CO-OFDM System with Self-Organizing Map (SOM) for Improving the Spectral Efficiency by the Compensation of Phase Noise

For optical signal transmission to increase the spectral efficiency in coherent systems, the phase noise compensator (PNC) without any pilot and with extreme learning machine (ELM) was proposed earlier. Moreover, in place of fast Fourier transform (FFT), it is preferred to use discrete wavelet transforms (DWPTs), since there is no need of cyclic prefix (CP) for removing the dispersion in ELM-based PNC. In this article, a self-organizing map (SOM)-based phase noise compensator is proposed for 16-QAM modulation format. It has been seen from the simulation results that there is improvement in performance of coherent systems with the proposed technique in comparison with ELM technique. Moreover, this proposed technique is improving the spectral efficiency comparatively.