Open AccessImproved polar decoding for optical PAM transmission via non-identical Gaussian distribution based LLR estimation
Author(s) -
Honghang Zhou,
Yan Li,
Tao Dong,
Jifang Qiu,
Xiaobin Hong,
Hongxiang Guo,
Yong Zuo,
Jie Yin,
Yanyan Su,
Jian Wu
Publication year - 2020
Publication title -
optics express
Language(s) - Uncategorized
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.403117
Subject(s) - optics , pulse amplitude modulation , gaussian , polar , physics , modulation (music) , transmission (telecommunications) , amplitude modulation , telecommunications , pulse (music) , frequency modulation , computer science , bandwidth (computing) , acoustics , quantum mechanics , astronomy , detector
In this paper, an improved polar decoder based on non-identical Gaussian distributions is proposed and experimentally demonstrated for optical pulse amplitude modulation (PAM) interconnection. The principle of the polar coded PAM system is illustrated theoretically and the non-identical Gaussian distributions based log-likelihood ratio (LLR) estimation is introduced in the polar decoder to mitigate nonlinearity. Transmission systems of 28-Gbaud 4-level pulse amplitude modulation (PAM-4) and 8-level pulse amplitude modulation (PAM-8) based on commercial 10-GHz directly modulated laser (DML) are both demonstrated over 10-km standard single-mode fiber (SSMF) in C-band without dispersion compensation. Experimental results show that, aided by the improved polar decoder, the channel nonlinearity can be taken into consideration and additional sensitivity gains of 0.7 dB and 1 dB are respectively achieved compared with traditional polar decoder for PAM-4 and PAM-8 systems.