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constrained coding techniques for the suppression of intrachannel nonlinear effects in high-speed optical transmission

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JOURNAL OF LIGHTWAVE TECHNOLOGY 2006年第1期24卷 411-419页

作者： Djordjevic, IB Vasic, B Univ Arizona Dept Elect & Comp Engn Tucson AZ 85721 USA

A problem of suppression of intrachannel nonlinearities through the use of constrained coding is considered. Three different techniques are proposed and compared with respect to their efficiency, namely 1) constrained coding;2) combined constrained and error control coding;and 3) deliberate error insertion. Significant Q-factor improvement up to 16 dB depending on code rate and number of spans is demonstrated. A combined constrained-iterative forward error correction (FEC) scheme can operate in the presence of strong intrachannel nonlinearities when even advanced FEC schemes would be overwhelmed with errors. It provides a coding gain of 12.1 dB at a bit error rate (BER) of 10(-9). Deliberate error insertion is an efficient approach to balance the encoder complexity and the achievable coding gain.

关键词： constrained coding intrachannel crossphase modulation intrachannel four-wave mixing optical communications

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PAPER WIDGETS: VISUALLY AESTHETIC "SMARTS" FOR DOCUMENT IMAGES

PAPER WIDGETS: VISUALLY AESTHETIC "SMARTS" FOR DOCUMENT IMAG...

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IEEE International Conference on Image Processing

作者： Sankarasubramaniam, Yogesh Munnangi, Krusheel Banerjee, Serene Kuchibhotla, Anjaneyulu HP Labs India Bangalore Karnataka India

ISBN: (纸本)9781424479948

Traditional 1D and 2D barcodes provide high data density, but they are visually jarring and require isolated whitemargins for placement. In this work, we introduce new machine-readable "smarts" for paper documents, called paper widgets. Like barcodes, paper widgets contain digital data which can be read upon scanning and decoding. However, unlike barcodes, they have very small footprint (fraction of ***.), and carry a human-readable component that provides visual meaning. Furthermore, paper widgets can be placed and recovered in a distributed fashion from any position on a document image. For example, they can be positioned right beside contents of interest, and need not be confined to isolated white margins. We describe how all these widget properties can be simultaneously achieved using simple operations that are robust to print-scan distortions. In particular, we highlight a novel constrained coding technique that helps combat print-scan inter-symbol interference (ISI), and a Gabor-filtering based extraction that accurately identifies widget regions from any position on a scanned document image. Experimental evaluations reveal that paper widgets can be recovered from print-scan distortions with near-100% accuracy.

关键词： Machine-readability Print-scan Document image Gabor filter constrained coding

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Methods for the Soft-decision Decoding of MTR Codes in Multiple-Head Magnetic Recording Systems

Methods for the Soft-decision Decoding of MTR Codes in Multi...

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2010 IEEE International Conference on Communications

作者： Djuric, Nikola Senk, Vojin Fac Tech Sci Novi Sad 21000 Serbia

ISBN: (纸本)9781424464043

Two different methods for the soft-decision decoding of the maximum-transition-run (MTR) codes have been considered in this paper. The first one, the maximum a posteriori (MAP) algorithm, is based on the Bayesian algorithm, computing a posteriori log-likelihood ratios (LLR) using MTR codewords. The second one, the soft-decision implementation in Boolean logic circuits has been used to propagate the soft-values through the MTR decoder. The MTR code performs as an inner encoding code, in a simple concatenation of the low-density parity-check (LDPC) and the MTR. The special case of two-track two-head E(2)PR4 channel model was used, assuming the low level of inter-track interference (ITI) and the AWGN noise presence. The soft-decision decoding results with nearly 1.7dB coding gain, using the MAP algorithm, while nearly 1.9dB, using the second one approach.

关键词： maximum-transition-run codes low-density parity-check codes multiple-head magnetic recording constrained coding soft-decision decoding

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Higher bit rates for dispersion-managed soliton communication systems via constrained coding

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JOURNAL OF LIGHTWAVE TECHNOLOGY 2006年第3期24卷 1149-1158页

作者： Pechenkin, V Kschischang, FR Univ Toronto Dept Elect & Comp Engn Toronto ON M5S 3G4 Canada

constrained coding as a method to increase the data rate in dispersion-managed soliton (DMS) communication systems is proposed. This approach is well known and widely used in the context of magnetic and optical recording systems. This paper shows that it is also applicable to DMS systems due to certain similarities between the underlying physical channels. Since timing jitter is an important error-generating mechanism for solitons, a coding scheme specifically designed to combat pulse shifts is also presented, and its properties in the framework of a particular information-theoretic channel model are analyzed. A connection between the model used and the real physical channel is then established. Next, the coded system is compared with the original one from the channel capacity point of view with the help of numerical examples. Finally, the fact that the application of constrained coding may alleviate soliton pulse-to-pulse interaction is exploited. This, in turn, opens the door to the usage of higher-than-usual map strengths and ultimately leads to a significant increase of up to 50% in the bit rate.

关键词： constrained coding dispersion-managed solitons error control fiber-optic communications

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Application of MTR soft-decision decoding in multiple-head magnetic recording systems

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SADHANA-ACADEMY PROCEEDINGS IN ENGINEERING SCIENCES 2009年第3期34卷 381-392页

作者： Djuric, Nikola Despotovic, Miroslav Univ Novi Sad Fac Tech Sci Novi Sad 21000 Serbia

Application of a simple approach for the soft-decision decoding of Maximum-Transition-Run (MTR) codes has been presented in this paper. A low-demanded hardware realization have been proposed for soft-decision decoding in MTR basic AND, OR and XOR logic circuits. The suggested approach is explored over the two-track, two-head E(2)PR4 partial response magnetic recording system. The overall two-track channel detection complexity reduction of 41.9% is offered in simulation scheme, encoded by Low-Density Parity-Check (LDPC) code, serially concatenated with inner MTR. The 1.9 dB coding gain has been obtained, comparing to uncoded channel and assuming the AWGN noise presence.

