Performance Enhancement of 4-D QAM-MDPSK Optical Transmission Using Set-Partitioning

In multidimensional optical modulation combining both optical intensity and phase signals, inter-dimensional interference (IDI) occurs which degrades the error performances. We propose 4-D set partitioning QAM-MDPSK optical transmissions which lowers the error floor effectively, and more than 3 dB SNR gain was obtained in simulations.