Finding an optimal solution to the problem of fast and efficient provisioning of reliable connections and failure recovery in future intelligent optical networks is an ongoing challenge. In this dissertation, we investigate and compare the performance of an adapted shared-path protection algorithm with a more conventional approach; both designed for survivable optical Wavelength Division Multiplexing (WDM) mesh networks. The effect of different classes of service on performance is also investigated. Dedicated path protection is a proactive scheme which reserves spare resources to combat single link failures. Conventional Shared-path Protection (CSP) is desirable due to the efficient utilization of resources which results from the sharing of backup paths. Availability is an important performance assessment factor which measures the probability that a connection is in an operational state at some point in time. It is the instantaneous counterpart of reliability. Therefore, connections that do not meet their availability requirements are considered to be unreliable. Reliability Aware Shared-path Protection (RASP) adopts the advantages of CSP by provisioning reliable connections efficiently, but provides protection for unreliable connections only. With the use of a link disjoint parameter, RASP also permits the routing of partial link disjoint backup paths. A simulation study, which evaluates four performance parameters, is undertaken using a South African mesh network. The parameters that are investigated are: 1. Blocking Probability (BP), which considers the percentage of connection requests that are blocked, 2. Backup Success Ratio (BSR), which considers the number of connections that are successfully provisioned with a backup protection path, 3. Backup Primary Resource Ratio (BPR), which considers the ratio of resources utilized to cater for working traffic to the resources reserved for protection paths and lastly 4. Reliability Satisfaction Ratio (RSR), which evaluates the ratio of provisioned connections that meet their availability requirements to the total number of provisioned connections. Under dynamic traffic conditions with varying network load, simulation results show that RASP can provision reliable connections and satisfy Service Level Agreement (SLA) requirements. A competitive Blocking Probability (BP) and lower Backup Primary Resource Ratio (BPR) signify an improvement in resource utilization efficiency. A higher Backup Success Ratio (BSR) was also achieved under high Quality of Service (QoS) constraints. The significance of different availability requirements is evaluated by creating three categories, high availability, medium availability and low availability. These three categories represent three classes of service, with availability used as the QoS parameter. Within each class, the performance of RASP and CSP is observed and analyzed, using the parameters described above. Results show that both the BP and BPR increase with an increase in the availability requirements. The RSR decreases as the reliability requirements increase and a variation in BSR is also indicated. / Dissertation (MEng)--University of Pretoria, 2009. / Electrical, Electronic and Computer Engineering / unrestricted

Transport demand planning in South Africa is a neglected field of study, using obsolete methods to model an extremely complex, dynamic system composed of an eclectic mix of First and Third World transport technologies, infrastructure and economic participants. We identify agent-based simulation as a viable modelling paradigm capable of capturing the effects emerging from the complex interactions within the South African transport system, and proceed to implement the Multi-Agent Transport Simulation Toolkit (MATSim) for South Africa's economically important Gauteng province. This report describes the procedure followed to transform household travel survey, census and Geographic Information System (GIS) data into an activity-based transport demand description, executed on network graphs derived from GIS shape files. We investigate the influence of network resolution on solution quality and simulation time, by preparing a full network representation and a small version, containing no street-level links. Then we compare the accuracy of our data-derived transport demand with a lower bound solution. Finally the simulation is tested for repeatability and convergence. Comparisons of simulated versus actual traffic counts on important road network links during the morning and afternoon rush hour peaks show a minimum mean relative error of less than 40%. Using the same metric, the small network differs from the full representation by a maximum of 2% during the morning peak hour, but the full network requires three times as much memory to execute, and takes 5.2 times longer to perform a single iteration. Our census- and travel survey-derived demand performs significantly better than uniformly distributed random pairings of home- and work locations, which we took to be analogous to a lower bound solution. The smallest difference in corresponding mean relative error between the two cases comes to more than 50%. We introduce a new counts ratio error metric that removes the bias present in traditional counts comparison error metrics. The new metric shows that the spread (standard deviation) of counts comparison values for the random demand is twice to three times as large as that of our reference case. The simulation proves highly repeatable for different seed values of the pseudo-random number generator. An extended simulation run reveals that full systematic relaxation requires 400 iterations. Departure time histograms show how agents 'learn' to gradually load the network while still complying with activity constraints. The initial implementation has already sparked further research. Current priorities are improving activity assignment, incorporating commercial traffic and public transport, and the development and implementation of the minibus taxi para-transit mode. Copyright / Dissertation (MEng)--University of Pretoria, 2009. / Industrial and Systems Engineering / unrestricted

