Метод описания изменения количества пользователей телекоммуникационной сети

предложен поход к разработке математической модели, адекватно описывающей изменение требований пользователей на подключение к сети и обслуживание этих требований исследуемой сетью. Решение задачи включает исследование модели требований на развитие сети за счет увеличения ее емкости, объема и видов предоставляемых инфокоммуникационных услуг

Topology design and performance analysis of an integrated communication network

A research study on the topology design and performance analysis for the Space Station Information System (SSIS) network is conducted. It is begun with a survey of existing research efforts in network topology design. Then a new approach for topology design is presented. It uses an efficient algorithm to generate candidate network designs (consisting of subsets of the set of all network components) in increasing order of their total costs, and checks each design to see if it forms an acceptable network. This technique gives the true cost-optimal network, and is particularly useful when the network has many constraints and not too many components. The algorithm for generating subsets is described in detail, and various aspects of the overall design procedure are discussed. Two more efficient versions of this algorithm (applicable in specific situations) are also given. Next, two important aspects of network performance analysis: network reliability and message delays are discussed. A new model is introduced to study the reliability of a network with dependent failures. For message delays, a collection of formulas from existing research results is given to compute or estimate the delays of messages in a communication network without making the independence assumption. The design algorithm coded in PASCAL is included as an appendix

Capacitated Trees, Capacitated Routing, and Associated Polyhedra

We study the polyhedral structure of two related core combinatorial problems: the subtree cardinalityconstrained minimal spanning tree problem and the identical customer vehicle routing problem. For each of these problems, and for a forest relaxation of the minimal spanning tree problem, we introduce a number of new valid inequalities and specify conditions for ensuring when these inequalities are facets for the associated integer polyhedra. The inequalities are defined by one of several underlying support graphs: (i) a multistar, a "star" with a clique replacing the central vertex; (ii) a clique cluster, a collection of cliques intersecting at a single vertex, or more generally at a central" clique; and (iii) a ladybug, consisting of a multistar as a head and a clique as a body. We also consider packing (generalized subtour elimination) constraints, as well as several variants of our basic inequalities, such as partial multistars, whose satellite vertices need not be connected to all of the central vertices. Our development highlights the relationship between the capacitated tree and capacitated forest polytopes and a so-called path-partitioning polytope,and shows how to use monotone polytopes and a set of simple exchange arguments to prove that valid inequalities are facets

Designing Satellite Communication Networks by Zero-One Quadratic Programming

In satellite communications networks, distinctive facilities called homing stations perform special transmission functions. Local demand nodes clustered around each homing station communicate with each other via a local switch at the homing station; demand nodes in different clusters communicate with each other via satellite earth stations at the homing stations. Designing such a communication network requires choices on the locations of the earth stations and on the assignments of demand nodes to the local clusters at the earth stations. We formulate this problem as a zero-one quadratic facility location problem and transform it into an equivalent zero-one integer linear program. Computational experience on real data shows that a branch and bound procedure is effective in solving problems with up to forty demand nodes (major cities) and that the solutions that this algorithm finds improve considerably upon management generated solutions. We also show that a greedy add heuristic, as implemented on an IBM PC, consistently generates optimal or near-optimal solutions

