QoS-VNS-CS: QoS constraints Core Selection Algorithm based on Variable Neighborhood Search Algorithm

Within the development of network multimedia technology, more and more real-time multimedia applications arrive with the need to transmit information using multicast communication. Multicast IP routing is an important topic, covering both theoretical and practical interest in different networks layers. In network layer, there are several multicast routing protocols using multicast routing trees different in the literature. However PIM-SM and CBT protocols remains the most used multicast routing protocols; they propose using a shared Core-based Tree CBT. This kind of tree provides efficient management of multicast path in changing group memberships, scalability and performance. The prime problem concerning construction of a shared tree is to determine the best position of the core. QoS-CS’s problem (QoS constraints core Selection) consists in choosing an optimal multicast router in the network as core of the Shared multicast Tree (CBT) within specified QoS constraints associated. The choice of this specific router, called RP in PIM-SM protocol and core in CBT protocol, affects the structure of multicast routing tree, and therefore influences performances of both multicast session and routing scheme. QoS-CS is an NP complete problem need to be solved through a heuristic algorithm, in this paper, we propose a new core Selection algorithm based on Variable Neighborhood Search algorithm and new CMP fitness function. Simulation results show that good performance is achieved in multicast cost, end-to-end delay, tree construction delay and others metrics

A hybrid ACO/PSO based algorithm for QoS multicast routing problem

AbstractMany Internet multicast applications such as videoconferencing, distance education, and online simulation require to send information from a source to some selected destinations. These applications have stringent Quality-of-Service (QoS) requirements that include delay, loss rate, bandwidth, and delay jitter. This leads to the problem of routing multicast traffic satisfying QoS requirements. The above mentioned problem is known as the QoS constrained multicast routing problem and is NP Complete. In this paper, we present a swarming agent based intelligent algorithm using a hybrid Ant Colony Optimization (ACO)/Particle Swarm Optimization (PSO) technique to optimize the multicast tree. The algorithm starts with generating a large amount of mobile agents in the search space. The ACO algorithm guides the agents’ movement by pheromones in the shared environment locally, and the global maximum of the attribute values are obtained through the random interaction between the agents using PSO algorithm. The performance of the proposed algorithm is evaluated through simulation. The simulation results reveal that our algorithm performs better than the existing algorithms

On Near Optimal Time and Dynamic Delay and Delay Variation Multicast Algorithms

Multicast is one of the most prevalent communication modes in computer networks. A plethora of systems and applications today rely on multicast communication to disseminate traffic including but not limited to teleconferencing, videoconferencing, stock exchanges, supercomputers, software update distribution, distributed database systems, and gaming. This dissertation elaborates and addresses key research challenges and problems related to the design and implementation of multicast algorithms. In particular, it investigates the problems of (1) Designing near optimal multicast time algorithms for mesh and torus connected systems and (2) Designing efficient algorithms for Delay and Delay Variation Bounded Multicast (DVBM). To achieve the first goal, improvements on four tree based multicast algorithms are made: Modified PAIR (MPAIR), Modified DIAG (MDIAG), Modified MIN (MMIN), and Modified DIST (MDIST). The proof that MDIAG generates optimal or optimal plus one multicast time in 2-Dimensional (2D) mesh networks is provided. The hybrid version of MDIAG (HMDIAG) is designed, that gives a 3-additive approximation algorithm on multicast time in 2D torus networks. To make HMDIAG applicable on systems using higher dimensional meshes and tori, it is extended and the proof that it gives a (2n-1)-additive approximation algorithm on multicast time in nD torus networks is given. To address the second goal, Directional Core Selection (DCS) algorithm for core selection and DVBM Tree generation is designed. To further reduce the delay variation of trees generated by DCS, a k-shortest-path based algorithm, Build Lower Variation Tree (BLVT) is designed. To tackle dynamic join/leave requests to the ongoing multicast session, the dynamic version of both algorithms is given that responds to requests by reorganizing the tree and avoiding session disruption. To solve cases where single-core based algorithms fail to construct a DVBM tree, a dynamic three-phase algorithm, Multi-core DVBM Trees (MCDVBMT) is designed, that semi-matches group members to core nodes