Avec les nouvelles technologies des réseaux optiques, une quantité de données de plus en plus grande peut être transportée par une seule longueur d'onde. Cette quantité peut atteindre jusqu’à 40 gigabits par seconde (Gbps). Les flots de données individuels quant à eux demandent beaucoup moins de bande passante. Le groupage de trafic est une technique qui permet l'utilisation efficace de la bande passante offerte par une longueur d'onde. Elle consiste à assembler plusieurs flots de données de bas débit en une seule entité de données qui peut être transporté sur une longueur d'onde. La technique demultiplexage en longueurs d'onde (Wavelength Division Multiplexing WDM) permet de transporter plusieurs longueurs d'onde sur une même fibre. L'utilisation des deux techniques : WDM et groupage de trafic, permet de transporter une quantité de données de l'ordre de terabits par seconde (Tbps) sur une même fibre optique. La protection du trafic dans les réseaux optiques devient alors une opération très vitale pour ces réseaux, puisqu'une seule panne peut perturber des milliers d'utilisateurs et engendre des pertes importantes jusqu'à plusieurs millions de dollars à l'opérateur et aux utilisateurs du réseau. La technique de protection consiste à réserver une capacité supplémentaire pour acheminer le trafic en cas de panne dans le réseau. Cette thèse porte sur l'étude des techniques de groupage et de protection du trafic en utilisant les p-cycles dans les réseaux optiques dans un contexte de trafic dynamique. La majorité des travaux existants considère un trafic statique où l'état du réseau ainsi que le trafic sont donnés au début et ne changent pas. En plus, la majorité de ces travaux utilise des heuristiques ou des méthodes ayant de la difficulté à résoudre des instances de grande taille. Dans le contexte de trafic dynamique, deux difficultés majeures s'ajoutent aux problèmes étudiés, à cause du changement continuel du trafic dans le réseau. La première est due au fait que la solution proposée à la période précédente, même si elle est optimisée, n'est plus nécessairement optimisée ou optimale pour la période courante, une nouvelle optimisation de la solution au problème est alors nécessaire. La deuxième difficulté est due au fait que la résolution du problème pour une période donnée est différente de sa résolution pour la période initiale à cause des connexions en cours dans le réseau qui ne doivent pas être trop dérangées à chaque période de temps. L'étude faite sur la technique de groupage de trafic dans un contexte de trafic dynamique consiste à proposer différents scénarios pour composer avec ce type de trafic, avec comme objectif la maximisation de la bande passante des connexions acceptées à chaque période de temps. Des formulations mathématiques des différents scénarios considérés pour le problème de groupage sont proposées. Les travaux que nous avons réalisés sur le problème de la protection considèrent deux types de p-cycles, ceux protégeant les liens (p-cycles de base) et les FIPP p-cycles (p-cycles protégeant les chemins). Ces travaux ont consisté d’abord en la proposition de différents scénarios pour gérer les p-cycles de protection dans un contexte de trafic dynamique. Ensuite, une étude sur la stabilité des p-cycles dans un contexte de trafic dynamique a été faite. Des formulations de différents scénarios ont été proposées et les méthodes de résolution utilisées permettent d’aborder des problèmes de plus grande taille que ceux présentés dans la littérature. Nous nous appuyons sur la méthode de génération de colonnes pour énumérer implicitement les cycles les plus prometteurs. Dans l'étude des p-cycles protégeant les chemins ou FIPP p-cycles, nous avons proposé des formulations pour le problème maître et le problème auxiliaire. Nous avons utilisé une méthode de décomposition hiérarchique du problème qui nous permet d'obtenir de meilleurs résultats dans un temps raisonnable. Comme pour les p-cycles de base, nous avons étudié la stabilité des FIPP p-cycles dans un contexte de trafic dynamique. Les travaux montrent que dépendamment du critère d'optimisation, les p-cycles de base (protégeant les liens) et les FIPP p-cycles (protégeant les chemins) peuvent être très stables. / With new technologies in optical networking, an increasing quantity of data can be carried by a single wavelength. This amount of data can reach up to 40 gigabits per second (Gbps). Meanwhile, the individual data flows require much less bandwidth. The traffic grooming is a technique that allows the efficient use of the bandwidth offered by a wavelength. It consists of assembling several low-speed data streams into a single data entity that can be carried on a wavelength. The wavelength division multiplexing (WDM) technique allows carrying multiple wavelengths on a single fiber. The use of the two techniques,WDMand traffic grooming, allows carrying a quantity of data in the order of terabits per second (Tbps) over a single optical fiber. Thus, the traffic protection in optical networks becomes an operation very vital for these networks, since a single failure can disrupt thousands of users and may result in several millions of dollars of lost revenue to the operator and the network users. The survivability techniques involve reserving additional capacity to carry traffic in case of a failure in the network. This thesis concerns the study of the techniques of grooming and protection of traffic using p-cycles in optical networks in a context of dynamic traffic. Most existing work considers a static traffic where the network status and the traffic are given at the beginning and do not change. In addition, most of these works concerns heuristic algorithms or methods suffering from critical lack of scalability. In the context of dynamic traffic, two major difficulties are added to the studied problems, because of the continuous change in network traffic. The first is due to the fact that the solution proposed in the previous period, even if optimal, does not necessarily remain optimal in the current period. Thus, a re-optimization of the solution to the problem is required. The second difficulty is due to the fact that the solution of the problem for a given period is different from its solution for the initial period because of the ongoing connections in the network that should not be too disturbed at each time period. The study done on the traffic grooming technique in the context of dynamic traffic consists of proposing different scenarios for dealing with this type of traffic, with the objective of maximizing the bandwidth of the new granted connections at each time period. Mathematical formulations of the different considered scenarios for the grooming problem are proposed. The work we have done on the problem of protection considers two types of p-cycles, those protecting links and FIPP p-cycles (p-cycle protecting paths). This work consisted primarily on the proposition of different scenarios for managing protection p-cycles in a context of dynamic traffic. Then, a study on the stability of cycles in the context of dynamic traffic was done. Formulations of different scenarios have been proposed and the proposed solution methods allow the approach of larger problem instances than those reported in the literature. We rely on the method of column generation to implicitly enumerate promising cycles. In the study of path protecting p-cycles or FIPP p-cycles, we proposed mathematical formulations for the master and the pricing problems. We used a hierarchical decomposition of the problem which allows us to obtain better results in a reasonable time. As for the basic p-cycles, we studied the stability of FIPP p-cycles in the context of dynamic traffic. The work shows that depending on the optimization criterion, the basic p-cycles (protecting the links) and FIPP p-cycles (protecting paths) can be very stable.

