In-Flight Entertainment and Connectivity (IFEC) is becoming a key trend and offering in-flight connectivity is one of the most essential demands of commercial airline passengers. A grand challenge is to provide in-flight connectivity in high altitudes and particularly in isolated locations, such as the oceans, where establishing an air-to-ground link is not possible. Moreover, the high speed and dynamic characteristics of such aircraft make this task difficult. Aeronautical Ad-Hoc Networking (AANET) intends to cope with this challenge by forming a network of airplanes having air-to-air (A2A) connections. However, the dynamic nature of such a network is likely to lead to unstable connections. The primary root cause of the majority of these stability issues is known to be the short life of A2A links which is the result of poor topology formation of aircraft. Concentrating on aircraft clustering and making them more stable can improve connection lifetime and improve the stability and performance of the network. Therefore the main objective in making AANETs feasible should be to form the topology as clusters of aircraft. With this in mind, the thesis's proposition is twofold: First, unveil the benefits of density-based clustering to improve the AANET performance. To do so, a modified DBSCAN algorithm is employed for the clustering problem that exploits several features of real flight datasets. This method also includes a weighted scheme to reflect the relative importance of each feature of the final calculation. The proposed method improved the packet delivery ratio and end-to-end latency of the state-of-the-art clustering-based AANET solutions by 51 % and 30 %, respectively. In addition, the proposed approach reduces the number of cluster changes by 22%. Second, selecting a well-connected cluster head is the next stage in enhancing connection and stability. This thesis presents a new cluster head selection technique for AANETs that calculates the Neighbor Nodes within a given distance of each node and selects the node with the most connections as the new cluster head. In instances where a cluster head cannot interact directly with another cluster, a Gateway node is chosen to facilitate connection with other clusters. According to simulations, the suggested method increases packet delivery ratio by 3, end-to-end delay by 9 and throughput by up to 10% compared to the current state of the art. In addition, the proposed method reduces cluster head replacements by 17% and increases cluster head longevity by 8%.

L'essor des communications par satellites et des nouvelles technologies de l'information et de la communication conduisent à une demande croissante de la part des utilisateurs. Ainsi, afin de répondre à ces nouveaux besoins, des services proposant de la connectivité en vol pour les passagers des compagnies aériennes voient le jour. Les travaux présentés dans ce mémoire portent sur la réalisation de modèles numériques rigoureux de grands réseaux d'antennes destinés à couvrir ce champ applicatif. Après une mise en contexte et un rappel des contraintes liées aux réseaux d'antennes, des véhicules de test numériques et expérimentaux, permettant de valider les méthodologies de modélisation, sont réalisés. La modélisation d'un grand panneau rayonnant à bipolarisation circulaire et acceptant d'importants angles de dépointage est enfin abordée. Cette étude permet alors de statuer sur les performances du panneau, en fonction des consignes de pointage et des dispersions éventuelles des chaînes actives. / The rapid expansion of satellite communications and information and communications technology led to an increasing demand from end-users. Hence, services offering In-Flight Connectivity for airlines passengers are emerging. This work is focused on the implementation of accurate numerical models of large antenna arrays meant for this scope. After having put things into context and recalled issues linked to antenna arrays, numerical and experimental test vehicles are made, allowing to validate the modelling methodologies. Finally, the modelling of a large, dual circular polarization and wide-angle scanning radiating panel is addressed. This study then allows to estimate the performance of the panel function of steering requirements and possible dispersions from the active channels.

Dans un monde où l’information va de plus en plus vite, il est important de pouvoir rester connecté en permanence. De nouvelles solutions émergent pour connecter les passagers à bord d’un avion grâce aux communications par satellite. Parmi elles, on retrouve les antennes à pointage électronique dans lesquelles cette thèse de doctorat s’intègre. Une étude sur les différentes antennes existantes ou en projet est présentée. Les puces électroniques MMIC AsGa permettent d’appliquer des lois d’amplitude et de phase pour chaque élément rayonnant d’une antenne réseau. Cette thèse de doctorat porte sur la conception d’un déphaseur, après avoir étudié les technologies et les topologies de celui-ci. Ensuite, la conception d’un amplificateur faible bruit à gain variable est proposée à partir d’un état de l’art. Les résultats de simulation et de mesures de ces deux fonctions sont exposés. / In a world where the information is moving faster and faster, it is important to be able to stay connected continuously. Some new solutions for air transport connectivity are in development thanks to the rise of satellite communications. This thesis work is part of an electronically steerable antenna array project, developed as a solution to achieve In-Flight Connectivity in Ka-band. A state- of-the art review on electronically steerable antenna arrays is also presented. In these arrays, each radiating element needs a specific amplitude and phase to obtain a scanning beam by adding their contribution. This thesis focus on the design of a GaAs MMIC chip inclusion two functions: a phase shifter and a variable-gain low-noise amplifier. The simulation and measurement results are presented for these two functions.