Un réseau mobile ad hoc (Mobile Ad hoc Network, MANET) est un réseau sans fil, formé dynamiquement par un ensemble d'utilisateurs équipés de terminaux mobiles, sans l'utilisation d'une infrastructure préexistante, ou d'une administration centralisée. Les équipements utilisés dans les MANETs sont limités par la capacité de la batterie, la puissance de calcul et la bande passante. Les utilisateurs des MANETs sont libres de se déplacer, ce qui induit à des topologies dynamiques dans le temps. Toutes ces contraintes ajoutent plus de challenges aux protocoles et services de communications afin de fonctionner dans les MANETs. L'évolution des réseaux de 4ème génération (4G) est appelée à intégrer les MANETs avec les autres types de réseaux afin d'étendre leurs portées. Nous nous sommes intéressés dans la première partie de cette thèse à quelques challenges connus dans les MANETs en proposant des solutions novatrices utilisant des propriétés intéressantes des topologies de graphes. Dans un premier temps, nous avons effectué une étude sur la prédiction de la mobilité afin de maintenir une topologie d'ensemble dominant connecté dans les MANETs. Nous avons proposé dans un autre travail comment construire des topologies de graphes ayant des propriétés globales en se basant seulement sur des informations locales des nœuds mobiles. Ces topologies servent comme overlay aux MANETs. Nous avons proposé des algorithmes distribués pour construire des alliances offensives et défensives globales minimales. Nous avons aussi défini des heuristiques pour ces algorithmes afin de réduire les tailles des alliances obtenues. La première partie de cette thèse est achevée par la proposition d'un framework pour la conception et l'analyse des protocoles de contrôle de topologie dans les MANETs. Nous avons identifié les points communs des algorithmes de contrôle de topologie conçus pour les réseaux mobiles ad hoc et nous avons enrichi le simulateur NS-2 avec un ensemble d'extensions pour supporter le contrôle de topologie / We are interested in this thesis to graph-based approaches to deal with some challenges in networking, namely, graph topologies of mobile ad hoc networks (MANETs) and process model matchmaking in large scale web service. We propose in the first part: (1) a generic mechanism using mobility information of nodes to maintain a graph topology of the network. We show particularly, how to use the prediction of future emplacements of nodes to maintain a connected dominating set of a given MANET. (2) distributed algorithms to construct minimal global offensive alliance and global defensive alliance sets in MANETs. We also introduce several heuristics to get a better approximation of the cardinality of the alliance sets which is a desirable property for practical considerations. (3) a framework to facilitate the design and evaluation of topology control protocols in MANETs. We propose in the framework, a common schema for topology control based on NS-2 simulator and inspired from the commonalities between the components of the topology control algorithms in MANETs. In the second part, we focus on process model matchmaking. We propose two graph-based solutions for process model inexact matching to deal with high computational time of existing work in the literature. In the first solution, we decompose the process models into their possible execution sequences. After, we propose generic graph techniques using string comparator metrics for process model matchmaking based on this decomposition. In order to get better optimization of the execution time and to deal with process model matching in large scale web services, the second solution combines a spectral graph matching with structural and semantic proposed approaches. This solution uses an eigen-decomposition projection technique that makes the runtime faster

Mobile Ad hoc Networks (MANETs) are of great interest to researchers and have become very popular in the last few years. One of the great challenges is to provide a routing protocol that is capable of offering the shortest and most reliable path in a MANET in which users are moving continuously and have no base station to be used as a reference for their position. This thesis proposes some new routing protocols based on the angles (directions) of the adjacent mobile nodes and also the node density. In choosing the next node in forming a route, the neighbour node with the closest heading angle to that of the node of interest is selected, so the connection between the source and the destination consists of a series of nodes that are moving in approximately the same direction. The rationale behind this concept is to maintain the connection between the nodes as long as possible. This is in contrast to the well known hop count method, which does not consider the connection lifetime. We propose three enhancements and modifications of the Ad-hoc on demand distance vector (AODV) protocol that can find a suitable path between source and destination using combinations and prioritization of angle direction and hop count. Firstly, we consider that if there are multiple routing paths available, the path with the minimum hop count is selected and when the hop counts are the same the path with the best angle direction is selected. Secondly, if multiple routing paths are available the paths with the best angle direction are chosen but if the angles are the same (fall within the same specified segment), the path with minimum hop count is chosen. Thirdly, if there is more than one path available, we calculate the average of all the heading angles in every path and find the best one (lowest average) from the source to the destination. In MANETs, flooding is a popular message broadcasting technique so we also propose a new scheme for MANETS where the value of the rebroadcast packets for every host node is dynamically adjusted according to the number of its neighbouring nodes. A fixed probabilistic scheme algorithm that can dynamically adjust the rebroadcasting probability at a given node according to its ID is also proposed; Fixed probabilistic schemes are one of the solutions to reduce rebroadcasts and so alleviate the broadcast storm problem. Performance evaluation of the proposed schemes is conducted using the Global Mobile Information System (GloMoSim) network simulator and varying a number of important MANET parameters, including node speed, node density, number of nodes and number of packets, all using a Random Waypoint (RWP) mobility model. Finally, we measure and compare the performance of all the proposed approaches by evaluating them against the standard AODV routing protocol. The simulation results reveal that the proposed approaches give relatively comparable overall performance but which is better than AODV for almost all performance measures and scenarios examined.

