The wavelength-division-multiplexed passive optical network (WDM-PON) offers many advantages such as large bandwidth per user, easy management, high network security and low insertion loss enabling long-reach and/or high split-ratio. However, with the rapid development and growing interest for deployment of WDM-PON, the PON systems are becoming increasingly vulnerable to various failures. Therefore, network supervision becomes extremely important to guarantee an appropriate level of network reliability performance. The aim of PON supervision is to provide automated test and diagnostic capability without compromising the available bandwidth for services. An essential function is to detect any kind of deterioration in the network that can cause suspended services and to remotely localize these faults in order to avoid the high cost arising from troubleshooting. In this thesis, we evaluate several existing WDM PON supervision methods, based on which two simple and cost-effective new solutions are proposed to localize fiber failures in WDM PON systems. In the first solution, a conventional optical time domain reflectometry (OTDR) and a switch unit are employed, while in the second method, a novel architecture based on N×N arrayed waveguide grating (AWG) is proposed. Both methods are able to localize failures in feeder fiber and drop fibers without e.g. using expensive tunable OTDRs. A patent has been filed based on the second solution. The first proposed method is validated by simulations using VPI Transmission Maker. According to the results, this supervision method is able to give accurate measurement of many different types of failures that may happen in a fiber link. Furthermore, VPI is examined in terms of its future applicability in modeling complete PON supervision methods based on OTDR.

Dans ce travail de thèse, un aperçu général sur les systèmes PON est présenté et sont étudiés les mécanismes et classification PON existants. Après, nous introduisons notre première contribution qui est un algorithme d'allocation dynamique de bande passante pour EPON. Cet algorithme proposé est désigné comme «hcDBA». Par la suite, une amélioration de l'algorithme de hcDBA avec mécanisme de prédiction précoce est présentée. Notre simulation montre bien que notre algorithme hcDBA est performant comparé aux mécanismes existants en termes de taux de perte de paquets et de délai d’accès. Dans notre seconde contribution, nous sommes intéressés au problème de consommation d’énergie qui est un sujet d’actualité dans les réseaux de télécommunication. Les études montrent aujourd’hui que les réseaux d'accès constituent une partie remarquable de la consommation totale d'énergie dans les réseaux de télécommunication. Les organisations ITU-T et IEEE ont publié la recommandation pour la conversation de l'énergie pour les réseaux PONs. Bien que, la consommation totale d'énergie des nœuds ONU est plus importantes que d'autres équipements dans le réseau d'accès fixe, les normes et la plupart des travaux de recherches ont porté sur les économies d'énergie du côté de ONU. Dans cette thèse, nous sommes concentrés sur une méthode d'efficacité énergétique basée sur la conservation de l'énergie du côté de l’OLT. La méthode proposée permet d’économiser de l'énergie en déplaçant dynamiquement des cartes d’OLT en mode de sommeil profond en fonction des charges de trafic entrant et sortant / In this thesis, general overview about PON systems is presented and existing PON mechanisms and classification are investigated. After, a novel dynamic bandwidth allocation algorithm for EPON is introduced. This proposed algorithm is named as “Half Cycling Dynamic Bandwidth Allocation-hcDBA” by the inspiration of its half cycling processing mode. Later, an improvement of hcDBA algorithm with early prediction mechanism is presented. As a result statement of the study, hcDBA algorithm performs better than existing mechanism in terms of packet loss ratio and access delays. Beside, simulation traffic behavior of EPON’s upstream channel has been investigated in order to support the decision of selecting suitable traffic generator in further studies. Energy conversation is one of the hot topics in telecommunication networks. Access networks constitute remarkable portion of the total energy consumption in telecommunication networks. ITU-T and IEEE organizations published recommendation for energy conversation in PONs. While, total energy consumption of ONUs is more than other equipment in fix access network the standards and most of the researches focused on saving energy at ONU side. In this thesis I focused on an energy efficiency method based on energy conversation on OLT side. The proposed method save energy by dynamically moving OLT cards to deep sleep mode according to the incoming and outgoing traffic loads

