Rate-adaptive non-binary-LDPC-coded polarization-multiplexed multilevel modulation with coherent detection for optically-routed networks

Adaptation to changing conditions in the transmission medium is a particularly desired property in optically-routed networks due to their heterogeneous nature. Toward this goal, we propose in this paper rate-adaptive polarization multiplexed coded multilevel modulation schemes based on non-binary quasi-cyclic low-density parity-check (LDPC) codes and coherent detection. The proposed scheme can support data rates at 100 Gb/s and beyond while offering comparably better forward error correction performance with less computational complexity than bit-interleaved coded modulation schemes. The ability to adapt changing channel conditions is achieved by exploiting the inherent structure of quasi-cyclic LDPC codes.