L'exclusion mutuelle de groupe est une généralisation de l'exclusion mutuelle. Ce problème a été présenté par Joung et quelques algorithmes pour le problème ont été proposés en incorporant ds algorithmes d'exclusion mutuelle. L'exclusion mutuelle de groupe se produit naturellement dans une situation ou une ressource peut être partagée par des processus du même groupe, mais pas par des processus de différents groupes. Il est aussi appelé "problème des philosophes parlant d'une même voix". <br />Un exemple d'application intéressant est un serveur CD (documentation, films...) sur Internet: plusieurs utilisateurs désirant accéder au même CD pourront le faire en même temps au lieu d'attendre la fin de la requête des autres utilisateurs. Des solutions efficaces, écrites dans le modèle à passage de messages et basées sur les quorums d'une part et sur la circulation de jeton d'autre part sont présentées dans cette thèse.<br />Nous abordons aussi le problème de l'exclusion mutuelle de groupe sur les réseaux mobiles ad hoc et nous proposons un algorithme qui est sensible aux formations et coupures de liens et est ainsi approprié pour les réseaux mobiles ad hoc.

With the proliferation of mobile devices and wireless connectivity technologies, mobile social communities offer novel opportunities for targeted marketing by service or product providers. Unfortunately, marketers are still unable to realize the full potential of these markets due to their inability to effectively target right audiences. This thesis presents a novel middleware for identifying spontaneous social communities (SSCs) of mobile users in ad hoc networks in order to facilitate marketers' advertisements. The contributions of the presented work are two fold; the first is a novel model for SSCs that captures their unique dynamic nature, in terms of community structure and interest in different \textit{hot-topics} over time. These time-varying interests are represented through an inferred \textit{community profile prototype} that reflects dominant characteristics of community members. This prototype is then employed to facilitate the identification of new potential members. The selected community prototypes are also used by marketers to identify the right communities for their services or products promotions. The second contribution of this paper is novel distributed techniques for efficient calculation of the community prototypes and identification of potential community links. In contrast to traditional models of detecting fixed and mobile social networks that rely on pre-existing friendships among its members to predict new ones, the proposed model focuses on measuring the degree of similarity between the new user's profile and the profiles of members of each community in order to predict new users' relationships in the community. The adopted model of SSCs can foster many existing and new socially-aware applications such as recommender systems for social events and tools for collaborative work. It is also an ideal target for business-oriented applications such as short-message-service (SMS) advertisement messages, podcasting news feeds in addition to location/context-aware services. The performance of the proposed work was evaluated using the NetLogo platform where obtained experimental results demonstrate the achieved high degree of stability in the resulting communities in addition to the effectiveness of the proposed middleware in terms of the reduction in the number of routing messages required for advertisements.

Wireless ad-hoc networks are based on a cooperative communication model, where all nodes not only generate traffic but also help to route traffic from other nodes to its final destination. In such an environment where there is no infrastructure support the lifetime of the network is tightly coupled with the lifetime of individual nodes. Most of the devices that form such networks are battery-operated, and thus it becomes important to conserve energy so as to maximize the lifetime of a node. In this thesis, we present JTP, a new energy-aware transport protocol, whose goal is to reduce power consumption without compromising delivery requirements of applications. JTP has been implemented within the JAVeLEN system. JAVeLEN~\cite{javelen08redi}, is a new system architecture for ad hoc networks that has been developed to elevate energy efficiency as a first-class optimization metric at all protocol layers, from physical to transport. Thus, energy gains obtained in one layer would not be offset by incompatibilities and/or inefficiencies in other layers. To meet its goal of energy efficiency, JTP (1) contains mechanisms to balance end-to-end vs. local retransmissions; (2) minimizes acknowledgment traffic using receiver regulated rate-based flow control combined with selected acknowledgments and in-network caching of packets; and (3) aggressively seeks to avoid any congestion-based packet loss. Within this ultra low-power multi-hop wireless network system, simulations and experimental results demonstrate that our transport protocol meets its goal of preserving the energy efficiency of the underlying network. JTP has been implemented on the actual JAVeLEN nodes and its benefits have been demoed on a real system.

