A survey on fiber nonlinearity compensation for 400 Gbps and beyond optical communication systems

Optical communication systems represent the backbone of modern communication networks. Since their deployment, different fiber technologies have been used to deal with optical fiber impairments such as dispersion-shifted fibers and dispersion-compensation fibers. In recent years, thanks to the introduction of coherent detection based systems, fiber impairments can be mitigated using digital signal processing (DSP) algorithms. Coherent systems are used in the current 100 Gbps wavelength-division multiplexing (WDM) standard technology. They allow the increase of spectral efficiency by using multi-level modulation formats, and are combined with DSP techniques to combat the linear fiber distortions. In addition to linear impairments, the next generation 400 Gbps/1 Tbps WDM systems are also more affected by the fiber nonlinearity due to the Kerr effect. At high input power, the fiber nonlinear effects become more important and their compensation is required to improve the transmission performance. Several approaches have been proposed to deal with the fiber nonlinearity. In this paper, after a brief description of the Kerr-induced nonlinear effects, a survey on the fiber nonlinearity compensation (NLC) techniques is provided. We focus on the well-known NLC techniques and discuss their performance, as well as their implementation and complexity. An extension of the inter-subcarrier nonlinear interference canceler approach is also proposed. A performance evaluation of the well-known NLC techniques and the proposed approach is provided in the context of Nyquist and super-Nyquist superchannel systems.Comment: Accepted in the IEEE Communications Surveys and Tutorial

Second-order perturbation theory-based digital predistortion for fiber nonlinearity compensation

The first-order (FO) perturbation theory-based nonlinearity compensation (PB-NLC) technique has been widely investigated to combat the detrimental effects of the intra-channel Kerr nonlinearity in polarization-multiplexed (Pol-Mux) optical fiber communication systems. However, the NLC performance of the FO-PB-NLC technique is significantly limited in highly nonlinear regimes of the Pol-Mux long-haul optical transmission systems. In this paper, we extend the FO theory to second-order (SO) to improve the NLC performance. This technique is referred to as the SO-PB-NLC. A detailed theoretical analysis is performed to derive the SO perturbative field for a Pol-Mux optical transmission system. Following that, we investigate a few simplifying assumptions to reduce the implementation complexity of the SO-PB-NLC technique. The numerical simulations for a single-channel system show that the SO-PB-NLC technique provides an improved bit-error-rate performance and increases the transmission reach, in comparison with the FO-PB-NLC technique. The complexity analysis demonstrates that the proposed SO-PB-NLC technique has a reduced computational complexity when compared to the digital back-propagation with one step per span

Enumerative Sphere Shaping for Rate Adaptation and Reach Increase in WDM Transmission Systems

The performance of enumerative sphere shaping (ESS), constant composition distribution matching (CCDM), and uniform signalling are compared at the same forward error correction rate. ESS is shown to offer a reach increase of approximately 10% and 22% compared to CCDM and uniform signalling, respectively.Comment: 4 Pages, 4 figure

First Experimental Demonstration of Probabilistic Enumerative Sphere Shaping in Optical Fiber Communications

We transmit probabilistic enumerative sphere shaped dual-polarization 64-QAM at 350Gbit/s/channel over 1610km SSMF using a short blocklength of 200. A reach increase of 15% over constant composition distribution matching with identical blocklength is demonstrated