Diseño y análisis comparativo del algoritmo hibrido ant colony-evolutivo con respecto al algoritmo ant colony en la solución de un problema de optimización multiobjetivo en redes opticas

En la presente investigación se plantea y soluciona un Modelo de Optimización Multiobjetivo (MOP) para la transmisión multicast en redes ópticas, propuesto por el Ing. Yesid Donoso Meisel Ph. D., en el modelo se consideraron 11 funciones objetivos a minimizar, las cuales involucran las siguientes variables de decisión: atenuación máxima en el enlace de la fibra óptica, retardo total, el retardo máximo, el retardo promedio, máxima variación del retardo, el número de longitudes de onda utilizadas, número de saltos total, el retardo promedio, el retardo máximo, máxima variación del retardo y ancho de banda, El modelo fue resuelto aplicando la metaheurística Ant Colony (Colonias de Hormigas) y un nuevo algoritmo de concepción hibrida en el cual se le aplica al algoritmo Ant Colony, asignación de fitness, selección ambiental y cruzamiento propios de los algoritmos evolutivos, estos procedimientos se obtuvieron del algoritmo evolutivo Strength Pareto Evolutionary Algorithm 2 (SPEA2). De acuerdo a los resultados obtenidos al aplicar los dos algoritmos en las topologías de redes NSF, MCI y Sprint, las métricas Generación de Vectores No Dominados (GVND), Distancia Generacional (DG) y Spacing, el algoritmo Ant Colony Evolutivo tuvo un mejor desempeño que el algoritmo Ant Colony al producir soluciones en promedio menores que el algoritmo Ant Colony. En lo que respecta al tiempo de ejecución se encontró que para el problema el algoritmo Ant Colony arrojó mejores promedios.MaestríaMagister en Ingeniería Industria

