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Routage Multichemins et Codage à Description Multiple dans les Réseaux Ad Hoc. (Multipath routing and Multiple Description Coding in Ad Hoc Networks)

Ad hoc networks are a special kind of wireless network with no fixed infrastructure. Because of this feature, routing is a difficult issue in case of unstability of links and nodes. The purpose of this PhD thesis is to evaluate the impact of unconventional strategy wich consists in, on one hand using several routes simultaneously, on the other hand introducing redundancy in the data spread over those routes thanks to coding methods called Multiple Description. The information to transmit is transformed in a given number of elements called descriptions. The loss of a certain number of description does not prevent from reconstructing the original data. The objective of such a strategy is thus to make every route less critical without increasing too much the amount of data transmitted in the network. In this context, an algorithm dedicated to selecting routes is proposed and different strategies for distributing descriptions on these routes are studied. In order to evaluate this approach, we have implemented two protocols, inspired from the standard routing mechanisms and including the ideas mentioned above. The first, MPOLSR is proactive. In this cas, we only need to extract routes from the information naturally gathered in nodes. The second, TMR, is reactive. Then, obtaining topological information requires to use unusual methods compared to classical reactive protocols. Simulations are realised thanks to the software NS2 in order to compare the performance of our propositions.