Nonlinear effects compensation for long-haul superchannel transmission system

Les systèmes de communications optiques jouent un role important pour satisfaire la demande incessante de trafics de données. Cette demande, induite par des applications gourmandes en termes de bande passante et débit, necéssite une augmentation de la capacité des réseaux optiques d’accès et par conséquent une augmentation des capacités de réseaux de transports métropolitains et longues distances. La prochaine génération de systèmes WDM longue distance devrait opérée à des débits de 400Gbps ou 1Tbps. Cette montée en débit s’appuiera sur des nouvelles formes d’ondes avancées de type mono-porteuse (Nyquist-WDM) ou multi-porteuse (OFDM multi-bande). Ces approches sont basées sur le multipléxage de plusieurs porteuses espacées par des intervalles de garde réduits. D’autre part, pour générer ces très haut débits, des modulations multi-états sont utilisées pour chaque porteuse grâce à leur efficacité spectrale élevée. Ces types de systèmes, qui combinent à la fois les approches multi-bande et les modulations multi-états, sont extrêmement vulnérables aux effets nonlinéaires de la fibre optique. En fait, les effets nonlinéaires sont dépendants de la puissance de transmission et inversement proportionels à l’intervalle de garde. Cela rend leur compensation indispensable pour maintenir des bonnes performances des systèmes en terme de distance de transmission. Grâce à l’emploi de récepteurs à détection cohérente, des techniques de traitement du signal numérique sont utlisées pour combattre les effets nonlinéaires. Dans cette thèse, nous avons proposé des nouvelles techniques basées sur les séries de Volterra et les égaliseurs à retour de decision pour compenser respectivement les effets nonlinéaires intrabande et les interférences nonlinéaires inter-bande.Optical communication systems have evolved since their deployment to meet the growing demand for high-speed communications. Over the past decades, the global demand for communication capacity has increased exponentially and the most of the growth has occurred in the last few years when data started dominating network traffic. In order to meet the increase of traffic demands fueled by the growth of internet services, an increase of access network capacity and consequently metro and long-haul network capacities is required. Next generation of long-haul WDM transmission systems is expected to operate at 400Gbps or 1Tbps bit rate. Superchannel approaches, such as Nyquist WDM and multi-band OFDM, allow both high spectral efficiency and small guardband which makes them promising candidates to generate these high bit rates in combination with multi-level modulations formats. Such transmission systems are strongly disturbed by fiber nonlinear effects which increase with the data rate and the small guard band. Therefore, fiber nonlinearities compensation is required to get the desired performance in terms of transmission reach. DSP based approaches such as digital back propagation and third-order Volterra based nonlinear equalizer have been already proposed to deal with intra-channel or intra-band nonlinear effects. In the context of superchannel systems, we have proposed two new compensation techniques to deal with fiber nonlinear effects. The first one, called fifth-order inverse Volterra based nonlinear equalizer, compensate for intra-band nonlinear effects. The second approach, which is the interband/ subcarrier nonlinear interference canceler, is proposed to combat the nonlinear interference insuperchannel systems

Inter-band nonlinear interference canceler based on decision feedback equalizer for long-haul CO-ODFM

International audienc

Fifth-order Volterra series based nonlinear equalizer for long-haul data rate optical fiber communications

International audienc

Enhanced regular perturbation-based nonlinearity compensation technique for optical transmission systems

The regular perturbation (RP) series used to analytically approximate the solution of the nonlinear Schrodinger equation has a serious energy-divergence problem when truncated to the first order. The enhanced RP (ERP) method can improve the accuracy of the first-order RP approximation by solving the energy divergence problem. In this paper, we propose an ERP-based nonlinearity compensation technique, referred to as ERP-NLC, to compensate for the fiber nonlinearity in a polarization-division multiplexed dispersion unmanaged optical communication system. We also propose a modified perturbation-based NLC (PB-NLC) technique by simple phase-rotation (PR) of the nonlinear coefficient matrix, referred to as the PR-PB-NLC. The PR-PB-NLC can be considered as a by-product of the ERP-NLC technique. We show through numerical simulation that, for a 256 Gb/s single-channel system, the proposed ERP-NLC technique improves the Q-factor performance by ∼1.2 dB and ∼0.6 dB when compared to the electronic dispersion compensation (EDC) and the PB-NLC techniques, respectively, at a transmission distance of 2800 km. Also, the result for a 1.28 Tb/s wavelength-division multiplexed five-channel transmission system at the same transmission distance shows that the Q-factor performance of the ERP-NLC technique is improved by ∼0.6 dB and ∼0.4 dB when compared to the EDC and the PB-NLC techniques, respectively. The simulation results for the PR-PB-NLC technique for a single-or five-channel transmission system show an improved Q-factor performance when compared to the EDC and PB-NLC techniques. Finally, we show that the proposed performance enhancement comes with a negligible increase in the computational complexity for the ERP-NLC and PR-PB-NLC techniques when compared to the PB-NLC technique

A machine learning-based detection technique for optical fiber nonlinearity mitigation

We investigate the performance of a machine learning classi?cation technique, called the Parzen window, to mitigate the ?ber nonlinearity in the context of dispersion managed and dispersion unmanaged systems. The technique is applied for detection at the receiver side, and deals with the non-Gaussian nonlinear effects by designing improved decision boundaries. We also propose a two-stage mitigation technique using digital back propagation and Parzen window for dispersion unmanaged systems. In this case, digital back propagation compensates for the deterministic nonlinearity and the Parzen window deals with the stochastic nonlinear signal-noise interactions, which are not taken into account by digital back propagation. A performance improvement up to 0.4 dB in terms of Q factor is observed

Fiber nonlinearity mitigation via the parzen window classifier for dispersion managed and unmanaged links

Machine learning techniques have recently received significant attention as promising approaches to deal with the optical channel impairments, and in particular, the nonlinear effects. In this work, a machine learning-based classification technique, known as the Parzen window (PW) classifier, is applied to mitigate the nonlinear effects in the optical channel. The PW classifier is used as a detector with improved nonlinear decision boundaries more adapted to the nonlinear fiber channel. Performance improvement is observed when applying the PW in the context of dispersion managed and dispersion unmanaged systems