A interligação de várias redes de telecomunicação ampliou a cobertura, mas tornou a operabilidade entre elas complexa, principalmente por causa da arquitetura resultante, formada por várias camadas. Estas camadas lidam com protocolos e taxas de transmissão diferentes e com sinais elétricos e ópticos. Diante desse cenário, a alternativa usual de expandir os recursos proporcionalmente ao crescimento da demanda é inviável devido ao elevado custo. Assim, soluções eficientes que agregam os benefícios das tecnologias ópticas e eletrônicas na arquitetura de nós e no gerenciamento de tráfego tornaram-se uma necessidade importante no projeto, expansão e gerenciamento de redes de telecomunicação. Os nós que permitem a comutação de tráfego na camada óptica e eletrônica e a agregação de tráfego em várias granularidades têm sido empregados para fazer o melhor uso possível dos recursos disponíveis nas redes. Esses nós são conhecidos na literatura como MG-OXCs. Nessa pesquisa, foi proposta uma abordagem dos nós MG-OXCs de uma e três camadas com a inclusão de recursos como conversão de comprimento de onda e agregação de tráfego. Também foi proposto um método de cálculo do custo desses nós baseado no volume de utilização das portas. Posteriormente foram inseridos fatores de degradação do sinal óptico para a análise da camada física de redes com os nós MGOXCs. Adicionalmente, para o gerenciamento de tráfego, foi proposto um esquema de escolha de comprimentos de onda chamado de canal específico e um esquema de monitoramento baseado na intensidade de tráfego. A meta principal é a redução da probabilidade de bloqueio de solicitação de conexão. Em redes ópticas, os modelos de nós propostos conseguem diminuir o número de portas dos nós comutadores tradicionais além de realizar a comutação de tráfego de conexões de diferentes valores de largura de banda. O esquema do canal específico consegue melhorar a utilização da largura de banda dos comprimentos de onda e diminui a probabilidade de bloqueio e o esquema do monitoramento diminui o número de conexões bloqueadas devido ao aumento dos recursos. Resultados numéricos apresentados demonstram a potencialidade dos algoritmos propostos para gerenciar recursos e rotear o tráfego das redes de telecomunicação. / Integrating telecommunication networks has enlarged the coverage, but has made operations more complex, mainly because of the architecture, formed by various layers. These layers deal with different protocols and transmission rates, as well as electrical and optical signals. The usual alternative of expanding the resources proportionally to the demand is impractical due to the high cost. Therefore, efficient solutions which add to the benefits of optical and electronic technology in node architecture and traffic management are essential in the design, expansion and management of telecommunications networks. The nodes that enable traffic switching in the optical and electronic layer and traffic grooming have been used to make the best use of the available resources in the networks. These nodes are known as MG-OXCs. In this research, an approach based on MG-OXCs was proposed with one and three layers, which include the wavelength conversion and traffic grooming. Additionally, a method to calculate the node costs based on their use of ports was proposed. The work also considered optical signal impairments in order to analyze the network physical layer with MG-OXCs nodes. For the purpose of traffic management, a scheme which sets specific wavelengths for different bandwidths and a scheme which monitors the flow of traffic were proposed. The main aim is to reduce the blocking probability of connection requests. In optical networks, the node models proposed are able to reduce the number of ports used in usual optical cross connects and switch the traffic connections using different bandwidths. The scheme of setting specific wavelengths for different bandwidths improves the bandwidth use and the blocking probability. The scheme which monitors the flow of traffic achieves blocking probability reduction due to the increase in resources. The numerical results presented show the feasibility of the proposed algorithms to manage resources and switch traffic in telecommunication networks.

