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Träfflista för sökning "L773:1094 4087 ;pers:(Agrell Erik 1965)"

Sökning: L773:1094 4087 > Agrell Erik 1965

  • Resultat 1-10 av 16
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1.
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2.
  • Beygi, Lotfollah, 1977, et al. (författare)
  • On nonlinearly-induced noise in single-channel optical links with digital backpropagation
  • 2013
  • Ingår i: Optics Express. - 1094-4087 .- 1094-4087. ; 21:22, s. 26376-26386
  • Tidskriftsartikel (refereegranskat)abstract
    • In this paper, we investigate the performance limits of electronic chromatic dispersion compensation (EDC) and digital backpropagation (DBP) for a single-channel non-dispersion-managed fiber-optical link. A known analytical method to derive the performance of the system with EDC is extended to derive a first-order approximation for the performance of the system with DBP. In contrast to the cubic growth of the variance of the nonlinear noise-like interference, often called nonlinear noise, with input power for EDC, a quadratic growth is observed with DBP using this approximation. Finally, we provide numerical results to verify the accuracy of the proposed approach and compare it with existing analytical models.
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3.
  • Czegledi, Cristian Bogdan, 1988, et al. (författare)
  • Digital backpropagation accounting for polarization-mode dispersion
  • 2017
  • Ingår i: Optics Express. - 1094-4087 .- 1094-4087. ; 25:3, s. 1903-1915
  • Tidskriftsartikel (refereegranskat)abstract
    • Digital backpropagation (DBP) is a promising digital-domain technique to mitigate Kerr-induced nonlinear interference. While it successfully removes deterministic signal-signal interactions, the performance of ideal DBP is limited by stochastic effects, such as polarizationmode dispersion (PMD). In this paper, we consider an ideal full-field DBP implementation and modify it to additionally account for PMD; reversing the PMD effects in the backward propagation by passing the reverse propagated signal also through PMD sections, which concatenated equal the inverse of the PMD in the forward propagation. These PMD sections are calculated analytically at the receiver based on the total accumulated PMD of the link estimated from channel equalizers. Numerical simulations show that, accounting for nonlinear polarization-related interactions in the modified DBP algorithm, additional signal-to-noise ratio gains of 1.1 dB are obtained for transmission over 1000 km.
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4.
  • Eriksson, Tobias, 1986, et al. (författare)
  • Single parity check-coded 16QAM over spatial superchannels in multicore fiber transmission
  • 2015
  • Ingår i: Optics Express. - : The Optical Society. - 1094-4087 .- 1094-4087. ; 23:11, s. 14569-14582
  • Tidskriftsartikel (refereegranskat)abstract
    • We experimentally investigate single-parity check (SPC) coded spatial superchannels based on polarization-multiplexed 16-ary quadrature amplitude modulation (PM-16QAM) for multicore fiber transmission systems, using a 7-core fiber. We investigate SPC over 1, 2, 4, 5 or 7 cores in a back-to-back configuration and compare the sensitivity to uncoded PM-16QAM, showing that at symbol rates of 20 Gbaud and at a bit-error-rate (BER) of 10(-3), the SPC superchannels exhibit sensitivity improvements of 2.7 dB, 2.0 dB, 1.7 dB, 1.3 dB, and 1.1 dB, respectively. We perform both single channel and wavelength division multiplexed (WDM) transmission experiments with 22 GHz channel spacing and 20 Gbaud channel symbol rate for SPC over 1, 3 and 7 cores and compare the results to PM-16QAM with the same spacing and symbol rate. We show that in WDM signals, SPC over hl1 core can achieve more than double the transmission distance compared to PM-16QAM at the cost of 0.91 bit/s/Hz/core in spectral efficiency (SE). When sharing the parity-bit over 7 cores, the loss in SE becomes only 0.13 bit/s/Hz/core while the increase in transmission reach over PM-16QAM is 44 %. (C) 2015 Optical Society of America
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5.
  • Galdino, Lidia, et al. (författare)
  • On the limits of digital back-propagation in the presence of transceiver noise
  • 2017
  • Ingår i: Optics Express. - 1094-4087 .- 1094-4087. ; 25:4, s. 4564-4578
  • Tidskriftsartikel (refereegranskat)abstract
    • © 2017, OSA - The Optical Society. All rights reserved. This paper investigates the impact of transceiver noise on the performance of digital back-propagation (DBP). A generalized expression to estimate the signal-to-noise ratio (SNR) obtained using DBP in the presence of transceiver noise is described. This new expression correctly accounts for the nonlinear beating between the transceiver noise and the signal in the optical fiber transmission link. The transceiver noise-signal nonlinear beating has been identified as the main reason for the discrepancy between predicted and practical performance of DBP; which has not been previously suggested. This nonlinear beating has been included in the GN model, allowing DBP gains in practical systems to be predicted analytically. Experiments and split-step simulations with and without polarization-mode dispersion (PMD) in the transmission link have been performed. The results show that the impact of transceiver noise greatly outweighs that of PMD, and the analytical expressions are confirmed by the numerical simulations.
