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Auteur / Autrice : Fabio Rocha Jimenez Vieira
Direction : Serge Fdida
Type : Thèse de doctorat
Discipline(s) : Informatique
Date : Soutenance en 2012
Etablissement(s) : Paris 6

Résumé

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We present algorithmic solutions for two problems related to the wireless network interference. The first one proposes to schedule the links of a given set of routes under the assumption of a heavy-traffic pattern. We assume some TDMA protocol provides a background of synchronized time slots and seek to schedule the routes' links to maximize the number of packets that get delivered to their destinations per time slot. Our approach is to construct an undirected graph G and to heuristically obtain node multicolorings for G that can be turned into efficient link schedules. In G each node represents a link to be scheduled and the edges are set up to represent every possible interference for any given set of interference assumptions. We present two multicoloring-based heuristics and study their performance through extensive simulations. One of the two heuristics is based on relaxing the notion of a node multicoloring by dynamically exploiting the availability of communication opportunities that would otherwise be wasted. We have found that, as a consequence, its performance is significantly superior to the other's. In the second proposal, we consider wireless mesh networks and the problem of routing end-to-end traffic over multiple paths for the same origin-destination pair with minimal interference. We introduce a heuristic for path determination with two distinguishing characteristics. First, it works by refining an extant set of paths, determined previously by a single- or multi-path routing algorithm. Second, it is totally local, in the sense that it can be run by each of the origins on information that is available no farther in the network than the node's immediate neighborhood. We have conducted extensive computational experiments with the new heuristic, using AODV and OLSR as well as their multi-path variants as the underlying routing method. For one TDMA setting running a path-oriented link scheduling algorithm and two different CSMA settings (as implemented on 802. 11), we have demonstrated that the new heuristic is capable of improving the average throughput network-wide. When working from the paths generated by the multi-path routing algorithms, the heuristic is also capable to provide a more evenly distributed traffic pattern.