| 1. |
- Alvarado, Alex, 1982, et al.
(författare)
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LDPC codes for optical channels: Is the "FEC limit" a good predictor of post-FEC BER?
- 2015
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Ingår i: 2015 Optical Fiber Communications Conference and Exhibition, (OFC) 2015, Los Angeles, United States, 22-26 March 2015. - Washington, D.C. : OSA. - 9781557529374 ; , s. 7121706-
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Konferensbidrag (refereegranskat)abstract
- We answer the question in the title negatively. More precisely, the FEC limit is invalid for soft decision decoding and low to medium code rates. A better predictor is the generalized mutual information.
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| 2. |
- Czegledi, Cristian Bogdan, 1988, et al.
(författare)
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Digital backpropagation accounting for polarization-mode dispersion
- 2017
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Ingår i: Optics Express. - 1094-4087 .- 1094-4087. ; 25:3, s. 1903-1915
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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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| 3. |
- Czegledi, Cristian Bogdan, 1988, et al.
(författare)
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Modified Digital Backpropagation Accounting for Polarization-Mode Dispersion
- 2017
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Ingår i: Optical Fiber Communication Conference. - 9781943580231
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Konferensbidrag (refereegranskat)abstract
- We propose a modified DBP algorithm accounting for PMD. The accumulated PMD at the receiver is factorized into several PMD sections, and inserted into the DBP routine to distributively compensate for PMD, outperforming the conventional approach by 1.1 dB in SNR.
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| 4. |
- Czegledi, Cristian Bogdan, 1988, et al.
(författare)
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Polarization-Mode Dispersion Aware Digital Backpropagation
- 2016
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Ingår i: 42nd European Conference on Optical Communication, ECOC 2016; Dusseldorf; Germany; 18 September 2016 through 22 September 2016. - 9783800742745 ; , s. 1091-1093
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Konferensbidrag (refereegranskat)abstract
- We study a modified DBP algorithm that accounts for PMD. Based on the accumulated PMD at the receiver, the algorithm distributively compensates for PMD in the reverse propagation and outperforms the conventional approach by up to 2.1 dB.
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| 5. |
- Galdino, Lidia, et al.
(författare)
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On the limits of digital back-propagation in the presence of transceiver noise
- 2017
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Ingår i: Optics Express. - 1094-4087 .- 1094-4087. ; 25:4, s. 4564-4578
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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. |
- Liga, Gabriele, et al.
(författare)
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Achievable information rates of nonbinary codes for optical fiber transmission
- 2017
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Ingår i: 2016 IEEE Photonics Conference, IPC 2016. ; , s. 309-310
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Konferensbidrag (refereegranskat)abstract
- Achievable information rates (AIRs) are calculated for optical fiber systems employing soft-decision and hard-decision nonbinary codes. We show that, despite the lower decoding complexity, hard-decision AIRs approach soft-decision AIRs for high spectral efficiencies and long transmission distances.
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| 7. |
- Liga, Gabriele, et al.
(författare)
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Information rates of next-generation long-haul optical fiber systems using coded modulation
- 2017
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Ingår i: Journal of Lightwave Technology. - 0733-8724 .- 1558-2213. ; 35:1, s. 113-123
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Tidskriftsartikel (refereegranskat)abstract
- A comprehensive study of the coded performance of long-haul spectrally-efficient WDM optical fiber transmission systems with different coded modulation decoding structures is presented. Achievable information rates are derived for three different square QAM formats and the optimal format is identified as a function of distance and specific decoder implementation. The four cases analyzed combine hard-decision (HD) or softdecision (SD) decoding together with either a bit-wise or a symbol-wise demapper, the last two suitable for binary and nonbinary codes, respectively. The information rates achievable for each scheme are calculated based on the mismatched decoder principle. These quantities represent true indicators of the coded performance of the system for specific decoder implementations and when the modulation format and its input distribution are fixed. In combination with the structure of the decoder, two different receiver-side equalization strategies are also analyzed: electronic dispersion compensation and digital backpropagation. We show that, somewhat unexpectedly, schemes based on nonbinary HD codes can achieve information rates comparable to SD decoders and that, when SD is used, switching from a symbol-wise to a bit-wise decoder results in a negligible penalty. Conversely, from an information-theoretic standpoint, HD binary decoders are shown to be unsuitable for spectrally-efficient, long-haul systems.
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| 8. |
- Liga, Gabriele, et al.
(författare)
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Optimum detection in presence of nonlinear distortions with memory
- 2015
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Ingår i: 41st European Conference on Optical Communication, ECOC 2015, Valencia, Spain, 27 September - 1 October 2015. - 9788460817413 ; 2015-November
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Konferensbidrag (refereegranskat)abstract
- The performance of nonlinearity-tailored detection for single channel, single span optical fibre systems is studied. Monotonically decreasing bit error rate with transmitted power can be achieved without any nonlinearity compensation.
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| 9. |
- Liga, Gabriele, et al.
(författare)
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Ultra-Wideband Nonlinearity Compensation Performance in the Presence of PMD
- 2016
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Ingår i: 42nd European Conference on Optical Communication, ECOC 2016; Dusseldorf; Germany; 18 September 2016 through 22 September 2016. - 9783800742745 ; , s. 794-796
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Konferensbidrag (refereegranskat)abstract
- We investigate the performance of multi-channel digital backpropagation for 1 THz bandwidth optical fibre transmission in the presence of polarisation-mode dispersion. We show that the average SNR performance rapidly saturates as a function of the compensation bandwidth.
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