The main subject of this diploma thesis is to make a proposal to improve the optical access network for the transmission of Triple play services. I would here to the reader clarify method of proposal of optical network. There are described the kinds of optical access networks with parameters, for which we must look by their construction. There are described the modern methods of construction optical network too. In the theoretical part are discussed used architecture of networks too. I met here known standards, which I compared for big importance by their choice. A reason of construction of optical network are services known like Triple play. These services together with their problems and parameters are here discussed too. At the end of theoretical part I listed here measuring method for getting negative attribute distorting the led signal. In practical part the locality witch use the optical signal as the source of information is ordered. These network use unfit connections and has less possibilities than usual and this is the reason, why is the network not able to supply Triple play in requested quality. At first the analysis of ordered network was needed. Situation was complicated by the fact, that it has been prohibited entrance to me. The structure of network and network parts was known and documented by me. I made the proposals to improve this network in practical part. By the first proposal remained original kind of access network FTTB, but used new parts with higher performance. By the second proposal I made the network FTTH, by which it was possible to use the last haul optical cables with treatment and using new elements. It was needed to create solution by flat units. The resulting proposals are here evaluated, compared and cost evaluated. For rejection of access to optical network I did not make measuring, so I made simulation for variant FTTH for getting some parameters negative acting transmission.

O crescimento do tráfego de serviços de telecomunicações tem aumentado o consumo de energia e, em consequência, aumentado as emissões de CO2 que tem efeitos nocivos sobre o meio ambiente. É assim que a economia de energia torna-se um fator chave no planejamento de redes de telecomunicações. Para garantir a disponibilidade e confiabilidade, as redes possuem arquitetura redundante e são projetadas para suportar a demanda de pico de tráfego. Redes com mecanismos de proteção como proteção dedicada de caminhos (DPP), proveem caminhos alternativos para cada demanda de conexão. Os elementos da rede que suportam esses caminhos estão em estado ativo (consumindo energia), apesar de, na maior parte do tempo, não transportarem tráfego efetivo. Um método para diminuir o gasto de energia é utilizar roteamento adaptado à carga real de tráfego baseado em modo suspenso (estado de baixo consumo de energia que pode passar a estado ativo rapidamente). Assim, o tráfego é roteado com vistas à maximizar a quantidade de componentes que são parte de caminhos de proteção, que podem ser postos em modo suspenso. Neste trabalho, as redes usadas para os testes são a rede europeia Cost239, a rede estadunidense UsNet e a rede brasileira Ipê. Abordamos o problema de economia de energia em redes WDM com DPP através de quatro estratégias de roteamento. Cada uma tem objetivos diferentes, a Shortest Path-DPP (SP-DPP) faz o roteamento por caminho mais curto, a Energy Aware-DPP (EA-DPP) aloca as demandas por enlaces que estejam ativos, a Energy Aware-DPP with Mixing (EA-DPP-MixS) evita que caminhos principais sejam roteados por enlaces que já são parte de caminhos de proteção e a Energy Aware-DPP with Differentation (EA-DPP-Dif) evita a mistura de caminhos por um mesmo enlace. Em nossas simulações computacionais observamos que a EA-DPP-Dif economiza energia de maneira eficiente, mas a probabilidade de bloqueio aumenta. A EA-DPP-MixS diminui o bloqueio em detrimento da energia economizada. Já a SP-DPP e a EA-DPP são menos eficientes na diminuição da energia consumida. É assim que propomos um roteamento com busca de recursos mais ampla, usando cada uma das estratégias. A proposta será chamada de roteamento intensivo. A EA-DPP-Dif-Intensivo diminui a probabilidade de bloqueio e economiza energia mediante modo suspenso. Neste trabalho, analisamos o desempenho das estratégias para cada uma das redes e avaliamos o impacto da energia economizada sobre a probabilidade de bloqueio. A proposta de roteamento i>intensivo diminui a energia consumida em até 50%, diminuindo a probabilidade de bloqueio. Porém, os resultados estão diretamente relacionados com a carga de rede e as características particulares da topologia de cada rede. / The growth of data traffic in telecommunication networks has increased energy consumption and hence increased CO2 emissions, with harmful effects on the environment. Thus, energy saving becomes a key and a differential factor when planning telecommunication networks. In order to guarantee availability and reliability, core networks have redundant architecture and are designed to support peak-hour traffic demand. Networks with dedicated path protection (DPP) mechanisms provide alternative paths for each connection request. Network elements supporting these paths are in active state (consuming energy), although most of the time they dont carry traffic. One technique to decrease energy waste is by adaptive real traffic routing using sleep mode (a low energy consumption state which is able to rapidly change to an active state). Thus, traffic is routed in order to maximize the amount of network components used by protection paths, which can be set in sleep mode. In this work, European Cost239, American UsNet and Brazilian Ipê networks were used in computational simulations. We addressed the energy saving problem in WDM networks with DPP through four routing strategies, each with different goals. The Shorthest Path-Dedicated Path Protection (SP-DPP) technique uses shortest path for routing, Energy Aware-Dedicated Path Protection (EA-DPP) allocates demands in active links, Energy Aware-Dedicated Path Protection with Mixing (EA-DPP-MixS) prevents primary paths to be formed by links that are already part of the protection paths and Energy Aware-Dedicated Path Protection with Differentation (EA-DPP-Dif) prevents mixing primary and protection paths through the same link. We observe that EA-DPP-Dif efficiently saved energy, however blocking probability has increased. EA-DPP-MixS reduced blocking rather than saved energy. At least, SP-DPP and EA-DPP are less efficient in reducing energy consumption. Hence, we propose a wider resource search routing, the in-depth routing, using each of these strategies. Thus, EA-DPP-Dif-In-depth decreased blocking probability while maintaining energy saving through sleep mode. In this work, we analyze the strategies performance for each network and evaluate the impact of energy saved on the blocking probability. Our in-depth routing strategy reduced the energy consumption up to 50%, decreasing blocking probability. However, the results are directly related with the network load and the specific properties of each network topology.