Reliable Multicast transport of the video over the WiFi network

Le transport multicast est une solution efficace pour envoyer le même contenu à plusieurs récepteurs en même temps. Ce mode est principalement utilisé pour fournir des flux multimédia en temps réel. Cependant, le multicast classique de l IEEE 802.11 n'utilise aucun mécanisme d acquittement. Ainsi, l échec de réception implique la perte définitive du paquet. Cela limite la fiabilité du transport multicast et impact la qualité des applications vidéo. Pour résoudre ce problème, 802.11v et 802.11aa sont définis récemment. Le premier amendement propose Direct Multicast Service (DMS). D'autre part, le 802.11aa introduit GroupCast with Retries (GCR). GCR définit deux nouvelles politiques de retransmission : Block Ack (BACK) et Unsolicited Retry (UR).Dans cette thèse, nous évaluons et comparons les performances de 802.11v/aa. Nos résultats montrent que tous les nouveaux protocoles multicast génèrent un overhead de transmission important. En outre, DMS a une scalabilité très limitée, et GCR-BACK n'est pas approprié pour des grands groupes multicast. D autre part, nous montrons que DMS et GCR-BACK génèrent des latences de transmission importantes lorsque le nombre de récepteurs augmente. Par ailleurs, nous étudions les facteurs de pertes dans les réseaux sans fil. Nous montrons que l'indisponibilité du récepteur peut être la cause principale des pertes importantes et de leur nature en rafales. En particulier, nos résultats montrent que la surcharge du processeur peut provoquer un taux de perte de 100%, et que le pourcentage de livraison peut être limité à 35% lorsque la carte 802.11 est en mode d économie d'énergie.Pour éviter les collisions et améliorer la fiabilité du transport multicast, nous définissons le mécanisme Busy Symbol (BS). Nos résultats montrent que BS évite les collisions et assure un taux de succès de transmission très important. Afin d'améliorer davantage la fiabilité du trafic multicast, nous définissons un nouveau protocole multicast, appelé Block Negative Acknowledgement (BNAK). Ce protocole opère comme suit. L AP envoi un bloc de paquets suivi par un Block NAK Request (BNR). Le BNR permet aux membres de détecter les données manquantes et d envoyer une demande de retransmission, c.à.d. un Block NAK Response (BNAK). Un BNAK est transmis en utilisant la procédure classique d accès au canal afin d'éviter toute collision avec d'autres paquets. En plus, cette demande est acquittée. Sous l'hypothèse que 1) le récepteur est situé dans la zone de couverture du débit de transmission utilisé, 2) les collisions sont évitées et 3) le terminal a la bonne configuration, très peu de demandes de retransmission sont envoyées, et la bande passante est préservée. Nos résultats montrent que BNAK a une très grande scalabilité et génère des délais très limités. En outre, nous définissons un algorithme d'adaptation de débit pour BNAK. Nous montrons que le bon débit de transmission est sélectionné moyennant un overhead très réduit de moins de 1%. En plus, la conception de notre protocole supporte la diffusion scalable de lavvidéo. Cette caractéristique vise à résoudre la problématique de la fluctuation de la bande passante, et à prendre en considération l'hétérogénéité des récepteurs dans un réseau sans fil.The multicast transport is an efficient solution to deliver the same content to many receivers at the same time. This mode is mainly used to deliver real-time video streams. However, the conventional multicast transmissions of IEEE 802.11 do not use any feedback policy. Therefore missing packets are definitely lost. This limits the reliability of the multicast transport and impacts the quality of the video applications. To resolve this issue, the IEEE 802.11v/aa amendments have been defined recently. The former proposes the Direct Multicast Service (DMS). On the other hand, 802.11aa introduces Groupcast with Retries (GCR) service. GCR defines two retry policies: Block Ack (BACK) and Unsolicited Retry (UR).In this thesis we evaluate and compare the performance of 802.11v/aa. Our simulation results show that all the defined policies incur an important overhead. Besides, DMS has a very limited scalability, and GCR-BACK is not appropriate for large multicast groups. We show that both DMS and GCR-BACK incur important transmission latencies when the number of the multicast receivers increases. Furthermore, we investigate the loss factors in wireless networks. We show that the device unavailability may be the principal cause of the important packet losses and their bursty nature. Particularly, our results show that the CPU overload may incur a loss rate of 100%, and that the delivery ratio may be limited to 35% when the device is in the power save mode.To avoid the collisions and to enhance the reliability of the multicast transmissions, we define the Busy Symbol (BS) mechanism. Our results show that BS prevents all the collisions and ensures a very high delivery ratio for the multicast packets. To further enhance the reliability of this traffic, we define the Block Negative Acknowledgement (BNAK) retry policy. Using our protocol, the AP transmits a block of multicast packets followed by a Block NAK Request (BNR). Upon reception of a BNR, a multicast member generates a Block NAK Response (BNAK) only if it missed some packets. A BNAK is transmitted after channel contention in order to avoid any eventual collision with other feedbacks, and is acknowledged. Under the assumption that 1) the receiver is located within the coverage area of the used data rate, 2) the collisions are avoided and 3) the terminal has the required configuration, few feedbacks are generated and the bandwidth is saved. Our results show that BNAK has a very high scalability and incurs very low delays. Furthermore, we define a rate adaptation scheme for BNAK. We show that the appropriate rate is selected on the expense of a very limited overhead of less than 1%. Besides, the conception of our protocol is defined to support the scalable video streaming. This capability intends to resolve the bandwidth fluctuation issue and to consider the device heterogeneity of the group members.BORDEAUX1-Bib.electronique (335229901) / SudocSudocFranceF