<p>Wireless communication has grown very popular, and communication is the key</p><p>to success in many situations. However, most of the common technologies today</p><p>rely on infrastructure and in disaster situations infrastructure might be lost or</p><p>get severely overloaded. This master thesis concerns intermittently connected</p><p>mobile ad hoc networks. A network in which the devices may move freely in any</p><p>direction and still be able to communicate. To be able to demonstrate a network</p><p>protocol called random-walk gossip-based manycast (RWG) my assignment has been</p><p>to implement this protocol using off-the-shelf hardware and software.</p><p>RWG is a multi-hop and partition-tolerant mobile ad hoc manycast network</p><p>protocol. Multi-hop refers to information being able to hop between more than</p><p>two nodes in a network and partition-tolerant means that the protocol works even</p><p>though a network is partitioned. Manycast means that the information should</p><p>be successfully delivered to K of all the potential nodes in the area. The RWG</p><p>protocol makes use of four different packet types, request to forward (REQF), ac-</p><p>knowledgement (ACK), ok to forward (OKTF) and be silent (BS). The actual data</p><p>being sent is carried by REQFs, and is referred to as messages. When a message</p><p>is sent it takes what could be described as a random walk among the nodes in the</p><p>network, hence the name.</p><p>The implementation of the RWG protocol resides in user-space and depends on</p><p>the IEEE 802.11b standard and the raw socket that is specified in the BSD socket</p><p>API. It is written in C and was developed on a machine running Ubuntu. It runs</p><p>on systems that use Linux 2.6 kernels and it supports cross-compiling for ARM</p><p>based devices such as the Nokia N810 internet tablet and the Android dev phone</p><p>1. To be able to demonstrate the protocol I developed my own client application.</p><p>Moreover, an already existing application for Android, Portable Open Search and</p><p>Identification Tool (POSIT), was successfully extended to run on top of the RWG</p><p>implementation. The extension was developed by people in the POSIT project</p><p>and tested in a physical experiment covering five devices.</p><p>The report covers the RWG protocol, the system choice, the implementation</p><p>and the testing of the implementation.</p>

Recently, researchers have introduced the notion of super-peers to improve signaling efficiency as well as lookup performance of peer-to-peer (P2P) systems. In a separate development, recent works on applications of mobile ad hoc networks (MANET) have seen several proposals on utilizing mobile fleets such as city buses to deploy a mobile backbone infrastructure for communication and Internet access in a metropolitan environment. This paper further explores the possibility of deploying P2P applications such as content sharing and distributed computing, over this mobile backbone infrastructure. Specifically, we study how city buses may be deployed as a mobile system of super-peers. We discuss the main motivations behind our proposal, and outline in detail the design of a super-peer based structured P2P system using a fleet of city buses. / Singapore-MIT Alliance (SMA)

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With the proliferation of mobile devices and wireless connectivity technologies, mobile social communities offer novel opportunities for targeted marketing by service or product providers. Unfortunately, marketers are still unable to realize the full potential of these markets due to their inability to effectively target right audiences. This thesis presents a novel middleware for identifying spontaneous social communities (SSCs) of mobile users in ad hoc networks in order to facilitate marketers' advertisements. The contributions of the presented work are two fold; the first is a novel model for SSCs that captures their unique dynamic nature, in terms of community structure and interest in different \textit{hot-topics} over time. These time-varying interests are represented through an inferred \textit{community profile prototype} that reflects dominant characteristics of community members. This prototype is then employed to facilitate the identification of new potential members. The selected community prototypes are also used by marketers to identify the right communities for their services or products promotions. The second contribution of this paper is novel distributed techniques for efficient calculation of the community prototypes and identification of potential community links. In contrast to traditional models of detecting fixed and mobile social networks that rely on pre-existing friendships among its members to predict new ones, the proposed model focuses on measuring the degree of similarity between the new user's profile and the profiles of members of each community in order to predict new users' relationships in the community. The adopted model of SSCs can foster many existing and new socially-aware applications such as recommender systems for social events and tools for collaborative work. It is also an ideal target for business-oriented applications such as short-message-service (SMS) advertisement messages, podcasting news feeds in addition to location/context-aware services. The performance of the proposed work was evaluated using the NetLogo platform where obtained experimental results demonstrate the achieved high degree of stability in the resulting communities in addition to the effectiveness of the proposed middleware in terms of the reduction in the number of routing messages required for advertisements.

The growing number of wireless devices and wireless systems present many challenges on the design and operation of these networks. We focus on massively dense ad hoc networks and cellular systems. We use the continuum modeling approach, useful for the initial phase of deployment and to analyze broad-scale regional studies of the network. We study the routing problem in massively dense ad hoc networks, and similar to the work of Nash, and Wardrop, we define two principles of network optimization: user- and system-optimization. We show that the optimality conditions of an appropriately constructed optimization problem coincides with the user-optimization principle. For different cost functions, we solve the routing problem for directional and omnidirectional antennas. We also find a characterization of the minimum cost paths by extensive use of Green's theorem in directional antennas. In many cases, the solution is characterized by a partial differential equation. We propose its numerical analysis by finite elements method which gives bounds in the variation of the solution with respect to the data. When we allow mobility of the origin and destination nodes, we find the optimal quantity of active relay nodes. In Network MIMO systems and MIMO broadcast channels, we show that, even when the channel offers an infinite number of degrees of freedom, the capacity is limited by the ratio between the size of the antenna array at the base station and the mobile terminals position and the wavelength of the signal. We also find the optimal mobile association for the user- and system-optimization problem under different policies and distributions of the users.