Opt Lett. 2022 Nov 1;47(21):5606-5609. doi: 10.1364/OL.475764.
Chromatic dispersion appears to be a major performance limiting problem in optical intensity modulation direct detection (IM/DD) transmission systems, especially for a double-sideband (DSB) signal. We propose a complexity-reduced look-up-table based maximum likelihood sequence estimation (LUT-MLSE) for DSB C-band IM/DD transmission based on pre-decision-assisted trellis compression and a path-decision-assisted Viterbi algorithm. To further compress the size of the LUT and reduce the length of the training sequence, we proposed a finite impulse response (FIR) and LUT hybrid channel model for the LUT-MLSE. For PAM-6 and PAM-4, the proposed methods can compress the size of the LUT into 1/6 and 1/4, and reduce the number of multipliers by 98.1% and 86.6% with slight performance degradation. We successfully demonstrate a 20-km 100-Gb/s PAM-6 and a 30-km 80-Gb/s PAM-4 C-band transmission over dispersion-uncompensated links.
在光强度调制直接检测（IM/DD）传输系统中，色度色散似乎是一个主要的性能限制问题，特别是对于双边带（DSB）信号。我们提出了一种复杂度降低的基于查找表的最大似然序列估计（LUT-MLSE），用于基于预判决辅助网格压缩和路径判决辅助维特比算法的 DSB C 波段 IM/DD 传输。为了进一步压缩 LUT 的大小并减少训练序列的长度，我们提出了一种用于 LUT-MLSE 的有限脉冲响应（FIR）和 LUT 混合信道模型。对于 PAM-6 和 PAM-4，所提出的方法可以将 LUT 的大小压缩到 1/6 和 1/4，并减少乘法器的数量，分别为 98.1%和 86.6%，而性能略有下降。我们成功地演示了在未补偿色散链路中传输 20km 100Gb/s PAM-6 和 30km 80Gb/s PAM-4 的 C 波段。