A tecnologia WDM (Wavelength Division Multiplexing) e a introdução de OXCs (Optical Cross Connect) e OADMs (Optical Add/Drop Multiplexer) puramente ópticos podem dotar as redes ópticas da função de networking, ou seja, da capacidade de manipular comprimentos de onda de forma a implementar o roteamento destes. Esta possibilidade implica em uma nova forma de relacionamento das aplicações com a camada física, sendo a arquitetura GMPLS candidata a estabelecer tal relacionamento. Soluções eficientes para o problema de alocação de recursos e roteamento de tráfego tornam-se uma necessidade imperiosa em projeto, expansão e gerenciamento de redes ópticas. A contribuição desta tese consiste em relacionar funcionalidades tais como: agregação (grooming) de tráfego, mecanismo de controle de admissão de chamadas (CAC), mecanismos de restauração e alocação de conversores em redes ópticas heterogêneas, avaliando-se as métricas de probabilidade de bloqueio, probabilidade do tráfego bloqueado e imparcialidade (fairness). Tais funcionalidades são tratadas separadamente na literatura. Com este objetivo em mente modela-se a rede com duas camadas: a camada física e a camada virtual. Estabelecem-se duas políticas de agregação de tráfego MrTV (minimização da rota na topologia virtual) e MrTF (minimização da rota na topologia física) e analisa-se o desempenho destas em relação à porcentagem de tráfego bloqueado. Em seguida um mecanismo de controle de admissão de chamadas (CAC) é implementado e sua influência em termos de imparcialidade (fairness) e probabilidade de bloqueio é analisada. A simulação e análise de redes ópticas, como a Rede NSFnet e a Rede Nacional Italiana são executadas por meio da implementação de um grafo baseado em Zhu e Mukherjee [28]. Como resultado, a política MrTF apresenta menor porcentagem de tráfego bloqueado do que a política MrTV para as redes simuladas e a implementação de um mecanismo de janela deslizante (rolling window) tornou o mecanismo de CAC mais otimizado. A utilidade de se implantar conversores de comprimento de onda apenas em alguns nós da rede (conversão esparsa) é estudada e uma análise sobre a probabilidade de bloqueio e a imparcialidade da rede desta distribuição de conversores é apresentada. Finalmente, técnicas de restauração na camada física e virtual são implementadas e uma análise da influência destes sobre a probabilidade de bloqueio e a imparcialidade da rede é executada. / The Wavelength Division Multiplexing (WDM) technology as well as both the introduction of all optical OXCs (Optical Cross Connect) and OADMs (Optical Add/Drop Multiplexer) may provide the optical network with the networking function, i.e, the capacity to manipulate wavelengths in order to implement their routing. This possibility implies a new type of relationship between applications and the physical layer. The likely candidate to establish such relationships is GMPLS architecture. Efficient solutions to both the problems of allocating resources and traffic routing become an enhanced requirement in the design, expansion and management of optical networking. The present study focus at the relationship between functionalities such as traffic grooming, network fairness improvement, protection/restoring mechanisms and wavelength conversion in heterogeneous optical networks, evaluating the metrics of blocking probability, probability of traffic blocked and fairness. These functionalities are separately treated in literature. With this goal in mind, a two-layer representation is used in order to model the network: the physical and virtual layers, respectively. Two policies on traffic grooming are set up, as follows: MrTV (route minimizing on virtual topology) and MrTF (route minimizing on physical topology). The performance of such policies is analyzed regarding the percentage of blocked traffic. Next, a mechanism for call admission control (CAC) is implemented and its influence in terms of fairness and blocking probability is discussed. The simulations of optical networks such as NSFnet and the Italian National Network are carried out through a graph based in Zhu and Mukherjee [28]. As a result, MrTF policy presents a smaller percentage of blocked traffic than the MrTV for the simulated networks and the rolling window mechanism has allowed the optimization of the call admission control (CAC) mechanism. The usefulness of placing wavelength converters in a few networks nodes (spare conversion) is studied and an analysis on the blocking probability is presented. Next, the network fairness for this distribution of wavelength converters is presented. Finally, techniques for restoring both physical and virtual layers are also implemented and an analysis regarding their influence on the blocking probability and the network fairness is carried out.

