Engenharia Elétrica

URI Permanente desta comunidade

http://repositorio.ufes.br/handle/10/17617

Programa de Pós-Graduação em Engenharia Elétrica

Centro: CT
Telefone: (27) 4009 2663
URL do programa: https://engenhariaeletrica.ufes.br/pt-br/pos-graduacao/PPGEE

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Agora exibindo 1 - 5 de 5

Contribuições 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 de
The 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.
Equalização para sistemas OFDM óptico
(Universidade Federal do Espírito Santo, 2010-03-18) Valentim, Bernardo Lopes; Silva, Jair Adriano Lima; Segatto, Marcelo Eduardo Vieira; Andreão, Rodrigo Varejão; Almeida, Renato Tannure Rotta de
In the last decade the OFDM (Orthogonal Frequency Division Multiplex ) technique had a great growth in wireless and wireline communications. The optical communication area had a great development too in the last years. The union of this two areas has recently started: the OFDM technique and the optical channel. Inside this background this thesis had as main objective study this union and propose a simple optical system wich the dispertion compensation and frequency band allocation lays under OFDM responsability through the pilote tones technique. This technique is named OOFDM (Optical OFDM ). In this thesis we present an optical system composed of standard monomode fiber with intensity modulation and direct detection (IM-DD). We have used a base band OFDM transmission system with hermitian symmetry, 16-QAM mapping and bit loading for band allocation. In order to minimize the chromatic dispersion effects over the optical channel we have developed channel estimation and equalization based on pilot tones and linear interpolation. Our simulations have shown that the transmission in 20 km fiber with 47 Gbps rate, BER ≈ 10−5 and EV M ≈ −22 dB. This overcomes assured this technique actuation in metropolitans networks and as last-mile solution for high rates.
Projeto 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 banca
Optical 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.
Um modelo eficiente para o projeto completo de redes ópticas
(Universidade Federal do Espírito Santo, 2010-05-10) Lima, Fabio de Oliveira; Almeida, Renato Tannure Rotta de; Oliveira, Elias Silva de; Segatto, Marcelo Eduardo Vieira; Assis, Karcius Day Rosario
This dissertation presents a new mixed integer linear programming model for the design of optical communication networks. This is a extensive modeling, which includes the design of logical and physical topology, routing of traffic demands, in addition to routing and wavelength assignment. The formulation supports multiple connections between each pair of network nodes, whether in the physical or logic topology. In its basic version, the model minimizes installation cost of the physical network and the operating cost of the network designed. However, its formulation allows explore various metrics such as network congestion, which was used for comparison with literature. This work presents results of experiments in order to validate the efficiency of this formulation with respect to quality of solutions and computational performance of previous work on the same subject. Also presented is a new way to obtain lower bounds on congestion, with minor computational cost, whose efficiency contrasts with the alternate MILP formulations found in literature.
Uma 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 López
The 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.

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