Performance study of end-to-end traffic-aware routing

There has been a lot research effort on developing reactive routing algorithms for mobile ad hoc networks (MANETs) over the past few years. Most of these algorithms consider finding the shortest path from source to destination in building a route. However, this can lead to some network nodes being more overloaded than the others. In MANETs resources, such as node power and channel bandwidth are often at a premium and, therefore, it is important to optimise their use as much as possible. Consequently, a traffic-aware technique to distribute the load is very desirable in order to make good utilisation of nodes' resources. A number of traffic aware techniques have recently been proposed and can be classified into two categories: end-to-end and on-the-spot. The performance merits of the existing end-to-end traffic aware techniques have been analysed and compared against traditional routing algorithms. There has also been a performance comparison among the existing on-the-spot techniques. However, there has so far been no similar study that evaluates and compares the relative performance merits of end-to-end techniques. In this paper, we describe an extensive performance evaluation of two end-to-end techniques, based on degree of nodal activity and traffic density, using measures based on throughput, end-to-end delay and routing overhead

Performance evaluation of a new end-to-end traffic-aware routing in MANETs

There has been a lot of research effort on developing reactive routing algorithms for mobile ad hoc networks (MANETs) over the past few years. Most of these algorithms consider finding the shortest path from source to destination in building a route. However, this can lead to some network nodes being more overloaded than the others. In MANETs resources, such as node power and channel bandwidth are often at a premium and, therefore, it is important to optimise their use as much as possible. Consequently, a traffic-aware technique to distribute the load is very desirable in order to make good utilisation of nodes' resources. Therefore a number of end-to-end traffic aware techniques have been proposed for reactive routing protocols to deal with this challenging issue. In this paper we contribute to this research effort by proposing a new traffic aware technique that can overcome the limitations of the existing methods. Results from an extensive comparative evaluation show that the new technique has superior performance over similar existing end-to-end techniques in terms of the achieved throughput, end-to-end delay and routing overhead

Study of Load Balanced Routing Protocols in Mobile Ad hoc Networks

Mobile ad hoc network is a collection of wireless mobile nodes, such devices as PDAs, mobile phones, laptops etc. that are connected over a wireless medium. There is no pre-existing communication infrastructure (no access points, no base stations) and the nodes can freely move and self-organize into a network topology. Such a network can contain two or more nodes. Hence, balancing the load in a MANET is important because The nodes in MANET have limited communication resources such as bandwidth, buffer space, battery power. This paper discusses various load metric and various load balancing routing protocols for efficient data transmission in MANETs. Keywords: Load Balancing, Mobile Ad hoc Networks, Routing

A Survey on Investigating the Need for Intelligent Power-Aware Load Balanced Routing Protocols for Handling Critical Links in MANETs

In mobile ad hoc networks connectivity is always an issue of concern. Due to dynamism in the behavior of mobile nodes, efficiency shall be achieved only with the assumption of good network infrastructure. Presence of critical links results in deterioration which should be detected in advance to retain the prevailing communication setup. This paper discusses a short survey on the specialized algorithms and protocols related to energy efficient load balancing for critical link detection in the recent literature. This paper also suggests a machine learning based hybrid power-aware approach for handling critical nodes via load balancing

Routage adaptatif et stabilité dans les réseaux maillés sans fil

Grâce à leur flexibilité et à leur facilité d’installation, les réseaux maillés sans fil (WMNs) permettent un déploiement d’une infrastructure à faible coût. Ces réseaux étendent la couverture des réseaux filaires permettant, ainsi, une connexion n’importe quand et n’importe où. Toutefois, leur performance est dégradée par les interférences et la congestion. Ces derniers causent des pertes de paquets et une augmentation du délai de transmission d’une façon drastique. Dans cette thèse, nous nous intéressons au routage adaptatif et à la stabilité dans ce type de réseaux. Dans une première partie de la thèse, nous nous intéressons à la conception d’une métrique de routage et à la sélection des passerelles permettant d’améliorer la performance des WMNs. Dans ce contexte nous proposons un protocole de routage à la source basé sur une nouvelle métrique. Cette métrique permet non seulement de capturer certaines caractéristiques des liens tels que les interférences inter-flux et intra-flux, le taux de perte des paquets mais également la surcharge des passerelles. Les résultats numériques montrent que la performance de cette métrique est meilleure que celle des solutions proposées dans la littérature. Dans une deuxième partie de la thèse, nous nous intéressons à certaines zones critiques dans les WMNs. Ces zones se trouvent autour des passerelles qui connaissent une concentration plus élevé du trafic ; elles risquent de provoquer des interférences et des congestions. À cet égard, nous proposons un protocole de routage proactif et adaptatif basé sur l’apprentissage par renforcement et qui pénalise les liens de mauvaise qualité lorsqu’on s’approche des passerelles. Un chemin dont la qualité des liens autour d’une passerelle est meilleure sera plus favorisé que les autres chemins de moindre qualité. Nous utilisons l’algorithme de Q-learning pour mettre à jour dynamiquement les coûts des chemins, sélectionner les prochains nœuds pour faire suivre les paquets vers les passerelles choisies et explorer d’autres nœuds voisins. Les résultats numériques montrent que notre protocole distribué, présente de meilleurs résultats comparativement aux protocoles présentés dans la littérature. Dans une troisième partie de cette thèse, nous nous intéressons aux problèmes d’instabilité des réseaux maillés sans fil. En effet, l’instabilité se produit à cause des changements fréquents des routes qui sont causés par les variations instantanées des qualités des liens dues à la présence des interférences et de la congestion. Ainsi, après une analyse de l’instabilité, nous proposons d’utiliser le nombre de variations des chemins dans une table de routage comme indicateur de perturbation des réseaux et nous utilisons la fonction d’entropie, connue dans les mesures de l’incertitude et du désordre des systèmes, pour sélectionner les routes stables. Les résultats numériques montrent de meilleures performances de notre protocole en comparaison avec d’autres protocoles dans la littérature en termes de débit, délai, taux de perte des paquets et l’indice de Gini.Thanks to their flexibility and their simplicity of installation, Wireless Mesh Networks (WMNs) allow a low cost deployment of network infrastructure. They can be used to extend wired networks coverage allowing connectivity anytime and anywhere. However, WMNs may suffer from drastic performance degradation (e.g., increased packet loss ratio and delay) because of interferences and congestion. In this thesis, we are interested in adaptive routing and stability in WMNs. In the first part of the thesis, we focus on defining new routing metric and gateway selection scheme to improve WMNs performance. In this context, we propose a source routing protocol based on a new metric which takes into account packet losses, intra-flow interferences, inter-flow interferences and load at gateways together to select best paths to best gateways. Simulation results show that the proposed metric improves the network performance and outperforms existing metrics in the literature. In the second part of the thesis, we focus on critical zones, in WMNs, that consist of mesh routers which are located in neighborhoods of gateways where traffic concentration may occur. This traffic concentration may increase congestion and interferences excessively on wireless channels around the gateways. Thus, we propose a proactive and adaptive routing protocol based on reinforcement learning which increasingly penalizes links with bad quality as we get closer to gateways. We use Q-learning algorithm to dynamically update path costs and to select the next hop each time a packet is forwarded toward a given gateway; learning agents in each mesh router learn the best link to forward an incoming packet and explore new alternatives in the future. Simulation results show that our distributed routing protocol is less sensitive to interferences and outperforms existing protocols in the literature. In the third part of this thesis, we focus on the problems of instability in WMNs. Instability occurs when routes flapping are frequent. Routes flapping are caused by the variations of link quality due to interferences and congestion. Thus, after analyzing factors that may cause network instability, we propose to use the number of path variations in routing tables as an indicator of network instability. Also, we use entropy function, usually used to measure uncertainty and disorder in systems, to define node stability, and thus, select the most stable routes in the WMNs. Simulation results show that our stability-based routing protocol outperforms existing routing protocols in the literature in terms of throughput, delay, loss rate, and Gini index

