<p align="justify">The main contribution of this thesis is the emphasis made on the reusability concept, on one side, for designing a simulation environment, and on the other side, for defining two different levels of granularity for reusable network component libraries.</p><p><p align="justify">The design of our simulation environment, called AMS for Atelier for Modeling and Simulation, was based on existing pieces of software, which proved their usefulness in their respective fields. In order to carry out this integration efficiently, a modular structure of the atelier was proposed. The structure has been divided into four phases. Each phase is responsible of a part of the performance evaluation cycle. The main novelty of this structure is the usage of a dedicated language as a means to define a clear border between the editing and simulation phases and to allow the portability of the atelier upon different platforms. A prototype of the atelier has been developed on a SUN machine running the SunOs operating system. It is developed in C language.</p><p><p align="justify">The kernel of the AMS is its library of Detailed Basic Models (DBMs). Each DBM was designed in order to comply with the most important criterion which is reusability. Indeed, each DBM can be used in aeveral network architectures and can be a component of generic and composite models. Before the effective usage of a DBM, it is verified and validated in order to increase the model credibility. The most important contribution of this research is the definition of a methodology for modeling protocol entities as DBMs. We then tried to partly bridge the gap between specification and modeling. This methodology is based on the concept of function. Simple functions are modeled as reusable modules and stored into a library. The Function Based Methodology was designed to help the modeler to build efficiently and rapidly new protocols designed for the new generation of networks where several services can be provided. These new protocols can be dynamically tailored to the user' s requirements.</p><p> / Doctorat en sciences appliquées / info:eu-repo/semantics/nonPublished

L’objectif de la thèse est d’évaluer la fiabilité des réseaux de capteurs (WSN) en milieu naturel. L’évaluation prend en compte les composants physiques des nœuds de capteurs, les cellules photovoltaïques éventuelles (PV), les batteries rechargeables ou non, les protocoles de communications et d’échange de données ainsi que les éléments nécessaires pour une détection efficace, en particulier les feux de forêt. L’étude traite d’abord du fonctionnement du réseau de capteur dans la nature en prenant en compte sa consommation d’énergie et les défaillances physiques et fonctionnelles pour évaluer sa fiabilité. Puis, la fiabilité est comparée entre un réseau sans PV (WSN) et avec PV (PV-WSN) dans des conditions d’échange de données difficiles. Enfin, l’évaluation de la fiabilité des PV-WSN est effectuée dans le cadre de la détection et de la propagation des feux de forêts avec les mêmes conditions d’échange de données. Les principales hypothèses considérées sont : des distributions de capteurs aléatoires dans des réseaux avec un seul nœud « sink », des nœuds identiques, l’affaiblissement du signal radio dû aux obstacles naturels, une propagation de feu uniforme et elliptique, une végétation homogène, une perte possible de paquets de données ainsi que l’utilisation du protocole de routage « Dynamic Source Routing (DSR) ». Un simulateur a été développé pour effectuer les différentes études. Les résultats obtenus montrent l’importance des défaillances physiques pour l’évaluation de la fiabilité et pour la prolongation de la durée de vie des WSN et PV-WSN / The objective of my thesis was to evaluate the reliability of wireless sensor networks (WSN) in natural settings. My evaluation takes into account the physical components of sensor nodes, photovoltaic (PV) cells, rechargeable and non-rechargeable batteries, communication and data transmission protocols, and elements necessary for effective detection, especially for the case of forest fires. The study first deals with the functioning of a WSN in nature by taking into account its energy consumption, and physical and functional failures to assess its reliability. Reliability is then compared between a PV-free (WSN) and PV- (PV-WSN) network under complex data exchange conditions. Finally, the evaluation of the reliability of the PV-WSN is carried out in the context of the detection and propagation of forest fires under the same conditions of data exchange. The main assumptions considered are: the WSN is structured randomly with one sink per cluster and identical sensors, environmental and orientation losses affect PV-cell recharge, the radio signal may be weakened by natural obstacles, fire propagation is uniform and elliptical, vegetation is homogeneous, and there is communication loss using the Dynamic Source Routing (DSR) protocol. A simulator was developed to carry out these assessments. The results obtained show the importance of physical failures in assessing reliability and extending WSN and PV-WSN lifetime