Tu Yucheng, Yang Hailin, Xiang Meng, Zhao Luming, Tang Ming, Qin Yuwen, Fu Songnian
Opt Lett. 2024 Jul 15;49(14):3874-3877. doi: 10.1364/OL.527844.
A nonlinear Tomlinson-Harashima precoding (NTHP) scheme has been verified for its capability to effectively address both the linear and nonlinear inter-symbol interferences (ISIs) arising in the intensity-modulation direct-detection (IM-DD) fiber optics transmission. Nevertheless, the application of the NTHP scheme may significantly increase the number of levels for the intensity modulated signals, resulting in the reduction of both eye width and receiver sensitivity. Here, we propose a fractionally spaced NTHP with a weight clustering (FS-NTHP-WC) scheme. Consequently, an accurate ISI feedback can be obtained to enlarge the eye width; meanwhile a hardware-efficient implementation without the equalization penalty can be achieved by weight clustering and pruning. When the C-band 100 Gbaud/λ PAM-4 signals are transmitted, our proposed FS-NTHP-WC scheme not only can achieve 0.25 dB and 0.5 dB gains of receiver sensitivity under back-to-back (B2B) and 2-km standard single-mode fiber (SSMF) transmission conditions, respectively, but can also cut down the computational complexity by 90% and 76% in terms of the number of multiplications and additions, respectively, in comparison with the NTHP scheme.
一种非线性汤姆林森-原岛预编码（NTHP）方案已被证实能够有效解决强度调制直接检测（IM-DD）光纤传输中出现的线性和非线性符号间干扰（ISI）。然而，NTHP方案的应用可能会显著增加强度调制信号的电平数，导致眼图宽度和接收机灵敏度降低。在此，我们提出一种带权重聚类的分数间隔NTHP（FS-NTHP-WC）方案。因此，可以获得准确的ISI反馈以扩大眼图宽度；同时，通过权重聚类和修剪，可以实现高效的硬件实现且无均衡代价。当传输C波段100 Gbaud/λ PAM-4信号时，我们提出的FS-NTHP-WC方案不仅在背对背（B2B）和2公里标准单模光纤（SSMF）传输条件下分别能实现接收机灵敏度0.25 dB和0.5 dB的增益，而且与NTHP方案相比，在乘法和加法次数方面分别能降低90%和76%的计算复杂度。
