| 1. |
- He, Zonglong, 1994, et al.
(författare)
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Experimental Demonstration of Learned Pulse Shaping Filter for Superchannels
- 2022
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Ingår i: 2022 Optical Fiber Communications Conference and Exhibition, OFC 2022 - Proceedings.
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Konferensbidrag (refereegranskat)abstract
- We demonstrate a pulse shaping filter enabled by machine learning for spectral superchannels. In contrast to a 1% roll-off root-raised cosine filter, our learned filter reduces the adaptive equalizer length by 47% for the same spectral efficiency.
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| 2. |
- He, Zonglong, 1994, et al.
(författare)
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Periodicity-Enabled Size Reduction of Symbol Based Predistortion for High-Order QAM
- 2022
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Ingår i: Journal of Lightwave Technology. - 0733-8724 .- 1558-2213. ; In press
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Tidskriftsartikel (refereegranskat)abstract
- We experimentally demonstrate a novel size reduction approach for symbol-based look-up table (LUT) digital predistortion (DPD) of the transmitter impairments taking advantage of the periodicity in the pattern-dependent distortions. Compared to other reduced-size LUT schemes, the proposed method can significantly lessen the storage memory requirements with negligible performance penalty for high-order modulation formats. To further alleviate the storage memory restriction, a twice reduced-size LUT scheme is proposed to provide further size reduction. Importantly, given a targeted memory length, we verify the importance of averaging over sufficient occurrences of the patterns to obtain a well-performing LUT. Moreover, it is necessary to evaluate the performance of LUT-based DPD using random data. Finally, we demonstrate a neural network (NN) based nonlinear predistortion technique, which achieves nearly identical performance to the full-size LUT for all employed constellations and is robust against a change of modulation format. The proposed techniques are verified in a back-to-back transmission experiment of 20 Gbaud 64-QAM, 256-QAM, and 1024-QAM signals considering 3 and 5 symbol memory. The performance of the LUT-based DPD is further validated in a noise loading experiment.
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| 3. |
- He, Zonglong, 1994, et al.
(författare)
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Symbol-Based Supervised Learning Predistortion for Compensating Transmitter Nonlinearity
- 2021
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Ingår i: 2021 European Conference on Optical Communication, ECOC 2021. - 9781665438681
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Konferensbidrag (refereegranskat)abstract
- We experimentally demonstrate a symbol-based nonlinear digital predistortion (DPD) technique utilizing supervised learning, which is robust against a change of modulation format. Back-to-back transmission of 30 Gbaud 32, 64 and 256QAM confirms that our scheme significantly outperforms the baseline of arcsine-based predistortion.
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| 4. |
- Song, Jinxiang, 1995, et al.
(författare)
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Blind Frequency-Domain Equalization Using Vector-Quantized Variational Autoencoders
- 2023
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Ingår i: 2023 European Conference on Optical Communications, ECOC 2023. ; In press
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Konferensbidrag (refereegranskat)abstract
- We propose a novel frequency-domain blind equalization scheme for coherent optical communications. The method is shown to achieve similar performance to its recently proposed time-domain counterpart with lower computational complexity, while outperforming the commonly used CMA-based equalizers.
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| 5. |
- Song, Jinxiang, 1995, et al.
(författare)
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End-to-end Autoencoder for Superchannel Transceivers with Hardware Impairments
- 2021
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Ingår i: 2021 Optical Fiber Communications Conference and Exhibition, OFC 2021 - Proceedings.
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Konferensbidrag (refereegranskat)abstract
- We propose an end-to-end learning-based approach for superchannel systems impaired by non-ideal hardware component. Our system achieves up to 60% SER reduction and up to 50% guard band reduction compared with the considered baseline scheme.
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| 6. |
- Song, Jinxiang, 1995, et al.