Support des applications multimédia dans les réseaux de prochaine génération

RÉSUMÉ Les applications multimédia sont devenues tellement populaires que certaines d’entre elles sont utilisées quotidiennement par les usagers. Cette popularité peut être attribuée à plusieurs facteurs, tels que la diversification du contenu et des services offerts, l’accès en tout temps grâce à la mobilité et à la nomadicité, ainsi qu’aux avancées au niveau des architectures et des protocoles utilisés, afin de supporter les requis plus exigeants de ces applications. Par exemple, ce qui était jadis un simple appel téléphonique, se transforme désormais en une vidéoconférence, permettant à un nombre dynamique d’usagers d’y participer. Un autre exemple d’application multimédia, qui connait également un essor fulgurant, est IP TeleVision (IPTV), soit la technologie permettant la transmission de la télévision, en direct et sur demande, sur des réseaux IP. On retrouve également sa version mobile, soit Mobile IP TeleVision (MobileTV). Du côté des opérateurs, le focus est mis sur le déploiement des réseaux de prochaine génération. Les opérateurs sans-fil se tournent vers les technologies cellulaires de quatrième génération, telles que 3GPP Long Term Evolution (LTE), alors que ceux qui offrent les services filaires regardent plutôt vers les réseaux basés sur la fibre optique, tels que Fiber to the Home (FTTH). Ces réseaux promettent d’augmenter le débit offert, ainsi que de réduire la latence, soit deux critères importants pour le déploiement des applications multimédia à grande échelle. Malgré ces avancées technologiques, il existe encore plusieurs obstacles au bon fonctionnement des applications multimédia. Dans cette optique, cette thèse se penche sur trois problématiques importantes dans les réseaux de prochaine génération, chacune faisant l’objet d’un article scientifique. Les deux premiers volets s’attardent sur la convergence des réseaux fixes et mobiles, ou Fixed-Mobile Convergence (FMC). Cette convergence vient brouiller la distinction entre les réseaux mobiles et les réseaux fixes. Entre autre, elle permet à un usager d’avoir accès à ses services, autant sur le réseau cellulaire (LTE, par exemple) que sur un réseau local (Wireless Fidelity (WiFi), par exemple). Pour s’y faire, l’usager est généralement muni d’un terminal pouvant se connecter sur les deux réseaux. La première problématique soulevée dans cette thèse est au niveau de la prise de décision de la relève. En effet, les deux protocoles de mobilité les plus populaires, soit Mobile IP (MIP) et Proxy Mobile IP (PMIP), adoptent deux approches diamétralement opposées. Avec le premier protocole, ce sont l’usager et son terminal qui prennent entièrement en charge la relève. Même si cette approche permet la FMC, les opérateurs préfèrent plutôt garder le contrôle sur la prise de décision, afin de pouvoir optimiser leur réseau. En effet, avec MIP, beaucoup de messages de signalisation sont envoyés, ce qui gaspille des ressources réseaux, surtout au niveau de l’accès radio, la partie la plus précieuse du réseau. De plus, en ne sollicitant pas le réseau, le terminal ne prend pas nécessairement les meilleures décisions. Il peut donc basculer vers un réseau qui est plus chargé et qui ne garantit pas nécessairement ses exigences au niveau de la qualité de service. De ce fait, le protocole PMIP a été proposé. Son approche est exactement à l’opposé de celle de MIP, soit la mobilité qui est entièrement gérée par le réseau. De ce fait, la mobilité est masquée au niveau du terminal, qui pense toujours se trouver dans son réseau mère. Grâce à l’ajout de nouveaux nœuds dans le réseau, qui gèrent la mobilité à la place du terminal, on élimine la signalisation sur l’accès radio. De plus, les informations supplémentaires que le réseau détient lui permettront de prendre une meilleure décision. Par contre, le problème avec ce protocole est que, sans l’intervention du terminal, il lui est impossible de détecter toutes les situations de relèves. Dans plusieurs cas, le réseau fixe de l’opérateur est masqué par un réseau interne, par exemple un réseau WiFi, et la détection de ce réseau n’est possible que grâce à l’intervention du terminal. Ainsi, PMIP n’est pas un protocole qui se prête bien au déploiement de FMC. Le premier article, qui s’intitule « Client-Based Network-Assisted Mobile