Reseaux ad hoc: Systeme d'adressage et methodes d'accessibilite aux donnees

During the last decade, a new type of wireless networks has stirred up great interest within the scientific community: there are ad hoc networks. They exist as mobile ad hoc networks (MANET), and wireless sensor (WSN). The mobile ad hoc networks consist of mobile nodes that communicate with each other without using a centralized infrastructure. The nodes move freely and are subject to frequent disconnections due to links instability. This has the effect of reducing data accessibility, and change the way data are shared across the network. Similar MANET networks, a WSN consists of a set of embedded processing units called sensors that communicate with each other via wireless links.;Our thesis runs through three scientific papers, each addressing a specific problem. In our first paper entitled "Joint Data Caching and Replication Scheme in Ad hoc Networks" and submitted to the Ad hoc Networks Journal (Elsevier), we investigate the problem of data accessibility in MANET where a server stores data items requested by mobile nodes. To this end, two caching models are proposed. The first one allows the mobile nodes to cooperatively share data items with neighbour nodes through a neighbourhood caching table. The role of this table is to link the caching space of the nodes in the same neighborhood. The second scheme combines the cooperative caching scheme and data replication on some key nodes. For that purpose, the partial data replication is formulated as an Integer Linear Programming model that aims to minimize data access and data replication costs. By showing that the partial data replication problem is NP-hard, we introduce an efficient heuristic to solve it. The proposed heuristic selects key nodes and partially replicates popular data items in their caching space by exploring various replication strategies. Performance analysis and simulation results show the effectiveness of the proposed schemes over some existing caching strategies.;The second paper entitled "SubCast: A distributed Addressing and Routing System for Large Scale Wireless Sensor and Actor Networks" published in the Computer Networks (Elsevier) proposes a distributed address assignment and routing scheme based on a Topic Clustering System and fractal theory Iterated Function Systems. In order to minimize data delivery costs, the proposed architecture first builds an actor overlay network and allocates addresses to network nodes. Location information in the allocated addresses allows establishing data delivery paths. Simulation results confirm that the proposed system efficiently guarantees the allocation of unique addresses and performs efficient data delivery while reducing communication costs, delays as well as the impact of imprecise locations.;Finally, our third paper entitled "QoSNet: An Integrated QoS Network for Routing Protocols in Large Scale Wireless Sensor Networks" and submitted in Computer Communications (Elsevier) proposes a promising multipath QoS routing protocol based on a separation of the nodes in two sub networks. The first sub-network includes specific nodes that are involved occasionally into the routing decision while the remaining nodes in the second sub-network fully take part into it. The QoS routing is formulated as an optimization problem that aims to extend the network lifetime, under the QoS constraints. Using percolation theory we design a routing algorithm to solve the problem on the respective sub-networks. Simulation results show the efficiency of this novel approach in terms of average end-to-end delay, on-time packet delivery ratio, and network lifetime. (Abstract shortened by UMI.);In this thesis, we address the problem of data accessibility in MANET, and that of addressing and routing in large scale WSN. This involves techniques such as data caching and replication to prevent the deterioration of data accessibility. The addressing system in WSN includes a distributed address allocation scheme and a routing infrastructure for both actors and sensors. Moreover, with the birth of the multimedia sensors, the traffic may be mixed with time sensitive packets and reliability-demanding packets. For that purpose, we also address the problem of providing quality of service (QoS) in the routing infrastructure for WSN.