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Topics in Routing and Network Coding for Wireless Networks
This dissertation presents topics in routing and network coding for wireless networks. We present a multipurpose multipath routing mechanism. We propose an efficient packet encoding algorithm that can easily integrate a routing scheme with network coding. We also discuss max-min fair rate allocation and scheduling algorithms for the flows in a wireless network that utilizes coding. We propose Polar Coordinate Routing (PCR) to create multiple paths between a source and a destination in wireless networks. Our scheme creates paths that are circular segments of different radii connecting source-destination pairs. We propose a non-euclidean distance metric that allows messages to travel along these paths. Using PCR it is possible to maintain a known separation among the paths, which reduces the interference between the nodes belonging to two separate routes. Our extensive simulations show that while PCR achieves a known separation between the routes, it does so with a small increase in overall hop count. Moreover, we demonstrate that the variances of average separation and hop count are lower for the paths created using PCR compared to the existing schemes, indicating a more reliable system. Existing multipath routing schemes in wireless networks do not perform well in the areas with obstacles or low node density. To overcome adverse areas in a network, we integrate PCR with simple robotic routing, which lets a message circumnavigate an obstacle and follow the multipath trajectory to the destination as soon as the obstacle is passed. Next we propose an efficient packet encoding algorithm to integrate a routing scheme with network coding. Note that this packet encoding algorithm is not dependent on PCR. In fact it can be coupled with any routing scheme in order to leverage the benefits offered by both an advanced routing scheme and an enhanced packet encoding algorithm. Our algorithm, based on bipartite graphs, lets a node exhaustively search its queue to identify the maximum set of packets that can be combined in a single transmission. We extend this algorithm to consider multiple next hop neighbors for a packet while searching for an optimal packet combination, which improves the likelihood of combining more packets in a single transmission. Finally, we propose an algorithm to assign max-min fair rates to the flows in a wireless network that utilizes coding. We demonstrate that when a network uses coding, a direct application of conventional progressive filling algorithm to achieve max-min fairness may yield incorrect or suboptimal results. To emulate progressive filling correctly for a wireless networks with coding, we couple a conflict graph based framework with a linear program. Our model helps us directly select a bottleneck flow at each iteration of the algorithm, eliminating the need of gradually increasing the rates of the flows until a bottleneck is found. We demonstrate the caveats in selecting the bottleneck flows and setting up transmission scheduling constraints in order to avoid suboptimal results. We first propose a centralized fair rate allocation algorithm assuming the global knowledge of the network. We also present a novel yet simple distributed algorithm that achieves the same results as the centralized algorithm. We also present centralized as well as distributed scheduling algorithms that help flows achieve their fair rates. We run our rate allocation algorithm on various topologies. We use various fairness metrics to show that our rate allocation algorithm outperforms existing algorithms (based on network utility maximization) in terms of fairness
Mobile Ad-Hoc Networks
Being infrastructure-less and without central administration control, wireless ad-hoc networking is playing a more and more important role in extending the coverage of traditional wireless infrastructure (cellular networks, wireless LAN, etc). This book includes state-of-the-art techniques and solutions for wireless ad-hoc networks. It focuses on the following topics in ad-hoc networks: quality-of-service and video communication, routing protocol and cross-layer design. A few interesting problems about security and delay-tolerant networks are also discussed. This book is targeted to provide network engineers and researchers with design guidelines for large scale wireless ad hoc networks
Radio Communications
In the last decades the restless evolution of information and communication technologies (ICT) brought to a deep transformation of our habits. The growth of the Internet and the advances in hardware and software implementations modified our way to communicate and to share information. In this book, an overview of the major issues faced today by researchers in the field of radio communications is given through 35 high quality chapters written by specialists working in universities and research centers all over the world. Various aspects will be deeply discussed: channel modeling, beamforming, multiple antennas, cooperative networks, opportunistic scheduling, advanced admission control, handover management, systems performance assessment, routing issues in mobility conditions, localization, web security. Advanced techniques for the radio resource management will be discussed both in single and multiple radio technologies; either in infrastructure, mesh or ad hoc networks
Software-based and regionally-oriented traffic management in Networks-on-Chip
Since the introduction of chip-multiprocessor systems, the number of integrated cores has been steady growing and workload applications have been adapted to exploit the increasing parallelism. This changed the importance of efficient on-chip communication significantly and the infrastructure has to keep step with these new requirements.
