An experimental investigation of high-rate nonbinary quasi-cyclic LDPC-coded modulation for coherent optical communication

Abstract

A rate-0.83 nonbinary quasi-cyclic LDPC-coded modulation scheme is experimentally investigated in a coherent optical QPSK system. Large coding gains are observed for both I/Q well balanced and highly imbalanced cases. By increasing the BCJR equalizer's memory, degradation caused by insufficient receiver bandwidth is successfully mitigated.