Doutorado em Engenharia Elétrica
URI Permanente para esta coleção
Nível: Doutorado
Ano de início:
Conceito atual na CAPES:
Ato normativo:
Periodicidade de seleção:
Área(s) de concentração:
Url do curso:
Navegar
Navegando Doutorado em Engenharia Elétrica por Autor "Almeida, Renato Tannure Rotta de"
Agora exibindo 1 - 3 de 3
Resultados por página
Opções de Ordenação
- ItemContribuições para o projeto de grooming de tráfego sobre redes ópticas WDM(Universidade Federal do Espírito Santo, 2008-10-10) Resendo, Leandro Colombi; Pires, João José de Oliveira; Ribeiro, Moisés Renato Nunes; Mateus, Geraldo Robson; Almeida, Renato Tannure Rotta de; Garcia, Anilton Salles; Oliveira, Elias Silva deThe Traffic Grooming Problem (TGP) consists in how to arrange low-bandwidth connection requests into high-capacity lightpaths efficiently. TGP solution aims at improving network capacity utilization. The minimal number optoelectronic transceivers that enable accommodating traffic demands is often used as the objec- tive function for solving TGP. However, TGP belongs to a class of NP-hard problems and optimal solutions are only possible to be found within feasible processing time for small networks (e.g., 6 nodes). This work proposes novel Integer Linear Pro- gramming (ILP) models, heuristic and a hybrid solution to TGP for medium-sized (i.e., around 12 nodes) translucent networks. Initially, ILP models using node-link and link-path paradigms are proposed and their solutions are compared. These models lay the foundations for more complex models addressing issues on network design. A hybrid method is then proposed. It makes use of a heuristic for selecting lightpaths (i.e., the virtual topology) and an ILP model to route the traffic demands over both physical and virtual topologies efficiently. The practical implications of such approach is that it allows, for the first time, the quantification of benefits of transparent lightpaths in terms of transceiver count reduction. Moreover, the miti-gation of transit traffic processing in the electronic layer is also analyzed. For large networks the ILP phase in the hybrid approach again becomes the bottleneck for optimal network design and a fully heuristic solution is necessary. This work shows that efficient solutions can be found through a simple and fast tool for network design without the need of complex parameter tuning, as comparisons with results obtained from solving the hybrid model. Finally, the integration of TGP with survivability is proposed. This work puts forward ILP models for an iterative method using two ILP models to design networks with incremental protection with minimal num- ber of transceivers in mesh networks. Dual Node Interconnected (DNI) multi-ring topologies are studied under inter-ring traffic protection using Virtual Ring (VR) and Drop and Continue (D&C) strategies. Results compare optimal solutions that take into account traffic grooming for different network scenarios including opaque vs. translucent configurations and inter vs. intra traffic growth.
- ItemProjeto de Topologias Virtuais para Redes Opticas Multiserviço(Universidade Federal do Espírito Santo, 2005-08-05) Almeida, Renato Tannure Rotta de; Calmon, Luiz de Calazans; 1º membro da bancaOptical communication systems have emerged as the best solution for large scale data transport network implementation, providing optical channels with very high bit rates and covering large distances with low error probability. The entire bandwidth of the optical fibers became available with the development of the wavelength division multiplexing (WDM) technology, which allows several channels of different wavelengths to share the same physical links. The increase in physical link capacity was not the only benefit of WDM. The development of WDM optical devices, e.g., optical switches, multiplexers, demultiplexers, and tunable devices, has allowed the implementation of wavelength-routed optical networks. In such networks, the optical channels, also called lightpaths, are not restricted to the physical link edges. Wavelength routing detaches the lightpath configuration, or virtual topology, from the physical topology, permitting lightpaths to optically bypass intermediate nodes, until it reaches the destination node. In this Thesis we propose a Mixed-Integer Linear Programming (MILP) formulation to design virtual topologies in wavelength-routed optical networks, considering as objective function the minimization of the traffic forwarded electronically at the network nodes. Our goal is twofold. Firstly, to reduce processing requirements of the electronic routers, and secondly, to get the most transparent traffic distribution for a given traffic matrix, using the available optical resources at the nodes. Traffic segregation in classes was also included in the formulation, allowing differentiated routing criteria to each class. The proposed formulation was applied successfully to reasonable sized networks yielding optimal solutions in few minutes. To the best knowledge of the authors, this is the first report of a large MILP formulation that optimizes virtual topology and traffic routing of optical networks with low computational cost.
- ItemUma contribuição ao modelamento analítico em amplificadores Raman(Universidade Federal do Espírito Santo, 2007-08-14) Cani, Shirley Peroni Neves; Pontes, Maria José; Segatto, Marcelo Eduardo Vieira; Ribeiro, Moisés Renato Nunes; Almeida, Renato Tannure Rotta de; Giraldi, Maria Thereza Miranda Rocco; Barbero, Andrés Pablo LópezThe recent advances in high power laser and WDM technologies have contributed to the increasing interest in broadband optical Raman amplifiers. The amplification of signals in such amplifiers occurs due to the stimulated Raman scattering nonlinear effect that occurs along the propagation of pumps and signals in an optical fiber link. The Raman amplifier can be implemented over the entire transmission fiber link, known as distributed Raman amplifier, or over a smaller fiber link in series with the transmission fiber, known as lumped Raman amplifier. One of the challenges in Raman amplifiers is to set the pump power and wavelengths to obtain a desired gain and ripple in a determined signal band. Some methods of optimization have already been proposed, and most of them resort to numerical solutions. This work describes the development of an analytical model of power evolution and signal gain in multi-pumps and multi-signals Raman amplifiers. The analytical model includes in its formulation the Raman interaction among all the frequencies and the polarization effects. Amplified spontaneous emission noise effects and elastic scattering of the light are neglected in the analytical model. The analytical model proposed is validated comparing analytical results with those obtained by numerical solution and experimental data, with a vast combination of input parameters. The comparisons have showed that the analytical model is a reliable and fast tool to design multi-pumps and multi-signal Raman amplifiers.