The capacitated minimum spanning tree problem

In this thesis we focus on the Capacitated Minimum Spanning Tree (CMST), an extension of the minimum spanning tree (MST) which considers a central or root vertex which receives and sends commodities (information, goods, etc) to a group of terminals. Such commodities flow through links which have capacities that limit the total flow they can accommodate. These capacity constraints over the links result of interest because in many applications the capacity limits are inherent. We find the applications of the CMST in the same areas as the applications of the MST; telecommunications network design, facility location planning, and vehicle routing. The CMST arises in telecommunications networks design when the presence of a central server is compulsory and the flow of information is limited by the capacity of either the server or the connection lines. Its study also results specially interesting in the context of the vehicle routing problem, due to the utility that spanning trees can have in constructive methods. By the simple fact of adding capacity constraints to the MST problem we move from a polynomially solvable problem to a non-polynomial one. In the first chapter we describe and define the problem, introduce some notation, and present a review of the existing literature. In such review we include formulations and exact methods as well as the most relevant heuristic approaches. In the second chapter two basic formulations and the most used valid inequalities are presented. In the third chapter we present two new formulations for the CMST which are based on the identification of subroots (vertices directly connected to the root). One way of characterizing CMST solutions is by identifying the subroots and the vertices assigned to them. Both formulations use binary decision variables y to identify the subroots. Additional decision variables x are used to represent the elements (arcs) of the tree. In the second formulation the set of x variables is extended to indicate the depth of the arcs in the tree. For each formulation we present families of valid inequalities and address the separation problem in each case. Also a solution algorithm is proposed. In the fourth chapter we present a biased random-key genetic algorithm (BRKGA) for the CMST. BRKGA is a population-based metaheuristic, that has been used for combinatorial optimization. Decoders, solution representation and exploring strategies are presented and discussed. A final algorithm to obtain upper bounds for the CMST is proposed. Numerical results for the BRKGA and two cutting plane algorithms based on the new formulations are presented in the fifth chapter . The above mentioned results are discussed and analyzed in this same chapter. The conclusion of this thesis are presented in the last chapter, in which we include the opportunity areas suitable for future research.En esta tesis nos enfocamos en el problema del Árbol de Expansión Capacitado de Coste Mínimo (CMST, por sus siglas en inglés), que es una extensión del problema del árbol de expansión de coste mínimo (MST, por sus siglas en inglés). El CMST considera un vértice raíz que funciona como servidor central y que envía y recibe bienes (información, objetos, etc) a un conjunto de vértices llamados terminales. Los bienes solo pueden fluir entre el servidor y las terminales a través de enlaces cuya capacidad es limitada. Dichas restricciones sobre los enlaces dan relevancia al problema, ya que existen muchas aplicaciones en que las restricciones de capacidad son de vital importancia. Dentro de las áreas de aplicación del CMST más importantes se encuentran las relacionadas con el diseño de redes de telecomunicación, el diseño de rutas de vehículos y problemas de localización. Dentro del diseño de redes de telecomunicación, el CMST está presente cuando se considera un servidor central, cuya capacidad de transmisión y envío está limitada por las características de los puertos del servidor o de las líneas de transmisión. Dentro del diseño de rutas de vehículos el CMST resulta relevante debido a la influencia que pueden tener los árboles en el proceso de construcción de soluciones. Por el simple de añadir las restricciones de capacidad, el problema pasa de resolverse de manera exacta en tiempo polinomial usando un algoritmo voraz, a un problema que es muy difícil de resolver de manera exacta. En el primer capítulo se describe y define el problema, se introduce notación y se presenta una revisión bibliográfica de la literatura existente. En dicha revisión bibliográfica se incluyen formulaciones, métodos exactos y los métodos heurísticos utilizados más importantes. En el siguiente capítulo se muestran dos formulaciones binarias existentes, así como las desigualdades válidas más usadas para resolver el CMST. Para cada una de las formulaciones propuestas, se describe un algoritmo de planos de corte. Dos nuevas formulaciones para el CMST se presentan en el tercer capítulo. Dichas formulaciones estás basadas en la identificación de un tipo de vértices especiales llamados subraíces. Los subraíces son aquellos vértices que se encuentran directamente conectados al raíz. Un forma de caracterizar las soluciones del CMST es a través de identificar los nodos subraíces y los nodos dependientes a ellos. Ambas formulaciones utilizan variables para identificar los subraices y variables adicionales para identificar los arcos que forman parte del árbol. Adicionalmente, las variables en la segunda formulación ayudan a identificar la profundidad con respecto al raíz a la que se encuentran dichos arcos. Para cada formulación se presentan desigualdades válidas y se plantean procedimientos para resolver el problema de su separación. En el cuarto capítulo se presenta un algoritmo genético llamado BRKGA para resolver el CMST. El BRKGA está basado en el uso de poblaciones generadas por secuencias de números aleatorios, que posteriormente evolucionan. Diferentes decodificadores, un método de búsqueda local, espacios de búsqueda y estrategias de exploración son presentados y analizados. El capítulo termina presentando un algoritmo final que permite la obtención de cotas superiores para el CMST. Los resultados computacionales para el BRKGA y los dos algoritmos de planos de corte basados en las formulaciones propuestas se muestran en el quinto capítulo. Dichos resultados son analizados y discutidos en dicho capítulo. La tesis termina presentando las conclusiones derivadas del desarrollo del trabajo de investigación, así como las áreas de oportunidad sobre las que es posible realizar futuras investigaciones

Models for planning the evolution of local telecommunication networks

Includes bibliographical references.Research initiated through a grant from GTE Laboratories, Inc. Supported in part by an AT&T research award. Supported in part by the Systems Theory and Operations Research Program of the National Science Foundation. ECS-8316224 Supported in part by ONR. N0000-14-86-0689A. Balakrishnan ... [et al.]

