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— An approximate dynamical extension of queueing theory result is described and is applied to Jac... more — An approximate dynamical extension of queueing theory result is described and is applied to Jackson’s and G’s Networks. It is shown that the dynamics of these networks may be represented by non-linear compartmental systems which are cooperative for the former case and may sometimes be competitive for the latter case. The implications in term of stability are discussed and an illustrative example is provided. I.

In this paper, a novel approach for wireless network emulation is proposed. The emulation infrast... more In this paper, a novel approach for wireless network emulation is proposed. The emulation infrastructure is built on a virtualized Linux kernel (User Mode Linux) which allows for highly realistic emulations. The virtualized kernel is extended with software based wireless cards which are plugged in a generic physical layer emulator. The emulator proposed in this paper tries to reduce the gap between simulations and implementations by allowing a developer to test his/her implementation in an almost real, but entirely software-based environment. The advantage of such an approach is that its cost, in terms of required infrastructure and learning curve for the developer is reduced to a minimum.

Le logiciel libre stimule un nouveau terrain de reflexions pour l'ensemble des sciences: ques... more Le logiciel libre stimule un nouveau terrain de reflexions pour l'ensemble des sciences: questions ethiques sur les pratiques, le controle, la regulation; questions economiques sur les modes d'echanges et ses transformations; questions juridiques sur l'eclatement des cadres nationaux; questions anthropologiques qui s'ouvrent devant l'immensite de ce nouveau terrain vierge. Nouvelle organisation, nouveau mode de cooperation entre les acteurs, nouveau rapport a la connaissance et a sa production: les nouvelles formes de collaboration engendrees par le logiciel libre posent question.

efficace et ses critiques constructives qui m’ont permis de mener à bien ce travail de thèse. Je ... more efficace et ses critiques constructives qui m’ont permis de mener à bien ce travail de thèse. Je remercie également Hugues Mounier pour son accueil ainsi que pour son encadrement scientifique durant mon séjour à l’Ecole des Mines de Paris organisé dans le cadre du programme Control Training Site ainsi que le Professeur Benoît Macq pour ses encouragements initiaux. Merci aux membres du jury pour leur relecture du manuscrit ainsi que pour la discussion fructueuse lors de la défense privée qui a activement contribué à la version finale de ce document. Enfin, je remercie les promoteurs du PAI et du CTS pour leur soutien financier. Preamble Packet switched networks offer a particularly challenging research subject to the control community: The dynamics of a network buffer, their simplest component, are nonlinear and exhibit a saturation effect that

Packet switched networks offer a particularly challenging research subject to the control communi... more Packet switched networks offer a particularly challenging research subject to the control community: the dynamics of a network buffer, their simplest component, are nonlinear and exhibit a saturation effect that cannot be neglected. In many practical cases, networks are made up of the interconnection of a large number of such basic elements. This gives rise to high dimensional nonlinear systems for which few general results exist today in the literature. Furthermore, these physical interconnections that may sometimes span a very long distance induce a transmission delay and the queues in intermediary nodes induce a buffering delay. Finding a model able to both take into account as much of this complexity as possible while being simple enough to be analysed mathematically and used for control purposes is the first objective of this thesis. To accomplish this goal, a so-called "fluid-flow model" based on fluid exchange between buffers is presented. Neglecting the transmissio...

An approximate dynamical extension of queueing theory result is described and is applied to Jacks... more An approximate dynamical extension of queueing theory result is described and is applied to Jackson's and G's Networks. It is shown that the dynamics of these networks may be represented by non-linear compartmental systems which are cooperative for the former case and may sometimes be competitive for the latter case. The implications in term of stability are discussed and an illustrative example is provided.