(författare)
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Model-Based End-to-End Learning for WDM Systems With Transceiver Hardware Impairments
- 2022
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Ingår i: IEEE Journal of Selected Topics in Quantum Electronics. - 1558-4542 .- 1077-260X. ; 28:4
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Tidskriftsartikel (refereegranskat)abstract
- We propose an AE-based transceiver for a WDM system impaired by hardware imperfections. We design our AE following the architecture of conventional communication systems. This enables to initialize the AE-based transceiver to have similar performance to its conventional counterpart prior to training and improves the training convergence rate. We first train the AE in a single-channel system, and show that it achieves performance improvements by putting energy outside the desired bandwidth, and therefore cannot be used for a WDM system. We then train the AE in a WDM setup. Simulation results show that the proposed AE significantly outperforms the conventional approach. More specifically, it increases the spectral efficiency of the considered system by reducing the guard band by 37% and 50% for a root-raised-cosine filter-based matched filter with 10% and 1% roll-off, respectively. An ablation study indicates that the performance gain can be ascribed to the optimization of the symbol mapper, the pulse-shaping filter, and the symbol demapper. Finally, we use reinforcement learning to learn the pulse-shaping filter under the assumption that the channel model is unknown. Simulation results show that the reinforcement-learning-based algorithm achieves similar performance to the standard supervised end-to-end learning approach assuming perfect channel knowledge.
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| 7. |
- Song, Jinxiang, 1995, et al.
(författare)
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Over-the-fiber Digital Predistortion Using Reinforcement Learning
- 2021
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Ingår i: 2021 European Conference on Optical Communication, ECOC 2021. - 9781665438681
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Konferensbidrag (refereegranskat)abstract
- We demonstrate, for the first time, experimental over-the-fiber training of transmitter neural networks (NNs) using reinforcement learning. Optical back-to-back training of a novel NN-based digital predistorter outperforms arcsine-based predistortion with up to 60% bit-error-rate reduction.
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| 8. |
- Ahmad, Tauseef, 1986, et al.
(författare)
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Methodology for Power-Aware Coherent Receiver Design
- 2013
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Ingår i: Optics InfoBase Conference Papers. - 2162-2701. ; , s. SPT4D.4-
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Konferensbidrag (refereegranskat)abstract
- We describe a methodology to design and evaluate DSP hardware for a coherent receiver. Important parameters that can be assessed include DSP power consumption and chip area.
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| 9. |
- Beygi, Lotfollah, 1977, et al.
(författare)
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A Discrete-Time Model for Uncompensated Single-Channel Fiber-Optical Links
- 2012
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Ingår i: IEEE Transactions on Communications. - 0090-6778 .- 1558-0857. ; 60:11, s. 3440-3450
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Tidskriftsartikel (refereegranskat)abstract
- An analytical discrete-time model is introduced for single-wavelength polarization multiplexed nonlinear fiber-optical channels based on the symmetrized split-step Fourier method (SSFM). According to this model, for high enough symbol rates, a fiber-optic link can be described as a linear dispersive channel with additive white Gaussian noise (AWGN) and a complex scaling. The variance of this AWGN noise and the attenuation are computed analytically as a function of input power and channel parameters. The results illustrate a cubic growth of the noise variance with input power. Moreover, the cross effect between the two polarizations and the interaction of amplifier noise and the transmitted signal due to the nonlinear Kerr effect are described. In particular, it is found that the channel noise variance in one polarization is affected twice as much by the transmitted power in that polarization than by the transmitted power in the orthogonal polarization.The effect of pulse shaping is also investigated through numerical simulations. Finally, it is shown that the analytical performance results based on the new model are in close agreement with numerical results obtained using the SSFM for a symbol rate of 28 Gbaud and above.
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| 10. |
- Beygi, Lotfollah, 1977, et al.
(författare)
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On nonlinearly-induced noise in single-channel optical links with digital backpropagation
- 2013
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Ingår i: Optics Express. - 1094-4087 .- 1094-4087. ; 21:22, s. 26376-26386
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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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