We consider time and frequency-packing (TFP) wavelength division-multiplexing (WDM) superchannel systems for longhaul optical fiber communication. Employing very high baud rates in conjunction with higher-order modulation formats is challenging due to practical constraints. TFP superchannels therefore become an attractive choice to facilitate high data rates with improved spectral efficiency. However, TFP introduces inter-symbol interference (ISI) and/or inter-carrier interference (ICI) that necessitate efficient interference handling techniques. Moreover, phase noise (PN) due to wide laser linewidth (LLW) may cause significant signal distortion in WDM transmission, and the presence of ISI and ICI in TFP systems further complicates carrier phase recovery (CPR). In this article, we propose a spectrally efficient TFP superchannel design equipped with powerful interference cancellation and PN mitigation techniques, targeting Terabit-per-second (Tbps) data rates. First, we propose a joint ISI and ICI channel estimation algorithm coupled with polarization-recovery and a coarse PN cancellation method. Second, we investigate two iterative CPR algorithms to mitigate the distortion due to the residual PN. Third, a combination of successive and parallel interference cancellation methods for ICI mitigation is investigated in tandem with turbo ISI equalization. The effectiveness of the proposed algorithms is demonstrated through computer simulations of a coded TFP superchannel system in the presence of linear fiber impairments, targeting a throughput of 1.2 Tbps. Numerical results suggest that the proposed TFP design offers more than 2 dB performance gains and as high as 960 km transmission distance improvement over existing competitive super-Nyquist designs. Simulation results also indicate that the proposed design exhibits excellent tolerance to high LLWs and aggressive optical filtering stemming from cascaded reconfigurable optical add-drop multiplexers in the fiber link.

中文翻译：

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时频打包WDM超信道传输系统的设计

我们考虑用于长途光纤通信的时间和频率打包 (TFP) 波分复用 (WDM) 超级信道系统。由于实际限制，将非常高的波特率与高阶调制格式结合使用具有挑战性。因此，TFP 超级通道成为一种有吸引力的选择，以提高频谱效率并促进高数据速率。然而，TFP 引入了符号间干扰 (ISI) 和/或载波间干扰 (ICI)，这需要有效的干扰处理技术。此外，由于宽激光线宽 (LLW) 引起的相位噪声 (PN) 可能会导致 WDM 传输中的明显信号失真，并且 TFP 系统中 ISI 和 ICI 的存在使载波相位恢复 (CPR) 进一步复杂化。在本文中，我们提出了一种频谱高效的 TFP 超级信道设计，配备了强大的干扰消除和 PN 缓解技术，目标是每秒太比特 (Tbps) 数据速率。首先，我们提出了一种联合 ISI 和 ICI 信道估计算法，结合极化恢复和粗略 PN 消除方法。其次，我们研究了两种迭代 CPR 算法来减轻由于残余 PN 引起的失真。第三，结合快速 ISI 均衡研究了用于 ICI 缓解的连续和并行干扰消除方法的组合。通过在存在线性光纤损伤的情况下对编码 TFP 超级信道系统进行计算机模拟，以 1.2 Tbps 的吞吐量为目标，证明了所提出算法的有效性。数值结果表明，与现有的竞争性超级奈奎斯特设计相比，所提出的 TFP 设计提供了超过 2 dB 的性能增益和高达 960 公里的传输距离改进。仿真结果还表明，所提出的设计对源自光纤链路中级联可重构光分插复用器的高 LLW 和激进的光学滤波具有出色的耐受性。