Avec les nouvelles technologies des réseaux optiques, une quantité de données de plus en plus grande peut être transportée par une seule longueur d'onde. Cette quantité peut atteindre jusqu’à 40 gigabits par seconde (Gbps). Les flots de données individuels quant à eux demandent beaucoup moins de bande passante. Le groupage de trafic est une technique qui permet l'utilisation efficace de la bande passante offerte par une longueur d'onde. Elle consiste à assembler plusieurs flots de données de bas débit en une seule entité de données qui peut être transporté sur une longueur d'onde. La technique demultiplexage en longueurs d'onde (Wavelength Division Multiplexing WDM) permet de transporter plusieurs longueurs d'onde sur une même fibre. L'utilisation des deux techniques : WDM et groupage de trafic, permet de transporter une quantité de données de l'ordre de terabits par seconde (Tbps) sur une même fibre optique. La protection du trafic dans les réseaux optiques devient alors une opération très vitale pour ces réseaux, puisqu'une seule panne peut perturber des milliers d'utilisateurs et engendre des pertes importantes jusqu'à plusieurs millions de dollars à l'opérateur et aux utilisateurs du réseau. La technique de protection consiste à réserver une capacité supplémentaire pour acheminer le trafic en cas de panne dans le réseau. Cette thèse porte sur l'étude des techniques de groupage et de protection du trafic en utilisant les p-cycles dans les réseaux optiques dans un contexte de trafic dynamique. La majorité des travaux existants considère un trafic statique où l'état du réseau ainsi que le trafic sont donnés au début et ne changent pas. En plus, la majorité de ces travaux utilise des heuristiques ou des méthodes ayant de la difficulté à résoudre des instances de grande taille. Dans le contexte de trafic dynamique, deux difficultés majeures s'ajoutent aux problèmes étudiés, à cause du changement continuel du trafic dans le réseau. La première est due au fait que la solution proposée à la période précédente, même si elle est optimisée, n'est plus nécessairement optimisée ou optimale pour la période courante, une nouvelle optimisation de la solution au problème est alors nécessaire. La deuxième difficulté est due au fait que la résolution du problème pour une période donnée est différente de sa résolution pour la période initiale à cause des connexions en cours dans le réseau qui ne doivent pas être trop dérangées à chaque période de temps. L'étude faite sur la technique de groupage de trafic dans un contexte de trafic dynamique consiste à proposer différents scénarios pour composer avec ce type de trafic, avec comme objectif la maximisation de la bande passante des connexions acceptées à chaque période de temps. Des formulations mathématiques des différents scénarios considérés pour le problème de groupage sont proposées. Les travaux que nous avons réalisés sur le problème de la protection considèrent deux types de p-cycles, ceux protégeant les liens (p-cycles de base) et les FIPP p-cycles (p-cycles protégeant les chemins). Ces travaux ont consisté d’abord en la proposition de différents scénarios pour gérer les p-cycles de protection dans un contexte de trafic dynamique. Ensuite, une étude sur la stabilité des p-cycles dans un contexte de trafic dynamique a été faite. Des formulations de différents scénarios ont été proposées et les méthodes de résolution utilisées permettent d’aborder des problèmes de plus grande taille que ceux présentés dans la littérature. Nous nous appuyons sur la méthode de génération de colonnes pour énumérer implicitement les cycles les plus prometteurs. Dans l'étude des p-cycles protégeant les chemins ou FIPP p-cycles, nous avons proposé des formulations pour le problème maître et le problème auxiliaire. Nous avons utilisé une méthode de décomposition hiérarchique du problème qui nous permet d'obtenir de meilleurs résultats dans un temps raisonnable. Comme pour les p-cycles de base, nous avons étudié la stabilité des FIPP p-cycles dans un contexte de trafic dynamique. Les travaux montrent que dépendamment du critère d'optimisation, les p-cycles de base (protégeant les liens) et les FIPP p-cycles (protégeant les chemins) peuvent être très stables. / With new technologies in optical networking, an increasing quantity of data can be carried by a single wavelength. This amount of data can reach up to 40 gigabits per second (Gbps). Meanwhile, the individual data flows require much less bandwidth. The traffic grooming is a technique that allows the efficient use of the bandwidth offered by a wavelength. It consists of assembling several low-speed data streams into a single data entity that can be carried on a wavelength. The wavelength division multiplexing (WDM) technique allows carrying multiple wavelengths on a single fiber. The use of the two techniques,WDMand traffic grooming, allows carrying a quantity of data in the order of terabits per second (Tbps) over a single optical fiber. Thus, the traffic protection in optical networks becomes an operation very vital for these networks, since a single failure can disrupt thousands of users and may result in several millions of dollars of lost revenue to the operator and the network users. The survivability techniques involve reserving additional capacity to carry traffic in case of a failure in the network. This thesis concerns the study of the techniques of grooming and protection of traffic using p-cycles in optical networks in a context of dynamic traffic. Most existing work considers a static traffic where the network status and the traffic are given at the beginning and do not change. In addition, most of these works concerns heuristic algorithms or methods suffering from critical lack of scalability. In the context of dynamic traffic, two major difficulties are added to the studied problems, because of the continuous change in network traffic. The first is due to the fact that the solution proposed in the previous period, even if optimal, does not necessarily remain optimal in the current period. Thus, a re-optimization of the solution to the problem is required. The second difficulty is due to the fact that the solution of the problem for a given period is different from its solution for the initial period because of the ongoing connections in the network that should not be too disturbed at each time period. The study done on the traffic grooming technique in the context of dynamic traffic consists of proposing different scenarios for dealing with this type of traffic, with the objective of maximizing the bandwidth of the new granted connections at each time period. Mathematical formulations of the different considered scenarios for the grooming problem are proposed. The work we have done on the problem of protection considers two types of p-cycles, those protecting links and FIPP p-cycles (p-cycle protecting paths). This work consisted primarily on the proposition of different scenarios for managing protection p-cycles in a context of dynamic traffic. Then, a study on the stability of cycles in the context of dynamic traffic was done. Formulations of different scenarios have been proposed and the proposed solution methods allow the approach of larger problem instances than those reported in the literature. We rely on the method of column generation to implicitly enumerate promising cycles. In the study of path protecting p-cycles or FIPP p-cycles, we proposed mathematical formulations for the master and the pricing problems. We used a hierarchical decomposition of the problem which allows us to obtain better results in a reasonable time. As for the basic p-cycles, we studied the stability of FIPP p-cycles in the context of dynamic traffic. The work shows that depending on the optimization criterion, the basic p-cycles (protecting the links) and FIPP p-cycles (protecting paths) can be very stable.

