96 research outputs found
A taxonomy and evaluation for developing 802.11âbased wireless mesh network testbeds
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/92433/1/dac1299.pd
An Optimization Framework for IEEE 802.11s Based Wireless Mesh Network
Wireless mesh network (WMN) is a promising area of research. Energy efficiency in WMN can play vital role in achieving green wireless communication. This research work considers IEEE 802.11s link based power saving modes. Energy aware joint optimization of routing, link scheduling under wireless interference and delay constraint has been considered. For given traffic load a model has been formulated to minimize network energy consumption by choosing optimum power saving mode for peer links. It is stressed that redundant links and nodes can be turned in low power state for energy savings
Heuristic algorithms for the min-max edge 2-coloring problem
In multi-channel Wireless Mesh Networks (WMN), each node is able to use
multiple non-overlapping frequency channels. Raniwala et al. (MC2R 2004,
INFOCOM 2005) propose and study several such architectures in which a computer
can have multiple network interface cards. These architectures are modeled as a
graph problem named \emph{maximum edge -coloring} and studied in several
papers by Feng et. al (TAMC 2007), Adamaszek and Popa (ISAAC 2010, JDA 2016).
Later on Larjomaa and Popa (IWOCA 2014, JGAA 2015) define and study an
alternative variant, named the \emph{min-max edge -coloring}.
The above mentioned graph problems, namely the maximum edge -coloring and
the min-max edge -coloring are studied mainly from the theoretical
perspective. In this paper, we study the min-max edge 2-coloring problem from a
practical perspective. More precisely, we introduce, implement and test four
heuristic approximation algorithms for the min-max edge -coloring problem.
These algorithms are based on a \emph{Breadth First Search} (BFS)-based
heuristic and on \emph{local search} methods like basic \emph{hill climbing},
\emph{simulated annealing} and \emph{tabu search} techniques, respectively.
Although several algorithms for particular graph classes were proposed by
Larjomaa and Popa (e.g., trees, planar graphs, cliques, bi-cliques,
hypergraphs), we design the first algorithms for general graphs.
We study and compare the running data for all algorithms on Unit Disk Graphs,
as well as some graphs from the DIMACS vertex coloring benchmark dataset.Comment: This is a post-peer-review, pre-copyedit version of an article
published in International Computing and Combinatorics Conference
(COCOON'18). The final authenticated version is available online at:
http://www.doi.org/10.1007/978-3-319-94776-1_5
Improving Inter-service bandwidth fairness in Wireless Mesh Networks
Includes bibliographical references.We are currently experiencing many technological advances and as a result, a lot of applications and services are developed for use in homes, offices and out in the field. In order to attract users and customers, most applications and / or services are loaded with graphics, pictures and movie clips. This unfortunately means most of these next generation services put a lot of strain on networking resources, namely bandwidth. Efficient management of bandwidth in next generation wireless network is therefore important for ensuring fairness in bandwidth allocation amongst multiple services with diverse quality of service needs. A number of algorithms have been proposed for fairness in bandwidth allocation in wireless networks, and some researchers have used game theory to model the different aspects of fairness. However, most of the existing algorithms only ensure fairness for individual requests and disregard fairness among the classes of services while some other algorithms ensure fairness for the classes of services and disregard fairness among individual requests
Redes em malha sem fios baseadas em contexto
Doutoramento em Engenharia ElectrotécnicaIn the modern society, new devices, applications and technologies, with sophisticated
capabilities, are converging in the same network infrastructure.
Users are also increasingly demanding in personal preferences and expectations,
desiring Internet connectivity anytime and everywhere. These aspects
have triggered many research efforts, since the current Internet is reaching
a breaking point trying to provide enough flexibility for users and profits for
operators, while dealing with the complex requirements raised by the recent
evolution.
Fully aligned with the future Internet research, many solutions have been
proposed to enhance the current Internet-based architectures and protocols,
in order to become context-aware, that is, to be dynamically adapted to
the change of the information characterizing any network entity. In this
sense, the presented Thesis proposes a new architecture that allows to create
several networks with different characteristics according to their context, on
the top of a single Wireless Mesh Network (WMN), which infrastructure
and protocols are very flexible and self-adaptable.
