Orientador: Helio Waldman / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação / Made available in DSpace on 2018-08-05T14:57:27Z (GMT). No. of bitstreams: 1 Savasini_MarcioSaenz_M.pdf: 1495771 bytes, checksum: 8580ad17c20a8326cbb9cee63471d096 (MD5) Previous issue date: 2005 / Resumo: Este trabalho tem como objetivo analisar a redução na probabilidade de bloqueio com o uso de conversores de comprimento de onda e esquemas de proteção em redes ópticas. É apresentada a proteção por roteamento em sub-grafos, um método de criar caminhos de proteção dependentes a falha para cada conexão. Alguns esquemas para eliminar realocações desnecessárias de conexões no caso de falha, sem penalizar fortemente a aceitação de novas conexões, foram sugeridos e comparados. Outro tema abordado no trabalho foi o ganho do uso de conversores de comprimento de onda em redes em malha em um ambiente dinâmico de tráfego. Foi utilizado nas simulações um número limitado de conversores plenos espalhados pela rede. Foi analisada a quantidade suficiente de conversores para se ter uma probabilidade de bloqueio satisfatória, pensando em minimizar os investimentos a serem feitos no momento de uma expansão da rede. Para um melhor entendimento dos problemas estudados há uma descrição do funcionamento da rede óptica e seus elementos principais e dos algoritmos de roteamento e alocação de comprimento de onda utilizados e descritos na literatura / Abstract: This work examines the blocking reduction with the use of wavelength converters and some protection schemes in optical networks. Sub-Graph Routing Protection, a protection method that creates different failure-dependent protection paths for each connection is presented. Some schemes were proposed and compared, aiming at eliminating unnecessary connection reallocations on a failure occurrence, without compromising the acceptance of new connections. Another topic studied for this work is the conversion gain, when wavelength converters are used in mesh topology networks under dynamic traffic. A limited number of total converters were used in the simulations. The sufficient amount of converters for a satisfactory blocking probability was analyzed, for minimizing investments in a network upgrade. For a better problem formulation understanding the optical network and its elements were explained. The routing and wavelength allocation algorithms proposed in the literature are also detailed. / Mestrado / Telecomunicações e Telemática / Mestre em Engenharia Elétrica

Master of Science / Department of Electrical and Computer Engineering / Caterina M. Scoglio / Recently, virtualization was proposed in many scientific fields. Virtualization is widely applied in telecommunications where networks are required to be extremely flexible to meet the current and the unpredictable future requirements. The creation of a virtual network over the physical network allows the application developers to design new services provided to the users without modifying the underlay resources. The creation of a virtual network of light paths and light trees over the optical network allows the resources managers to utilize the huge optical capacity more efficiently. In this thesis, we consider the optimal topology design for the virtual networks taking into consideration traffic demands and quality of service constraints of the applications. Considered examples of virtual networks are the overlay networks at the application layer and the virtual light path and light tree networks at the optical layer. In the design of overlay topologies, the performance of the virtual networks is affected by traffic characteristic, and behavior of nodes which can be selfish or cooperative. Both the static and dynamic traffic demand scenarios are considered. The static demand scenario follows well known probability distributions, while in the dynamic traffic scenario, the traffic matrix is predicted through measurements over each link in the network. We study the problem of finding the overlay topology that minimizes a cost function which takes into account the overlay link creation cost and the routing cost. We formulate the problem as an Integer Linear Programming and propose heuristics to find near-optimal overlay topologies with a reduced complexity. Virtual optical networks are designed to support many applications. Multicast sessions are an example of the applications running over the optical network. The main objective in creating the hybrid topology, composed by light paths and light trees, is to increase number of supported multicast sessions through sharing the network resources. The problem of establishing the hybrid topology is formulated using the Integer Linear Programming. Extensive data results and analysis are performed on the generated hybrid topologies for evaluation.

Filtering is an important part of digital processing, since the applications often require a change of features of a digital or analog signal. A digital filter is a device or a system that removes or alters certain parts of a signal. Optical fibers are used to transmit information over longer distances and at higher bandwidths than traditional copper cables. In order to enable high-rate transmission in optical communication systems, it is necessary to have a filter that compensates for chromatic dispersion in optic links, since the dispersion alters the signal in an unwanted way. This thesis presents the implementation and evaluation of two filter architectures, used in fiber-optic communication. The clock frequency of the implemented designs reaches 475 MHz, which results in a processing speed of 60 GS/s.