A tecnologia WDM (Wavelength Division Multiplexing) e a introdução de OXCs (Optical Cross Connect) e OADMs (Optical Add/Drop Multiplexer) puramente ópticos podem dotar as redes ópticas da função de networking, ou seja, da capacidade de manipular comprimentos de onda de forma a implementar o roteamento destes. Esta possibilidade implica em uma nova forma de relacionamento das aplicações com a camada física, sendo a arquitetura GMPLS candidata a estabelecer tal relacionamento. Soluções eficientes para o problema de alocação de recursos e roteamento de tráfego tornam-se uma necessidade imperiosa em projeto, expansão e gerenciamento de redes ópticas. A contribuição desta tese consiste em relacionar funcionalidades tais como: agregação (grooming) de tráfego, mecanismo de controle de admissão de chamadas (CAC), mecanismos de restauração e alocação de conversores em redes ópticas heterogêneas, avaliando-se as métricas de probabilidade de bloqueio, probabilidade do tráfego bloqueado e imparcialidade (fairness). Tais funcionalidades são tratadas separadamente na literatura. Com este objetivo em mente modela-se a rede com duas camadas: a camada física e a camada virtual. Estabelecem-se duas políticas de agregação de tráfego MrTV (minimização da rota na topologia virtual) e MrTF (minimização da rota na topologia física) e analisa-se o desempenho destas em relação à porcentagem de tráfego bloqueado. Em seguida um mecanismo de controle de admissão de chamadas (CAC) é implementado e sua influência em termos de imparcialidade (fairness) e probabilidade de bloqueio é analisada. A simulação e análise de redes ópticas, como a Rede NSFnet e a Rede Nacional Italiana são executadas por meio da implementação de um grafo baseado em Zhu e Mukherjee [28]. Como resultado, a política MrTF apresenta menor porcentagem de tráfego bloqueado do que a política MrTV para as redes simuladas e a implementação de um mecanismo de janela deslizante (rolling window) tornou o mecanismo de CAC mais otimizado. A utilidade de se implantar conversores de comprimento de onda apenas em alguns nós da rede (conversão esparsa) é estudada e uma análise sobre a probabilidade de bloqueio e a imparcialidade da rede desta distribuição de conversores é apresentada. Finalmente, técnicas de restauração na camada física e virtual são implementadas e uma análise da influência destes sobre a probabilidade de bloqueio e a imparcialidade da rede é executada. / The Wavelength Division Multiplexing (WDM) technology as well as both the introduction of all optical OXCs (Optical Cross Connect) and OADMs (Optical Add/Drop Multiplexer) may provide the optical network with the networking function, i.e, the capacity to manipulate wavelengths in order to implement their routing. This possibility implies a new type of relationship between applications and the physical layer. The likely candidate to establish such relationships is GMPLS architecture. Efficient solutions to both the problems of allocating resources and traffic routing become an enhanced requirement in the design, expansion and management of optical networking. The present study focus at the relationship between functionalities such as traffic grooming, network fairness improvement, protection/restoring mechanisms and wavelength conversion in heterogeneous optical networks, evaluating the metrics of blocking probability, probability of traffic blocked and fairness. These functionalities are separately treated in literature. With this goal in mind, a two-layer representation is used in order to model the network: the physical and virtual layers, respectively. Two policies on traffic grooming are set up, as follows: MrTV (route minimizing on virtual topology) and MrTF (route minimizing on physical topology). The performance of such policies is analyzed regarding the percentage of blocked traffic. Next, a mechanism for call admission control (CAC) is implemented and its influence in terms of fairness and blocking probability is discussed. The simulations of optical networks such as NSFnet and the Italian National Network are carried out through a graph based in Zhu and Mukherjee [28]. As a result, MrTF policy presents a smaller percentage of blocked traffic than the MrTV for the simulated networks and the rolling window mechanism has allowed the optimization of the call admission control (CAC) mechanism. The usefulness of placing wavelength converters in a few networks nodes (spare conversion) is studied and an analysis on the blocking probability is presented. Next, the network fairness for this distribution of wavelength converters is presented. Finally, techniques for restoring both physical and virtual layers are also implemented and an analysis regarding their influence on the blocking probability and the network fairness is carried out.