IPv6 », s’attaque donc à ce problème, en proposant un nouveau protocole, basé sur Mobile IP v6 (MIPv6), et qui introduit l’implication du réseau. Le résultat obtenu est un protocole hybride qui combine les avantages de MIPv6 et de Proxy Mobile IP v6 (PMIPv6). Pour s’y faire, deux étapes ont été nécessaires. La première consiste en une refonte du protocole MIPv6 qui, dans son état actuel, était difficile à modifier, à cause de ses spécifications qui sont lourdes. Le résultat de cette étape est un protocole beaucoup plus léger et offrant uniquement les fonctionnalités de base. Les autres fonctionnalités, telles que les mécanismes de sécurité, ont été séparées dans des modules. En deuxième lieu, un nouveau module a été proposé, qui introduit un nouveau nœud dans le réseau, capable de gérer la mobilité du terminal. Ainsi, la collaboration entre le terminal et ce nœud permet de réduire les messages de signalisation et d’optimiser les décisions au niveau des relèves, tout en offrant le support pour FMC. La deuxième problématique, sur laquelle la thèse porte, se trouve au niveau de la transparence de la relève entre les deux réseaux. On parle d’une relève qui est transparente si cette dernière n’engendre aucune interruption des services de l’usager. Par exemple, un appel en cours, qui est démarré sur le réseau cellulaire, ne doit pas être interrompu lorsque la connexion bascule sur le réseau local, et vice-versa. Les applications visées, par notre travail, sont les applications multimédia en temps réél, notamment IPTV et MobileTV (en mode télévision en direct). Ces applications emploient des protocoles de multidiffusion permettant l’envoi optimisé de données à partir d’une ou de plusieurs sources vers plusieurs destinataires, avec un nombre minimal de paquets. Le problème avec ces applications est que, lorsqu’une relève verticale survient (dans le cadre de FMC par exemple), la connexion est rompue et doit être réétablie. Ceci est dû au fait que le terminal change son adresse IP, ce qui le force à rejoindre ses services à partir de la nouvelle adresse. Cette déconnexion résulte en une perte de paquets, se traduisant par une interruption de l’application de l’usager. Le second article, qui s’intitule « Seamless handover for multicast Mobile IPv6 traffic », propose une solution à ce problème. Cette solution consiste en l’ajout d’un nouveau nœud, dans le réseau, dont le rôle est de mettre en tampon les paquets perdus, lors de la relève du terminal. Ainsi, lorsque ce dernier recouvre sa connectivité, il est en mesure de récupérer ces paquets auprès de ce nœud. L’application de l’usager se déroule alors sans interruption. La troisième problématique abordée dans cette thèse porte sur la planification des réseaux d’accès, afin de supporter les requis des applications multimédia au niveau du débit. Pour que la FMC soit réussie, il faut que le réseau local puisse supporter les débits nécessaires de l’application. Le réseau WiFi interne n’étant généralement pas un problème, la limitation se trouve plutôt au niveau de l’accès filaire. Afin d’augmenter les débits offerts, les opérateurs ont introduit la fibre optique dans leurs réseaux, complémentant ainsi les méthodes traditionnelles, tels les paires de cuivre torsadées et le câble coaxial. Ainsi, de nouvelles technologies optiques hybrides ont été proposées. Dans un contexte o`u une infrastructure est déjà existante, le choix d’une technologie hybride est très attrayant, car l’opérateur peut rentabiliser son investissement précédent, minimisant ainsi le coût de la mise à jour. Par contre, dans un environnement vierge, il n’existe pas d’infrastructure à réutiliser. Le consensus, dans un tel scénario, est que la meilleure technologie à déployer est celle qui n’emploie que des liens en fibre optique, car elle offre les meilleurs débits ainsi que la plus grande flexibilité au niveau de l’évolutivité. La différence, au niveau du coût, devient moins grande et n’est plus nécessairement le critère principal au niveau du choix de la technologie à déployer. Une des difficultés, qui compliquent la planification, est que ces réseaux sont souvent déployés par les opérateurs, en phases. La planification doit être alors dynamique et prendre en considération la nature évolutive de la demande des clients. Le troisième article, qui s’intitule « Dynamic Greenfield Fiber to the Home Planning », propose donc une modélisation dynamique du problème de planification des réseaux d’accès en fibre optique. Le résultat est un modèle mathématique linéaire, en nombres entiers, qui prend en entrée des paramètres, tels que les demandes des clients, et qui produit la planification minimisant le coût total du réseau et ce, sur plusieurs phases. Les résultats numériques obtenus en simulant notre modèle montrent sa supériorité par rapport aux méthodes séquentielles existantes.