633 research outputs found
EFFICIENT GREEDY-FACE-GREEDY GEOGRAPHIC ROUTING PROTOCOLS IN MOBILE AD HOC AND SENSOR NETWORKS
This thesis describes and develops two planarization algorithms for geographic routing and a geographic routing protocol for mobile ad hoc and sensor networks. As all nodes are mobile and there is no fixed infrastructure, the design of routing protocols is one of the most challenging issues in mobile ad hoc and sensor networks. In recent years, greedyface- greedy (GFG) geographic routing protocols have been widely used, which need nodes to construct planar graphs as the underlying graphs for face routing.
Two kinds of planarization algorithms have been developed, idealized and realistic planarization algorithms, respectively. The idealized planarization algorithms make the ideal assumption that the original network graph is a unit-disk graph (UDG). On the other hand, the realistic planarization algorithms do not need the original network to be a UDG.
We propose an idealized planarization algorithm, which constructs an Edge Constrained Localized Delaunay graph (ECLDel). Compared to the existing planarized localized Delaunay graph [42], the construction of an ECLDel graph is far simpler, which reduces the communication cost and saves the network bandwidth.
We propose a Pre-Processed Cross Link Detection Protocol (PPCLDP), which generates a planar spanning subgraph of the original network graph in realistic environments with obstacles. The proposed PPCLDP outperforms the existing Cross Link Detection Protocol [32] with much lower communication cost and better convergence time.
In GFG routing protocols, greedy routing may fail at concave nodes, in which case, face routing is applied to recover from the greedy routing failure. This may cause extra hops in routing in networks containing voids. We propose a Hill-Area-Restricted (HAR) routing protocol, which avoids the extra hops taken in the original GFG routing. Compared to the existing Node Elevation Ad hoc Routing [4], the proposed HAR guarantees the packet delivery and decreases the communication cost greatly
Design and Implementation of a Communication Protocol to Improve Multimedia QoS and QoE in Wireless Ad Hoc Networks
[EN] This dissertation addresses the problem of multimedia delivery over multi-hop ad hoc wireless networks, and especially over wireless sensor networks. Due to their characteristics of low power consumption, low processing capacity and low memory capacity, they have major difficulties in achieving optimal quality levels demanded by end users in such communications.
In the first part of this work, it has been carried out a study to determine the behavior of a variety of multimedia streams and how they are affected by the network conditions when they are transmitted over topologies formed by devices of different technologies in multi hop wireless ad hoc mode. To achieve this goal, we have performed experimental tests using a test bench, which combine the main codecs used in audio and video streaming over IP networks with different sound and video captures representing the characteristic patterns of multimedia services such as phone calls, video communications, IPTV and video on demand (VOD). With the information gathered in the laboratory, we have been able to establish the correlation between the induced changes in the physical and logical topology and the network parameters that measure the quality of service (QoS) of a multimedia transmission, such as latency, jitter or packet loss. At this stage of the investigation, a study was performed to determine the state of the art of the proposed protocols, algorithms, and practical implementations that have been explicitly developed to optimize the multimedia transmission over wireless ad hoc networks, especially in ad hoc networks using clusters of nodes distributed over a geographic area and wireless sensor networks.
Next step of this research was the development of an algorithm focused on the logical organization of clusters formed by nodes capable of adapting to the circumstances of real-time traffic. The stated goal was to achieve the maximum utilization of the resources offered by the set of nodes that forms the network, allowing simultaneously sending reliably and efficiently all types of content through them, and mixing conventional IP data traffic with multimedia traffic with stringent QoS and QoE requirements. Using the information gathered in the previous phase, we have developed a network architecture that improves overall network performance and multimedia streaming. In parallel, it has been designed and programmed a communication protocol that allows implementing the proposal and testing its operation on real network infrastructures.
In the last phase of this thesis we have focused our work on sending multimedia in wireless sensor networks (WSN). Based on the above results, we have adapted both the architecture and the communication protocol for this particular type of network, whose use has been growing hugely in recent years.[ES] Esta tesis doctoral aborda el problema de la distribuciĂłn de contenidos multimedia a travĂ©s de redes inalámbricas ad hoc multisalto, especialmente las redes inalámbricas de sensores que, debido a sus caracterĂsticas de bajo consumo energĂ©tico, baja capacidad de procesamiento y baja capacidad de memoria, plantean grandes dificultades para alcanzar los niveles de calidad Ăłptimos que exigen los usuarios finales en dicho tipo de comunicaciones.
