Performance comparison of probabilistic amplitude shaping and multidimensional modulation

We numerically evaluate Achievable Information Rate (AIR) and Bit Error Rate (BER) performances of Probabilistic Amplitude Shaping (PAS), eight-dimensional modulation with Bit-Interleaved Coded Modulation Iterative Detection (BICM-ID), and conventional two-dimensional 16QAM (Quadrature Amplitude Modulation) for future high-speed optical communication systems. We confirm that end-to-end BER performances of three modulation formats are almost identical at a same transmission rate when the error correction is used once, and the iterative detection makes the performance of eight-dimensional modulation format better. Further, we verify the BER error-free conditions can be estimated by Normalized General Mutual Information (NGMI) for each modulation format.