4 research outputs found
Real-Time Misbehavior Detection in IEEE 802.11e Based WLANs
The Enhanced Distributed Channel Access (EDCA) specification in the IEEE
802.11e standard supports heterogeneous backoff parameters and arbitration
inter-frame space (AIFS), which makes a selfish node easy to manipulate these
parameters and misbehave. In this case, the network-wide fairness cannot be
achieved any longer. Many existing misbehavior detectors, primarily designed
for legacy IEEE 802.11 networks, become inapplicable in such a heterogeneous
network configuration. In this paper, we propose a novel real-time hybrid-share
(HS) misbehavior detector for IEEE 802.11e based wireless local area networks
(WLANs). The detector keeps updating its state based on every successful
transmission and makes detection decisions by comparing its state with a
threshold. We develop mathematical analysis of the detector performance in
terms of both false positive rate and average detection rate. Numerical results
show that the proposed detector can effectively detect both contention window
based and AIFS based misbehavior with only a short detection window.Comment: Accepted to IEEE Globecom 201
Analysis and optimal configuration of distributed opportunistic scheduling techniques in wireless networks
The phenomenon of fading in wireless communications has traditionally been considered
as a source of unreliability that needs to be mitigated. In contrast, Opportunistic
Scheduling (OS) techniques exploit quick channel quality oscillations in fading links, during
the assignment of transmission opportunities, to improve the performance of wireless
networks. While centralized mechanisms rely on a central entity with global knowledge,
Distributed Opportunistic Scheduling (DOS) techniques have recently been proposed to
work in distributed networks, i.e., where either such a central entity is not available, or the
communication overhead to feed timely information to this central entity is prohibitive.
With DOS, each station contends for the channel with a certain access probability. If
a contention is successful, the station measures the channel conditions and transmits if
the channel quality is above a certain threshold. Otherwise, the station does not use the
transmission opportunity, allowing all stations to recontend. Given the fact that different
stations, in different time instances, experience different channel conditions, it is likely
that the channel is used by a link with better conditions, improving overall performance.
In this thesis we first propose ADOS, an adaptive mechanism that drives the system
to an optimal allocation of resources in terms of proportional fairness. We show that this
mechanism outperforms previous approaches, particularly in scenarios with non-saturated
stations (that do not always have data to transmit). The distributed nature of DOS makes
it particularly vulnerable to selfish users that seek to maximize their own performance at
the expense of those that cooperate for the common welfare. We thus design a punishing
mechanism, namely DOC, that (i) drives the system to the optimal point of operation
when all stations follow the protocol, and (ii) removes any potential gain by deviating
from it (and thus, the incentive to misbehave). Finally, we propose a novel allocation
criterion, namely the EF criterion, to balance between the most energy-eficient configuration (where all resources are given to the most energy e cient devices) and the
throughput-optimal allocation (where all devices evenly share the resources regardless of
their power consumption). Due to the lack of models that accurately predict the power
consumption behavior of wireless devices, we perform a thorough experimental study to
devise a power consumption model that completes existing literature. Finally, we apply
these findings to design an EF-optimal strategy in DOS networks. --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------El fenómeno de "fading" o desvanecimiento en comunicaciones inalámbricas se ha
considerado tradicionalmente como una fuente de problemas de fiabilidad que debe ser
mitigada. En contraste, las técnicas de asignación de recursos oportunistas aprovechan
las oscilaciones en la calidad de enlaces para mejorar el rendimiento global. Mientras
que los mecanismos centralizados requieren una entidad central con información global,
recientemente se han propuesto técnicas oportunistas distribuidas (DOS, por sus siglas
en inglés) para operar en redes donde dicha entidad no está disponible, o donde el coste
en la comunicación para proporcionarle información puntual es prohibitivo.
Con DOS, cada estación contiende por el canal con una cierta probabilidad. Si la contienda
resulta exitosa, la estación mide la calidad del canal y transmite si ésta supera un
cierto umbral. De lo contrario, la estación no aprovecha esa oportunidad para transmitir,
permitiendo a todas las estaciones contender de nuevo. Dado que estaciones diferentes, en
distintas instancias de tiempo, experimentan diferentes condiciones de canal, es probable
que un enlace con mejores condiciones use el canal, mejorando el rendimiento global.
En esta tesis proponemos primero ADOS, un mecanismo adaptativo que lleva al sistema
a un reparto óptimo de los recursos en términos de equidad proporcional. Mostramos
que este mecanismo supera el rendimiento de trabajos previos, particularmente en escenarios
con estaciones no saturados (que no siempre tienen datos que transmitir). La
naturaleza distribuida de DOS lo hace particularmente vulnerable a usuarios egoÃstas que
buscan maximizar su rendimiento a expensas de aquellos que cooperan por el bien común.
AsÃ, diseñamos un mecanismo, llamado DOC, que (i) optimiza el rendimiento si todos los
nodos obedecen el protocolo, y (ii) elimina cualquier posible beneficio por desviarse del
mismo (y asÃ, el incentivo a no cooperar). Finalmente, proponemos un nuevo criterio de
asignación de recursos, llamado EF, que supone un compromiso entre la configuración más
eficiente energéticamente (donde todos los recursos se asignan a los nodos más eficientes)
y una asignación donde todos comparten de forma equitativa los recursos sin tener en
cuenta su consumo. Dada la falta de modelos para predecir de forma precisa el consumo
de dispositivos inalámbricos, llevamos a cabo un estudio experimental que resulta
en un modelo energético que completa a la literatura existente. Finalmente, aplicamos lo
anterior para diseñar una estrategia que optimiza EF en redes basadas en DOS
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 Simulation—Describes how MANETs operate and perform through simulations and models Communication Protocols of MANETs—Presents cutting-edge research on key issues, including MAC layer issues and routing in high mobility Future Networks Inspired By MANETs—Tackles 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
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 Simulation—Describes how MANETs operate and perform through simulations and models Communication Protocols of MANETs—Presents cutting-edge research on key issues, including MAC layer issues and routing in high mobility Future Networks Inspired By MANETs—Tackles 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