Accumulation of cross-channel non-linear interference in dispersion-managed and disaggregated optical network segment

We evaluate the generation of the cross-channel interference (XCI) for coherent transmission through a variety of dispersion-managed segments in a disaggregated optical network framework, using split-step Fourier method (SSFM) simulations and an implementation of the Gaussian noise (GN) model. We observe that the small inline residual dispersion remaining after each span affects the accumulation of the XCI, causing GN model predictions to no longer be conservative. We find an asymptotic upper bound to this additional accumulation, providing a worst-case prediction, and observe that this depends upon the residual dispersion within the link. This upper bound scales similarly to the self-channel interference (SCI) accumulation, and is well characterized by the parameters of the underlying fiber spans and the transmitted signals.Comment: 11 pages, 5 figure

Quality of Transmission Estimation for Planning of Disaggregated Optical Networks

Modern optical networks depend upon advanced software-defined networking (SDN) technologies, which in turn rely on a network abstraction to infer the quality of transmission (QoT). In general, the QoT estimation is based upon the generalized signal-to-noise ratio (GSNR), which takes into account the ASE noise, cross-phase modulation (XPM) and self-phase modulation (SPM) components of the nonlinear interference (NLI). Uniquely, the SPM accumulates coherently, causing the total amount of SNR degradation to depend upon the physical lightpath (LP) history, preventing a fully disaggregated GSNR degradation evaluation. As the current signal symbol rate are increasing, the SPM will provide a progressively more significant contribution to the SNR degradation. We propose a method to evaluate the equivalent SPM component of the NLI that is generated in each fiber span within an optical line system (OLS), independent of the history or configuration of the optical network

Modelling non-linear interference in non-periodic and disaggregated optical network segments

We investigate the generation of nonlinear interference (NLI) within two disaggregated transmission scenarios, each considering a chain of three distinct optical line systems that contain fibers with different dispersion values, with 400G-ZR+ 64 GBd transmission simulated using the split-step Fourier method. Firstly, by separating the NLI into its main constituents: the self- and cross-phase modulations, we investigate the impact of accumulated dispersion upon NLI generation and compensate for the coherent accumulation of the former to produce a model that is fully spectrally and spatially separable, including for alien wavelengths. Considering ideal and optimized in-line amplification, we calculate the amplified spontaneous emission noise and combine this value with the recovered NLI to obtain the generalized signal-to-noise ratio. We show that this disaggregated model provides accurate and conservative results for both transmission scenarios, showing that abstracting these signals with a Gaussian noise approximation always results in a conservative prediction, even for non-uniform fiber dispersion scenarios

Simulative assessment of non-linear interference generation within disaggregated optical line systems

Lightpaths within optical line systems (OLS)s that deploy coherent optical technologies are mainly impaired by two additive Gaussian disturbances: the amplified spontaneous emission (ASE) noise from the optical amplifiers and the non-linear interference (NLI) from fiber propagation, together with some amount of phase noise, typically compensated for bythe carrier phase estimator module within the digital signal processing (DSP) unit. The main obstacle in accurately modelling the physical layer of a disaggregated optical network arises from the spatially-coherent and spectrally-aggregated general behavior of the NLI generation.Within this paper, we perform an accurate split-step Fourier method (SSFM) physical layer simulation campaign over a wide range of fiber chromatic dispersion values that range from 2to 16.7 ps / (nm·km) and channel symbol rates from 32 GBd to 85 GBd. For all the explored scenarios, we first show that the NLI generation in an OLS can be spectrally disaggregated in a practical manner by considering a superposition of self-channel (SC) and cross-channel (XC) NLI components only. Secondly, by considering the span-by-span generalized signal-to-noise ratio (GSNR) deterioration, we show that the XC-NLI accumulation components can also be considered as spatially disaggregated, leaving the SC-NLI as the only spatial coherency contribution. Consequently, by appropriately managing these coherent NLI contributions, we find that it is possible to produce a conservative physical layer model that is both spectrally and spatially disaggregated

Ofatumumab and Early Immunological Cells Subset Characterization in Naïve Relapsing Multiple Sclerosis Patients: A Real-World Study

Background: Ofatumumab (OFA) is a fully human anti-CD20 monoclonal antibody administered with a 20 mg subcutaneous monthly dosing regimen. Methods: Inclusion criteria were patients: 1) aged 18-55; 2) with a confirmed diagnosis of relapsing Multiple Sclerosis (RMS), per the revised 2010 McDonald criteria; 2) who started OFA according to Italian Medicines Agency prescription rules and within 12 months from the RMS diagnosis; 3) naïve to any disease-modifying therapy. The primary outcome was to offer an overview of cellular subsets of RMS naïve patients (time 0) and then after 4 weeks (time 1) and 12 weeks (time 2) on therapy with OFA in a real-world setting. Results: Fifteen patients were enrolled. CD3+ T cell frequencies were higher at time 1 ( .4, SD 7.7) and time 2 ( .6, SD 5.8) when compared to time 0 (r.4, SD 9.8), p = .013. B naïve cells were barely detectable in the OFA group at time 1 (%0.4, SD 0.5) and 2 (%1.4, SD 2.9) when compared to time 0 ( .5, SD 3.8), p < .001. Conclusion: The progressive and increasing use of anti-CD20 drugs imposes the need for larger, prospective, real-world, long-term studies to characterize further immunophenotypes of patients with RMS treated with OFA