A interligação de várias redes de telecomunicação ampliou a cobertura, mas tornou a operabilidade entre elas complexa, principalmente por causa da arquitetura resultante, formada por várias camadas. Estas camadas lidam com protocolos e taxas de transmissão diferentes e com sinais elétricos e ópticos. Diante desse cenário, a alternativa usual de expandir os recursos proporcionalmente ao crescimento da demanda é inviável devido ao elevado custo. Assim, soluções eficientes que agregam os benefícios das tecnologias ópticas e eletrônicas na arquitetura de nós e no gerenciamento de tráfego tornaram-se uma necessidade importante no projeto, expansão e gerenciamento de redes de telecomunicação. Os nós que permitem a comutação de tráfego na camada óptica e eletrônica e a agregação de tráfego em várias granularidades têm sido empregados para fazer o melhor uso possível dos recursos disponíveis nas redes. Esses nós são conhecidos na literatura como MG-OXCs. Nessa pesquisa, foi proposta uma abordagem dos nós MG-OXCs de uma e três camadas com a inclusão de recursos como conversão de comprimento de onda e agregação de tráfego. Também foi proposto um método de cálculo do custo desses nós baseado no volume de utilização das portas. Posteriormente foram inseridos fatores de degradação do sinal óptico para a análise da camada física de redes com os nós MGOXCs. Adicionalmente, para o gerenciamento de tráfego, foi proposto um esquema de escolha de comprimentos de onda chamado de canal específico e um esquema de monitoramento baseado na intensidade de tráfego. A meta principal é a redução da probabilidade de bloqueio de solicitação de conexão. Em redes ópticas, os modelos de nós propostos conseguem diminuir o número de portas dos nós comutadores tradicionais além de realizar a comutação de tráfego de conexões de diferentes valores de largura de banda. O esquema do canal específico consegue melhorar a utilização da largura de banda dos comprimentos de onda e diminui a probabilidade de bloqueio e o esquema do monitoramento diminui o número de conexões bloqueadas devido ao aumento dos recursos. Resultados numéricos apresentados demonstram a potencialidade dos algoritmos propostos para gerenciar recursos e rotear o tráfego das redes de telecomunicação. / Integrating telecommunication networks has enlarged the coverage, but has made operations more complex, mainly because of the architecture, formed by various layers. These layers deal with different protocols and transmission rates, as well as electrical and optical signals. The usual alternative of expanding the resources proportionally to the demand is impractical due to the high cost. Therefore, efficient solutions which add to the benefits of optical and electronic technology in node architecture and traffic management are essential in the design, expansion and management of telecommunications networks. The nodes that enable traffic switching in the optical and electronic layer and traffic grooming have been used to make the best use of the available resources in the networks. These nodes are known as MG-OXCs. In this research, an approach based on MG-OXCs was proposed with one and three layers, which include the wavelength conversion and traffic grooming. Additionally, a method to calculate the node costs based on their use of ports was proposed. The work also considered optical signal impairments in order to analyze the network physical layer with MG-OXCs nodes. For the purpose of traffic management, a scheme which sets specific wavelengths for different bandwidths and a scheme which monitors the flow of traffic were proposed. The main aim is to reduce the blocking probability of connection requests. In optical networks, the node models proposed are able to reduce the number of ports used in usual optical cross connects and switch the traffic connections using different bandwidths. The scheme of setting specific wavelengths for different bandwidths improves the bandwidth use and the blocking probability. The scheme which monitors the flow of traffic achieves blocking probability reduction due to the increase in resources. The numerical results presented show the feasibility of the proposed algorithms to manage resources and switch traffic in telecommunication networks.

L’objectif de ce travail consiste en la modélisation des flux de véhicules d’un grand et dense réseau de transport multimodal. Le travail s’organise en deux parties: un aspect théorique et un aspect développement. L’étude théorique met l’accent sur la façon dont un réseau multimodal peut être modélisé et comment sa performance en termes d’offre peut être optimisée. Pour ce faire, trois études principales sont réalisées: la prévision et la régulation des flux de trafic sur les grands réseaux de surface, la multimodalité véhiculaire dans les grands réseaux de surface prenant en compte les nouvelles formes de mobilité, et enfin l’impact de l’information sur le coût des itinéraires. La partie développement consiste en la conception d’un simulateur de flux de trafic pour réguler le trafic multimodal véhiculaire. Le simulateur développé devrait aider les opérateurs de transport et les collectivités territoriales dans leurs stratégies de gestion des flux de trafic / The objective of this work consists on the modeling of traffic flow of a large multimodaltransportation network. The work is organized in two parts: a theoretical study part anda development part. The theoretical study emphasizes on how a multimodal network canbe model and how its performance in terms of supply can be optimized. To do so, threemain studies are discussed: the traffic flow prediction and regulation on large surface net-works, the vehicular multimodality in big surface networks taking into account new forms ofmobility, and finally the impact of the information on the cost of the itineraries. The devel-opment part consists on the conception of a traffic flow simulator to regulate the vehicularmultimodal traffic. The developed simulator should assist transport operators and territorialcommunities in their traffic flow management strategies

