Transmission performance comparison of 128-SP-QAM and PM-16QAM in a WDM system

We numerically and experimentally compared the BER performance of 128-level set-partitioning quadrature amplitude modulation (128-SP-QAM) and polarization multiplexed 16-ary quadrature amplitude modulation (PM-16QAM). From our experimental results and numerical simulation, it can be concluded that 128-SP-QAM has significant BER improvement compared to PM-16QAM when optical signal to noise ratio (OSNR) is high. However, when it comes to low OSNR scenario such as transmission over a very long distance, 128-SP-QAM and PM-16QAM have similar performance.