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Multihop routing is an effective method for establishing connectivity between the nodes of a network. End-to-end outage probability and total power consumption are applied as the optimization criteria for routing protocol design in multihop networks based on the local channel state information measurement at the nodes of a network. The analysis shows that employing instantaneous channel state information in routing design results in significant performance improvement of multihop communication, e.g., achieving full diversity order when the optimization criterion is outage performance. The routing metrics derived from the optimization problems cannot be optimized in a distributed manner. Establishing an alternate framework, the metrics obtained are converted into new composite metrics, which satisfy the optimality and convergence requirements for implementation in distributed environments. The analysis shows that the running time of the proposed distributed algorithm is bounded by a polynomial. / Communications

Ce travail de thèse présente trois contributions qui portent sur le routage et la fourniture de qualité de service dans les réseaux maillés sans fil basés sur IEEE 802.11. La première contribution définit une métrique de routage qui permet de sélectionner les chemins empruntant des liens avec de bonnes performances exprimées en termes d’interférences physiques (qui causent des pertes), d’interférences logiques (qui causent des délais) et de capacité. L’évaluation de cette métrique par rapport aux principales métriques de la littérature scientifique montre une amélioration des performances du réseau. La deuxième contribution concerne l’amélioration du mécanisme de maintenance de route le plus souvent utilisé par les protocoles de routage réactifs. Ce mécanisme considère qu'une route est coupée si l'un de ses liens observe plusieurs échecs successifs de retransmission. Nos études montrent que ces échecs sont assez souvent dûs à de problèmes transitoires sur les liens (bruit, interférence etc.). Nous avons donc proposé des algorithmes de maintenance de route qui appréhendent mieux les problèmes ponctuels ou soutenus sur les liens ce qui permet de prendre une décision cohérente et réfléchie quant à la coupure d’un lien (et donc d'une route). Les études de performances montrent une amélioration conséquente des performances globales du réseau. La dernière contribution propose un cadre pour la fourniture de la Qualité de Service (garantie de bande passante) dans les réseaux maillés multi-interfaces, multi-canaux. Ce cadre intègre un protocole de routage réactif couplé à un mécanisme de contrôle d'admission et de partage de charge. Ces derniers exploitent la diversité des liens entre nœuds voisins afin d’améliorer le taux d’admission des flux avec garantie de bande passante / This thesis presents three contributions in the area of routing and Quality of Service for IEEE 802.11-based Wireless Mesh Networks. The first contribution defines a routing metric for the selection of route by taking into consideration the performance of wireless links in terms of physical interference (which causes packet losses), logical interference (which causes delay) and the capacity of the links. The performance evaluation of the proposed metric compared to the popular existing metrics shows an improvement in the performance of the network. The second contribution improves the route maintenance mechanism most often used by reactive routing protocols. The existing mechanism considers a route as broken if any of the links in the route experiences multiple successive transmission failures. Our study shows that the transmission failures are often caused by transient problems on the wireless link (noise, interference etc). We propose a novel mechanism of route maintenance which distinguishes between links with temporary or transient transmission problems compared to those with sustained problems in order to make a coherent decision about link breakage (and consequently route breakage). The performance evaluation shows a substantial improvement in the performance of the network. The final contribution proposes a framework for providing Quality of Service (bandwidth guarantee) in multi-radio multi-channel wireless mesh networks. The framework integrates a reactive routing protocol coupled with an admission control mechanism and load balancing. The framework exploits link diversity between neighboring nodes to improve the flow admission ratio with bandwidth guarantees