--------- ABSTRACT Multimedia applications have been gaining momentum and are finding their way into everyday life. Their popularity can be attributed to several factors, such as the diversification of content and services, ubiquitous access thanks to the mobility and nomadicity, as well as advances in architectures and protocols used to support their most demanding requirements. For example, what was once a simple phone call has morphed nowadays into a videoconference, allowing a dynamic number of users to participate. Another example of a multimedia application that gained popularity is IP TeleVision (IPTV), which is the technology that allows the transmission of live and on demand television, on IP networks. There also exists a mobile version, called Mobile IP TeleVision (MobileTV). From the operators’ point of view, the focus is put on the deployment of next generation networks. Wireless operators are therefore deploying fourth generation cellular technologies, such as 3GPP Long Term Evolution (LTE), while those offering wired connectivity are looking into fiber optical based networks, such as Fiber to the Home (FTTH). These new networks increase the rate offered, as well as reduce latency, which are two important criteria for the deployment of large-scale multimedia applications. However, despite these advances, there still exist several obstacles hindering the proper operation of multimedia applications. This thesis therefore focuses on three important issues in next generation networks, each of these subjects leading to a scientific article. The first two works deal with the issues of the Fixed-Mobile Convergence (FMC). This convergence is blurring the distinction between mobile and fixed networks. Among other things, it allows a user to have access to its services, both on the cellular network (LTE, for example) as well as on a local network (Wireless Fidelity (WiFi), for example). This is usually accomplished by equipping the user with a device with that can connect to both networks. The first issue raised in this thesis is about the decision of when to execute a handover. The two most popular mobility protocols, Mobile IP (MIP) and Proxy Mobile IP (PMIP), approach this problem with diametrically opposed views. With the first protocol, the decision is made by the user and his device. Although this approach allows for FMC, operators would much rather have complete control over the decision-making, in order to optimize their network. Indeed, with MIP, many signaling messages are sent, wasting valuable network resources, especially at the radio access, which is the most precious part of the network. Furthermore, by not involving the network, the decision taken by the device will not be necessarily optimal. It might request to switch to a more overloaded network, that cannot meet its demands of Quality of Service (QoS). For these reasons, the PMIP protocol was proposed. Its approach is the opposite of that of MIP, the mobility being managed entirely by the network. By doing so, the device is actually shielded from any aspect of the mobility, and is fooled into thinking that its always in its home network. This is possible by introducing new nodes in the networks that act on its behalf, which eliminates all signaling on the radio link. In addition, since the network is usually better suited to make the right decision, because of the additional information it holds, the mobility is optimized. However, the big issue that arises is that, without the intervention of the terminal, it is impossible to detect all the handover possibilities. In many cases, the operator’s fixed network is hidden by an internal network, usually a WiFi network, and the detection of the network is only possible with the help of the terminal. Thus, PMIP is not a protocol that is well suited to deploy FMC. The first article, entitled “Client-Based Network-Assisted Mobile IPv6”, therefore addresses this problem by proposing a new protocol based on Mobile IP v6 (MIPv6), in which we introduce the involvement of the network. The result is a hybrid protocol that draws upon the strength of MIPv6 and Proxy Mobile IP v6 (PMIPv6). To accomplish this, two steps were required. The first consisted of a complete overhaul of the MIPv6 protocol, as in its current state, it was near impossible to make any modifications, because of the complexity and heaviness of its specifications. The result is a much more lightweight protocol which provides only basic functionality. Other features, such as security mechanisms, were separated into modules. In the second step, we proposed a new module, which introduces a new node in the network that can handle the terminal mobility. Thus, the collaboration of the terminal and the new node reduces the signaling messages and optimizes the decisions for handing over, while still offering support for FMC. The second issue that this thesis tackles is the seamlessness of a handover between two networks. A handover is deemed seamless if it does not cause any disruption to the user’s services. For example, a call that is in progress on the cellular network should not be interrupted when the connection switches to a local network, and the same goes for the other way around. The applications targeted by our work are multimedia applications operating in real-time , such as IPTV and MobileTV (in live television mode). These applications employ multicast protocols that are optimized for the transmission of data from one or more sources to multiple receivers, while using the minimum number of packets required. The problem, however, with these applications is that when a vertical handover occurs (in the case of FMC, for example), the connection is lost and must be re-established. This is because the terminal changes its IP address, which forces it to rejoin the services from the new address. This disconnection results in a packet loss, which entails an interruption of the user application. The second article, entitled “Seamless handover for multicast Mobile IPv6 traffic”, proposes a solution to this problem. This is accomplished by introducing a new node in the network, whose role is to buffer the lost packets while the handover is occurring. Thus, when the device reconnects, it is able to recover these packets. The user application is therefore able to proceed without interruption. The third issue addressed in this thesis focuses on the planning of access networks, to support the high bandwidth required by multimedia applications. For the FMC to be successful, it is necessary that the local network supports the bandwidth requirements. The internal WiFi network is generally not an issue, the limitation rather lies in the wired network. To increase the offered rates, operators have started introducing fiber optic links in their networks, complementing the traditional links, such as twisted pair copper and coaxial cable. Thus, new hybrid optical technologies have been proposed. In a context where an infrastructure already exists, the choice of a hybrid technology is very attractive, because the operator can leverage its previous investment and minimize the cost of the upgrade. However, in a new environment, there is no infrastructure to reuse. Therefore, the consensus in such a scenario is that the best technology to deploy is the one that only uses fiber optic links, as it offers the best rates and the greatest scalability. The cost difference is smaller and therefore no longer the main criterion for selecting the technology to deploy. One of the difficulties of network planning is that these networks are often deployed by operators in phases. Therefore, the planning must be dynamic and take into account the changing nature of customer demands. The third article, entitled “Dynamic Greenfield Fiber to the Home Planning”, proposes a dynamic model for the network planning problem of fiber optic networks. The result is a linear integer mathematical model, which takes input parameters, such as customer demands, and produces a planning that minimizes the total cost of the network, over all of the phases. The numerical results obtained when simulating our solution show its superiority compared to existing sequential methods