The work at hand makes significant contributions to the state-of-the-art of the latest generation of such solutions, called Networks-on-Chip, to improve the performance, reliability, and flexible management of these on-chip infrastructures
Protocole de routage à chemins multiples pour des réseaux ad hoc
Ad hoc networks consist of a collection of wireless mobile nodes which dynamically exchange data without reliance on any fixed based station or a wired backbone network. They are by definition self-organized. The frequent topological changes make multi-hops routing a crucial issue for these networks. In this PhD thesis, we propose a multipath routing protocol named Multipath Optimized Link State Routing (MP-OLSR). It is a multipath extension of OLSR, and can be regarded as a hybrid routing scheme because it combines the proactive nature of topology sensing and reactive nature of multipath computation. The auxiliary functions as route recovery and loop detection are introduced to improve the performance of the network. The usage of queue length metric for link quality criteria is studied and the compatibility between single path and multipath routing is discussed to facilitate the deployment of the protocol. The simulations based on NS2 and Qualnet softwares are performed in different scenarios. A testbed is also set up in the campus of Polytech’Nantes. The results from the simulator and testbed reveal that MP-OLSR is particularly suitable for mobile, large and dense networks with heavy network load thanks to its ability to distribute the traffic into different paths and effective auxiliary functions. The H.264/SVC video service is applied to ad hoc networks with MP-OLSR. By exploiting the scalable characteristic of H.264/SVC, we propose to use Priority Forward Error Correction coding based on Finite Radon Transform (FRT) to improve the received video quality. An evaluation framework called SVCEval is built to simulate the SVC video transmission over different kinds of networks in Qualnet. This second study highlights the interest of multiple path routing to improve quality of experience over self-organized networks.Les réseaux ad hoc sont constitués d’un ensemble de nœuds mobiles qui échangent des données sans infrastructure de type point d’accès ou artère filaire. Ils sont par définition auto-organisés. Les changements fréquents de topologie des réseaux ad hoc rendent le routage multi-sauts très problématique. Dans cette thèse, nous proposons un protocole de routage à chemins multiples appelé Multipath Optimized Link State Routing (MP-OLSR). C’est une extension d’OLSR à chemins multiples qui peut être considérée comme une méthode de routage hybride. En effet, MP-OLSR combine la caractéristique proactive de la détection de topologie et la caractéristique réactive du calcul de chemins multiples qui est effectué à la demande. Les fonctions auxiliaires comme la récupération de routes ou la détection de boucles sont introduites pour améliorer la performance du réseau. L’utilisation de la longueur des files d’attente des nœuds intermédiaires comme critère de qualité de lien est étudiée et la compatibilité entre routage à chemins multiples et chemin unique est discutée pour faciliter le déploiement du protocole. Les simulations basées sur les logiciels NS2 et Qualnet sont effectuées pour tester le routage MP-OLSR dans des scénarios variés. Une mise en œuvre a également été réalisée au cours de cette thèse avec une expérimentation sur le campus de Polytech’Nantes. Les résultats de la simulation et de l’expérimentation révèlent que MP-OLSR est particulièrement adapté pour les réseaux mobiles et denses avec des trafics élevés grâce à sa capacité à distribuer le trafic dans des chemins différents et à des fonctions auxiliaires efficaces. Au niveau application, le service vidéo H.264/SVC est appliqué à des réseaux ad hoc MP-OLSR. En exploitant la hiérarchie naturelle délivrée par le format H.264/SVC, nous proposons d’utiliser un codage à protection inégale (PFEC) basé sur la Transformation de Radon Finie (FRT) pour améliorer la qualité de la vidéo à la réception. Un outil appelé SVCEval est développé pour simuler la transmission de vidéo SVC sur différents types de réseaux dans le logiciel Qualnet. Cette deuxième étude témoigne de l’intérêt du codage à protection inégale dans un routage à chemins multiples pour améliorer une qualité d’usage sur des réseaux auto-organisés
Prediction-enhanced Routing in Disruption-tolerant Satellite Networks
This thesis introduces a framework for enhancing DTN (Delay-/Disruption-Tolerant Networking) routing in dynamic LEO satellite constellations based on the prediction of contacts.
The solution is developed with a clear focus on the requirements imposed by the 'Ring Road' use case, mandating a concept for dynamic contact prediction and its integration into a state-of-the-art routing approach.
The resulting system does not restrict possible applications to the 'Ring Road,' but allows for flexible adaptation to further use cases.
