1,721,009 research outputs found
Adaptive Digital Equalization in Optical Coherent Receivers With Stokes-Space Update Algorithm
Full text linkIn this paper, we describe a novel update algorithm for the filter coefficients of the adaptive digital equalizer in coherent receivers, which is based on error signals evaluated in Stokes space and is insensitive to both phase-noise and frequency-offset. We also introduce an optimized decision rule in the Stokes space, which takes into account the exact statistics of noise and yields a performance improvement with respect to the minimum distance decision criterion. We compare the performance of the new algorithm to the standard constant-modulus algorithm (CMA) for polarization-multiplexed 16QAM modulation, achieving similar performance in the absence of phase noise, with comparable complexity. Differently from CMA, the proposed Stokes-space algorithm allows us to remove the phase offset between polarizations, thus enabling the use of a joint carrier-phase estimation algorithm on both polarizations, which in turns yields a nearly doubled phase noise toleranc
Extension and validation of the GN model for non-linear interference to uncompensated links using Raman amplification
No full textWe show the extension of the Gaussian Noise model, which describes non-linear propagation in uncompensated links of multilevel modulation formats, to systems using Raman amplification. We successfully validate the analytical results by comparison with numerical simulations of Nyquist-WDM PM-16QAM channels transmission over multi-span uncompensated links made of a single fiber type and using hybrid EDFA/Raman amplification with counter-propagating pumps. We analyze two typical high- and low-dispersion fiber types. We show that Raman amplification always induces a limited non-linear interference enhancement compared to the dominant ASE noise reductio
Network Planning Strategies for Next-Generation Flexible Optical Networks [Invited]
Full text linkUsing well-established results on nonlinear propagation modeling in coherent optical links, two different approaches for network planning are addressed and compared in terms of performance maximization and robustness to dynamic changes in the network, one based on maximization of the margin in the optical signal-to-noise ratio, the other on minimization of the pre-forward-errorcorrection bit error rate (BER). We show that, in pure coherent optical networks, the planning strategy that best supports the dynamic evolution of the network is the design aimed at BER minimization. A closed-form formula for the maximum reach (in terms of number of spans and loss budget) of each interface is analytically derived, which is a useful tool for the evaluation of the overall network cost for a desired traffic capacit
A Novel Update Algorithm in Stokes Space for Adaptive Equalization in Coherent ReceiversOptical Fiber Communication Conference
No full textWe propose a novel update algorithm based on error signals evaluated in Stokes space, independent of both phase-noise and frequency-offset. We compare its performance to standard CMA for PM-16QAM modulation, showing 0.5-dB gain at BER=1e-2
Extended TWDM-PON demonstration up to 100 km and 35 dB ODN loss on Burst-Mode Coherent Reflective PON
No full textWe demonstrate the upstream path for a TWDM-PON on up to 100 km installed fibers, 35 dB ODN loss and 4 wavelengths, using burst-mode self-coherent OLT receiver and reflective ONU transmitters without tunable lasers
Network Planning Strategies for Next-Generation Flexible Optical NetworksOptical Fiber Communication Conference
No full textUsing well-established results on non-linear propagation modeling in coherent optical links, two different approaches for network performance optimization are addressed and compared in terms of performance maximization and robustness to dynamic changes in the network
Non-linearity Compensation Limits in Optical Systems with Coherent Receivers
No full textWe use an analytical model for fiber propagation in uncompensated optical systems to analyze the bandwidth of non-linear noise in WDM transmission in order to assess the limits of non-linearity compensation in coherent receivers
Independence of the Impact of Inter-Channel Non-Linear Effects on Modulation Format and System Implications
No full textWe show by simulation that the impact of inter-channel non-linear effects is independent of modulation format in long-haul systems, once long-correlated non-linear phase-noise has been removed. We back-up the finding experimentally and investigate the system implications
EGN model of non-linear fiber propagation
Full text linkThe GN-model has been proposed as an approximate but sufficiently accurate tool for predicting uncompensated optical coherent transmission system performance, in realistic scenarios. For this specific use, the GN-model has enjoyed substantial validation, both simulative and experimental. Recently, however, it has been pointed out that its predictions, when used to obtain a detailed picture of non-linear interference (NLI) noise accumulation along a link, may be affected by a substantial NLI overestimation error, especially in the first spans of the link. In this paper we analyze in detail the GN-model errors. We discuss recently proposed formulas for correcting such errors and show that they neglect several contributions to NLI, so that they may substantially underestimate NLI in specific situations, especially over low-dispersion fibers. We derive a complete set of formulas accounting for all single, cross, and multi-channel effects, This set constitutes what we have called the enhanced GN-model (EGN-model). We extensively validate the EGN model by comparison with accurate simulations in several different system scenarios. The overall EGN model accuracy is found to be very good when assessing detailed span-by-span NLI accumulation and excellent when estimating realistic system maximum reach. The computational complexity vs. accuracy trade-offs of the various versions of the GN and EGN models are extensively discusse
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