1,721,145 research outputs found
Software defined transceivers for high-speed flexible optical networks
No full text"A novel high-capacity, energy-efficient and bit-rate flexible optical transceiver (Tx\/Rx), capable of supporting rates from 10Gb\/s to beyond 1Tb\/s, has been designed and its performance in long-haul transmission has been carefully investigated. The device can realize both orthogonal frequency division multiplexing (OFDM) and Nyquist wavelength division multiplexing (NWDM), for flexible super-channel generation; the inverse discrete Fourier transform (IDFT) and the discrete Fourier transform (DFT) are implemented directly in the optical domain, using a specially designed arrayed waveguide grating (AWG). Therefore, the transceiver can provide ultra-high capacity with significant improvements on the energy efficiency per transmitted bit. In addition, different modulation formats are possible, and different bit rates. In the present paper, we provide complete design guidelines of the AWG-based device that performs the IDFT\/DFT, evaluating the influence of the slab diffraction effect on the orthogonality of the subchannels. The complete functionality of the transceiver is numerically simulated and the influence of the noise from the inline amplifiers, chromatic dispersion, non-linear effects have been evaluated. In addition, to simplify the receiver architecture, a pulsed local oscillator is used for coherent balanced photodetection, and the impairments due to the phase noise have been investigated. The system performance is evaluated considering both bit error rate (BER) and the error vector magnitude (EVM) parameters.
Lightpath establishment in distributed GMPLS-controlled dynamic transparent optical networks using Quality of Transmission estimation
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Lightpath establishment in dynamic transparent optical networks assisted by end-to-end Quality of Transmission estimation
No full textGoing 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
Lightpath establishment in distributed transparent dynamic optical networks using network kriging
No full textVariations 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
Impact of Traffic Profile on the Performance of Spatial Superchannel Switching in SDM Networks
No full textWe compare the performance of three SDM switching paradigms under different traffic profiles. We show that their performance is highly traffic dependent. We also show that increasing the spectral switching granularity, significantly improves the performance of spatial group switching
Nyquist-WDM-Based Flexible Optical Networks: Exploring Physical Layer Design Parameters
No full textWe focus on Nyquist-WDM-based flexible optical networks and examine the impact of introducing flexibility in physical layer design parameters on the network level performance. The considered physical layer parameters include the modulation format, the symbol-rate, the inter-subcarrier spacing, the inter-superchannel spacing, and the launch power. In order to examine the impact of allowing the symbol rate to be tuned on a super channel basis, three alternative launch power schemes are considered: (i) optimum launch power, (ii) constant launch power, and (iii) constant power spectral density. Case study results from a realistic reference core network highlight the identified trade-offs with respect to the utilized spectrum and the required transponders. It is shown that significant savings can be achieved by allowing the symbol rate to be dynamically tuned under different launch power options
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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