Channel Estimation for Coherent Optical OFDM System with PDM 64-QAM

In this study, we first present a coherent optical orthogonal frequency division multiplexing (CO-OFDM)with polarization division multiplexing (PDM)and 64-order quadrature amplitude modulation (QAM). We then proposed an efficient channel estimation method based on minimum mean square error(MMSE)to further improve the performance of the system. The results show that a CO-OFDM system use of PDM, high order QAM technology, and our improved MMSE channel estimation algorithm can significantly improve the transmission performance and built higher speed rates, large capacity and long haul distance transmission via optical networks.