During the last three decades, the significant increase in electricity demand, and its consequences, has appeared as a serious concern for the utility companies, but no major changes have been applied to the conventional power grid infrastructure. Recently, researchers have identified efficient control and power distribution mechanisms as the immediate challenges for conventional power grids. The next step for conventional power grid towards the Smart Grid is to provide energy efficiency management along with higher reliability via smart services, in which the application of Information and Communication Technology (ICT) is inevitable. ICT introduces powerful tools to comply with the smart grid requirements. Among various ICT properties, the telecommunication network plays a key role for providing a secure infrastructure. The two-way digital communication system provides an interaction between energy suppliers and consumers for managing, controlling and optimizing energy distribution. We can also define the smart grid as a two-way flow of energy and control information, where the electricity consumers can generate energy using green energy resources. The main objective of this thesis is to select an effective data communication infrastructure to support the smart grid services by considering a hybrid wireless and optical communication technologies. Radio-over-Fibre (RoF) networks are considered as a potential solution to provide a fast, reliable and efficient network backbone with the optical access network integration and the flexibility and mobility of the wireless network. Therefore, we adopt the integration of RoF to Passive Optical Network (PON) as a broadband access network to transmit smart grid data along with the Fiber to the Home/Building/Curb (FTTx) traffic through the shared fibre, and utilizing Wavelength Division Multiplexing (WDM). Finally, we present and analyze the simulation results for the aforementioned infrastructure based on our enhanced ROF-PON integration model.

Orientador: Christian Rodolfo Esteve Rothenberg / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação / Made available in DSpace on 2018-08-27T08:39:20Z (GMT). No. of bitstreams: 1 Siqueira_MarcosAntoniode_D.pdf: 7263131 bytes, checksum: fad0f39a012c338503de664fbec8fe8c (MD5) Previous issue date: 2015 / Resumo: Esta tese apresenta uma proposta de arquitetura para controle de redes ópticas de transporte que utiliza o paradigma de redes definidas por software, com suporte a operação autonômica com base em políticas. A arquitetura é constituída pelos seguintes pilares: (i) modelagem dos elementos de rede, incluindo suas interconexões, restrições, capacidades, entre outros, utilizando a linguagem YANG; (ii) composição dos modelos dos elementos de rede e suas relações em um modelo que representa a rede, suportando transformações para representação da rede como grafos de propriedades; e (iii) um modelo de políticas baseado em objetos associados ao grafo de propriedades da rede que viabiliza a operação autonômica do controlador. A proposta foi validada através de provas de conceito realizadas por simulações, protótipos e experimentos, incluindo casos de uso de segmentação e virtualização da rede óptica de transporte, aplicações SDN para ajuste de parâmetros operacionais da rede com base em políticas, bem como a operação autônoma do controlador SDN com auxílio de ferramentas de simulação com rotinas de planejamento automatizado / Abstract: This thesis proposes an architecture for optical transport networks control, using the software defined networking paradigm, with support for policy-based autonomic operation. The architecture is composed of three pillars: (i) modeling of network elements, its interconnections, constraints and capabilities using the YANG language; (ii) composition of the network element models and its interconnections forming a network model, supporting transformations for representing the network as property graphs; and (iii) a policy model based on objects associated to the network graph designed for allowing autonomic operation of the network controller. The proposal has been validated through a set of proofs of concept performed via simulations, prototypes and experiments, including use cases for optical transport network slicing and virtualization, SDN applications for policy-based operational parameters adjustment, and autonomic operation of the SDN controller assisted by simulation tools with routines for automated planning / Doutorado / Engenharia de Computação / Doutor em Engenharia Elétrica

Access networks have been going through many reformations to make them adapt to arising traffic trends and become better suited for many new demanding applications. To that end, incorporating fog and edge computing has become a necessity for supporting many emerging applications as well as alleviating network congestions. At the same time, energy-efficiency has become a strong imperative for access networks to reduce both their operating costs and carbon footprint. In this dissertation, we address these two challenges in long-reach optical access networks. We first study the integration of fog and edge computing with optical access networks, which is believed to form a highly capable access network by combining the huge fiber capacity with closer-to-the-edge computing and storage resources. In our study, we examine the offloading performance under different cloudlet placements when the underlying bandwidth allocation is either centralized or decentralized. We combine between analytical modeling and simulation results in order to identify the different factors that affect the offloading performance within each paradigm. To address the energy efficiency requirement, we introduce novel enhancements and modifications to both allocation paradigms that aim to enhance their network performance while conserving energy. We consider this work to be one of the first to explore the integration of fog and edge computing with optical access networks from both bandwidth allocation and energy efficiency perspectives in order to identify which allocation paradigm would be able to meet the requirements of next-generation access networks.

