SETHOM Kaouthar

PhD graduated
Team : Phare
Departure date : 10/01/2008
Supervision : Guy PUJOLLE
Co-supervision : AFIFI

Gestion de la mobilité dans les réseaux sans fil de nouvelle génération

Mobility and transparency are the intrinsic characteristics of the pervasive computing environment. In such a context, users are of high mobility; they roam around and access various services through different access networks that are available to them on the spot. These access systems are heterogeneous, embedded in their surroundings, and vary from location to location. Users are willing to have seamless IP connectivity to third party services at all times, and in all places, while using the “best” available connection. Although such a definition of pervasive computing is clear from a user perspective, the technological path for building such an anytime, anywhere networking environment is less simple. Obviously, realizing this goal will require new enhancements at the conventional protocol stack to support mobility so that users can continuously interact with the available services without disruption. In this thesis, we address the design of intelligent mobility management techniques that take advantage of IP-based technologies to achieve transparent roaming among various access technologies and domains. In order to develop an efficient technology agnostic solution, we first propose to manage the problem just above the link layer. We thus propose a novel architecture for the vertical handoff problem that operates at the layer 2.5. It provides efficient micro-mobility with continuous QoS support by combining the advantages of MPLS, such as IP QoS support, with these of a host-based link layer solution (Virtual Interface), such as low-latency handoffs. This approach allows transparent operations of the upper layer protocols during roaming of mobile nodes since applications do not see IP address change due to handoff. We then extend the virtual interface concept to the case of an entire mobile network (Personal Area network (PAN)). Since the PAN context may change dynamically, PAN-to-infrastructure connectivity needs to be updated frequently. The Distributed Virtual Network Interface allows dynamic PAN configuration while inducing minimum complexity to end users and applications. The last section of the thesis is devoted to describing tools for mobility assistance. We first present PALMA; a distributed database for mobile nodes location management. Since, a static configuration runs the risk of providing poor performance; we opt for a distributed and collaborative architecture based on the P2P paradigm. The result is a highly efficient location service that exploits proximity in lookup and update operations. Finally, a secure architecture for discovering and selecting next access router in a dynamic and distributed fashion is proposed. Feasibility and performance studies, resulting from simulations, analytical analysis as well as from implementations on different test-beds are very satisfactory and show that seamless and optimized handoffs are globally achieved. Results analyses show the robustness of our contributions.
Defence : 11/30/2006

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