Abstract The high increase in traffic and data rate for future generations of mobile communication systems, with simultaneous requirement for reduced power consumption, makes Multihop Cellular Networks (MCNs) an attractive technology. To exploit the potentials of MCNs a number of new network paradigms are proposed in this thesis. First, a new algorithm for efficient relaying topology control is presented to jointly optimize the relaying topology, routing and scheduling resulting in a two dimensional or space time routing protocol. The algorithm is aware of intercell interference (ICI), and requires coordinated action between the cells to jointly choose the relaying topology and scheduling to minimize the system performance degradation due to ICI. This framework is extended to include the optimization of power control. Both conventional and cooperative relaying schemes are considered. In addition, a novel sequential genetic algorithm (SGA) is proposed as a heuristic approximation to reconfigure the optimum relaying topology as the network traffic changes. Network coding is used to combine the uplink and downlink transmissions, and incorporate it into the optimum bidirectional relaying with ICI awareness. Seeking for a more tractable network model to effectively use context awareness and relying on the latest results on network information theory, we apply a hexagonal tessellation for inner partition of the cell into smaller subcells of radius r. By using only one single topology control parameter (r), we jointly optimize routing, scheduling and power control to obtain the optimum trade-off between throughput, delay and power consumption in multicast MCNs. This model enables high resolution optimization and motivates the further study of network protocols for MCNs. A new concept for route discovery protocols is developed and the trade-off between cooperative diversity and spatial reuse is analyzed by using this model. Finally, a new architecture for MCN is considered where multihop transmissions are performed by a Delay Tolerant Network, and new solutions to enhance the performance of multicast applications for multimedia content delivery are presented. Numerical results have shown that the algorithms suggested in this thesis provide significant improvement with respect to the existing results, and are expected to have significant impact in the analysis and design of future cellular networks. / Tiivistelmä Tiedonsiirron ja tiedonsiirtonopeuksien suuri kasvu sekä tehonkulutuksen pieneneminen tulevien sukupolvien matkapuhelinjärjestelmissä tekevät monihyppyiset matkapuhelinverkot houkutteleviksi vaihtoehdoiksi. Tässä työssä esitetään uusia tiedonsiirtoverkkojen paradigmoja monihyppyisten matkapuhelinverkkojen hyödyntämiseksi. Työssä esitellään uusi algoritmi tehokkaaseen releointitopologian hallintaan, joka optimoi yhtäaikaisesti topologian, reitityksen sekä lähetyshetkien ajoituksen ja mahdollistaa tila-aika-reititysprotokollan toteutuksen. Esitetty algoritmi huomioi solujen keskinäishäiriön ja vaaditulla solujen välisellä koordinoidulla hallinnalla saadaan yhdessä valittua topologia ja ajoitus, jotka minimoivat solujen keskinäisistä häiriöistä johtuvan suorituskyvyn heikentymisen. Myöhemmin tätä viitekehystä on laajennettu lisäämällä siihen tehonsäädön optimointi. Työssä on tutkittu sekä perinteisiä että kooperatiivisia releointimenetelmiä. Lisäksi työssä esitetään uusi geneettinen algoritmi heuristiseksi approksimaatioksi verkon liikenteen muutoksen vaatimaan releointitopologian uudelleen järjestelyyn. Työssä tarkastellaan lisäksi verkkokoodausta ylä- ja alasuuntaan tapahtuvan tiedonsiirron yhdistämiseksi sisällyttämällä se solujen keskinäishäiriön huomioivaan kahdensuuntaiseen releointiin. Etsittäessä paremmin mukautuvaa ja kontekstitietoisuutta hyödyntävää verkkomallia, joka käyttää hyväkseen viimeisimpiä verkkojen informaatioteoreettisia tuloksia, voidaan verkon solut pilkkoa pienempiin kuusikulmaisiin alisoluihin. Käyttämällä ainoastaan näiden alisolujen sädettä r voidaan puolestaan verkon reititys, ajoitus ja tehon säätö optimoida yhtäaikaisesti saavuttaen paras mahdollinen kompromissi verkon läpäisyn, viiveen ja tehonkulutuksen välillä. Kehitetty malli mahdollistaa korkean resoluution optimoinnin ja motivoi uusien verkkoprotokollien kehitystä monihyppyisissä matkapuhelinverkoissa. Tätä mallia käyttäen esitellään myös uusi konsepti reitinetsintäprotokollille sekä analysoidaan kooperatiivisen diversiteetin ja tila-avaruudessa tapahtuvan uudelleenkäytön välistä kompromissiratkaisua. Lopuksi työssä tarkastellaan monihyppyisen matkapuhelinverkon uutta arkkitehtuuria, jossa monihyppylähetykset suoritetaan viivesietoisella verkolla ja esitetään uusia ratkaisuja multimediasisällön monilähetysten tehokkuuden parantamiseksi. Työssä saadut tulokset osoittavat, että ehdotetut algoritmit parantavat järjestelmien suorituskykyä verrattuna aiemmin tiedossa olleisiin tuloksiin. Työn tuloksilla voidaan olettaa myös olevan suuri vaikutus tulevaisuuden matkapuhelinverkkojen analysointiin ja suunnitteluun.