Zipper Codes Sukmadji, Alvin Y.; Martinez-Penas, Umberto; Kschischang, Frank R.
Journal of lightwave technology,
10/2022, Letnik:
40, Številka:
19
Journal Article
Recenzirano
Odprti dostop
Zipper codes are a framework for describing spatially-coupled product-like codes. Many well-known codes, such as staircase codes and braided block codes, are subsumed into this framework. New types ...of codes such as tiled diagonal and delayed diagonal zipper codes are introduced along with their software simulation results. Stall patterns that can arise in iterative decoding are analyzed, giving a means of error floor estimation.
Staircase Codes: FEC for 100 Gb/s OTN Smith, B. P.; Farhood, A.; Hunt, A. ...
Journal of lightwave technology,
2012-Jan.1,, 2012, 2012-01-00, Letnik:
30, Številka:
1
Journal Article
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Staircase codes, a new class of forward-error-correction (FEC) codes suitable for high-speed optical communications, are introduced. An ITU-T G.709-compatible staircase code with rate R = 239/255 is ...proposed, and field-programmable-gate-array-based simulation results are presented, exhibiting a net coding gain of 9.41 dB at an output error rate of 10 -15 , an improvement of 0.42 dB relative to the best code from the ITU-T G.975.1 recommendation. An error floor analysis technique is presented, and the proposed code is shown to have an error floor at 4.0 × 10 -21 .
Roadmap of optical communications Agrell, Erik; Karlsson, Magnus; Chraplyvy, A R ...
Journal of optics (2010),
06/2016, Letnik:
18, Številka:
6
Journal Article
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Lightwave communications is a necessity for the information age. Optical links provide enormous bandwidth, and the optical fiber is the only medium that can meet the modern society's needs for ...transporting massive amounts of data over long distances. Applications range from global high-capacity networks, which constitute the backbone of the internet, to the massively parallel interconnects that provide data connectivity inside datacenters and supercomputers. Optical communications is a diverse and rapidly changing field, where experts in photonics, communications, electronics, and signal processing work side by side to meet the ever-increasing demands for higher capacity, lower cost, and lower energy consumption, while adapting the system design to novel services and technologies. Due to the interdisciplinary nature of this rich research field, Journal of Optics has invited 16 researchers, each a world-leading expert in their respective subfields, to contribute a section to this invited review article, summarizing their views on state-of-the-art and future developments in optical communications.
Factor graphs and the sum-product algorithm Kschischang, F.R.; Frey, B.J.; Loeliger, H.-A.
IEEE transactions on information theory,
02/2001, Letnik:
47, Številka:
2
Journal Article
Recenzirano
Algorithms that must deal with complicated global functions of many variables often exploit the manner in which the given functions factor as a product of "local" functions, each of which depends on ...a subset of the variables. Such a factorization can be visualized with a bipartite graph that we call a factor graph, In this tutorial paper, we present a generic message-passing algorithm, the sum-product algorithm, that operates in a factor graph. Following a single, simple computational rule, the sum-product algorithm computes-either exactly or approximately-various marginal functions derived from the global function. A wide variety of algorithms developed in artificial intelligence, signal processing, and digital communications can be derived as specific instances of the sum-product algorithm, including the forward/backward algorithm, the Viterbi algorithm, the iterative "turbo" decoding algorithm, Pearl's (1988) belief propagation algorithm for Bayesian networks, the Kalman filter, and certain fast Fourier transform (FFT) algorithms.
In soliton communication systems, the continuous nonlinear spectrum, ideally zero, is conventionally ignored at the receiver. In this paper, we exploit correlation between the received continuous ...spectrum and perturbations of the discrete soliton eigenvalue. We propose four estimation schemes, classified into two categories, one based on the nonlinear Fourier transform (NFT) and the other based on minimum Euclidean distance. Both categories comprise two schemes, one that exploits the received continuous spectral function to achieve improved estimation and one that does not. Numerical simulations demonstrate that significant reduction in estimation error can be achieved when the continuous spectrum is exploited, translating into improved information transmission rates of up to 46% compared to the reference NFT-based scheme.
Multieigenvalue Communication Hari, Siddarth; Yousefi, Mansoor I.; Kschischang, Frank R.