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6.
  • Häger, Christian, 1986, et al. (författare)
  • Improving soft FEC performance for higher-order modulations via optimized bit channel mappings
  • 2014
  • Ingår i: Optics Express. - 1094-4087 .- 1094-4087. ; 22:12, s. 14544-14558
  • Tidskriftsartikel (refereegranskat)abstract
    • Soft forward error correction with higher-order modulations is often implemented in practice via the pragmatic bit-interleaved coded modulation paradigm, where a single binary code is mapped to a nonbinary modulation. In this paper, we study the optimization of the mapping of the coded bits to the modulation bits for a polarization-multiplexed fiber-optical system without optical inline dispersion compensation. Our focus is on protograph-based low-density parity-check (LDPC) codes which allow for an efficient hardware implementation, suitable for high-speed optical communications. The optimization is applied to the AR4JA protograph family, and further extended to protograph-based spatially coupled LDPC codes assuming a windowed decoder. Full field simulations via the split-step Fourier method are used to verify the analysis. The results show performance gains of up to 0.25 dB, which translate into a possible extension of the transmission reach by roughly up to 8%, without significantly increasing the system complexity.
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7.
  • Johannisson, Pontus, 1976, et al. (författare)
  • Modified constant modulus algorithm for polarization-switched QPSK
  • 2011
  • Ingår i: Optics Express. - 1094-4087 .- 1094-4087. ; 19:8, s. 7734-7741
  • Tidskriftsartikel (refereegranskat)abstract
    • A modified constant modulus algorithm (CMA) is presentedthat allows polarization demultiplexing and equalization of polarizationswitchedQPSK. An implementation is suggested that allows easy switchingbetween the traditional and the modified CMA. Using numerical simulations,the suggested algorithm is shown to have similar performance asCMA has for polarization-multiplexed QPSK.
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8.
  • Karlsson, Magnus, 1967, et al. (författare)
  • Multilevel pulse-position modulation for optical power-efficient communication
  • 2011
  • Ingår i: Optics Express. - 1094-4087 .- 1094-4087. ; 19:26, s. B799-B804
  • Tidskriftsartikel (refereegranskat)abstract
    • A family of modulation formats is derived by combining pulse-position modulation (PPM) with multilevel dual-polarization signal constellations. With 16-PPM, gains of up to 5.4 dB are obtained over dual-polarization QPSK, at the cost of reduced spectral efficiency.
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9.
  • Karlsson, Magnus, 1967, et al. (författare)
  • Which is the most power-efficient modulation format in optical links?
  • 2009
  • Ingår i: Optics Express. - 1094-4087 .- 1094-4087. ; 17:13, s. 10814-10819
  • Tidskriftsartikel (refereegranskat)abstract
    • By exploiting the electromagnetic wave's four-dimensional signal space, we find that for the additive white Gaussian noise channel, the modulation format with best sensitivity to be an 8-level format with 1.76 dB asymptotic gain over BPSK, for uncoded optical transmission with coherent detection. Low-complexity modulators are presented for the format, as well as an interpretation in terms of quantum-limited sensitivity.
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10.
  • Karout, Johnny, 1985, et al. (författare)
  • Power efficient subcarrier modulation for intensity modulated channels
  • 2010
  • Ingår i: Optics Express. - 1094-4087 .- 1094-4087. ; 18:17, s. 17913-17921
  • Tidskriftsartikel (refereegranskat)abstract
    • We compare formats for optical intensity modulation limited by thermal noise with the assumption of having ideal devices. At the same bitrate and bandwidth, a hitherto unknown format turns out to be more power efficient than known formats. This new modulation, which is a hybrid between on-off keying and phase-shift keying, belongs to the subcarrier modulation family. At asymptotically high signal-to-noise ratios, this hybrid scheme has a 1.2 dB average electrical power gain and 0.6 dB average optical power gain compared to OOK, while it has a 3.0 dB average electrical power gain and 2.1 dB average optical power gain compared to subcarrier QPSK.
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