Due to the tremendous growth of traffic volume caused by both exponential increase of number of Internet users and continual emergence of new bandwidth demanding applications, high capacity networks are required in order to satisfactorily handle the extremely large amount of traffic. Hence, optical fiber communication is the key technology for the network infrastructure. This thesis addresses design, analysis and simulation of access and core networks targeting important research problems, which need to be tackled for the effective realization of next generation optical networks. Among different fiber access architectures, passive optical network (PON) is considered as the most promising alternative for the last mile connection due to its relatively low cost and resource efficiency. The inherent bursty nature of the user generated traffic results in dynamically changing bandwidth demand on per subscriber basis. In addition, access networks are required to support differentiated quality of service and accommodate multiple service providers. To address these problems we proposed three novel scheduling algorithms to efficiently realize dynamic bandwidth allocation in PON, along with guaranteeing both the priority and fairness of the differentiated services among multiple users and/or service providers. Meanwhile, because of the increasing significance of reliable access to network services, an efficient fault management mechanism needs to be provided in PON. In addition, access networks are very cost sensitive and the cost of protection should be kept as low as possible. Therefore, we proposed three novel cost-effective protection architectures keeping in mind that reliability requirement in access networks should be satisfied at the minimal cost. Regarding the optical core networks, replacing electronic routers with all-optical switching nodes can offer significant advantages in realizing high capacity networks. Because of the technological limitations for realizing all-optical nodes, the focus is put on the ingenious architecture design. Therefore, we contributed on novel switching node architectures for optical circuit and packet switching networks. Furthermore, we addressed different aspects of routing and wavelength assignment (RWA) problem, which is an important and hard task to be solved in wavelength routed networks. First, we proposed an approach based on the information summary protocol to reduce the large amount of control overhead needed for dissemination of the link state information in the case of adaptive routing. In addition, transparency in optical networks may cause vulnerability to physical layer attacks. To target this critical security related issue, we proposed an RWA solution to minimize the possible reachability of a jamming attack. Finally, in order to evaluate our ideas we developed two tailor-made simulators based on discrete event driven system for the detailed studies of PON and switched optical networks. Moreover, the proposed tabu search heuristic for our RWA solution was implemented in C++. / QC 20100707

This thesis focuses on the survivable routing problem in WDM mesh networks where the objective is to minimize the total number of wavelengths used for establishing working and protection paths in the WDM networks. The past studies for survivable routing suffers from the scalability problem when the number of nodes/links or connection requests grow in the network. In this thesis, a novel path based shared protection framework namely Inter-Group Shared protection (I-GSP) is proposed where the traffic matrix can be divided into multiple protection groups (PGs) based on specific grouping policy. Optimization is performed on these PGs such that sharing of protection wavelengths is considered not only inside a PG, but between the PGs. Simulation results show that I-GSP based integer linear programming model, namely, ILP-II solves the networks in a reasonable amount of time for which a regular integer linear programming formulation, namely, ILP-I becomes computationally intractable. For most of the cases the gap between the optimal solution and the ILP-II ranges between (2-16)%. The proposed ILP-II model yields a scalable solution for the capacity planning in the survivable optical networks based on the proposed I-GSP protection architecture.