[pt] Neste trabalho são estudadas cascatas de amplificadores a fibra óptica dopada com Érbio (EDFAs) inseridas em redes ópticas multiplexadas em comprimento de onda (WDM). Modelos numéricos são desenvolvidos e implementados para estudar o efeito da variação do número de canais amplificados pela cascata de EDFAs no desempenho de redes WDM submetidas a funções de adição/retirada de canais. Considerando condições em estado estacionário, é desenvolvida uma inovadora configuração amplificadora WDM, que oferece robustez e bom desempenho diante da carga variável de canais transportados em enlaces de redes ópticas WDM. Transientes de potência em cascatas de EDFAs, assim como técnicas de compensação dos mesmos, são analisados. O estudo permite avaliar as vantagens e limitações dos modelos dinâmicos apresentados, assim como o desempenho das técnicas de controle de transientes de potência em cascatas de EDFAs, em condições realistas de operação. / [en] In this work Erbium Fiber-Doped Amplifiers (EDFAs) cascades in Wavelength Division Multiplexed optical networks (WDMs) are studied. Computer numerical models are developed and implemented in order to study the effect of the EDFA channel number variation in the performance of optical networks submitted to channels add/drop function. Initially, steady state conditions are considered. Then, a WDM amplifier configuration formed by EDFAs, power compensators and optical filters is developed. This configuration - which is a novel one - has shown to be robust and to offer a good performance, in regard to the variable load of the transported channels in WDM network links. In order to obtain a more detailed study of power transients in cascades of EDFA, two dynamic computer models of these amplifiers are implemented: (i) - a simple one, that neglects the amplified spontaneous emission (ASE) and; (ii) - a second one, which rigorously consider all noise-derived effects in an EDFA cascade. In order to achieve power transients control, several compensation techniques are studied and implemented. A comparative analysis, concerning the efficiency of the above mentioned compensation techniques is carried out. Advantages and limitations of two dynamic introduced models were also evaluated, as well the control techniques of power transients in EDFA cascades.

Optical networking, employing wavelength division multiplexing (WDM), is seen as the technology of the future for the Internet. This dissertation investigates several important problems affecting optical circuit switching (OCS) and optical burst switching (OBS) networks. Novel algorithms and new approaches to improve the performance of these networks through effective routing and channel scheduling are presented. Extensive simulations and analytical modeling have both been used to evaluate the effectiveness of the proposed algorithms in achieving lower blocking probability, better fairness as well as faster switching. The simulation tests were performed over a variety of optical network topologies including the ring and mesh topologies, the U.S. Long-Haul topology, the Abilene high-speed optical network used in Internet 2, the Toronto Metropolitan topology and the European Optical topology. Optical routing protocols previously published in the literature have largely ignored the noise and timing jitter accumulation caused by cascading several wavelength conversions along the lightpath of the data burst. This dissertation has identified and evaluated a new constraint, called the wavelength conversion cascading constraint. According to this constraint, the deployment of wavelength converters in future optical networks will be constrained by a bound on the number of wavelength conversions that a signal can go through when it is switched all-optically from the source to the destination. Extensive simulation results have conclusively demonstrated that the presence of this constraint causes significant performance deterioration in existing routing and wavelength assignment (RWA) algorithms. Higher blocking probability and/or worse fairness have been observed for existing RWA algorithms when the cascading constraint is not ignored. To counteract the negative side effect of the cascading constraint, two constraint-aware routing algorithms are proposed for OCS networks: the desirable greedy algorithm and the weighted adaptive algorithm. The two algorithms perform source routing using link connectivity and the global state information of each wavelength. Extensive comparative simulation results have illustrated that by limiting the negative cascading impact to the minimum extent practicable, the proposed approaches can dramatically decrease the blocking probability for a variety of optical network topologies. The dissertation has developed a suite of three fairness-improving adaptive routing algorithms in OBS networks. The adaptive routing schemes consider the transient link congestion at the moment when bursts arrive and use this information to reduce the overall burst loss probability. The proposed schemes also resolve the intrinsic unfairness defect of existing popular signaling protocols. The extensive simulation results have shown that the proposed schemes generally outperform the popular shortest path routing algorithm and the improvement could be substantial. A two-dimensional Markov chain analytical model has also been developed and used to analyze the burst loss probabilities for symmetrical ring networks. The accuracy of the model has been validated by simulation. Effective proactive routing and preemptive channel scheduling have also been proposed to address the conversion cascading constraint in OBS environments. The proactive routing adapts the fairness-improving adaptive routing mentioned earlier to the environment of cascaded wavelength conversions. On the other hand, the preemptive channel scheduling approach uses a dynamic priority for each burst based on the constraint threshold and the current number of performed wavelength conversions. Empirical results have proved that when the cascading constraint is present, both approaches would not only decrease the burst loss rates greatly, but also improve the transmission fairness among bursts with different hop counts to a large extent.

