Showing papers by "Karine Altisen published in 2011"
29 Nov 2011
TL;DR: This paper shows how to apply the causality closure on this class of curves, proves that this causal representative is still in the class and gives algorithms to compute it, which provides the tightest pair of curves among the curves which accept the same sets of streams.
Abstract: Real-Time Calculus (RTC) [14] is a framework to analyze heterogeneous real-time systems that process event streams of data. The streams are characterized by arrival curves which express upper and lower bounds on the number of events that may arrive over any specified time interval. System properties may then be computed using algebraic techniques in a compositional way.The property of causality on arrival curves essentially characterizes the absence of deadlock in the corresponding generator. A mathematical operation called causality closure transforms arbitrary curves into causal ones.In this paper, we extend the existing theory on causality to the class Upac of infinite curves represented by a finite set of points plus piecewise affine functions, where existing algorithms did not apply. We show how to apply the causality closure on this class of curves, prove that this causal representative is still in the class and give algorithms to compute it. This provides the tightest pair of curves among the curves which accept the same sets of streams.
8 citations
23 May 2011
TL;DR: In this paper, the authors propose an approach to reduce the number of sauts in a march aleatoire by atteindre un noeud particulier du reseau without compromettre les autres avantages.
Abstract: Nous proposons d'ameliorer les marches aleatoires en utilisant des listes tabous. Notre objectif est de reduire le nombre de sauts pour atteindre un noeud particulier du reseau sans compromettre les autres avantages des marches aleatoires. Nos solutions permettent ainsi de resoudre efficacement le routage dans les reseaux de capteurs sans fil.
3 citations
01 Jan 2011
TL;DR: This work designs a new secure routing protocol for wireless sensor networks based on random walks using tabu lists that ensures data confidentiality, integrity, authenticity and a high delivery rate, even in presence of compromised nodes.
Abstract: In this report, we propose a provably secure routing protocol for wireless sensor networks (WSNs) based on random walks using tabu lists. Many approaches have been developed in the literature to solve security problems of routing protocols for WSNs. But most of them are not resilient against attacks from compromised nodes because they only use cryptographic solutions. In our work, we design a new secure routing protocol to improve this resiliency using realistic assumptions such as asynchronous communication. We propose a probabilistic approach that allows us to save energy and to avoid malicious nodes with a detection system of safe paths using tabu lists, acknowledgments and trust counters. Our main result is that, even in presence of compromised nodes, our protocol ensures data confidentiality, integrity, authenticity and a high delivery rate.
3 citations