| 1. |
- Farsi, Mohammad, 1994, et al.
(författare)
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Improved Polarization Tracking in the Presence of PDL
- 2022
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Ingår i: European Conference on Optical Communication, ECOC. - 9781957171159
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Konferensbidrag (refereegranskat)abstract
- We propose a novel tracking algorithm for optical channels suffering from fast state of polarization (SOP) rotations and polarization-dependent loss (PDL). Unlike gradient descent-based algorithms that require step size adjustment when the channel conditions change, our algorithm performs similarly or better without parameter tuning.
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| 2. |
- Farsi, Mohammad, 1994, et al.
(författare)
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Learning to Extract Distributed Polarization Sensing Data from Noisy Jones Matrices
- 2024
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Ingår i: 2024 Optical Fiber Communication Conference and Exhibition, OFC 2024 - Proceeding. - 2162-2701.
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Konferensbidrag (refereegranskat)abstract
- We consider the problem of recovering spatially resolved polarization information from receiver Jones matrices. We introduce a physics-based learning approach, improving noise resilience compared to previous inverse scattering methods, while highlighting challenges related to model overparameterization.
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| 3. |
- Farsi, Mohammad, 1994, et al.
(författare)
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Polarization Tracking in the Presence of PDL and Fast Temporal Drift
- 2022
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Ingår i: Journal of Lightwave Technology. - 0733-8724 .- 1558-2213. ; 40:19, s. 6408-6416
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we analyze the effectiveness of polarization tracking algorithms in optical transmission systems suffering from fast state of polarization (SOP) rotations and polarization-dependent loss (PDL). While most of the gradient descent (GD)-based algorithms in the literature may require step size adjustment when the channel condition changes, we propose tracking algorithms that can perform similarly or better without parameter tuning. Numerical simulation results show higher robustness of the proposed algorithms to SOP and PDL drift compared to GD-based algorithms, making them promising candidates to be used in aerial fiber links where the SOP can potentially drift rapidly, and therefore becomes challenging to track.
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| 4. |
- Graell i Amat, Alexandre, 1976, et al.
(författare)
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Spatially-Coupled Codes for Optical Communications: State-of-the-Art and Open Problems
- 2015
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Ingår i: 20th OptoElectronics and Communications Conference, OECC 2015. - 9781467379441 ; , s. Art. no. 7340116-
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Konferensbidrag (refereegranskat)abstract
- We give a brief survey of a particularly interesting class of codes, called spatially-coupled codes, which are strong candidates for future optical communication systems. We discuss some recent research on this class of codes in the area of optical communications, and summarize some open research problems.
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| 5. |
- Gümüş, Kadir, et al.
(författare)
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End-to-End Learning of Geometrical Shaping Maximizing Generalized Mutual Information
- 2020
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Ingår i: 2020 Optical Fiber Communications Conference and Exhibition, OFC 2020 - Proceedings. - 2162-2701.
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Konferensbidrag (refereegranskat)abstract
- GMI-based end-to-end learning is shown to be highly nonconvex. We apply gradient descent initialized with Gray-labeled APSK constellations directly to the constellation coordinates. State-of-the-art constellations in 2D and 4D are found providing reach increases up to 26% w.r.t. to QAM.
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| 6. |
- Häger, Christian, 1986, et al.
(författare)
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A Deterministic Construction and Density Evolution Analysis for Generalized Product Codes
- 2016
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Generalized product codes (GPCs) are extensions of product codes (PCs) where code symbols are protected by two component codes but not necessarily arranged in a rectangular array. In this tutorial paper, we review a deterministic construction for GPCs that has been previously proposed by the authors together with an accompanying density evolution (DE) analysis. The DE analysis characterizes the asymptotic performance of the resulting GPCs under iterative bounded-distance decoding of the component codes over the binary erasure channel. As an application, we discuss the analysis and design of three different classes of GPCs: spatially-coupled PCs, symmetric GPCs, and GPCs based on component code mixtures.
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| 7. |
- Häger, Christian, 1986, et al.
(författare)
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A Low-Complexity Detector for Memoryless Polarization-Multiplexed Fiber-Optical Channels
- 2014
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Ingår i: IEEE Communications Letters. - 1558-2558 .- 1089-7798. ; 18:2, s. 368-371
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Tidskriftsartikel (refereegranskat)abstract
- A low-complexity detector is introduced for polarization-multiplexed M-ary phase shift keying modulation in a fiber-optical channel impaired by nonlinear phase noise, generalizing a previous result by Lau and Kahn for single-polarization signals. The proposed detector uses phase compensation based on both received signal amplitudes in conjunction with simple straight-line rather than four-dimensional maximum-likelihood decision boundaries.
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| 8. |
- Häger, Christian, 1986, et al.
(författare)
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Comparison of Terminated and Tailbiting Spatially Coupled LDPC Codes With Optimized Bit Mapping for PM-64-QAM
- 2014
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Ingår i: 2014 European Conference on Optical Communication, ECOC 2014; Cannes; France; 21 September 2014 through 25 September 2014. - 9782954944401 ; , s. Art. no. 6964047-
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Konferensbidrag (refereegranskat)abstract
- We optimize the allocation of coded bits to modulation bits for spatially coupled low-density parity-check (SC-LDPC) codes and PM-64-QAM. Tailbiting SC-LDPC codes are shown to offer a similar gap to capacity as their terminated counterparts, at a lower FEC overhead.
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| 9. |
- Häger, Christian, 1986, et al.
(författare)
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Constellation Optimization for Coherent Optical Channels Distorted by Nonlinear Phase Noise
- 2012
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Ingår i: Proceedings - IEEE Global Communications Conference, GLOBECOM. - 2334-0983 .- 2576-6813. ; , s. 2870-2875
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Konferensbidrag (refereegranskat)abstract
- We consider the design of amplitude phase-shift keying (APSK) constellations, targeting their application to coherent fiber-optical communications. Phase compensation is used at the receiver to combat nonlinear phase noise caused by the Kerr-effect. We derive the probability density function of the post- compensated observation for multilevel constellations. Optimal APSK constellations in terms of symbol error probability (SEP) are found assuming a two-stage detector. Performance gains of 3.2 dB can be achieved compared to 16-QAM at a SEP of 10^−2. We optimize the number of rings, the number of points per ring, as well as the radius distribution of the constellation. For low to moderate nonlinearities, radius optimization only yields minor improvements over an equidistant spacing of rings. In the highly nonlinear regime, however, a smaller SEP can be achieved by “sacrificing” the outer ring of the constellation, in favor of achieving good SEP in the remaining rings.
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| 10. |
- Häger, Christian, 1986, et al.
(författare)
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Data-Driven Estimation of Capacity Upper Bounds
- 2022
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Ingår i: IEEE Communications Letters. - 1558-2558 .- 1089-7798.
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Tidskriftsartikel (refereegranskat)abstract
- We consider the problem of estimating an upper bound on the capacity of a memoryless channel with unknown channel law and continuous output alphabet. A novel data-driven algorithm is proposed that exploits the dual representation of capacity where the maximization over the input distribution is replaced with a minimization over a reference distribution on the channel output. To efficiently compute the required divergence maximization between the conditional channel and the reference distribution, we use a modified mutual information neural estimator that takes the channel input as an additional parameter. We numerically evaluate our approach on different memoryless channels and show empirically that the estimated upper bounds closely converge either to the channel capacity or to best-known lower bounds.
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