En la primera parte de este trabajo se ha llevado a cabo un estudio para determinar el comportamiento de una gran variedad de flujos multimedia y como se ven afectados por las condiciones de la red cuando son transmitidos a travĂ©s topologĂas formadas por dispositivos de diferentes tecnologĂas que se comunican en modo ad hoc multisalto inalámbrico. Para ello, se han realizado pruebas experimentales sobre una maqueta de laboratorio, combinando los principales cĂłdecs empleados en la transmisiĂłn de audio y video a travĂ©s de redes IP con diversas capturas de sonido y video que representan patrones caracterĂsticos de servicios multimedia tales como las llamadas telefĂłnicas, videoconferencias, IPTV o video bajo demanda (VOD). Con la informaciĂłn reunida en el laboratorio se ha podido establecer la correlaciĂłn entre los cambios inducidos en la topologĂa fĂsica y lĂłgica de la red con los parámetros que miden la calidad de servicio (QoS) de una transmisiĂłn multimedia, tales como la latencia el jitter o la pĂ©rdida de paquetes. En esta fase de la investigaciĂłn se realiza un estudio para determinar el estado del arte de las propuestas de desarrollo e implementaciĂłn de protocolos y algoritmos que se han generado de forma explĂcita para optimizar la transmisiĂłn de tráfico multimedia sobre redes ad hoc inalámbricas, especialmente en las redes inalámbricas de sensores y redes ad hoc utilizando clĂşsteres de nodos distribuidos en un espacio geográfico.
El siguiente paso en la investigaciĂłn ha consistido en el desarrollo de un algoritmo propio para la organizaciĂłn lĂłgica de clĂşsteres formados por nodos capaces de adaptarse a las circunstancias del tráfico en tiempo real. El objetivo planteado es conseguir un aprovechamiento máximo de los recursos ofrecidos por el conjunto de nodos que forman la red, permitiendo de forma simultánea el envĂo de todo tipo de contenidos a travĂ©s de ellos de forma confiable y eficiente, permitiendo la convivencia de tráfico de datos IP convencional con tráfico multimedia con requisitos exigentes de QoS y QoE. A partir de la informaciĂłn conseguida en la fase anterior, se ha desarrollado una arquitectura de red que mejora el rendimiento general de la red y el de las transmisiones multimedia de audio y video en particular. De forma paralela, se ha diseñado y programado un protocolo de comunicaciĂłn que permite implementar el modelo y testear su funcionamiento sobre infraestructuras de red reales.
En la Ăşltima fase de esta tesis se ha dirigido la atenciĂłn hacia la transmisiĂłn multimedia en las redes de sensores inalámbricos (WSN). Partiendo de los resultados anteriores, se ha adaptado tanto la arquitectura como el protocolo de comunicaciones para este tipo concreto de red, cuyo uso se ha extendido en los Ăşltimos años de forma considerable[CA] Esta tesi doctoral aborda el problema de la distribuciĂł de continguts multimèdia a travĂ©s de xarxes sense fil ad hoc multi salt, especialment les xarxes sense fil de sensors que, a causa de les seues caracterĂstiques de baix consum energètic, baixa capacitat de processament i baixa capacitat de memòria, plantegen grans dificultats per a aconseguir els nivells de qualitat òptims que exigixen els usuaris finals en eixos tipus de comunicacions.
En la primera part d'este treball s'ha dut a terme un estudi per a determinar el comportament d'una gran varietat de fluxos multimèdia i com es veuen afectats per les condicions de la xarxa quan sĂłn transmesos a travĂ©s topologies formades per dispositius de diferents tecnologies que es comuniquen en mode ad hoc multi salt sense fil. Per a això, s'han realitzat proves experimentals sobre una maqueta de laboratori, combinant els principals cĂłdecs empleats en la transmissiĂł d'Ă udio i vĂdeo a travĂ©s de xarxes IP amb diverses captures de so i vĂdeo que representen patrons caracterĂstics de serveis multimèdia com son les cridades telefòniques, videoconferències, IPTV o vĂdeo baix demanda (VOD). Amb la informaciĂł reunida en el laboratori s'ha pogut establir la correlaciĂł entre els canvis induĂŻts en la topologia fĂsica i lògica de la xarxa amb els parĂ metres que mesuren la qualitat de servei (QoS) d'una transmissiĂł multimèdia, com la latència el jitter o la pèrdua de paquets. En esta fase de la investigaciĂł es realitza un estudi per a determinar l'estat de l'art de les propostes de desenvolupament i implementaciĂł de protocols i algoritmes que s'han generat de forma explĂcita per a optimitzar la transmissiĂł de trĂ fic multimèdia sobre xarxes ad hoc sense fil, especialment en les xarxes sense fil de sensors and xarxes ad hoc utilitzant clusters de nodes distribuĂŻts en un espai geogrĂ fic.
