Survivability aspects of future optical backbone networks

In huidige glasvezelnetwerken kan een enkele vezel een gigantische hoeveelheid data dragen, ruwweg het equivalent van 25 miljoen gelijktijdige telefoongesprekken. Hierdoor zullen netwerkstoringen, zoals breuken van een glasvezelkabel, de communicatie van een groot aantal eindgebruikers verstoren. Netwerkoperatoren kiezen er dan ook voor om hun netwerk zo te bouwen dat zulke grote storingen automatisch opgevangen worden. Dit proefschrift spitst zich toe op twee aspecten rond de overleefbaarheid in toekomstige optische netwerken. De eerste doelstelling die beoogd wordt is het tot stand brengen vanrobuuste dataverbindingen over meerdere netwerken. Door voldoende betrouwbare verbindingen tot stand te brengen over een infrastructuur die niet door een enkele entiteit wordt beheerd kan men bv. weredwijd Internettelevisie van hoge kwaliteit aanbieden. De bestudeerde oplossing heeft niet enkel tot doel om deze zeer betrouwbare verbinding te berekenen, maar ook om dit te bewerkstelligen met een minimum aan gebruikte netwerkcapaciteit. De tweede doelstelling was om een antwoord te formuleren om de vraag hoe het toepassen van optische schakelsystemen gebaseerd op herconfigureerbare optische multiplexers een impact heeft op de overleefbaarheid van een optisch netwerk. Bij lagere volumes hebben optisch geschakelde netwerken weinig voordeel van dergelijke gesofistikeerde methoden. Elektronisch geschakelde netwerken vertonen geen afhankelijkheid van het datavolume en hebben altijd baat bij optimalisatie

IMPAIRMENT AWARE DYNAMIC ROUTING AND WAVELENGTH ASSIGNMENT IN WDM NETWORKS

Optical networks play a major role in supporting the traffic in backbone computer networks. Routing and Wavelength Assignment (RWA) is the technique used to establish a light-path from a source node to a destination node in a Wavelength Division Multiplexed (WDM) optical network. As an optical signal propagates through the network, the quality of the signal degrades due to physical layer impairments. To address this problem, in translucent WDM networks, the signal is regenerated at intervals. The main objective of this research is to propose a fast heuristic for dynamic lightpath allocation in translucent WDM networks and to compare the heuristic with an optimal algorithm that was proposed recently

Impairment Aware Routing in Translucent Optical Networks

Optical networks are ideally suited to meet today\u27s rapidly increasing bandwidth demands due to the large fiber bandwidth capacity, low attenuation, low distortion and low cost. When an optical signal propagates along the fiber links, its quality degrades due to physical layer impairments such as optical noise, chromatic dispersion, polarization mode dispersion and nonlinear effects. As a result, bit error rate (BER) may become so high that signal may not be properly detected at the receiver. In order to address this problem, we have developed an impairment aware dynamic routing and wavelength assignment (IA-RWA) algorithm. Our algorithm not only takes into account the physical layer impairments but also resolves any wavelength conflict if there is a cycle in the path from a source to a destination. Our results indicate that the proposed algorithm significantly reduce the blocking probability in dynamic lightpath allocation if the impact of physical layer impairments is compensated by the use of regenerators

Impairment -Aware Static Route and Wavelength Assignment in WDM Networks

Routing and Wavelength Assignment (RWA) is a fundamentally important aspect of WDM optical network design. RWA is performed to determine a route and wavelength for each demand requesting resources between a given source and destination node. Classic RWA has only been concerned with determining a route while only taking into account network layer wavelength availability constraints. In recent years the size of WDM optical communication networks has exponentially increased in size. Resulting in the use of very long fibers for interconnecting nodes. On these modern WDM networks, researchers have identified at the physical layer, linear and non-linear impairments. Impairment occurs during the propagation of optical signals across a fiber cable and within the optical switching fabric of routing equipment. These impairments have the potential to either, greatly reduce the efficiency of WDM optical networks, or to completely render lightpaths unusable. Impairment-aware routing and wavelength assignment (IA-RWA) takes different types of impairments of lightpaths into account, while performing the RWA. The use of IA-RWA improves the quality of transmission among lightpaths as well as reduce the blocking ratio. A new heuristic for IA-RWA has been reported in this thesis for use in WDM optical network planning and design. This heuristic takes both linear and non-linear impairments into account during the RWA process. The heuristic uses existing techniques from graph theory, operations research, and optical network design, to determine an IA-RWA in an efficient manner