This thesis focuses on the survivable routing problem in WDM mesh networks where the objective is to minimize the total number of wavelengths used for establishing working and protection paths in the WDM networks. The past studies for survivable routing suffers from the scalability problem when the number of nodes/links or connection requests grow in the network. In this thesis, a novel path based shared protection framework namely Inter-Group Shared protection (I-GSP) is proposed where the traffic matrix can be divided into multiple protection groups (PGs) based on specific grouping policy. Optimization is performed on these PGs such that sharing of protection wavelengths is considered not only inside a PG, but between the PGs. Simulation results show that I-GSP based integer linear programming model, namely, ILP-II solves the networks in a reasonable amount of time for which a regular integer linear programming formulation, namely, ILP-I becomes computationally intractable. For most of the cases the gap between the optimal solution and the ILP-II ranges between (2-16)%. The proposed ILP-II model yields a scalable solution for the capacity planning in the survivable optical networks based on the proposed I-GSP protection architecture.

In response to the development of a next-generation networking (NGN) generalized multi-protocol label switching (GMPLS) technology is required for automatically switched optical network (ASON). Reconfigurable optical add-drop multiplexer (ROADM) is an indispensable device for the ASON, and the dense wavelength division multiplexed (DWDM) signals can be transmitted through the network under the management of the network administrator to configure dynamic customer needs and the desired quality of service (QoS). The ROADM can also increase the efficiency of utilizing the existing capacity of the optical fiber lines and can reduce or waive to set up additional optical fiber lines. This thesis studies a novel ROADM based on the arrayed waveguide grating (AWG) and the fiber Bragg grating (FBG) to overcome that the current ROADM cannot process that the input signal channels is greater than the wavelengths channels of AWG. Many types of ROADMs have been proposed and realized through different optical devices. Among these, hybrid optical circulator and FBG based ROADM is more attractive because of its low crosstalk and polarization insensitivity. However, it still suffers from many component counts and high insertion losses due to the use of many circulators and a multiplexer-demultiplexer pair. In this master thesis, we focus on demonstrating a novel ROADM and evaluating its crosstalk performance. It is found that the proposed ROADM has the advantage on extending the number of wavelength signal to make the system configurable and flexible.

abstract: The integration of passive optical networks (PONs) and wireless mesh networks (WMNs) into Fiber-Wireless (FiWi) networks has recently emerged as a promising strategy for providing flexible network services at relative high transmission rates. This work investigates the effectiveness of localized routing that prioritizes transmissions over the local gateway to the optical network and avoids wireless packet transmissions in radio zones that do not contain the packet source or destination. Existing routing schemes for FiWi networks consider mainly hop-count and delay metrics over a flat WMN node topology and do not specifically prioritize the local network structure. The combination of clustered and localized routing (CluLoR) performs better in terms of throughput-delay compared to routing schemes that are based on minimum hop-count which do not consider traffic localization. Subsequently, this work also investigates the packet delays when relatively low-rate traffic that has traversed a wireless network is mixed with conventional high-rate PON-only traffic. A range of different FiWi network architectures with different dynamic bandwidth allocation (DBA) mechanisms is considered. The grouping of the optical network units (ONUs) in the double-phase polling (DPP) DBA mechanism in long-range (order of 100~Km) FiWi networks is closely examined, and a novel grouping by cycle length (GCL) strategy that achieves favorable packet delay performance is introduced. At the end, this work proposes a novel backhaul network architecture based on a Smart Gateway (Sm-GW) between the small cell base stations (e.g., LTE eNBs) and the conventional backhaul gateways, e.g., LTE Servicing/Packet Gateway (S/P-GW). The Sm-GW accommodates flexible number of small cells while reducing the infrastructure requirements at the S-GW of LTE backhaul. In contrast to existing methods, the proposed Sm-GW incorporates the scheduling mechanisms to achieve the network fairness while sharing the resources among all the connected small cells base stations. / Dissertation/Thesis / Doctoral Dissertation Electrical Engineering 2016