On the performance of traffic-aware reactive routing in MANETs

Research on mobile ad hoc networks (MANETs) has intensified over recent years, motivated by advances in wireless technology and also by the range of potential applications that might be realised with such infrastructure-less networks. Much work has been devoted to developing reactive routing algorithms for MANETs which generally try to find the shortest path from source to destination. However, this approach can lead to some nodes being loaded much more than others in the network. As resources, such as node power and channel bandwidth, are often at a premium in MANETs, it is important to optimise their usage as far as possible. Incorporating traffic aware techniques into routing protocols in order to distribute load among the network nodes would helps to ensure fair utilisation of nodes' resources, and prevent the creation of congested regions in the network. A number of such traffic aware techniques have been proposed. These can be classified into two main categories, namely end-to-end and on-the-spot, based on the method of establishing and maintaining routes between source and destination. In the first category, end-to-end information is collected along the path with intermediate nodes participating in building routes by adding information about their current load status. However the decision as to which path to select is taken at one of the endpoints. In the second category, the collected information does not have to be passed to an endpoint to make a path selection decision as intermediate nodes can do this job. Consequently, the decision of selecting a path is made locally, generally by intermediate nodes. Existing end-to-end traffic aware techniques use some estimation of the traffic load. For instance, in the traffic density technique, this estimation is based on the status of the MAC layer interface queue, whereas in the degree of nodal activity technique it is based on the number of active flows transiting a node. To date, there has been no performance study that evaluates and compares the relative performance merits of these approaches and, in the first part of this research, we conduct such a comparative study of the traffic density and nodal activity approaches under a variety of network configurations and traffic conditions. The results reveal that each technique has performance advantages under some working environments. However, when the background traffic increases significand, the degree of nodal activity technique demonstrates clear superiority over traffic density. In the second part of this research, we develop and evaluate a new traffic aware technique, referred to here as load density, that can overcome the limitations of the existing techniques. In order to make a good estimation of the load, it may not be sufficient to capture only the number of active paths as in the degree of nodal activity technique or estimate the number of packets at the interface queue over a short period of time as in the traffic density technique. This is due to the lack of accuracy in measuring the real traffic load experienced by the nodes in the network, since these estimations represent only the current traffic, and as a result it might not be sufficient to represent the load experienced by the node over time which has consumed part of its battery and thus reduced its operational lifetime. The new technique attempts to obtain a more accurate picture of traffic by using a combination of the packet length history at the node and the averaged number of packets waiting at node's interface queue. The rationale behind using packets sizes rather than just the number of packets is that it provides a more precise estimation of the volume of traffic forwarded by a given node. Our performance evaluation shows that the new technique makes better decisions than existing ones in route selection as it preferentially selects less frequently used nodes, which indeed improves throughput and end-to-end delay, and distributes load more, while maintaining a low routing overhead. In the final part of this thesis, we conduct a comparative performance study between the end-to-end and on-the-spot approaches to traffic aware routing. To this end, our new load density technique has been adapted to suggest a new "on-the-spot" traffic aware technique. The adaptation is intended to ensure that the comparison between the two approaches is fair and realistic. Our study shows that in most realistic traffic and network scenarios, the end-to-end performs better than the local approach. The analysis also reveals that relying on local decisions might not be always good especially if all the potential paths to a destination pass through nodes with an overload condition in which case an optimal selection of a path may not be feasible. In contrast, there is most often a chance in the end-to-end approach to select the path with lower load