More specifically, this Thesis models the context of users, which can span
from their security, cost and mobility preferences, devicesâ capabilities or
servicesâ quality requirements, in order to turn a WMN into a set of logical
networks. Each logical network is configured to meet a set of user context
needs (for instance, support of high mobility and low security). To
implement this user-centric architecture, this Thesis uses the network virtualization,
which has often been advocated as a mean to deploy independent
network architectures and services towards the future Internet, while allowing
a dynamic resource management. This way, network virtualization can
allow a flexible and programmable configuration of a WMN, in order to be
shared by multiple logical networks (or virtual networks - VNs). Moreover,
the high level of isolation introduced by network virtualization can be used
to differentiate the protocols and mechanisms of each context-aware VN.
This architecture raises several challenges to control and manage the VNs
on-demand, in response to user and WMN dynamics. In this context, we
target the mechanisms to: (i) discover and select the VN to assign to an
user; (ii) create, adapt and remove the VN topologies and routes. We
also explore how the rate of variation of the user context requirements can
be considered to improve the performance and reduce the complexity of
the VN control and management. Finally, due to the scalability limitations
of centralized control solutions, we propose a mechanism to distribute the
control functionalities along the architectural entities, which can cooperate
to control and manage the VNs in a distributed way.Na sociedade actual, novos dispositivos, aplicaçÔes e tecnologias, com capacidades
sofisticadas, estĂŁo a convergir na mesma infra-estrutura de rede.
Os utilizadores sĂŁo tambĂ©m cada vez mais exigentes nas suas preferĂȘncias e
expectativas pessoais, desejando conetividade `a Internet em qualquer hora
e lugar. Estes aspectos tĂȘm desencadeado muitos esforços de investigação,
dado que a Internet atual estĂĄ a atingir um ponto de rutura ao tentar promover
flexibilidade para os utilizadores e lucros para os operadores, enquanto
lida com as exigĂȘncias complexas associadas `a recente evolução.
Em sintonia com a linha de investigação para a Internet do futuro, muitas
soluçÔes tĂȘm sido propostas para melhorar as arquiteturas e protocolos da
Internet atual, de forma a tornĂĄ-los sensĂveis ao contexto, isto Ă©, adaptĂĄ-los
dinamicamente `a alteração da informação que caracteriza qualquer entidade
de rede. Neste sentido, a presente Tese propÔe uma nova arquitetura que
permite criar vĂĄrias redes com diferentes caracterĂsticas de acordo com o
contexto das mesmas, sobre uma Ășnica rede em malha sem fios (WMN),
cuja infra-estructura e protocolos sĂŁo muito flexĂveis e auto-adaptĂĄveis.
Mais especificamente, esta Tese modela o contexto dos utilizadores, que
pode abranger as suas preferĂȘncias de segurança, custo e mobilidade, capacidades
dos seus dispositivos ou requisitos de qualidade dos seus serviços,
de forma a transformar uma WMN num conjunto de redes lĂłgicas. Cada
rede lĂłgica ÂŽe configurada para satisfazer um conjunto de necessidades de
contexto do utilizador (como exemplo, suporte de mobilidade elevada e
de baixa seguranžca). Para implementar esta arquitetura centrada no utilizador,
esta Tese utiliza a virtualização de redes, que tem muitas vezes
sido defendida como um meio para implementar arquiteturas e serviços de
rede de uma forma independente, enquanto permite uma gestĂŁo dinĂąmica
dos recursos. Desta forma, a virtualização de redes pode permitir uma
configuração flexĂvel e programĂĄvel de uma WMN, a fim de ser partilhada
por vårias redes lógicas (ou redes virtuais - VNs). Além disso, o grau de
isolamento introduzido pela virtualização de redes pode ser utilizado para
diferenciar os protocolos e mecanismos de cada VN baseada em contexto.
Esta arquitetura levanta vĂĄrios desafios para controlar e gerir as VNs em
tempo real, e em resposta `a dinĂąmica dos utilizadores e da WMN. Neste
contexto, abordamos os mecanismos para: (i) descobrir e selecionar a VN
a atribuir a um utilizador; (ii) criar, adaptar e remover as topologias e
rotas das VNs. Também exploramos a possibilidade de considerar a taxa
de variação dos requisitos de contexto dos utilizadores de forma a melhorar
o desempenho e reduzir a complexidade do controlo e gestĂŁo das VNs.
Finalmente, devido Žas limitaçÔes de escalabilidade das soluçÔes de controlo
centralizadas, propomos um mecanismo para distribuir as funcionalidades
de controlo ao longo das entidades da arquitectura, que podem cooperar
para controlar e gerir as VNs de uma forma distribuĂda
Recommended from our members
Performance modelling and evaluation of heterogeneous wired / wireless networks under Bursty Traffic. Analytical models for performance analysis of communication networks in multi-computer systems, multi-cluster systems, and integrated wireless systems.