Models for planning the evolution of local telecommunication networks

Includes bibliographical references.Research initiated through a grant from GTE Laboratories, Inc. Supported in part by an AT&T research award. Supported in part by the Systems Theory and Operations Research Program of the National Science Foundation. ECS-8316224 Supported in part by ONR. N0000-14-86-0689A. Balakrishnan ... [et al.]

Problema da árvore de suporte de custo mínimo com restrições de diâmetro

Mestrado em MatemáticaNesta tese desenvolvem-se alguns métodos heurísticos para o Problema da Árvore de Suporte de Custo Mínimo com Restrições de Diâmetro que é um problema de Optimização Combinatória. Este problema tem aplicação na área das telecomunicações e insere-se no âmbito de problemas do Desenho Topológico de Redes de Telecomunicações. O Problema do Desenho de Redes de Terminais consiste em encontrar a melhor maneira de ligar n terminais em diferentes localizações a um nodo central. A topologia óptima deste problema corresponde a uma árvore de suporte de custo mínimo. No Problema da Árvore de Suporte de Custo Mínimo com Restrições de Diâmetro pretende-se determinar uma árvore de suporte de custo mínimo cujo diâmetro não ultrapasse um determinado valor máximo (D). Esta imposição melhora o desempenho da rede. Apresentam-se três heurísticas greedy que seleccionam iterativamente uma aresta a ser incluída na árvore e que se distinguem apenas na forma como são escolhidos os elementos iniciais (nodo/aresta). Descreve-se uma heurística de trocas locais (ou melhoramento) que efectua algumas trocas de arestas de acordo com uma regra estabelecida. Descrevem-se quatro heurísticas de aproximação que adaptam soluções de outro problema ao problema em questão. Na primeira destas heurísticas eliminam-se arestas da árvore de suporte de custo mínimo e, depois, constrói-se a árvore a partir da subárvore obtida. Na segunda proíbe-se a presença na solução de cada uma das arestas de um dado conjunto. Na terceira heurística exige-se que cada aresta de um dado conjunto esteja na solução e, na última exige-se que cada uma das arestas de um dado conjunto esteja na solução e que um conjunto de arestas não esteja na solução. Apresentam-se resultados computacionais que mostram que as Heurísticas de Aproximação são as que obtêm melhores resultados.In this thesis we present some heuristics methods developed to the Diameter constrained Minimum Spanning Tree problem (DMST), which is a Combinatorial Optimization Problem. This is a telecommunication network design problem and the terminal layout problem consists of finding the best way to link n terminals, at different locations, to a central node. The optimal topology for these problems corresponds to a minimum spanning tree. In the DMST we want to obtain a minimum spanning tree which diameter does not surpass a maximum value (D). The diameter constraint improves the performance of the network. We present three greedy heuristics that iteratively select an edge to be added to the tree and are distinguished in the form how initial elements (a node or an edge) are selected. We describe a local exchanges heuristic where improvements are accomplished with some edges exchanges according to an established rule. We also describe four approximation heuristics that adapt solutions from another problem to this problem. On the first heuristic we start it by eliminating edges from the minimal spanning tree and then we build the new tree from the obtained subtree. On the second heuristic, the presence of each edge of a certain set is forbidden in the solution. On the third heuristic, it is demanded that each edge of a certain set is present in the solution, and on the last heuristic it is demanded that each one of the edges of a certain set is present in the solution and that a set of edges is not in the solution. Our computational experience shows that the best results are achieved with the approximation heuristics

Applications of network optimization

Includes bibliographical references (p. 41-48).Ravindra K. Ahuja ... [et al.]

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