1,721,016 research outputs found
Synergetical use of analytical models and machine-learning for data transport abstraction in open optical networks
Full text linkThe key-operation to enabling an effective data transport abstraction in open optical line systems (OLS) is the capability to predict the quality of transmission (QoT), that is given by the generalized signal-to-noise ratio (GSNR), including both the effects of the ASE noise and the nonlinear interference (NLI) accumulation. Among the two impairing effects, the estimation of the ASE noise is the most challenging task, because of the spectrally resolved working point of the erbium-doped fiber amplifiers (EDFA) depending on the spectral load, given the overall gain. While, the computation of the NLI is well addressed by mathematical models based on the knowledge of parameters and spectral load of fiber spans. So, the NLI prediction is mainly impaired by the uncertainties on insertion losses an spectral tilting. An accurate and spectrally resolved GSNR estimation enables to optimize the power control and to reliably and automatically deploy lightpaths with minimum margin, consequently maximizing the transmission capacity. We address the potentialities of machine-learning (ML) methods combined with analytic models for the NLI computation to improve the accuracy in the QoT estimation. We also analyze an experimental data-set showing the main uncertainties and addressing the use of ML to predict their effect on the QoT estimation
Final system results from the EU FP7 project FABULOUS
No full textIn the framework of the EU-funded research project 'FABULOUS' we experimentally demonstrate an innovative FDMA-PON architecture whose upstream transmission is based on a reflective Mach-Zehnder modulator, reaching an overall upstream capacity of 32 Gbps per wavelength over 31 dB ODN loss in several previously published experiments targeting 1 Gbps per user and using 16-QAM as a modulation format. In this paper, we focus on the experimental demonstration of the flexibility of our system to a variety of different working conditions, targeting higher bit-rates per user (up to 10 Gbps) and different modulation formats
Single-wavelength full-duplex 10 Gbps reflective PON capable of 31 dB of ODN loss
No full textWe demonstrate a single-wavelength fully-bidirectional and symmetrical 10 Gbps OOK transmission using simple direct-detection in downstream, and self-coherent detection in upstream over a standard 31 dB loss splitter-based PON, relying on wavelength remodulatio
QoT Computation for 100G Lightpaths Routed on 10G-loaded Dispersion-Managed Network Segments
Full text linkThe core and backbone optical network market segment is largely dominated by coherent transmission delivering 100Gbps and beyond thanks to the DSP-based coherent transceivers technology optical line systems without chromatic dispersion compensation. The metro and access segment instead is still often made of dispersion-compensated optical line systems operated with cheap 10G transceivers because of the still excessive CAPEX required to upgrade this segment to coherent technology. In the context of the gradual rise of SDN technology, aimed at dynamically, transparently and automatically managing and orchestrating optical networks, the ability to route 100G coherent channels through a section of dispersion managed network populated with legacy 10G channels enables more flexibility and CAPEX savings. In this work we propose a simple, fast and conservative quality-of-transmission estimator, tailored to the needs of a software module for optical path computation, able to estimate of the 10G-to-100G non-linear effects
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Alternative solutions for fronthauling based on DSP-assisted Radio-over-Fiber
No full textWe review alternative solutions for optical fronthauling in next generation fixed-mobile converged architectures that try to solve the problems related to the extremely high bit rates required by current fronthauling implementations based on the so-called digitized Radio over Fiber (as for the CPRI or OBSAI standards). In particular, we present our most recent results on Digital Signal Processing (DSP) assisted Frequency Division Multiplexed (FDM) aggregated radio over fiber solutions. We experimentally show two DSP-based optimization at the transmitter and/or receiver that improves the received Error Vector Magnitude (EVM). Moreover, we discuss on simple spectral estimation of the EVM parameter at the Remote Radio Head (RRH)
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