A thorough evaluation shows that employing proactive routing in concert with a prediction mechanism offers significantly improved performance when compared to alternative opportunistic routing techniques
IP and ATM integration: A New paradigm in multi-service internetworking
ATM is a widespread technology adopted by many to support advanced data communication, in particular efficient Internet services provision. The expected challenges of multimedia communication together with the increasing massive utilization of IP-based applications urgently require redesign of networking solutions in terms of both new functionalities and enhanced performance. However, the networking context is affected by so many changes, and to some extent chaotic growth, that any approach based on a structured and complex top-down architecture is unlikely to be applicable. Instead, an approach based on finding out the best match between realistic service requirements and the pragmatic, intelligent use of technical opportunities made available by the product market seems more appropriate. By following this approach, innovations and improvements can be introduced at different times, not necessarily complying with each other according to a coherent overall design. With the aim of pursuing feasible innovations in the different networking aspects, we look at both IP and ATM internetworking in order to investigating a few of the most crucial topics/ issues related to the IP and ATM integration perspective. This research would also address various means of internetworking the Internet Protocol (IP) and Asynchronous Transfer Mode (ATM) with an objective of identifying the best possible means of delivering Quality of Service (QoS) requirements for multi-service applications, exploiting the meritorious features that IP and ATM have to offer. Although IP and ATM often have been viewed as competitors, their complementary strengths and limitations from a natural alliance that combines the best aspects of both the technologies. For instance, one limitation of ATM networks has been the relatively large gap between the speed of the network paths and the control operations needed to configure those data paths to meet changing user needs. IP\u27s greatest strength, on the other hand, is the inherent flexibility and its capacity to adapt rapidly to changing conditions. These complementary strengths and limitations make it natural to combine IP with ATM to obtain the best that each has to offer. Over time many models and architectures have evolved for IP/ATM internetworking and they have impacted the fundamental thinking in internetworking IP and ATM. These technologies, architectures, models and implementations will be reviewed in greater detail in addressing possible issues in integrating these architectures s in a multi-service, enterprise network. The objective being to make recommendations as to the best means of interworking the two in exploiting the salient features of one another to provide a faster, reliable, scalable, robust, QoS aware network in the most economical manner. How IP will be carried over ATM when a commercial worldwide ATM network is deployed is not addressed and the details of such a network still remain in a state of flux to specify anything concrete. Our research findings culminated with a strong recommendation that the best model to adopt, in light of the impending integrated service requirements of future multi-service environments, is an ATM core with IP at the edges to realize the best of both technologies in delivering QoS guarantees in a seamless manner to any node in the enterprise
Escalonamento de pacotes áudio e vídeo em redes WiMAX em malha com QoS
Mestrado em Engenharia Electrónica e Telecomunicações´E evidente na actualidade que os utilizadores procuram cada vez mais aceder
a servi¸cos multim´edia e aplica¸c˜oes interactivas nos seus terminais m´oveis.
H´a, portanto, uma necessidade de implementar arquitecturas de Qualidadede-
Servi¸co (QoS) e Qualidade-de-Experiˆencia (QoE) robustas, que sejam
capazes de fornecer um atraso baixo para as aplica¸c˜oes interactivas, ao
mesmo tempo que lidam com outro tipo de aplica¸c˜oes que requerem uma
maior largura de banda, mas com mais tolerˆancia a atrasos, desta forma
maximizando a utiliza¸c˜ao dos recursos dispon´ıveis na rede e melhorando a
experiˆencia do utilizador final.
A norma IEEE 802.16 representa uma das tecnologias mais avan¸cadas e de
maior relevˆancia para o acesso sem fios em banda larga a redes de ´area
metropolitana. O modo de opera¸c˜ao Ponto-multiponto (PMP) do IEEE
802.16 foi desenvolvido para suportar requisitos de QoS, control´avel pelo
operador da rede, e desta forma complementando as solu¸c˜oes m´oveis de
terceira-gera¸c˜ao j´a existentes. Um modo alternativo de opera¸c˜ao em malha
(MESH) permite a cria¸c˜ao de redes flex´ıveis e auto-configur´aveis em que o
tr´afego ´e encaminhado atrav´es de v´arios n´os.
Esta tese aborda os temas de QoS e QoE quando aplicados a redes sem
fios em malha, operando sobre a norma IEEE 802.16. S˜ao contribu´ıdos
melhoramentos e an´alises de desempenho a uma nova arquitectura para
trazer suporte de QoS ao modo de opera¸c˜ao MESH do standard 802.16.
Tamb´em ´e apresentado um novo escalonador de pacotes com o objectivo de
melhorar a qualidade subjectiva de servi¸cos de ´audio, v´ıdeo e transferˆencia
de ficheiros que o utilizador final experiencia.
Os resultados provenientes de simula¸c˜oes demonstram tanto a eficiˆencia da
arquitectura QoS em termos de medidas objectivas como taxa de transfer
ˆencia e atraso de pacotes, como o bom funcionamento do escalonador
de pacotes para QoE, com melhorias vis´ıveis em m´etricas de qualidade subjectiva.It is clear nowadays that users are becoming increasingly interested in accessing
multimedia and interactive applications on their mobile terminals.
Therefore, there is a need to implement robust Quality-of-Service (QoS) and
Quality-of-Experience (QoE) architectures capable of providing low delay
for such interactive applications, while at the same time dealing with other
bandwidth-hungry but more delay-tolerant services, and thereby maximizing
the network’s available resources and improving the end-user experience.
The IEEE 802.16 standard represents one of the most relevant and advanced
technologies for broadband wireless access in metropolitan area networks.
The point-to-multipoint (PMP) mode of IEEE 802.16 has been designed to
support quality of service (QoS) requirements, controlled by the network operator,
thus complementing the existing third-generation mobile solutions.
An alternative mesh (MESH) mode of operation allows the creation of flexible,
self-configuring networks with traffic routing through various nodes.
This thesis approaches the subjects of QoS and QoE when applied to wireless
mesh networks operating under the IEEE 802.16 standard. It provides
improvements and performance evaluations of a new architecture to bring
QoS support to the 802.16 MESH mode of operation. It also presents a new
packet scheduler with the aim to improve the subjective quality of audio,
video and file transfer services, as experienced by the end user.
Simulation results demonstrate both the efficiency of the QoS architecture in
terms of objective measurements such as throughput and packet delay, and
the good functioning of the QoE-aware packet scheduler, with noticeable
increases in subjective quality metrics
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