Computer networks can be classified into two broad categories: wired networks and
wireless networks, according to the hardware and software technologies used to
interconnect the individual devices. Wired interconnection networks are hardware
fabrics supporting communications between individual processors in highperformance
computing systems (e.g., multi-computer systems and cluster systems).
On the other hand, due to the rapid development of wireless technologies, wireless
networks have emerged and become an indispensable part for peopleÂżs lives. The
integration of different wireless technologies is an effective approach to
accommodate the increasing demand of the users to communicate with each other
and access the Internet.
This thesis aims to investigate the performance of wired interconnection
networks and integrated wireless networks under the realistic working conditions.
Traffic patterns have a significant impact on network performance. A number of
recent measurement studies have convincingly demonstrated that the traffic
generated by many real-world applications in communication networks exhibits
bursty arrival nature and the message destinations are non-uniformly distributed.
Analytical models for the performance evaluation of wired interconnection networks
and integrated wireless networks have been widely reported. However, most of these
models are developed under the simplified assumption of non-bursty Poisson process
with uniformly distributed message destinations.
To fill this gap, this thesis first presents an analytical model to investigate the
performance of wired interconnection networks in multi-computer systems. Secondly,
the analytical models for wired interconnection networks in multi-cluster systems are
developed. Finally, this thesis proposes analytical models to evaluate the end-to-end
delay and throughput of integrated wireless local area networks and wireless mesh
networks. These models are derived when the networks are subject to bursty traffic
with non-uniformly distributed message destinations which can capture the
burstiness of real-world network traffic in the both temporal domain and spatial
domain. Extensive simulation experiments are conducted to validate the accuracy of
the analytical models. The models are then used as practical and cost-effective tools
to investigate the performance of heterogeneous wired or wireless networks under
the traffic patterns exhibited by real-world applications
Routage adaptatif et stabilité dans les réseaux maillés sans fil
GrĂące Ă leur flexibilitĂ© et Ă leur facilitĂ© dâinstallation, les rĂ©seaux maillĂ©s sans fil (WMNs) permettent un dĂ©ploiement dâune infrastructure Ă faible coĂ»t. Ces rĂ©seaux Ă©tendent la couverture des rĂ©seaux filaires permettant, ainsi, une connexion nâimporte quand et nâimporte oĂč. Toutefois, leur performance est dĂ©gradĂ©e par les interfĂ©rences et la congestion. Ces derniers causent des pertes de paquets et une augmentation du dĂ©lai de transmission dâune façon drastique. Dans cette thĂšse, nous nous intĂ©ressons au routage adaptatif et Ă la stabilitĂ© dans ce type de rĂ©seaux.
Dans une premiĂšre partie de la thĂšse, nous nous intĂ©ressons Ă la conception dâune mĂ©trique de routage et Ă la sĂ©lection des passerelles permettant dâamĂ©liorer la performance des WMNs. Dans ce contexte nous proposons un protocole de routage Ă la source basĂ© sur une nouvelle mĂ©trique. Cette mĂ©trique permet non seulement de capturer certaines caractĂ©ristiques des liens tels que les interfĂ©rences inter-flux et intra-flux, le taux de perte des paquets mais Ă©galement la surcharge des passerelles. Les rĂ©sultats numĂ©riques montrent que la performance de cette mĂ©trique est meilleure que celle des solutions proposĂ©es dans la littĂ©rature.
Dans une deuxiĂšme partie de la thĂšse, nous nous intĂ©ressons Ă certaines zones critiques dans les WMNs. Ces zones se trouvent autour des passerelles qui connaissent une concentration plus Ă©levĂ© du trafic ; elles risquent de provoquer des interfĂ©rences et des congestions. Ă cet Ă©gard, nous proposons un protocole de routage proactif et adaptatif basĂ© sur lâapprentissage par renforcement et qui pĂ©nalise les liens de mauvaise qualitĂ© lorsquâon sâapproche des passerelles. Un chemin dont la qualitĂ© des liens autour dâune passerelle est meilleure sera plus favorisĂ© que les autres chemins de moindre qualitĂ©. Nous utilisons lâalgorithme de Q-learning pour mettre Ă jour dynamiquement les coĂ»ts des chemins, sĂ©lectionner les prochains nĆuds pour faire suivre les paquets vers les passerelles choisies et explorer dâautres nĆuds voisins. Les rĂ©sultats numĂ©riques montrent que notre protocole distribuĂ©, prĂ©sente de meilleurs rĂ©sultats comparativement aux protocoles prĂ©sentĂ©s dans la littĂ©rature.
