Performance of Coherent Optical OFDM in WDM System Based on QPSK and 16-QAM Modulation through Super channels

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Author(s) Laith Ali Abdul-Rahaim | Ibraheem Abdullah Murdas | Mayasah Razzaq
Pages 141-158
Volume 5
Issue 3
Date March, 2015
Keywords Coherent Optical Ofdm, Qpsk And 16-Qam, Pdm, Wdm System.

Abstract

In this paper, Polarization Division Multiplexing Coherent Optical Orthogonal Frequency-division Multiplexing (PDM CO-OFDM) system is designed with two modulation formats (QPSK and 16-QAM) at 40 and 100 Gb/s bit rates to show their linear and nonlinear behaver, and the maximum achievement reach at difference data rate. The system is first simulated with a single channel to analyze the performance. Then the system of 8-WDM channels is simulated at 50 GHz (0.4 nm) channel spacing. In order to evaluate the systems performance, spectrum result, electrical constellation diagrams, maximum reach versus the input power curves and BER verses OSNR curves are presented. A reference BER to evaluate the performance of the systems is taken as 1×10-12. PDM CO-OFDM QPSK is found to be the best performance for high capacity networks. In the case of single channel the optimal input power is found to be -2 dBm and 1dBm, which corresponding to the maximum reach of 4080 km and 2480 km at 40 Gb/s and 100 Gb/s respectively. For 8-WDM system the optimum input power was found to be -5 dBm and -2dBm, which corresponding to the maximum reach of 2320 km and 1440km at 40 Gb/s and 100 Gb/s respectively. The advantages of PDM CO-OFDM 16-QAM (improve spectral efficiency, decrease electrical bandwidth) come at the expense of reduced maximum reach and optimum input power. In the case of single channel the optimum input power was found to be -4 dBm and -1dBm, which corresponding to the maximum reach of 1760 km and 960km at 40 Gb/s and 100 Gb/s respectively. For 8-WDM system the optimum input power was determine to be -8 dBm and -4dBm, which give the maximum reach of 1040 km and 480km at 40 Gb/s and 100 Gb/s respectively. Simulation results are obtained using Optisystem (version 11.0) software package.

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