Accès opportuniste au spectre et contrôle optimal dans les réseaux sans fil hétérogènes

The present dissertation deals with how to use the precious wireless resources that are usually wasted by under-utilization of networks. We have been particularly interested by all resources that can be used in an opportunistic fashion using different technologies. We have designed new schemes for better and more efficient use of wireless systems by providing mathematical frameworks. In the first part, We have been interested in cognitive radio networks, where a cellular service provider can lease a part of its resources to secondary users or virtual providers. In the second part, we have chosen delay-tolerant networks as a solution to reduce the pressure on the cell traffic, where mobile users come to use available resources effectively and with a cheaper cost. We have focused on optimal strategy for smartphones in hybrid wireless networks. In the last part, an alternative to delay-tolerant networks, specially in regions that are not covered by the cellular network, is to use Ad-hoc networks. Indeed, they can be used as an extension of the coverage area. We have developed a new analytical modeling of the IEEE 802.11e DCF/EDCF. We have investigated the intricate interactions among layers by building a general cross-layered framework to represent multi-hop ad hoc networks with asymmetric topology and trafficDurant cette thèse l’objectif été d’améliorer la manière d'utiliser la précieuse bande passante, qui est gaspillée à cause de la sous-utilisation des réseaux sans fil. Nous étions particulièrement intéressés à toutes les ressources qui peuvent être utilisées de façon opportuniste en utilisant différentes technologies. Nous avons conçu de nouveaux modèles pour une utilisation meilleure et plus efficace des systèmes sans fil. Dans ce sens nous nous sommes focalisés sur les réseaux de communication cognitifs dans la première partie, où un fournisseur de service cellulaire peut louer une partie de ses ressources à des utilisateurs secondaires ou des fournisseurs virtuels. Dans la deuxième partie, nous nous sommes intéressés aux réseaux tolérants au délai comme étant une alternative à l’augmentation importante de la charge de trafic dans le réseau cellulaire. Dans les régions où l'implémentation d'infrastructures réseaux est géographiquement difficile, l'utilisation des réseaux ad-hoc semble une solution adéquate. En effet, nous avons développé dans la dernière partie, une nouvelle modélisation analytique du protocole IEEE 802.11e utilisé dans ce type de réseau

Accès opportuniste au spectre et contrôle optimal dans les réseaux sans fil hétérogènes

Durant cette thèse l objectif été d améliorer la manière d'utiliser la précieuse bande passante, qui est gaspillée à cause de la sous-utilisation des réseaux sans fil. Nous étions particulièrement intéressés à toutes les ressources qui peuvent être utilisées de façon opportuniste en utilisant différentes technologies. Nous avons conçu de nouveaux modèles pour une utilisation meilleure et plus efficace des systèmes sans fil. Dans ce sens nous nous sommes focalisés sur les réseaux de communication cognitifs dans la première partie, où un fournisseur de service cellulaire peut louer une partie de ses ressources à des utilisateurs secondaires ou des fournisseurs virtuels. Dans la deuxième partie, nous nous sommes intéressés aux réseaux tolérants au délai comme étant une alternative à l augmentation importante de la charge de trafic dans le réseau cellulaire. Dans les régions où l'implémentation d'infrastructures réseaux est géographiquement difficile, l'utilisation des réseaux ad-hoc semble une solution adéquate. En effet, nous avons développé dans la dernière partie, une nouvelle modélisation analytique du protocole IEEE 802.11e utilisé dans ce type de réseauxThe present dissertation deals with how to use the precious wireless resources that are usually wasted by under-utilization of networks. We have been particularly interested by all resources that can be used in an opportunistic fashion using different technologies. We have designed new schemes for better and more efficient use of wireless systems by providing mathematical frameworks. In the first part, We have been interested in cognitive radio networks, where a cellular service provider can lease a part of its resources to secondary users or virtual providers. In the second part, we have chosen delay-tolerant networks as a solution to reduce the pressure on the cell traffic, where mobile users come to use available resources effectively and with a cheaper cost. We have focused on optimal strategy for smartphones in hybrid wireless networks. In the last part, an alternative to delay-tolerant networks, specially in regions that are not covered by the cellular network, is to use Ad-hoc networks. Indeed, they can be used as an extension of the coverage area. We have developed a new analytical modeling of the IEEE 802.11e DCF/EDCF. We have investigated the intricate interactions among layers by building a general cross-layered framework to represent multi-hop ad hoc networks with asymmetric topology and trafficAVIGNON-Bib. numérique (840079901) / SudocSudocFranceF

Cost-Effective Energy Usage in a Microgrid Using a Learning Algorithm

The microgrid is a new concept of integrating the distributed energy resources (DER) within the grid. The management of the heterogeneous sources of energy presents a challenge, especially as most of the DER are unpredictable. Besides, implementing microgrids should be economically beneficial to the customer; this will raise the challenge of decreasing the costs while ensuring the energy balance. In this paper, we used a stochastic approach based on a model-free Markov decision process (MDP) to derive the optimal strategy for the home energy management system. The approach aims to decrease the energy bill while taking into account the intermittency of the renewable energy resources (DER) and other constraints. While other proposals charge the battery from the utility energy, making the state of charge (SOC) of the battery a deterministic variable, our work adopts a scenario where the battery is charged from the excess of the generated energy, which makes the SOC a nondeterministic variable affected by the uncertain character of the renewable energy. Therefore, our model considers the randomness at two levels: renewable energy level and battery SOC level. We take into account the complexity of the solution, and we propose a simple strategy that can be implemented easily in microgrids

NOMA Clustering for Improved Multicast IoT Schemes

In the context of future ultra-dense mobile networks, spectrum and energy efficiencies (SE and EE) are critical measures in designing efficient systems for the sixth-generation (6G) of wireless networks. Recognized for their benefits in increasing SE and EE, non-orthogonal multiple access (NOMA) and device-to-device (D2D) communications are combined in this work to present a new NOMA-based D2D scheme increasing the performance in terms of SE and EE. The users in the proposed scheme are split into coalitions. Coalition heads are served in NOMA directly from the base stations, while the other users within the coalitions get the service through D2D links. We investigate the system’s SE and EE for different mobility patterns, and we discuss optimal system configurations with the help of Monte Carlo simulations. The obtained results show that the proposed system exhibits a better performance compared to conventional OMA and NOMA models, especially in low mobility contexts

A Unified NET-MAC-PHY Cross-layer Framework for Performance Evaluation of Multi-hop Ad hoc WLANs

Most of the existing works have been evaluated the performance of 802.11 multihop networks by considering the MAC layer or network layer separately. Knowing the nature of the multi-hop ad hoc networks, many factors in different layers are crucial for study the performance of MANET. In this paper we present a new analytic model for evaluating average end-to-end throughput in IEEE 802.11e multihop wireless networks. In particular, we investigate an intricate interaction among PHY, MAC and Network layers. For instance, we incorporate carrier sense threshold, transmission power, contention window size, retransmissions retry limit, multi rates, routing protocols and network topology together. We build a general cross-layered framework to represent multi-hop ad hoc networks with asymmetric topology and asymmetric traffic. We develop an analytical model to predict throughput of each connection as well as stability of forwarding queues at intermediate nodes in saturated networks. To the best of our knowledge, it seems that our work is the first wherein general topology and asymmetric parameters setup are considered in PHY/MAC/Network layers. Performance of such a system is also evaluated through simulation. We show that performance measures of the MAC layer are affected by the traffic intensity of flows to be forwarded. More precisely, attempt rate and collision probability are dependent on traffic flows, topology and routing