El segĂĽent pas en la investigaciĂł ha consistit en el desenvolupament d'un algoritme propi per a l'organitzaciĂł lògica de clusters formats per nodes capaços d'adaptar-se a les circumstĂ ncies del trĂ fic en temps real. L'objectiu plantejat Ă©s aconseguir un aprofitament mĂ xim dels recursos oferits pel conjunt de nodes que formen la xarxa, permetent de forma simultĂ nia l'enviament de qualsevol tipus de continguts a travĂ©s d'ells de forma confiable i eficient, permetent la convivència de trĂ fic de dades IP convencional amb trĂ fic multimèdia amb requisits exigents de QoS i QoE. A partir de la informaciĂł aconseguida en la fase anterior, s'ha desenvolupat una arquitectura de xarxa que millora el rendiment general de la xarxa i el de les transmissions multimèdia d'Ă udio i vĂdeo en particular. De forma paralÂżlela, s'ha dissenyat i programat un protocol de comunicaciĂł que permet implementar el model i testejar el seu funcionament sobre infraestructures de xarxa reals.
En l'Ăşltima fase d'esta tesi s'ha dirigit l'atenciĂł cap a la transmissiĂł multimèdia en les xarxes de sensors sense fil (WSN). Partint dels resultats anteriors, s'ha adaptat tant l'arquitectura com el protocol de comunicacions per a aquest tipus concret de xarxa, l'Ăşs del qual s'ha estĂ©s en els Ăşltims anys de forma considerable.DĂaz Santos, JR. (2016). Design and Implementation of a Communication Protocol to Improve
Multimedia QoS and QoE in Wireless Ad Hoc Networks [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/62162TESI
Routing and Security in Mobile Ad Hoc Networks
A Mobile Ad hoc Network (MANET) consists of a set of nodes which can form a network among themselves. MANETs have applications in areas such as military, disaster rescue operations, monitoring animal habitats, etc. where establishing fixed communication infrastructure is not feasible. Routing protocols designed for MANETs can be broadly classified as position-based (geographic), topology-based and hybrid. Geographic routing uses location information of nodes to route messages. Topology-based routing uses network state information for route discovery and maintenance. Hybrid routing protocols use features in both position-based and topology-based approaches. Position-based routing protocols route packets towards the destination using greedy forwarding (i.e., an intermediate node forwards packets to a neighbor that is closer to the destination than itself). If a node has no neighbor that is closer to the destination than itself, greedy forwarding fails. In this case, we say there is void. Different position-based routing protocols use different methods for dealing with voids. Topology-based routing protocols can be classified into on-demand (reactive) routing protocols and proactive routing protocols. Generally, on-demand routing protocols establish routes when needed by flooding route requests throughout the entire network, which is not a scalable approach. Reactive routing protocols try to maintain routes between every pair of nodes by periodically exchanging messages with each other which is not a scalable approach also. This thesis addresses some of these issues and makes the following contribution.
First, we present a position-based routing protocol called Greedy Routing Protocol with Backtracking (GRB) which uses a simple backtracking technique to route around voids, unlike existing position-based routing protocols which construct planarized graph of the local network to route around voids. We compare the performance of our protocol with the well known Greedy Perimeter Stateless Routing (GPSR) protocol and the Ad-Hoc On-demand Distance Vector (AODV) routing protocol as well as the Dynamic Source Routing (DSR) protocol. Performance evaluation shows that our protocol has less control overhead than those of DSR, AODV, and GPSR. Performance evaluation also shows that our protocol has a higher packet-delivery ratio, lower end-to-end delay, and less hop count, on average, compared to AODV, DSR and GPSR. We then present an on-demand routing protocol called ``Hybrid On-demand Greedy Routing Protocol with Backtracking for Mobile Ad-Hoc Networks which uses greedy approach for route discovery. This prevents flooding route requests, unlike the existing on-demand routing protocols. This approach also helps in finding routes that have lower hop counts than AODV and DSR. Our performance evaluation confirms that our protocol performs better than AODV and DSR, on average, with respect to hop count, packet-delivery ratio and control overhead.
