, e de este
para as redes ad hoc Ă© apresentada. A rede geral onde a rede ad hoc Ă© integrada
suporta novas tecnologias e tendĂŞncias em gestĂŁo de mobilidade, tais
como o protocolo em desenvolvimento IEEE 802.21 Media Independent Handover
e gestĂŁo de mobilidade baseada em DomĂnios de Mobilidade Local. A
forma como a rede ad hoc se integra com as tecnologias presentes na rede
infra-estruturada, e como as especificidades da rede ad hoc sĂŁo escondidas, Ă©
descrita e explicada.
ABSTRACT: Mobile Ad hoc network is a subject that has gained lots of attention from the
research community in recent years. The problems inherent to this types of networks
have been studied and exposed, solutions have been created and even
standardized. However, the vast majority of the work performed is dedicated to
only one problem at the time. In addition, the tests performed to validate the
produced solutions are, most of the times, obtained through simulation work.
The work presented in this thesis gathers together a set of ad hoc protocols,
providing functionalities such as auto-configuration, unicast and multicast routing,
quality of service and charging and rewarding in one integrated testbed,
serving as a stub network in a hotspot scenario. A experimental evaluation is
performed, and results are presented and discussed. Additionally, since the
network belongs to a hotspot of fourth generation, a architecture that supports
mobility of nodes between the ad hoc network and infrastructure networks is
presented. The general network that includes ad hoc network integrates and
supports the new technologies and tendencies in mobility management, such
as the IEEE 802.21 Media Independent Handover and mobility management
based on Local Mobility Domains. The way the MANET fully integrates with the
infrastructure network, and how the ad hoc networks specific characteristics
are hidden, is also presented and explained
Clustering Algorithms for Scale-free Networks and Applications to Cloud Resource Management
In this paper we introduce algorithms for the construction of scale-free
networks and for clustering around the nerve centers, nodes with a high
connectivity in a scale-free networks. We argue that such overlay networks
could support self-organization in a complex system like a cloud computing
infrastructure and allow the implementation of optimal resource management
policies.Comment: 14 pages, 8 Figurs, Journa
Communication Aware Mobile Robot Teams
The type of scenarios that could benefit from a team of robots that are able to self configure into an ad-hoc multi-hop mobile communication network while completing a task in an unknown environment, range from search and rescue in a partially collapsed building to providing a security perimeter around a region of interest. In this thesis, we present a hybrid system that enables a team of robots to maintain a prescribed end-to-end data rate while moving through a complex unknown environment, in a distributed manner, to complete a specific task. This is achieved by a systematic decomposition of the real-time situational awareness problem into subproblems that can be efficiently solved by distributed optimization. The validity of this approach is demonstrated through multiple simulations and experiments in which the a team of robots is able to accurately map an unknown environment and then transition to complete a traditional situational awareness task.
We also present MCTP, a lightweight communication protocol that is specifically designed for use in ad-hoc multi-hop wireless networks composed of low-cost low-power transceivers. This protocol leverages the spatial diversity found in mobile robot teams as well as recently developed robust routing systems designed to minimize the variance of the end-to-end communication link.
The combination of the hybrid system and MCTP results in a system that is able to complete a task, with minimal global coordination, while providing near loss-less communication over an ad-hoc multi-hop network created by the members of the team in unknown environments
Mobile Networks
The growth in the use of mobile networks has come mainly with the third generation systems and voice traffic. With the current third generation and the arrival of the 4G, the number of mobile users in the world will exceed the number of landlines users. Audio and video streaming have had a significant increase, parallel to the requirements of bandwidth and quality of service demanded by those applications. Mobile networks require that the applications and protocols that have worked successfully in fixed networks can be used with the same level of quality in mobile scenarios. Until the third generation of mobile networks, the need to ensure reliable handovers was still an important issue. On the eve of a new generation of access networks (4G) and increased connectivity between networks of different characteristics commonly called hybrid (satellite, ad-hoc, sensors, wired, WIMAX, LAN, etc.), it is necessary to transfer mechanisms of mobility to future generations of networks. In order to achieve this, it is essential to carry out a comprehensive evaluation of the performance of current protocols and the diverse topologies to suit the new mobility conditions
5G and beyond networks
This chapter investigates the Network Layer aspects that will characterize the merger of the cellular paradigm and the IoT architectures, in the context of the evolution towards 5G-and-beyond, including some promising emerging services as Unmanned Aerial Vehicles or Base Stations, and V2X communications
Recommended from our members
Multimedia delivery in the future internet
The term “Networked Media” implies that all kinds of media including text, image, 3D graphics, audio
and video are produced, distributed, shared, managed and consumed on-line through various networks,
like the Internet, Fiber, WiFi, WiMAX, GPRS, 3G and so on, in a convergent manner [1]. This white
paper is the contribution of the Media Delivery Platform (MDP) cluster and aims to cover the Networked
challenges of the Networked Media in the transition to the Future of the Internet.
Internet has evolved and changed the way we work and live. End users of the Internet have been confronted
with a bewildering range of media, services and applications and of technological innovations concerning
media formats, wireless networks, terminal types and capabilities. And there is little evidence that the pace
of this innovation is slowing. Today, over one billion of users access the Internet on regular basis, more
than 100 million users have downloaded at least one (multi)media file and over 47 millions of them do so
regularly, searching in more than 160 Exabytes1 of content. In the near future these numbers are expected
to exponentially rise. It is expected that the Internet content will be increased by at least a factor of 6, rising
to more than 990 Exabytes before 2012, fuelled mainly by the users themselves. Moreover, it is envisaged
that in a near- to mid-term future, the Internet will provide the means to share and distribute (new)
multimedia content and services with superior quality and striking flexibility, in a trusted and personalized
way, improving citizens’ quality of life, working conditions, edutainment and safety.
In this evolving environment, new transport protocols, new multimedia encoding schemes, cross-layer inthe
network adaptation, machine-to-machine communication (including RFIDs), rich 3D content as well as
community networks and the use of peer-to-peer (P2P) overlays are expected to generate new models of
interaction and cooperation, and be able to support enhanced perceived quality-of-experience (PQoE) and
innovative applications “on the move”, like virtual collaboration environments, personalised services/
media, virtual sport groups, on-line gaming, edutainment. In this context, the interaction with content
combined with interactive/multimedia search capabilities across distributed repositories, opportunistic P2P
networks and the dynamic adaptation to the characteristics of diverse mobile terminals are expected to
contribute towards such a vision.
Based on work that has taken place in a number of EC co-funded projects, in Framework Program 6 (FP6)
and Framework Program 7 (FP7), a group of experts and technology visionaries have voluntarily
contributed in this white paper aiming to describe the status, the state-of-the art, the challenges and the way
ahead in the area of Content Aware media delivery platforms
Telecommunications Networks
This book guides readers through the basics of rapidly emerging networks to more advanced concepts and future expectations of Telecommunications Networks. It identifies and examines the most pressing research issues in Telecommunications and it contains chapters written by leading researchers, academics and industry professionals. Telecommunications Networks - Current Status and Future Trends covers surveys of recent publications that investigate key areas of interest such as: IMS, eTOM, 3G/4G, optimization problems, modeling, simulation, quality of service, etc. This book, that is suitable for both PhD and master students, is organized into six sections: New Generation Networks, Quality of Services, Sensor Networks, Telecommunications, Traffic Engineering and Routing
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