Biased Random Walk Model to estimate Routing Performance in Wireless Sensor Networks

International audienceLes réseaux de capteurs sans fils sont constitués d'un grand nombre de noeuds assujettis `à de sévères contraintes en terme d'énergie, de capacité de traitement et de communication. Dans ce contexte, afin de réduire la complexité, un des défis majeurs rencontrés dans ce type de réseau est le calcul des routes et la mise en oeuvre de schémas de routage efficaces tout en minimisant la quantité d'information utilisée sur l' état du système. De nombreux travaux ont ́etudié ce compromis de façon qualitative ou grâce à des simulations. Nous proposons un modèle basé sur la théorie de la marche aléatoire pour estimer analytiquement ce compromis en considérant plus particulièrement l'influence du degré de connaissance de l'état du système que posséde un noeud sur le temps moyen de collecte dans un réseau de capteurs sans fils

Random Walk Based Routing Protocol for Wireless Sensor Networks

International audienceIn recent years, design of wireless sensor networks using methodologies and mechanisms from other disciplines has gained popularity for addressing many networking aspects and providing more flexible and robust algorithms. We address in this paper the problem of random walk to model routing for data gathering in wireless sensor networks. While at first glance, this approach may seem to be overly simplistic and highly inefficient, many encouraging results that prove its comparability with other approaches have been obtained over the years. In this approach, a packet generated from a given sensor node performs a random motion until reaching a sink node where it is collected. The objective of this paper is to give an analytical model to evaluate the performance of the envisioned routing scheme with special attention to two metrics: the mean system data gathering delay and the induced spatial distribution of energy consumption. The main result shows that this approach achieves acceptable performance for applications without too stringent QoS requirements provided that the ratio of sink nodes over the total number of sensor nodes is carefully tuned

Neocortical Long-Term Depression and Depotentiation in the Adult Freely Moving Rat

Information is believed to be stored in the brain by constructing new neural circuits, and these circuits are shaped by changes in the strength of the synaptic connections between the neurons making up the circuit. According to most theories of memory, new circuits can be formed by either increasing or decreasing the strength of synaptic connections. Bidirectional modifications in synaptic efficacy are also central components in recent computer simulations of learning and memory. While long-term potentiation (LTP) has been the focus of extensive research into the mechanisms underlying information storage in the mammalian brain, long-term depression (LTD) and depotentiation, its depressive counterparts, have not. Furthermore, most of the LTD research has involved the use of anaesthetized animals and in vitro slice preparations, making it more difficult to determine the role of this synaptic phenomenon in learning and memory in the intact behaving animal. This thesis provides the first detailed examination of: 1) the induction and decay of both LTD and depotentiation in the neocortex of the awake, freely moving animal; 2) the effects of N-methyl D-Aspartate receptor (NMDAR) blockade on the induction of LTD, LTP, and depotentiation (NMDA receptor activation is known to play a major role in most forms of LTP); and 3) the interactions between these synaptic phenomena. LTD was expressed as a significant reduction in the amplitude of both short and long-latency field potential components. Depotentiation was expressed as a long lasting decrease in the amplitude of a previously enhanced late component. LTD was found to be greater in magnitude and longer lasting when the conditioning stimulation was repeated. However, unlike LTP induction, the conditioning stimulation was equally effective whether spaced over hours or days. NMDA receptor antagonism blocked LTP induction and instead produced a depression effect similar to LTD. Unlike LTP, LTD and depotentiation were found to be NMDAR-independent in the neocortex of the freely moving rat. LTP and LTD are both reversible phenomena and LTD-inducing stimulation can modulate the effects of LTP-inducing stimulation. LTD-inducing stimulation, when delivered following to LTP-inducing stimulation, attenuates the induction rate for potentiation. LTD and depotentiation may play important roles in the ongoing experience-induced modification of neuronal connectivity. Furthermore, these results are consistent with the hypothesis that potentiation and depression reflect the physiological instantiation of a bidirectional learning rule.ThesisDoctor of Philosophy (PhD

On the data delivery delay taken by random walks in wireless sensor networks

International audienceIn recent years, the use of random walk techniques in wireless sensor networks has attracted considerable interest among numerous research efforts. The popularity of this approach is attributed to the natural properties of random walks such as locality, simplicity, low-overhead and inherent robustness. However, throughout the variety of research works that assess the effectiveness of random walk techniques, most results are derived from a qualitative view or by means of simulations. Furthermore, when analytical tools are used, the obtained results often provide bounds on various performance metrics of interest, which may have little consequences for practical applications. Instead, our goal in this paper is to quantify the effectiveness of such techniques based on the derivation of closed-form expressions. In particular, we focus on the data delivery delay taken for the random walk to deliver messages from sensor to sink nodes and study its statistics through closed-form derivations

Segundo idioma extranjero III: Francés, Introduction aux Relations Internationales (A2.2)

Doble Grado en Administración y Dirección de Empresas y Relaciones Internacionales (E-6), Grado en Derecho y Grado en Relaciones Internacionales (E-5), Instituto de Idiomas Moderno

Francés (A1) /Francés I/Francés II

Doble Grado en Psicología y Criminología, Grado en Filosofía, Grado en Psicología, Grado en Trabajo Social y Diploma en Cooperación Internacional al Desarrollo, Grado en Traducción e Interpretación, Doble Grado en Administración y Dirección de Empresas y Relaciones Internacionales (E-6), Grado en Administración y Dirección de Empresas (E-2), Grado en Administración y Dirección de Empresas Mención Internacional (E-4), Grado en Derecho (E1), Grado en Derecho y Grado en Relaciones Internacionales (E-5), Grado en Ingeniería de Tecnologías de Telecomunicación, Grado en Ingeniería de Tecnologías Industriales, Instituto de Idiomas Moderno

Segundo idioma extranjero II y III: Francés, Introduction aux Relations Internationales (A2.2)

Doble Grado en Administración y Dirección de Empresas y Relaciones Internacionales (E-6), Grado en Derecho y Grado en Relaciones Internacionales (E-5), Instituto de Idiomas Moderno

Francés (A1) /Francés I/Francés II

Doble Grado en Criminología y Trabajo Social, Doble Grado en Psicología y Criminología, Grado en Filosofía, Grado en Psicología, Grado en Trabajo Social y Diploma en Cooperación Internacional al Desarrollo, Grado en Traducción e Interpretación, Doble Grado en Administración y Dirección de Empresas y Relaciones Internacionales (E-6), Grado en Administración y Dirección de Empresas (E-2), Grado en Administración y Dirección de Empresas Mención Internacional (E-4), Grado en Derecho (E1), Grado en Derecho y Grado en Relaciones Internacionales (E-5), Grado en Ingeniería de Tecnologías de Telecomunicación, Grado en Ingeniería de Tecnologías Industriale