Submitted by Erika Demachki (erikademachki@gmail.com) on 2015-02-05T19:42:01Z No. of bitstreams: 2 Dissertação - Diógenes Antonio Marques José - 2014.pdf: 9980108 bytes, checksum: eea0a39505448f7845d92bdbb4716ff2 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Approved for entry into archive by Erika Demachki (erikademachki@gmail.com) on 2015-02-05T19:42:44Z (GMT) No. of bitstreams: 2 Dissertação - Diógenes Antonio Marques José - 2014.pdf: 9980108 bytes, checksum: eea0a39505448f7845d92bdbb4716ff2 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Made available in DSpace on 2015-02-05T19:42:45Z (GMT). No. of bitstreams: 2 Dissertação - Diógenes Antonio Marques José - 2014.pdf: 9980108 bytes, checksum: eea0a39505448f7845d92bdbb4716ff2 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Previous issue date: 2014-06-05 / This work contributes with an extension to the Optimized Link State Routing protocol (OLSR) called Fuzzy Cost OLSR (OLSR-FC). In order to prevent selfish nodes as well as to improve the traffic flow over Mobile Ad-hoc Networks (MANETs), the routing metrics implemented in OLSR-FC make use of a Fuzzy Inference System (FIS) composed of 8 inference rules. Aiming at the choose of paths with low packet loss, better energy capacity and high connectivity, OLSR-FC implements a procedure of election of routes that takes into account the following parameters: Packet Loss Index (PLI), Residual Energy (RE) and Connectivity Index (CI). The OLSR-FC was evaluated by simulation through the NS- 2, in which two scenarios were implemented: a static one with 10 nodes (in testing phase), and a mobile one with up to 50 nodes. In the former scenario, a comparison was made between OLSR-FC and the original OLSR protocol which results showed that OLSR-FC overcomes OLSR in terms of throughput the packet loss. In the latter scenario, besides the original OLSR protocol, OLSR-FC was also faced up with the OLSR-ETX, OLSR-ML and OLSR-MD extensions in terms of the following performance metrics: throughput, energy consumption, packet loss rate, overhead, delay end-to-end, jitter, and packet delivery rate. In this context, results pointed that OLSR-FC achieved better performance in scenarios with a maximum of 10% of selfish nodes in comparison with every OSLR extension and the OLSR. Besides, by evaluating the main network performance metrics, such as throughput and delivery packet rate, OLSR-FC achieved eleven favorable cases against five cases in comparison with OLSR protocol. / O presente trabalho propõe uma extensão ao protocolo Optimized Link State Routing (OLSR) denominada OLSR Fuzzy Cost (OLSR-FC). A métrica de roteamento utilizada pelo OLSR-FC faz uso de um Sistema de Inferência Fuzzy (SIF), composto por 8 regras de inferência, que tem como objetivos evitar nós egoístas e melhorar o fluxo do tráfego nas redes móveis ad-hoc (MANETs). O critério de escolha de rotas leva em consideração os seguintes parâmetros: Índice de Perda de Pacotes (IPP), Energia Residual (ER) e Índice de Conectividade (IC), o propósito disso, consiste em escolher caminhos que possuam baixa perda de pacotes, melhor capacidade energética e alta conectividade. A proposta foi avaliada por simulação utilizando o simulador de redes NS-2. Foram considerados na avaliação dois cenários, um estático com 10 nós (utilizado na fase de testes) e um móvel com até 50 nós. No cenário estático o OLSR-FC foi comparado ao OLSR e os resultados mostraram que a proposta obtém vantagens com relação às métricas de desempenho vazão e perda de pacotes. No cenário móvel o OLSR-FC, além do OLSR, foi comparado às extensões OLSR-ETX, OLSR-ML e OLSR-MD, com relação as seguintes métricas de desempenho: vazão, consumo de energia, perda de pacotes, overhead, atraso fim-a-fim, jitter e taxa de entrega de pacotes. Nesse contexto, os resultados obtidos mostram que em ambientes com até 10% de nós egoístas o OLSR-FC obtém melhor desempenho que as extensões testadas e com relação ao OLSR, na mesma situação, avaliando as principais métricas de desempenho de redes, como vazão e taxa de entrega de pacotes, o OLSR-FC obteve onze casos favoráveis contra apenas cinco casos do OLSR.

Les incitations économiques et environnementales poussent dorénavant à intégrer des considérations énergétiques dès les premiers stades de développement des réseaux. Dans les réseaux sans fil multi-sauts, l'approche la plus courante consiste à répartir le trafic sur l'ensemble des nœuds afin de réduire équitablement la consommation énergétique de chacun, avec pour objectif la maximisation de la durée de vie du réseau. Or cette approche n'est pas optimale vis-à-vis de la consommation globale du réseau, le niveau d'activité d'un nœud n'ayant souvent que peu d'influence sur sa propre consommation. Nous montrons que la meilleure approche consiste à éteindre un maximum de nœuds. Parmi les travaux réalisés, nous avons développé une solution s'appuyant sur de la programmation linéaire en nombres entiers et des simulations de graphes et de réseaux. La solution proposée permet ainsi une agrégation de flux optimale, réduisant significativement le nombre de nœuds utilisés dans le réseau. Afin de la rendre applicable en pratique, une heuristique est détaillée permettant une mise en œuvre distribuée grâce à l'utilisation d'une métrique de routage. Ainsi, tout algorithme de plus court chemin peut nativement réaliser de l'agrégation de flux efficace. Il est important de souligner que la qualité de service en termes de débit est respectée. En effet, les interférences sont prises en compte et il est possible de profiter de la synergie offerte par l'utilisation conjointe de l'agrégation de flux et du codage réseau. Nos résultats améliorent significativement les méthodes d'économie d'énergie basées sur l'extinction des nœuds en leur permettant d'en éteindre davantage. / Economic and ecologic incentives are now leading people to design networks with energetic considerations at early stages of development. Most of the works for multi-hop wireless networks tend to spread the traffic uniformly over the network to reduce the energy consumption of each node individually. However, considering that the traffic of a node doesn't impact significantly its energy consumption, this approach is not optimal regarding the global energy consumption of the network. Finding a way to turnoff as much node as possible seems then to be a better way. This PhD thesis focus on routing a set of flows over a multi-hop wireless network while minimizing the number of used nodes. This is done by using a distributed metric that allows the shortest path routing algorithms to perform flow aggregation. Using integer linear programming and simulations, we proposed an efficient solution to aggregate flows to significantly reduce the number of nodes used in the network. It allows, then, to improve algorithms that reduce the energy consumption of networks by increasing the number of nodes that can be turned off.