Study of special modulation formats for optical communication / Estudo de formatos especiais na modulação digital para comunicações ópticas

AUTOR(ES)
DATA DE PUBLICAÇÃO

2009

RESUMO

This MSc thesis investigates optical modulation formats as an alternative to the use of the traditional intensity binary format NRZ (Non-return-to-zero). Those formats, classified as advanced, represent one of the key technologies aimed to enable the high data volume and broadband, demanded by the present telecommunication market, with cost reduction of transmitted information per bit. Those technologies have been intensevely studied with purpose of overcoming the challenges imposed by the new generation of optical systems, with bit rates from 40 Gb/s. This work focuses on the study of modulation formats most discussed currently, presenting an overview of their main characteristics and implementation techniques. The performance of some intensity and phase formats, in terms of receiver sensitivity, optical filtering cascading, dispersion and nonlinear effects robustness, have been theoretically analyzed from simulations carried out with the commercial software Optisystem v. 7.0, of the Canadian company Optiwave Systems Inc. The analysis has been applied to real optical links, with characteristics that, potentially, demand their use. A cost analysis, based on estimated values associated to devices required for implementing the formats investigated in this work, is also presented. Among the formats studied, those based on RZ (Return-to zero) presented the highest receiver sensitivity and best tolerance to nonlinear effects, in comparison to their equivalent formats, based on NRZ. However, they are less tolerant to dispersive effects and optical filtering cascading. The duobinary format (DB) has shown a weak performance in terms of sensitivity, though has been proved to be the most tolerant to chromatic dispersion and filtering cascading effects. Among all formats, the phase modulation ones presented the highest resistance against nonlinear and dispersive effects.

ASSUNTO(S)

formatos de modulação de fase phase modulation formats dispersão cromática filtering cascading custos de implementação intensity modulation formats efeitos não-lineares nonlinear effects optical communication implementation cost. filtragem em cascata formatos de modulação de intensidade comunicação óptica chromatic dispersion

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