Journal of lightwave technology,
07/2016, Letnik:
34, Številka:
13
Journal Article
Recenzirano
In the most general case, all three components-the discrete eigenvalues, the discrete spectral amplitudes, and the continuous spectrum-of the nonlinear Fourier transform of a signal can be ...independently modulated. This paper examines information transmission using only the discrete eigenvalues, and presents heuristic designs for multisoliton signal sets with spectral efficiencies greater than 3 b/s/Hz. The first design, called multieigenvalue position encoding, is based on an exhaustive search followed by pruning of the signal set to remove high pulsewidth or high bandwidth outliers. The second design, called trellis encoding, achieves comparable efficiencies to the fist method at much lower complexity. These multisoliton signals do not undergo any pulse broadening, but are significantly limited by bandwidth expansion if the system length is not much smaller than the dispersion length parameter. This limitation suggests that modulating the eigenvalues alone cannot address the problem of nonlinearity in commercial fiber transmission systems, and that our proposed methods are only meaningful when dispersion is very small and dominated by nonlinearity, e.g., close to the zero-dispersion wavelength at 1300 nm.
Sequential decoding of short length binary codes for the additive white Gaussian noise channel is considered. A variant of the variable-bias term (VBT) metric is introduced, producing useful ...trade-offs between performance and computational complexity. Comparisons are made with tail-biting convolutional codes decoded with a wrap-around Viterbi algorithm (WAVA) and with polar codes under successive-cancellation list (SCL) decoding. It is found that sequential decoding with the improved VBT metric has a better performance-complexity tradeoff than tail-biting codes under WAVA decoding (except at low complexities) but a worse performance-complexity tradeoff than polar codes under SCL decoding (except at high complexities).
Multilevel coding (MLC) is compared with bit-interleaved coded modulation (BICM) from a performance-versus-complexity standpoint. In both approaches, complexity-optimized error-reducing low-density ...parity-check inner codes are designed for concatenation with an outer hard-decision code, for various modulation orders. The codes are designed to achieve various points on the Pareto frontier characterizing the performance-complexity tradeoff. Computer simulations of the resulting codes reveal that MLC not only provides significant advantages compared with BICM, but also outperforms several existing MLC and BICM proposals. At 25% overhead, MLC provides a net coding gain of up to 12.8 dB with 16-QAM (1.0 dB from the constrained Shannon limit), a net coding gain of up to 13.6 dB with 64-QAM (1.2 dB from the constrained Shannon limit), and a net coding gain of up to 14 dB with 256-QAM (1.65 dB from the constrained Shannon limit), all with reasonable decoding complexity.
Power Reduction Techniques for LDPC Decoders Darabiha, A.; Chan Carusone, A.; Kschischang, F.R.
IEEE journal of solid-state circuits,
08/2008, Letnik:
43, Številka:
8
Journal Article, Conference Proceeding
Recenzirano
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This paper investigates VLSI architectures for low-density parity-check (LDPC) decoders amenable to low-voltage and low-power operation. First, a highly-parallel decoder architecture with low routing ...overhead is described. Second, we propose an efficient method to detect early convergence of the iterative decoder and terminate the computations, thereby reducing dynamic power. We report on a bit-serial fully-parallel LDPC decoder fabricated in a 0.13-mum CMOS process and show how the above techniques affect the power consumption. With early termination, the prototype is capable of decoding with 10.4 pJ/bit/iteration, while performing within 3 dB of the Shannon limit at a BER of 10 -5 and with 3.3 Gb/s total throughput. If operated from a 0.6 V supply, the energy consumption can be further reduced to 2.7 pJ/bit/iteration while maintaining a total throughput of 648 Mb/s, due to the highly-parallel architecture. To demonstrate the applicability of the proposed architecture for longer codes, we also report on a bit-serial fully-parallel decoder for the (2048, 1723) LDPC code in 10 GBase-T standard synthesized with a 90-nm CMOS library.
The message-passing approach to model-based signal processing is developed with a focus on Gaussian message passing in linear state-space models, which includes recursive least squares, linear ...minimum-mean-squared-error estimation, and Kalman filtering algorithms. Tabulated message computation rules for the building blocks of linear models allow us to compose a variety of such algorithms without additional derivations or computations. Beyond the Gaussian case, it is emphasized that the message-passing approach encourages us to mix and match different algorithmic techniques, which is exemplified by two different approaches - steepest descent and expectation maximization - to message passing through a multiplier node.
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