An Intertrack Interference Subtraction Scheme for a Rate-4/5 Modulation Code for Two-Dimensional Magnetic Recording

Pituso, Kotchakorn; Warisarn, Chanon; Tongsomporn, Damrongsak; Kovintavewat, Piya

doi:10.1109/lmag.2016.2589218

Cited by 17 publications

(7 citation statements)

References 14 publications

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“…Each new population corresponds to a new generation that produces decoded sequences with higher likelihoods. The perturbed received signal, as a result of the genetic algorithm process, is expressible as: y p2 = y + n p2 (14) where n p2 represents the random noise from the genetic algorithm process. The new outputs of the SSC polar decoder (d p2 ) are then assessed by CRC.…”

Section: Post-processing Decoding Technique For 2-d Isi Channelmentioning

confidence: 99%

Error correction in data storage systems using polar codes

2021

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This paper investigates error correction in two-dimensional (2-D) intersymbol interference (ISI) channels using polar codes. 2-D channels offer high data storage capacity compared to traditional one-dimensional (1-D) channels but suffer from greater ISI effects. Error correction codes can be used to mitigate the effects of ISI in 2-D data storage systems and improve their performance and reliability. Polar codes achieve the symmetric capacity for the class of binary-input discrete memoryless channels (B-DMCs). A post-processing technique is proposed to improve the performance of polar codes in the 2-D ISI channel. The simplified successive cancellation (SSC) polar decoder is useful for data storage systems owing to its good waterfall region performance, low error floors and good throughput rates and is therefore adopted for the study. Simulation results indicate that the proposed technique has an error correction performance comparable to some existing decoders and has better performance than other decoding techniques.This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

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Section: Post-processing Decoding Technique For 2-d Isi Channelmentioning

confidence: 99%

Error correction in data storage systems using polar codes

2021

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“…Otherwise, the function results in 0. If y i,1 = 0, then y i,2 = 0 automatically from (27), resulting in both f mer 0 (•) and f mer x (•) being zeros (the rest of cases). Using these two merging functions, the unified expression representing the contribution of a bit c i to the codeword index g(c) can be written as:…”

Section: B Binary Symmetric Loco Codesmentioning

confidence: 99%

“…The codes we present are non-binary LOCO codes, associated with certain mapping-demapping and level-based signaling, designed to prevent the SIS and PIS patterns. While there are efficient TD constrained codes in the literature [24]- [27], they either are not customized for TDMR systems, are not systematic, or do not exploit the nature of wide read heads. First, we introduce optimal codes, with respect to the rate, that prevent the SIS and PIS patterns, and we call them optimal square LOCO (OS-LOCO) and optimal plus LOCO (OP-LOCO) codes.…”

Section: Introductionmentioning

confidence: 99%

The Secret Arithmetic of Patterns: A General Method for Designing Constrained Codes Based on Lexicographic Indexing

Hareedy,

Dabak,

Calderbank

2020

Preprint

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Constrained codes are used to prevent errors from occurring in various data storage and data transmission systems. They can help in increasing the storage density of magnetic storage devices, in managing the lifetime of electronic storage devices, and in increasing the reliability of data transmission over wires. Over the years, designing practical (complexity-wise) capacityachieving constrained codes has been an area of research gaining significant interest. We recently designed various constrained codes based on lexicographic indexing. We introduced binary symmetric lexicographically-ordered constrained (S-LOCO) codes, q-ary asymmetric LOCO (QA-LOCO) codes, and a class of two-dimensional LOCO (TD-LOCO) codes. These families of codes achieve capacity with simple encoding and decoding, and they are easy to reconfigure. We demonstrated that these codes can contribute to notable density and lifetime gains in magnetic recording (MR) and Flash systems, and they find application in other systems too. In this paper, we generalize our work on LOCO codes by presenting a systematic method that guides the code designer to build any constrained code based on lexicographic indexing once the finite set of data patterns to forbid is known. In particular, we connect the set of forbidden patterns directly to the cardinality of the LOCO code and most importantly to the rule that uncovers the index associated with a LOCO codeword. By doing that, we reveal the secret arithmetic of patterns, and make the design of such constrained codes significantly easier. We give examples illustrating the method via codes based on lexicographic indexing from the literature. We then design optimal (rate-wise) constrained codes for the new two-dimensional magnetic recording (TDMR) technology. Over a practical TDMR model, we show notable performance gains as a result of solely applying the new codes. Moreover, we show how near-optimal constrained codes for TDMR can be designed and used to further reduce complexity and error propagation. All the newly introduced LOCO codes are designed using the proposed general method, and they inherit all the desirable properties in our previously designed LOCO codes.

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“…In the last decade, new Flash memory technologies emerged, giving a significant boost in density for electronic storage devices [1], [2]. Two-dimensional magnetic recording (TDMR) technology is a recent technology that enables magnetic storage devices to stay competitive [3]- [7]. In particular, it enables densities of terabits per square inch by squeezing storage tracks together and reducing magnetic isolation.…”

Section: Introductionmentioning

confidence: 99%

“…More details are discussed in Section II. There is prior work on efficient TD constrained codes [7], [18]- [22], for example, TD-RLL codes, but these codes are either not customized to forbid the error-prone patterns in TDMR systems or do not exploit the properties of modern TDMR systems to reduce redundancy.…”

Section: Introductionmentioning

confidence: 99%

Non-Binary Constrained Codes for Two-Dimensional Magnetic Recording

Dabak,

Hareedy,

Calderbank

2020

Preprint

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The two-dimensional magnetic recording (TDMR) technology promises storage densities of 10 terabits per square inch. However, when tracks are squeezed together, a bit stored in the two-dimensional (TD) grid suffers inter-symbol interference (ISI) from adjacent bits in the same track, and inter-track interference (ITI) from nearby bits in the adjacent tracks. A bit is highly likely to be read incorrectly if it is isolated in the middle of a 3×3 square; surrounded by its complements, horizontally and vertically. We improve the reliability of TDMR systems by designing two-dimensional constrained codes that prevent these square isolation patterns. We exploit the way TD read heads operate to design our codes, and we focus on TD read heads that collect signals from three adjacent tracks. We represent the two-dimensional square isolation constraint as a one-dimensional constraint on an alphabet of eight non-binary symbols. We use this new representation to construct a non-binary lexicographically-ordered constrained code where one third of the information bits are unconstrained. Our TD constraint codes are capacity-achieving, and the data protection is achieved with redundancy less than 3% and at modest complexity.

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An Intertrack Interference Subtraction Scheme for a Rate-4/5 Modulation Code for Two-Dimensional Magnetic Recording

Cited by 17 publications

References 14 publications

Error correction in data storage systems using polar codes

Error correction in data storage systems using polar codes

The Secret Arithmetic of Patterns: A General Method for Designing Constrained Codes Based on Lexicographic Indexing

Non-Binary Constrained Codes for Two-Dimensional Magnetic Recording

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