| 141. |
- 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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| 142. |
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| 143. |
- 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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| 144. |
- Ghasemmehdi, Arash, 1981, et al.
(författare)
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Faster Recursions in Sphere Decoding
- 2011
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Ingår i: IEEE Transactions on Information Theory. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-9448 .- 1557-9654. ; 57:6, s. 3530-3536
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Tidskriftsartikel (refereegranskat)abstract
- Most of the calculations in standard sphere decoders are redundant in the sense that they either calculate quantities that are never used or calculate some quantities more than once. A new method, which is applicable to lattices as well as finite constellations, is proposed to avoid these redundant calculations while still returning the same result. Pseudocode is given to facilitate immediate implementation. Simulations show that the speed gain with the proposed method increases linearly with the lattice dimension. At dimension 60, the new algorithms avoid about 75% of all floating-point operations.
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| 145. |
- Graell i Amat, Alexandre, 1976, et al.
(författare)
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Asymptotically optimal trellis coded modulation systems
- 2012
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Ingår i: Information Theory and Applications Workshop (ITA) 2012, San Diego, CA [Invited].
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- An asymptotically optimal trellis-coded modulation (TCM) system requires thejoint design of the encoder and the binary labeling of the constellation. Thisproblem can only be solved via exhaustive searches over the encoder and thelabeling which is unfeasible for large constellation sizes. In this paper, westudy binary labelings for TCM and show how they can be grouped in (modifiedHadamard) classes, which considerably reduces the search space. Using thisclassification, we formally prove that it is always possible to design a TCMsystem based on the binary-reflected Gray code (among many other labelings)with identical performance to the one proposed by Ungerboeck in 1982.
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| 146. |
- 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
-
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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| 147. |
- Gümüş, Kadir, et al.
(författare)
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End-to-End Learning of Geometrical Shaping Maximizing Generalized Mutual Information
- 2020
-
Ingår i: 2020 Optical Fiber Communications Conference and Exhibition, OFC 2020 - Proceedings. - 2162-2701. ; Part F174-OFC 2020
-
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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| 148. |
- Hadi, Mohammad, 1989, et al.
(författare)
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Dynamic Resource Allocation in Metro Elastic Optical Networks using Lyapunov Drift Optimization
- 2019
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Ingår i: Journal of Optical Communications and Networking. - 1943-0620 .- 1943-0639. ; 11:6, s. 250-259
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Tidskriftsartikel (refereegranskat)abstract
- Consistent growth in the volume and dynamic behavior of traffic mandates new requirements for fast and adaptive resource allocation in metro networks. We propose a dynamic resource allocation technique for adaptive minimization of spectrum usage in metro elastic optical networks. We consider optical transmission as a service specified by its bandwidth profile parameters, which are minimum, average, and maximum required transmission rates. To consider random traffic events, we use a stochastic optimization technique to develop a novel formulation for dynamic resource allocation in which service level specifications and network stability constraints are addressed. Next, we employ the elegant theory of Lyapunov optimization to solve the stochastic optimization problem and derive a fast integer linear program, which is periodically solved to create an adaptation between available resources and dynamic network state. To quantize the performance of the proposed technique, we report its spectral efficiency as a function of peak to average traffic ratio and Lyapunov penalty coefficient. Simulation results show that the dynamic resource allocation procedure can improve spectral efficiency by a factor of 3.3 for a peak to average traffic ratio of 1.37 and a Lyapunov penalty coefficient of 1000 in comparison with fixed network planning. There is also a trade-off between transmission delay and spectrum utilization in the proposed technique, which can be adjusted by a Lyapunov penalty coefficient.
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| 149. |
- Hadi, Mohammad, 1989, et al.
(författare)
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General QoS-Aware Scheduling Procedure for Passive Optical Networks
- 2020
-
Ingår i: Journal of Optical Communications and Networking. - 1943-0620 .- 1943-0639. ; 12:7, s. 217-226
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Tidskriftsartikel (refereegranskat)abstract
- Increasing volume, dynamism, and diversity of access traffic have complicated the challenging problem of dynamic resource allocation in passive optical networks. We introduce a general scheduling procedure for passive optical networks, which optimizes a desired performance metric for an arbitrary set of operational constraints. The proposed scheduling has a fast and causal iterative implementation, where each iteration involves a local optimization problem followed by a recursive update of some status information. The generality of the platform enables a proper description of the diverse quality of service requirements, while its low computational complexity makes agile tracking of the network dynamism possible. To demonstrate its versatility and generality, the applications of the scheme for service-differentiated dynamic bandwidth allocation in time- and wavelength-division-multiplexed passive optical networks are discussed. To further reduce the computational complexity, a closed-form solution of the involved optimization in each iteration of the scheduling is derived. We directly incorporate transmission delay in the scheduling and show how the consumed power is traded for the tolerable amount of transmission delay. Furthermore, a 50% power efficiency improvement is reported by exploiting the inherent service diversity among subscribers. The impact of service prioritization, finite buffer length, and packet drops on the power efficiency of the scheme are also investigated.
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| 150. |
- Hadi, Mohammad, 1989, et al.
(författare)
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Iterative configuration in elastic optical networks [Invited]
- 2020
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Ingår i: 2020 24th International Conference on Optical Network Design and Modeling, ONDM 2020.
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Konferensbidrag (refereegranskat)abstract
- A general dynamic resource allocation scheme is introduced, which iteratively reconfigures an elastic optical network according to traffic dynamism and service diversity. As an application example, the scheme is employed for impairment-aware power-efficient resource allocation in a short-haul metro elastic optical network to demonstrate a typical 5% power plus service penalty for compensating bandwidth limitations compared with the corresponding limitless counterpart.
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