Carrier Recovery Schemes of 16-QAM in Repeater-Less Transmission System

In this paper, an off-line processing scheme is proposed to solve the damage of 16-ary quadrature amplitude modulation (16-QAM) signal caused by laser linewidth and frequency deviation by adopting block approximate processing method without considering the reference value of ring segmentation. The simulation tool based on VPItransmissionMaker10.1 is equipped with the 16-QAM signal transmission system and the off-line DSP module is applied to MATLAB to prove the method proposed in this paper. The simulation results show that the proposed method can complete the compensation of frequency offset and phase offset, and recover 16-QAM signal with the symbol rate of 24-GBaud.