Efficient Chromatic and Residual Dispersion Post compensation for Coherent Optical OFDM

Abstract

In lieu of other impairments associated with fiber communication such as; fiber nonlinearity, fading, Intersymbol Interference (ISI), Intercarrier Interference (ICI), Chromatic Dispersion (CD) is compensated by Coherent Optical Orthogonal Frequency Division Multiplexing (CO-OFDM) technique. This technique divides the available bandwidth into five subbands, each modulated at a low data rate and postcompensated for the Chromatic Dispersion. Implementation of the Optical OFDM involves the use of Digital Signal Processing (DSP); Inverse Discrete Fourier Transform (IDFT) and Discrete Fourier Transform (DFT) both at the transmitter and receiver respectively. The Residual Dispersion left after CD is compensated by Constellation Adjustment Method (CAM). Simulation results using Optisystem show 107-Gb/s single-channel transmission over 1000-km Standard Single Mode Fiber (SSMF) with polarization division multiplexing Four Quadrature Amplitude Multiplexing (4-QAM) using 128 DFT, 82 subcarriers, 5 pilot subcarriers and 16 guard intervals. Equally, the simulation analysis were done at various transmission distances, OFDM systems show a better Min. BER and Max. Q factor than the conventional Non-Return to Zero (NRZ) systems.