Dans une troisiĂšme partie de cette thĂšse, nous nous intĂ©ressons aux problĂšmes dâinstabilitĂ© des rĂ©seaux maillĂ©s sans fil. En effet, lâinstabilitĂ© se produit Ă cause des changements frĂ©quents des routes qui sont causĂ©s par les variations instantanĂ©es des qualitĂ©s des liens dues Ă la prĂ©sence des interfĂ©rences et de la congestion. Ainsi, aprĂšs une analyse de lâinstabilitĂ©, nous proposons dâutiliser le nombre de variations des chemins dans une table de routage comme indicateur de perturbation des rĂ©seaux et nous utilisons la fonction dâentropie, connue dans les mesures de lâincertitude et du dĂ©sordre des systĂšmes, pour sĂ©lectionner les routes stables. Les rĂ©sultats numĂ©riques montrent de meilleures performances de notre protocole en comparaison avec dâautres protocoles dans la littĂ©rature en termes de dĂ©bit, dĂ©lai, taux de perte des paquets et lâindice de Gini.Thanks to their flexibility and their simplicity of installation, Wireless Mesh Networks (WMNs) allow a low cost deployment of network infrastructure. They can be used to extend wired networks coverage allowing connectivity anytime and anywhere. However, WMNs may suffer from drastic performance degradation (e.g., increased packet loss ratio and delay) because of interferences and congestion. In this thesis, we are interested in adaptive routing and stability in WMNs.
In the first part of the thesis, we focus on defining new routing metric and gateway selection scheme to improve WMNs performance. In this context, we propose a source routing protocol based on a new metric which takes into account packet losses, intra-flow interferences, inter-flow interferences and load at gateways together to select best paths to best gateways. Simulation results show that the proposed metric improves the network performance and outperforms existing metrics in the literature.
In the second part of the thesis, we focus on critical zones, in WMNs, that consist of mesh routers which are located in neighborhoods of gateways where traffic concentration may occur. This traffic concentration may increase congestion and interferences excessively on wireless channels around the gateways. Thus, we propose a proactive and adaptive routing protocol based on reinforcement learning which increasingly penalizes links with bad quality as we get closer to gateways. We use Q-learning algorithm to dynamically update path costs and to select the next hop each time a packet is forwarded toward a given gateway; learning agents in each mesh router learn the best link to forward an incoming packet and explore new alternatives in the future. Simulation results show that our distributed routing protocol is less sensitive to interferences and outperforms existing protocols in the literature.
In the third part of this thesis, we focus on the problems of instability in WMNs. Instability occurs when routes flapping are frequent. Routes flapping are caused by the variations of link quality due to interferences and congestion. Thus, after analyzing factors that may cause network instability, we propose to use the number of path variations in routing tables as an indicator of network instability. Also, we use entropy function, usually used to measure uncertainty and disorder in systems, to define node stability, and thus, select the most stable routes in the WMNs. Simulation results show that our stability-based routing protocol outperforms existing routing protocols in the literature in terms of throughput, delay, loss rate, and Gini index
Mobile Ad Hoc Networks
Guiding readers through the basics of these rapidly emerging networks to more advanced concepts and future expectations, Mobile Ad hoc Networks: Current Status and Future Trends identifies and examines the most pressing research issues in Mobile Ad hoc Networks (MANETs). Containing the contributions of leading researchers, industry professionals, and academics, this forward-looking reference provides an authoritative perspective of the state of the art in MANETs. The book includes surveys of recent publications that investigate key areas of interest such as limited resources and the mobility of mobile nodes. It considers routing, multicast, energy, security, channel assignment, and ensuring quality of service. Also suitable as a text for graduate students, the book is organized into three sections: Fundamentals of MANET Modeling and SimulationâDescribes how MANETs operate and perform through simulations and models Communication Protocols of MANETsâPresents cutting-edge research on key issues, including MAC layer issues and routing in high mobility Future Networks Inspired By MANETsâTackles open research issues and emerging trends Illustrating the role MANETs are likely to play in future networks, this book supplies the foundation and insight you will need to make your own contributions to the field. It includes coverage of routing protocols, modeling and simulations tools, intelligent optimization techniques to multicriteria routing, security issues in FHAMIPv6, connecting moving smart objects to the Internet, underwater sensor networks, wireless mesh network architecture and protocols, adaptive routing provision using Bayesian inference, and adaptive flow control in transport layer using genetic algorithms
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