关键词： Soft-decision decoding partial response multiple-head magnetic recording systems maximum transition run codes constrained coding

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MAP Decoding of MTR Codes in LDPC-MTR Encoded Magnetic Recording Systems

MAP Decoding of MTR Codes in LDPC-MTR Encoded Magnetic Recor...

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9th International Conference on Telecommunications in Modern Satellite, Cable and Broadcasting Services

作者： Duric, Nikola Univ Novi Sad Fac Tech Sci Novi Sad 21000 Serbia

ISBN: (纸本)9781424443819

A MAP algorithm for decoding maximum transition run (MTR) codes, using the soft-decision approach, is presented in this paper. The algorithm is based on the Bayesian algorithm, and computes a posteriori log-likelihood ratio (LLR) for output bits, using codewords of the MTR code. The log MAP and max-log MAP version of the algorithm have been developed, showing performance comparable to that of the original version. MAP algorithm offers 2dB coding gain, in combination with LDPC, comparing to the uncoded system, while utilization of the MTR, the 25% decreasing in overall required operations of detector over E(2)PR4 magnetic recording system.

关键词： constrained coding soft-decision decoding magnetic recording and partial response channel

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Capacity of the trapdoor channel with feedback

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IEEE TRANSACTIONS ON INFORMATION THEORY 2008年第7期54卷 3150-3165页

作者： Permuter, Haim Cuff, Paul Van Roy, Benjamin Weissman, Tsachy Stanford Univ Dept Elect Engn Stanford CA 94305 USA Technion Israel Inst Technol Dept Elect Engn IL-32000 Haifa Israel

We establish that the feedback capacity of the trapdoor channel is the logarithm of the golden ratio and provide a simple communication scheme that achieves capacity. As part of the analysis, we formulate a class of dynamic programs that characterize capacities of unifilar finite-state channels. The trapdoor channel is an instance that admits a simple closed-form solution.

关键词： Bellman equation chemical channel constrained coding directed information feedback capacity golden-ratio infinite-horizon dynamic program trapdoor channel value iteration

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Fixed-rate maximum-runlength-limited codes from variable-rate bit stuffing

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IEEE TRANSACTIONS ON INFORMATION THEORY 2007年第8期53卷 2769-2790页

作者： Sankarasubramaniam, Yogesh McLaughlin, Steven W. Georgia Inst Technol Sch Elect & Comp Engn Atlanta GA 30332 USA

We introduce the fixed-rate bit stuff (FRB) for efficiently encoding and decoding maximum-runlength-limited (MRL) sequences. Our approach is based on a simple, variable-rate technique called bit stuffing. Bit stuffing produces near-capacity achieving codes for a wide range of constraints, encoding is variable-rate, which is unacceptable in most applications. In this work, we design near-capacity fixed-rate codes using a three-step procedure. The fixed-length input data block first undergoes iterative preprocessing, followed by variable-rate bit stuffing, and finally dummy-bit padding to a fixed output length. The iterative preprocessing is key to achieving high encoding rates. We discuss rate computation for the proposed FRB algorithm and show that the asymptotic (in input block length) encoding rate is close to the average rate of the variable-rate bit stuff code. Then, we proceed to explore the effect of decreasing/increasing the number of preprocessing iterations. Finally, we derive a lower bound on the encoding rate with finite-length input blocks and tabulate the parameters required to design FRB codes with rate close to 100/101 and 200/201.

关键词： bit stuffing constrained coding fixed-rate codes

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Timing metrics for constrained codes

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IEEE TRANSACTIONS ON INFORMATION THEORY 2006年第1期52卷 300-307页

作者： Patapoutian, A Maxtor Corp Shrewsbury MA 01545 USA

The effect of data constraints on synchronization is quantified by the use of three simple timing metrics that respectively measure the ensemble average, the worst, and the best timing qualities attainable with a given binary pulse amplitude modulation (PAM) waveform. These timing metrics are computed with the help of a graph which represents the constrained PAM system. The timing metrics of the (0, k) constraint are studied in detail for selected PAM pulses.

关键词： constrained coding Cramer-Rao bound Fisher information magnetic recording run-length-limited systems shortest route synchronization timing-error detector

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Tensor-product parity codes: Combination with constrained codes and application to perpendicular recording

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IEEE TRANSACTIONS ON MAGNETICS 2006年第2期42卷 214-219页

作者： Chaichanavong, P Siegel, PH Marvell Semicond Santa Clara CA 95054 USA Univ Calif San Diego Ctr Magnet Recording Res La Jolla CA 92093 USA

A parity code and a distance enhancing constrained code are often concatenated with a Reed-Solomon code to form a coding system for magnetic recording. The tensor-product parity coding scheme helps to improve efficiency of the parity code while retaining the same level of performance. In this paper, we present two methods for combining a tensor-product parity code with a distance-enhancing constrained code. The first method incorporates a constrained code with unconstrained positions. The second method uses a new technique, which we call word-set partitioning, to achieve a higher code rate relative to the first method. We simulate the performance of several coding systems based upon the two combination methods on a perpendicular recording channel, and we compare their symbol error rates and sector error rates with those of a system that uses only a Reed-Solomon code.

关键词： constrained coding parity code perpendicular magnetic recording tensor-product code

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