In MANETs, all nodes need to cooperate to establish routes. Establishing secure and valid routes in the presence of adversaries is a challenge in MANETs. Some of the well-known source routing protocols presented in the literature (e.g., Ariadne and endairA) which claim to establish secure routes are susceptible to hidden channel attacks. We address this issue and present a secure routing protocol called SAriadne, based on sanitizable signatures. We show that our protocol detects and prevents hidden channel attacks
Medium Access Control Protocols for Ad-Hoc Wireless Networks: A Survey
Studies of ad hoc wireless networks are a relatively new field gaining more popularity for various new applications. In these networks, the Medium Access Control (MAC) protocols are responsible for coordinating the access from active nodes. These protocols are of significant importance since the wireless communication channel is inherently prone to errors and unique problems such as the hidden-terminal problem, the exposed-terminal problem, and signal fading effects. Although a lot of research has been conducted on MAC protocols, the various issues involved have mostly been presented in isolation of each other. We therefore make an attempt to present a comprehensive survey of major schemes, integrating various related issues and challenges with a view to providing a big-picture outlook to this vast area. We present a classification of MAC protocols and their brief description, based on their operating principles and underlying features. In conclusion, we present a brief summary of key ideas and a general direction for future work
Self-organizing Network Optimization via Placement of Additional Nodes
Das Hauptforschungsgebiet des Graduiertenkollegs "International Graduate
School on Mobile Communication" (GS Mobicom) der Technischen Universität
Ilmenau ist die Kommunikation in Katastrophenszenarien. Wegen eines
Desasters oder einer Katastrophe können die terrestrischen Elementen der
Infrastruktur eines Kommunikationsnetzwerks beschädigt oder komplett
zerstört werden. Dennoch spielen verfügbare Kommunikationsnetze eine sehr
wichtige Rolle während der Rettungsmaßnahmen, besonders für die
Koordinierung der Rettungstruppen und fĂĽr die Kommunikation zwischen ihren
Mitgliedern. Ein solcher Service kann durch ein mobiles Ad-Hoc-Netzwerk
(MANET) zur VerfĂĽgung gestellt werden. Ein typisches Problem der MANETs
ist Netzwerkpartitionierung, welche zur Isolation von verschiedenen
Knotengruppen führt. Eine mögliche Lösung dieses Problems ist die
Positionierung von zusätzlichen Knoten, welche die Verbindung zwischen den
isolierten Partitionen wiederherstellen können. Hauptziele dieser Arbeit
sind die Recherche und die Entwicklung von Algorithmen und Methoden zur
Positionierung der zusätzlichen Knoten. Der Fokus der Recherche liegt auf
Untersuchung der verteilten Algorithmen zur Bestimmung der Positionen fĂĽr
die zusätzlichen Knoten. Die verteilten Algorithmen benutzen nur die
Information, welche in einer lokalen Umgebung eines Knotens verfĂĽgbar ist,
und dadurch entsteht ein selbstorganisierendes System. Jedoch wird das
gesamte Netzwerk hier vor allem innerhalb eines ganz speziellen Szenarios -
Katastrophenszenario - betrachtet. In einer solchen Situation kann die
Information ĂĽber die Topologie des zu reparierenden Netzwerks im Voraus
erfasst werden und soll, natĂĽrlich, fĂĽr die Wiederherstellung mitbenutzt
werden. Dank der eventuell verfügbaren zusätzlichen Information können
die Positionen für die zusätzlichen Knoten genauer ermittelt werden. Die
Arbeit umfasst eine Beschreibung, Implementierungsdetails und eine
Evaluierung eines selbstorganisierendes Systems, welche die
Netzwerkwiederherstellung in beiden Szenarien ermöglicht.The main research area of the International Graduate School on Mobile
Communication (GS Mobicom) at Ilmenau University of Technology is
communication in disaster scenarios. Due to a disaster or an accident, the
network infrastructure can be damaged or even completely destroyed.
However, available communication networks play a vital role during the
rescue activities especially for the coordination of the rescue teams and
for the communication between their members. Such a communication service
can be provided by a Mobile Ad-Hoc Network (MANET). One of the typical
problems of a MANET is network partitioning, when separate groups of nodes
become isolated from each other. One possible solution for this problem is
the placement of additional nodes in order to reconstruct the communication
links between isolated network partitions. The primary goal of this work is
the research and development of algorithms and methods for the placement of
additional nodes. The focus of this research lies on the investigation of
distributed algorithms for the placement of additional nodes, which use
only the information from the nodes’ local environment and thus form a
self-organizing system. However, during the usage specifics of the system
in a disaster scenario, global information about the topology of the
network to be recovered can be known or collected in advance. In this case,
it is of course reasonable to use this information in order to calculate
the placement positions more precisely. The work provides the description,
the implementation details and the evaluation of a self-organizing system
which is able to recover from network partitioning in both situations
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)
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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
- …