Orientadores: Nelson Luis Saldanha da Fonseca, Marcos Rogério Salvador / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Computação / Made available in DSpace on 2018-08-16T21:55:02Z (GMT). No. of bitstreams: 1 Figueiredo_GustavoBittencourt_D.pdf: 3834927 bytes, checksum: ec5c4028c4e9daddb1935b922f19a729 (MD5) Previous issue date: 2009 / Resumo: A demanda cada vez maior por largura de banda tem levado a implantação de uma Internet de nova geração, com backbones com alta capacidade de transmissão baseados nas tecnologia de multiplexação Wavelength Division Multiplexing (WDM). Para o eficiente transporte do tráfego da Internet, é necessário o uso de um paradigma de transmissão flexível e capaz de se adequar às flutuações do tráfego da rede. Devido a imaturidade da tecnologia de comutação de pacotes ópticos (do inglês Optical Packet Switching - OPS) e das desvantagens da comutação de circuitos ópticos (do inglês Optical Circuit Switching - OCS), a comutação de rajadas ópticas (do inglês Optical Burst Switching - OBS) é uma opção atrativa, dada a sua flexibilidade, maturidade tecnológica e eficiência. Nas redes OBS, os pacotes IP são agrupados em unidades de transmissão maiores, denominadas rajadas, cuja transmissão é precedida por um pacote de controle que sinaliza, entre outras coisas, o momento em que os recursos devem ser reservados. O processo de reserva de recursos é feito em uma via, o que indica que o transmissor não necessita aguardar confirmação por parte do receptor antes de enviar as rajadas. Se não houver recursos disponíveis no momento da transmissão, a rajada é sumariamente descartada. O fato do transmissor não esperar confirmação por parte do receptor para a transmissão das rajadas, implica na necessidade de um dimensionamento adequado da rede, sob pena de alta probabilidade de bloqueio. Nesta tese, são propostos diferentes mecanismos de controle para redes OBS que podem ser usados conjuntamente, a fim de melhorar o desempenho da rede. Esta tese apresenta, inicialmente, um estudo sobre a ocorrência de transformações nas propriedades estatísticas do tráfego submetido à redes OBS, devido ao processo de montagem de rajadas, que ocorre na borda das redes OBS. Verificou-se que a transformação do tráfego está relacionada à escala limitante do tráfego multifractal. Além disso, verificou-se que o tráfego transformado em monofractal demanda menos recursos da rede. Assim, foi proposto um método para identificação automática da escala limitante de fluxos multifractais, além de um conjunto de algoritmos de montagem capazes de induzir as transformações nas propriedades estatísticas do tráfego. Foi proposto, também, na tese, um algoritmo adaptativo para escalonamento de canais em redes OBS que aloca comprimentos de onda com menor chance de reutilização por rajadas futuras. Analisou-se também, nesta tese, o problema de escalonamento em lote de canais em redes OBS. Foram propostos dois algoritmos ótimos: um para o caso quando as requisições que transitam pela rede não possuem diferenciação, e outro para quando a rede exige tratamento diferenciado das requisições. Além disso, foi proposta uma estratégia para a formação dos lotes que pode ser considerada uma extinção do protocolo Just Enough Time - JET. Os mecanismos propostos foram avaliados em comparação com outros existentes na literatura. Os resultados obtidos evidenciam ganhos e a adequabilidade para implementação em redes OBS, a fim de melhorar o desempenho destas redes / Abstract: The growth of the number of Internet users has led to the increase of the bandwidth demand which, consequently, led to the need of adoption of high capacity links in the Internet backbone. Moreover, a flexible switching paradigm is necessary to provide efficient transport of Internet traffic. Due to the limitations of both optical packet switching (OPS) and optical circuit switching (OCS), optical burst switching (OBS) emerged as an attractive switching choice. In OBS networks, IP packets are aggregated into larger transmission units, called bursts. The transmission of a burst follows the transmission of its associated control packet, which carries among other information, the time that bandwidth should be reserved for that burst. In OBS networks, the process of bandwidth reservation is done in one way, which means that the burst is discarded if there is not enough bandwidth for the transmission of the burst at a node when the burst arrives. Therefore, scheduling and burst assembling mechanisms should be conceived to avoid burst loss as well as to support the quality of service of applications running over an OBS network. Initially, a study on traffic transformation at the edge of the network was conducted for the derivation of efficient mechanisms. The study aimed at verifying the changes of traffic descriptors due to the assembly of packets into bursts. It was found that the cutoff time scale of multifractal traffic impacts the traffic transformation. Moreover, it was found that these transformations can lead to smaller bandwidth demands. Based on findings, an automatic method was proposed for the identification of the cutoff time scale of multifractal flows, and a set of burst assembly algorithms for inducing such transformations were introduced. Furthermore, an adaptive algorithm for channel scheduling that allocates wavelengths with small chances of being reused by future requests was proposed. Two optimal algorithms were introduced for the provisioning of differentiated services. In addition, a batch assembly strategy, which can be considered an extension of JET protocol, was created. The proposed mechanisms were evaluated in comparison with other mechanisms in the literature via simulation. Results evince that the mechanisms introduced in this thesis are effective for the improvement of OBS networks performance / Doutorado / Redes de Computadores / Doutor em Ciência da Computação