Fast‐adaptive weighted constellation designs based on hybrid constellation shaping for long‐haul optical fiber communication systems

Abstract A novel fast‐adaptive weighted hybrid‐shaped M‐ary quadrature amplitude modulation (HS‐MQAM) format is proposed in this paper. By introducing a fast‐adaptive weighting factor array related to geometric shaping and probabilistic shaping, the non‐linear impairment is mitigated and the bit error rate (BER) and mutual information (MI) performances are further improved. The simulation results show that the proposed HS‐61QAM outperforms both geometric‐shaped 61 quadrature amplitude modulation (GS‐61QAM) and regular 64QAM, and has more obvious advantages in the long‐haul optical transmission system. For a 120‐Gb/s optical communication system over 10 × 75 km fiber transmission link, compared with GS‐61QAM and regular 64QAM, the proposed approach can achieve about 4.2 and 8 dB OSNR gain at the BER of 10 −2 , and 0.21 and 0.55 bits/symbol MI gain at the OSNR of 22 dB.