A cascaded bit-weighted distribution matching for LDPC-coded PS-64QAM DMT in a high-speed Unamplified IM-DD system

作     者：Zhang, Long Yang, Xiongwei Wang, Kaihui Liu, Jiaxuan Wang, Chen Shi, Junting He, Wenzhong Wu, Ying Zhao, Feng Zhou, Wen Yu, Jianjun 

作者机构：Fudan Univ State Key Lab ASIC & Syst Key Lab Informat Sci Electromagnet Waves MoE Shanghai 200433 Peoples R China Fudan Univ Sch Informat Sci & Technol Shanghai 200433 Peoples R China Xian Univ Posts & Telecommun Xian 710121 Peoples R China 

出 版 物：《OPTICAL FIBER TECHNOLOGY》 (光纤技术)

年 卷 期：2024年第86卷

核心收录：

学科分类：0810[工学-信息与通信工程] 0808[工学-电气工程] 0809[工学-电子科学与技术（可授工学、理学学位）] 08[工学] 0702[理学-物理学] 

主　　题：Probabilistic shaping Two-stage bit-weighted distribution matching DMT Sampling frequency offset Intensity modulation and direct detection 

摘      要：We experimentally demonstrate the generation and transmission of probabilistic shaping (PS) 64-ary quadrature amplitude modulation (64-QAM) discrete multi-tone (DMT) signal with low-density parity-check (LDPC)-coded modulation based on two-stage bit-weighted distribution matching (TS-BWDM) in a high-speed unamplified intensity modulation and direct detection system. The TS-BWDM scheme is based on a two-stage bit-weighted inversion algorithm, which has the advantages of no complex multiplication and division operations and low hardware implementation complexity. As the key content of TS-BWDM, before FEC coding, the bit-weighted intervention operation is used to change the bit probability of a specific sequence in the parallel binary sequence. The two-stage bit-weighted inversion operation and one-stage weight-labeling bit insertion is performed for achieving the target symbol probability distribution. As a result, it does not add a significant amount of extra redundant bits. Additionally, the high-accuracy training symbols-based sampling frequency offset (SFO) estimation method and digital interpolation are used to compensate SFO. In our experiments, the TS-BWDMbased PS-64QAM DMT signals with a net rate of 157.3-Gb/s transmission over 10-km non-zero dispersionshifted fiber can be achieved. The system performance is investigated under two LDPC code rates (3/4 and 9/10) and three PS parameter values (k = 3, 5 and 9). The experimental results show that the receiver power sensitivity and the system fiber nonlinear effect tolerance can be significantly improved compared with uniformlydistributed signals.