Ciência-IUL    Autores    Luís Gonçalo Lecoq Vences e Costa Cancela    Projetos de Investigação
Projetos de Investigação
Physical Impairment Modelling in Flexible Optical Node Architectures
One major goal in this project is to develop an analytical formulation,as well as a stochastic Monte-Carlo (MC) simulator, that allow us to study in a rigorous way the impact of in-band crosstalk, both incoherent and coherent, originated in CDC ROADMs in the performance of flexible grid networks, considering 16-QAM and 64-QAM 400 Gbps signals.On a network-side perspective, the emergence of modulation formats with higher-order constellations and, consequently, with stricter performance margins has increased the importance of physical impairment awareness in the network planning process. Thus, it is essential to incorporate the effects of in-band crosstalk, along with other effects, in an impairment-aware routing and spectrum assignment (RSA) framework. This framework should be able to efficiently provision paths and spectrum for superchannels based on M-QAM carriers in a CDC-ROADM network, while using the physical model as a performance validation tool for candidate optical paths
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Analysis and Mitigation of crosstalk Effects in multicore fibre -based Networks
Neste projecto, desenvolvem-se e analisam-se modelos para a caracterização estatística dos efeitos da ICXT em MCFs, propõem-se técnicas para a mitigação daqueles efeitos em redes baseadas em MCF, e usam-se aqueles modelos e técnicas no desenvolvimento de algoritmos de encaminhamento e alocação de espectro e núcleo (RSCA) em redes ópticas elásticas (EONs). O projecto foca-se principalmente em estudos de simulação e teóricos sobre a caracterização estatística dos efeitos da ICXT em MCF e sobre técnicas de modulação para mitigação daqueles efeitos em redes baseadas em MCF. Estes estudos são complementados pela realização de demonstrações laboratoriais dos principais resultados de simulação e teóricos. O projecto tira proveito dos conhecimentos de trabalho experimental (em laboratório) e de projecto de sistemas baseados em tecnologia de MCFs do NICT (National Institute of Information and Communications Technology, Japão) combinado com a experiência do IT (Grupo de Comunicações Ópticas do pólo de Lisboa do Instituto de Telecomunicações) na modelação teórica e análise de sistemas e redes de telecomunicações por fibra óptica.
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In-band crosstalk in optical communications systems with differential direct detection
This project is within the optical communication networks area. In particular, in the area that studies the physical constraints in optical networks.One of the most severe limitations in the network physical layer is crosstalk. This phenomenon has its origin, primarily, in the imperfect isolation of optical components, such as optical switches, multiplexers, and demultiplexers, that are key components in the design of an optical node. The type of crosstalk that causes the higher degradation to the system performance is the in-band crosstalk, in which the interfering (crosstalk) signals and the selected signal, despite coming from distinct optical sources, have the same nominal wavelength.The main objectives of this project are:* Develop a formalism to evaluate the impact of in-band crosstalk in optical DQPSK systems.* Evaluate the impact of in-band crosstalk in a DPSK and DQPSK systems when the signal propagates through an optical network. Each optical node is formed by an optical switching architecture, optical amplifiers, optical filters, and possibly wavelength converters. * Implement Monte Carlo (MC) simulation to study the impact of ASE noise and in-band crosstalk on the performance of DPSK and DQPSK systems and confirm the analytical results.* Implement the multicanonical Monte Carlo (MMC) method to simulate the tails of the probability density function of the decision variable and to obtain lower values of the bit error rate (BER) than in the MC standard procedure.* Evaluate by simulation the impact of in-band crosstalk in optical networks with DPSK and DQPSK signals, for a rigorous model of the optical node and validate the analytical tool developed for this case.
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