Multichannel Nonlinear Equalization in Coherent WDM Systems Based on Bi-Directional Recurrent Neural Networks
Multichannel Nonlinear Equalization in Coherent WDM Systems Based on Bi-Directional Recurrent Neural Networks
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DOI：
10.1109/jlt.2023.3318559
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发表时间：
2023-06
影响因子：
4.7
通讯作者：
S. Deligiannidis;K. Bottrill;Kostas Sozos;C. Mesaritakis;P. Petropoulos;A. Bogris
中科院分区：
文献类型：
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作者：
S. Deligiannidis;K. Bottrill;Kostas Sozos;C. Mesaritakis;P. Petropoulos;A. Bogris
自相位调制和交叉相位调制形式的克尔非线性对波分复用（WDM）光通信系统的容量施加了基本限制。数字反向传播（DBP）是一种广泛采用的技术，用于减轻克尔非线性引起的损害。然而，多信道DBP太复杂而不能在WDM系统中商业实现。递归神经网络（RNN）最近已被用于光通信背景下的非线性信号处理。在这项工作中，我们提出了多通道均衡通过双向香草递归神经网络（bi-VRNN），以提高性能的单通道bi-VRNN算法在WDM偏振复用信号的传输。我们将所提出的数字算法与全场DBP和单通道双RNN进行比较，以揭示其在性能和复杂度方面的优点。最后，我们在QPSK传输中提供了实验验证，展示了超过2.5 dB的光信噪比（OSNR）增益和显着降低误码率（BER）的数量级相比，单通道均衡。此外，与单通道RNN相比，实现了高达43%的复杂度降低，在24跨度长距离传输的情况下，与单通道DBP相比，降低了高达550%。
Kerr nonlinearity in the form of self- and cross-phase modulation imposes a fundamental limitation to the capacity of wavelength division multiplexed (WDM) optical communication systems. Digital back-propagation (DBP) is a widely adopted technique for the mitigation of impairments induced by Kerr nonlinearity. However, multi-channel DBP is too complex to be implemented commercially in WDM systems. Recurrent neural networks (RNNs) have been recently exploited for nonlinear signal processing in the context of optical communications. In this work, we propose multi-channel equalization through a bidirectional vanilla recurrent neural network (bi-VRNN) in order to improve the performance of the single-channel bi-VRNN algorithm in the transmission of WDM polarization multiplexed signals. We compare the proposed digital algorithm to full-field DBP and to the single channel bi-RNN in order to reveal its merits with respect to both performance and complexity. We finally provide experimental verification in QPSK transmission, showcasing over 2.5 dB optical signal-to-noise ratio (OSNR) gain and a significant reduction in bit-error-rate (BER) by an order of magnitude compared to single channel equalization. Moreover, a complexity reduction of up to 43% was achieved compared to the single-channel RNN, and up to 550% compared to the single channel DBP in the case of 24-span long haul transmission.