Simulation and Performance Analysis of MP-OLSR for Mobile Ad hoc Networks

Mobile ad hoc networks (MANETs) consist of a collection of wireless mobile nodes which dynamically exchange data without reliance on a fixed base station or a wired backbone network, which makes routing a crucial issue for the design of a ad hoc networks. In this paper we discussed a hybrid multipath routing protocol named MP-OLSR. It is based on the link state algorithm and employs periodic exchange of messages to maintain topology information of the networks. In the mean time, it updates the routing table in an on-demand scheme and forwards the packets in multiple paths which have been determined at the source. If a link failure is detected, the algorithm recovers the route automatically. Concerning the instability of the wireless networks, the redundancy coding is used to improve the delivery ratio. The simulation in NS2 shows that the new protocol can effectively improve the performance of the networks

Implementation of Multipath and Multiple Description Coding in OLSR

In this paper we discussed the application and the implementation of multipath routing and multiple description coding (MDC) extension of OLSR, called MP-OLSR. It is based on the link state algorithm and employs periodic exchange of messages to maintain topology information of the networks. In the mean time, it updates the routing table in an on-demand scheme and forwards the packets in multiple paths which have been determined at the source. If a link failure is detected, the algorithm recovers the route automatically. Concerning the instability of the wireless networks, the multiple description coding is used to improve reliability of the network transmission, and several methods are proposed to allocate the redundancy in different paths. The simulation in NS2 shows that the new protocol can effectively improve the performance of the networks. The implementation of MP-OLSR is also proposed in the end

Routage Multichemins et Codage à Description Multiple dans les Réseaux Ad Hoc

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.Les réseaux ad hoc sont un type particulier de réseaux sans fil privés de toute infrastructure fixe. Cette particularité rend le routage très problématique en cas de grande instabilité des éléments qui les composent (n\oe{}uds et liens). Le but de cette thèse est d'évaluer l'impact d'une stratégie non conventionnelle consistant à, d'une part, utiliser plusieurs routes en parallèle, d'autre part, introduire de la redondance entre les données réparties sur ces routes grâce à des méthodes de codage à description multiple. Ces méthodes permettent de transformer l'information à transmettre en un nombre défini d'éléments appelés descriptions, et tels que la perte d'un certain nombre d'entre eux n'empêche pas la reconstruction de l'information initiale. L'objectif d'une telle stratégie est de rendre chaque route moins critique, tout en veillant à modérer la redondance globale introduite. Dans ce contexte, un algorithme de sélection de routes est proposé, et différentes stratégies de répartition de descriptions sur ces routes sont étudiées. Afin d'évaluer cette approche, nous avons mis en œuvre de deux protocoles inspirés de mécanismes standards et incluant les idées précédemment mentionnées. Le premier, MPOLSR, est proactif. Dans ce cas, il suffit d'extraire un ensemble de routes intéressantes de l'information topologique rassemblée. Le second, TMR, est réactif. La récupération d'informations topologiques suffisament variées nécessite alors des mécanismes différents de ceux utilisés dans les protocoles réactifs standards. Des simulations sont réalisées à l'aide de NS2 pour comparer les performances de ces propositions

Routage multichemins et codage à transcription multiple dans les réseaux ad hoc

Les réseaux ad hoc sont un type particulier de réseaux sans fil privés de toute infrastructure fixe. Cette particularité rend le routage très problématique en cas de grande instabilité des éléments qui les composent (nœuds et liens). Le but de cette thèse est d'évaluer l'impact d'une stratégie non conventionnelle consistant à, d'une part, utiliser plusieurs routes en parallèle, d'autre part, introduire de la redondance entre les données réparties sur ces routes grâce à des méthodes de codage à description multiple. Ces méthodes permettent de transformer l'information à transmettre en un nombre défini d'éléments appelés descriptions, et tels que la perte d'un certain nombre d'entre eux n'empêche pas la reconstruction de l'information initiale. L'objectif d'une telle stratégie est de rendre chaque route moins critique, tout en veillant à modérer la redondance globale introduite. Dans ce contexte, un algorithme de sélection de routes est proposé, et différentes stratégies de répartition de descriptions sur ces routes sont étudiées. Afin d'évaluer cette approche, nous avons mis en œuvre de deux protocoles inspirés de mécanismes standards et incluant les idées précédemment mentionnées. Le premier, MPOLSR, est proactif. Dans ce cas, il suffit d'extraire un ensemble de routes intéressantes de l'information topologique rassemblée. Le second, TMR, est réactif. La récupération d'informations topologiques suffisamment variées nécessite alors des mécanismes différents de ceux utilisés dans les protocoles réactifs standards. Des simulations sont réalisées à l'aide de NS2 pour comparer les performances de ces propositions.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 ina 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.NANTES-BU Sciences (441092104) / SudocNANTES-BU Technologie (441092105) / SudocSudocFranceF

Multi-sensor semantic mapping and exploration of indoor environments

environment

RGBD object recognition and visual texture classification for indoor semantic mapping

International audienceWe present a mobile robot whose goal is to autonomously explore an unknown indoor environment and to build a semantic map containing high-level information similar to those extracted by humans. This information includes the rooms, their connectivity, the objects they contain and the material of the walls and ground. This robot was developed in order to participate in a French exploration and mapping contest called CAROTTE whose goal is to produce easily interpretable maps of an unknown environment. In particular we present our object detection approach based on a color+depth camera that fuse 3D, color and texture information through a neural network for robust object recognition. We also present the material recognition approach based on machine learning applied to vision. We demonstrate the performances of these modules on image databases and provide examples on the full system working in real environments