Roteamento multicast multisessão: modelos e algoritmos

Multicast Technology has been studied over the last two decades and It has shown to be a good approach to save network resources. Many approaches have been considered to solve the multicast routing problem considering only one session and one source to attending session‘s demand, as well, multiple sessions with more than one source per session. In this thesis, the multicast routing problem is explored taking in consideration the models and the algorithms designed to solve it when where multiple sessions and sources. Two new models are proposed with different focuses. First, a mono-objective model optimizing residual capacity, Z, of the network subject to a budget is designed and the objective is to maximize Z. Second, a multi-objective model is designed with three objective functions: cost, Z and hops counting. Both models consider multisession scenario with one source per session. Besides, a third model is examined. This model was designed to optimize Z in a scenario with multiple sessions with support to more than one source per session. An experimental analysis was realized over the models considered. For each model, a set of algorithms were designed. First, an ACO, a Genetic algorithm, a GRASP and an ILS algorithm were designed to solve the mono-objective model – optimizing Z subject to a budget. Second, a set of algorithm were designed to solve the multi-objective model. The classical approaches were used: NSGA2, ssNSGA2, SMS-EMOA, GDE3 and MOEA/D. In addition, a transgenetic algorithm was designed to solve the problem and it was compared against the classical approaches. This algorithm considers the use of subpopulations during the evolution. Each subpopulation is based on a solution construction operator guided by one of the objective functions. Some solutions are considered as elite solutions and they are considered to be improved by a transposon operator. Eight versions of the transgenetic algorithm were evaluated. Third, an algorithm was designed to solve the problem with multiple sessions and multiple sources per sessions. This algorithm is based on Voronoi Diagrams and it is called MMVD. The algorithm designed were evaluated on large experimental analysis. The sample generated by each algorithm on the instances were evaluated based on non-parametric statistical tests. The analysis performed indicates that ILS and Genetic algorithm have outperformed the ACO and GRASP. The comparison between ILS and Genetic has shown that ILS has better processing time performance. In the multi-objective scenario, the version of Transgenetic called cross0 has shown to be statistically better than the other algorithms in most of the instances based on the hypervolume and addictive/multiplicative epsilon quality indicators. Finally, the MMVD algorithm has shown to be better than the algorithm from literature based on the experimental analysis performed for the model with multiple session and multiple sources per session.A tecnologia multicast tem sido amplamente estudada ao longo dos anos e apresenta-se como uma solução para melhor utilização dos recursos da rede. Várias abordagens já foram avaliadas para o problema de roteamento desde o uso de uma sessão com apenas uma fonte a um cenário com múltiplas sessões e múltiplas fontes por sessão. Neste trabalho, é feito um estudo dos modelos matemáticos para o problema com múltiplas sessões e múltiplas fontes. Dois modelos matemáticos foram propostos: uma versão multissessão mono-objetivo que visa a otimização da capacidade residual sujeito a um limite de custo e uma versão multiobjetivo com três funções-objetivo. Ambos os modelos levam em conta o cenário multissessão com uma fonte por sessão. Além disso, um estudo algorítmico foi realizado sobre um modelo da literatura que utiliza múltiplas fontes por sessão. Três conjuntos de algoritmos foram propostos. O primeiro conjunto trata do problema mono-objetivo proposto e considera as abordagens ACO, Genético, GRASP e ILS. O segundo conjunto consiste dos algoritmos propostos para o modelo multiobjetivo. Foram projetados os seguintes algoritmos: NSGA2, ssNSGA2, GDE3, MOEA/D e SMS-EMOA. Além disso, foi projetado um algoritmo transgenético com subpopulações baseadas em operadores de criação de solução direcionados por objetivos do problema. Também foi utilizado o conceito de soluções de elite. No total, 8 versões do algoritmo transgenético foram avaliadas. O terceiro conjunto de algoritmos consiste da heurística MMVD proposta para o modelo da literatura com múltiplas fontes por sessão. Esta heurística é baseada no uso de diagramas de Voronoi. O processo experimental foi realizado com amplo número de instâncias configuradas de modo a avaliar diferentes situações. Os resultados foram comparados utilizando métodos estatísticos não-paramétricos. A análise final indicou que o ILS e o Genético obtiveram resultados muito similares, entretanto o ILS possui melhor tempo de processamento. A versão cross0 do algoritmo transgenético obteve o melhor resultado em praticamente todos os cenários avaliados. A heurística MMVD obteve excelentes resultados sobre algoritmos da literatura

Air Force Institute of Technology Research Report 2001

This report summarizes the research activities of the Air Force Institute of Technology’s Graduate School of Engineering and Management. It describes research interests and faculty expertise; lists student theses/dissertations; identifies research sponsors and contributions; and outlines the procedures for contacting the school. Included in the report are: faculty publications, conference presentations, consultations, and funded research projects. Research was conducted in the areas of Aeronautical and Astronautical Engineering, Electrical Engineering and Electro-Optics, Computer Engineering and Computer Science, Systems and Engineering Management, Operational Sciences, and Engineering Physics