Reconfigurable optical networks with dynamic physical impairments

Orientador: Helio WaldmanDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de ComputaçãoResumo: As redes ópticas reconfiguráveis compõem o backbone de grande parte das redes de transporte em operação ao redor do mundo. No entanto, os desafios para ampliar a capacidade e eficiência destas redes ainda são enormes. Com objetivo de maximizar a carga útil de tráfego suportada nas redes ópticas WDM reconfiguráveis é de fundamental importância adotar eficientes algoritmos RWA. Os algoritmos RWA são responsáveis pela escolha adequada de recursos na rede para provisionar novas conexões de forma a maximizar a probabilidade de atendimento das futuras conexões. Nesta dissertação, o problema RWA será investigado sob diversas novas perspectivas através de um ambiente de simulação. Com a preocupação de retratar os reais problemas vivenciados pelas redes ópticas reconfiguráveis, os elementos de rede foram modelados de acordo com as tecnologias e arquiteturas atualmente empregadas no mercado. No caso dos elementos de comutação ROADM e amplificadores EDFA, serão adotadas modelagens ainda não exploradas na literatura relacionada ao problema RWA. Diversos estudos abordam o problema RWA levando em consideração as degradações de camada física na escolha dos recursos apropriados para o provisionamento de novas conexões. Esta abordagem é conhecida na literatura como RWA-IA. Neste trabalho será adotada uma abordagem mais realista, considerando não apenas as condições de camada física para o provisionamento de novas conexões, mas também o impacto na camada física causado pelo estabelecimento de novas conexões nas demais já ativas na rede. Ainda neste trabalho serão propostos dois novos algoritmos de alocação de comprimento de onda sensíveis às degradações dinâmicas da camada física. Um extenso estudo com a avaliação de desempenho destes algoritmos será realizado, contemplando também um estudo comparativo com outros algoritmos encontrados na literatura e utilizados com frequência no mercado. Os algoritmos propostos demonstraram excelente desempenho, conseguindo inclusive superar o desempenho dos demais algoritmos avaliados em termos de probabilidade de bloqueioAbstract: Reconfigurable optical networks has been adopted as the backbone solution by most of transport networks around the world. However, in order to expand the capacity and efficiency of these networks, there are still many challenges to overcome. In order to improve the reconfigurable optical network capacity is very important to work with efficient RWA algorithms capable to find appropriate network resources for new lightpaths and, at the same, to minimize the blocking probability of future demands. In this dissertation, the RWA problem will be investigated under several new perspectives through a simulation environment. Committed to retract real problems experienced by reconfigurable optical networks, network elements were design according to the technologies and architectures currently employed in the industry. The ROADM switching elements and EDFA amplifiers were design in an unprecedented way in the RWA literature. Several studies addressing the RWA problem have already incorporated the physical layer impairments in order to find the appropriate resources for establishing new lightpaths. This approach has become known in the literature as Impairment Aware RWA (IA-RWA). In this dissertation, we adopted a more realistic approach to the RWA-IA problem, also considering the impact on the physical layer caused by the establishment of new connections in the others already established in the network. Moreover, in this work we will propose two new wavelength assignment algorithms aware to the physical layer dynamic impairments. An extensive performance evaluation study about these algorithms will be performed, also contemplating a comparative study with other algorithms from the literature and widely used in the industry. The proposed new algorithms have shown excellent performance, outperforming other algorithms evaluated in terms of blocking probabilityMestradoTelecomunicações e TelemáticaMestre em Engenharia Elétric

Advances in Computer Recognition, Image Processing and Communications, Selected Papers from CORES 2021 and IP&C 2021

As almost all human activities have been moved online due to the pandemic, novel robust and efficient approaches and further research have been in higher demand in the field of computer science and telecommunication. Therefore, this (reprint) book contains 13 high-quality papers presenting advancements in theoretical and practical aspects of computer recognition, pattern recognition, image processing and machine learning (shallow and deep), including, in particular, novel implementations of these techniques in the areas of modern telecommunications and cybersecurity