No description available.

A crescente demanda de tráfego em redes de acesso pressiona a melhor utilização das redes backbone, que são utilizadas para transporte de grandes taxas de dados em diversos domínios (Sistemas Autônomos, SAs). Com o aumento destas redes, aumenta-se a complexidade de topologia das interligações entre domínios. Desta maneira, roteamento de tráfego e pontos de interconexão de SAs (nós de borda) são questões importantes para o desempenho destas redes, que são operadas por diversos provedores que podem utilizar protocolos de comunicação distintos. Neste sentido, o roteamento interdomínio apresenta desafios como a publicação ou não de informações de parâmetros de rede de SAs e como tratar esta questão de maneira globalizada, com novos protocolos e suas especificações. Em termos de pontos de interconexão de SAs, a especificação dos locais onde enlaces inter-redes são conectados aos domínios são importantes para seu desempenho, já que são responsáveis por toda troca de tráfego entre redes distintas. O trabalho considera redes ópticas opacas e translúcidas em cenário multidomínio com bandas multigranulares. Neste cenário é estudado um algoritmo de roteamento multidomínio. No trabalho também é feito um planejamento, especificando em quais nós serão conectados enlaces interdomínio. A principal contribuição deste trabalho é o estudo de planejamento de enlaces interdomínio, com a proposta de um método para escolha de nós de borda (sistematização), com objetivo de diminuir a probabilidade de bloqueio interdomínio. A sistematização é baseada em estudos de resultados de algoritmo genético desenvolvido para o mesmo propósito e sua utilização diminui em até 42% o bloqueio interdomínio. Um algoritmo de alocação de banda também foi desenvolvido para redes multidomínio, que considera parâmetros da camada de rede e óptica para o cálculo de peso de enlaces para encontrar caminhos ópticos entre nós fonte e destino. Os resultados mostram diminuição de até 35% no bloqueio interdomínio com a modificação feita em algoritmo proposto na literatura. / The huge demand for traffic in last mile networks push the better utilization of backbone networks, which are used to transport large data rates in several domains (Autonomous Systems, ASs). With this growth, the topology complexity of interdomain links increases. Then, traffic routing and interconnection points of ASs (border nodes) are relevant questions for the performance of these networks, which are managed by several providers that can use distinct communications protocols. Thus, the interdomain routing presents challenges such as the decision on publishing or not the network´s parameters from ASs and how to deal with this issue in a global way, with new protocols and its specifications. For interconnection points between ASs, the points where interdomain links are connected are important for their performances, since they are responsible for all traffic exchange between distinct networks. This work considers opaque and translucent optical networks in a multidomain scenario with multigranular data rates. In this scenario a multidomain routing algorithm is studied and a network planning is developed, specifying the nodes where interdomain links are connected. The main contribution of this work is the planning of interdomain links, with the proposal of a method for border nodes selection (systematization), with the objective of decreasing the interdomain blocking probability. The systematization is based on the results from a genetic algorithm developed for the same purpose and its utilization decrease up to 42% of the interdomain blocking. A bandwidth allocation algorithm was also created for multidomain scenarios, that considers parameters from network and optical layer for the link weight calculation in order to find optimal paths. The results show a decreasing of up to 35% for interdomain blocking with a contribution based on literature\'s work.