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.

The objective of this dissertation is to investigate the factors that influence the design of wide-area wavelength division multiplexing (WDM) optical networks. Wide-area networks are presented as communication networks capable of transporting voice and data communication over large geographical areas. These networks typically span a whole country, region or even continent.The rapid development and maturation of WDM technology over the last decade have been well-received commercially and warrants the development of skills in the field of optical network design.The fundamental purpose of all communication networks and technologies is to satisfy the demand of end-users through the provisioning of capacity over shared and limited physical infrastructure. Consideration of the business aspects related to communications traffic and the grooming thereof are crucial to developing an understanding of customer requirements in terms of the selection and quality of services and applications. Extensive communication networks require complex management techniques that aim to ensure high levels of reliability and revenue generation.An integrated methodology is presented for the design of wide-area WDM optical networks. The methodology harnesses physical, logical, and virtual topologies together with routing and channel assignment (RCA) and clustering processes to enhance objectivity of the design process. A novel approach, based on statistical clustering using the Ward linkage as similarity metric, is introduced for solving the problem of determining the number and positions of the backbone nodes of a wide-area network, otherwise defined as the top level hub nodes of the multi-level network model. The influence of the geographic distribution of network traffic, and the intra/inter-cluster traffic ratios are taken into consideration through utilisation of modified gravity models and novel network node weighting. / Dissertation (MEng)--University of Pretoria, 2005. / Electrical, Electronic and Computer Engineering / unrestricted