Non-Binary LDPC Codes for Magnetic Recording Channels: Error Floor Analysis and Optimized Code Design

Hareedy, Ahmed; Amiri, Behzad; Galbraith, Rick; Dolecek, Lara

doi:10.1109/tcomm.2016.2574869

Cited by 33 publications

(66 citation statements)

References 26 publications

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“…It is of course possible to protect all the bits of the LDPC code, but our method limits the rate loss. Our demonstration uses a modified version of the PR system described in [9], and a spatially-coupled (SC) LDPC code constructed as in [27]. 3) We prove that the inherent symmetry of LOCO codes makes balancing easy.…”

Section: Introductionmentioning

confidence: 91%

“…PR channel: We use the PR channel described in [9]. The MR channel effects are inter-symbol interference (intrinsic memory), jitter, and electronic noise.…”

Section: Density Gains In Mr Systemsmentioning

confidence: 99%

“…The MR channel effects are inter-symbol interference (intrinsic memory), jitter, and electronic noise. The channel density [9], [29], which is the ratio of the read-head pulse duration at half the amplitudes to the bit duration, is swept to generate the plots. The signal-to-noise ratio (SNR) is 13.00 dB.…”

Section: Density Gains In Mr Systemsmentioning

confidence: 99%

“…Constrained codes were used to extend the life of MR systems employing peak detection, and they continue to be used in modern MR systems [5], [6] to improve the performance of sequence detection on partial response (PR) channels such as extended PR4 (EPR4 and E 2 PR4) channels [7], [8]. PR channels with equalization targets that follow the channel impulse response [9] require forbidden patterns to be symmetric. Moreover, constrained codes improve the performance on low resolution media by preventing short pulses, which might be missed when reading [10].…”

Section: Introductionmentioning

confidence: 99%

“…From Table IV, the C-LOCO code C c 90,1 has rate 0.6923 and adder size 63 bits. The same rate is achieved in [26] for an RLL code with d = 1 at code (resp., message) length 13 (resp., 9) bits. However, the technique in [26] is based on lookup tables; thus, the complexity of the encoding and decoding is governed by lookup tables of size 2 9 × 13 = 6656 bits.…”

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confidence: 99%

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LOCO Codes: Lexicographically-Ordered Constrained Codes

Hareedy

Calderbank

2020

IEEE Trans. Inform. Theory

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Line codes make it possible to mitigate interference, to prevent short pulses, and to generate streams of bipolar signals with no direct-current (DC) power content through balancing. They find application in magnetic recording (MR) devices, in Flash devices, in optical recording devices, and in some computer standards. This paper introduces a new family of fixed-length, binary constrained codes, named lexicographically-ordered constrained codes (LOCO codes), for bipolar non-return-to-zero signaling. LOCO codes are capacity-achieving, the lexicographic indexing enables simple, practical encoding and decoding, and this simplicity is demonstrated through analysis of circuit complexity. LOCO codes are easy to balance, and their inherent symmetry minimizes the rate loss with respect to unbalanced codes having the same constraints. Furthermore, LOCO codes that forbid certain patterns can be used to alleviate inter-symbol interference in MR systems and inter-cell interference in Flash systems. Numerical results demonstrate a gain of up to 10% in rate achieved by LOCO codes with respect to other practical constrained codes, including run-length-limited codes, designed for the same purpose. Simulation results suggest that it is possible to achieve a channel density gain of about 20% in MR systems by using a LOCO code to encode only the parity bits, limiting the rate loss, of a low-density parity-check code before writing.

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Section: Introductionmentioning

confidence: 91%

“…PR channel: We use the PR channel described in [9]. The MR channel effects are inter-symbol interference (intrinsic memory), jitter, and electronic noise.…”

Section: Density Gains In Mr Systemsmentioning

confidence: 99%

Section: Density Gains In Mr Systemsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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LOCO Codes: Lexicographically-Ordered Constrained Codes

Hareedy

Calderbank

2020

IEEE Trans. Inform. Theory

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The finite length analysis of spatially-coupled codes for 1-D magnetic recording channels

Esfahanizadeh

Hareedy

Dolecek

2016

2016 50th Asilomar Conference on Signals, Systems and Computers

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Design Guidelines of Low-Density Parity-Check Codes for Magnetic Recording Systems

Fang

Han

Cai

et al. 2018

IEEE Commun. Surv. Tutorials

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As one of the most classical data-storage systems, magnetic recording (MR) systems have attracted a significant amount of research attention in the past several decades due to the advantages of low cost and high storage density. Along with the continual increase of areal density of modern MR devices, more severe inter-symbol interference (ISI) and noise appear and thus reliable storage becomes more difficult. To address this challenging problem, turbo detections and errorcorrection codes (ECCs) have been applied to MR systems so as to significantly improve the overall data-storage reliability. Among all the existing ECCs, low-density parity-check (LDPC) codes are of particular interest because they can offer excellent error performance with relatively low encoding and decoding complexity. This paper presents a comprehensive survey of the latest research advancements in LDPC-code design for MR systems from the perspectives of code construction, decoder design, as well as asymptotic performance-evaluation methodology. More specifically, we summarize the design guidelines of LDPC encoder and decoder over both one-dimensional (OD) ISI and two-dimensional (TD) ISI channels, which are commonly used to characterize MR systems with different areal densities. We also concisely portray the research progress in the design of some LDPC-code variants, such as protograph codes, repeataccumulate (RA) codes, spatially-coupled (SC) codes, and their non-binary counterparts over the aforementioned ISI channels. In particular, we restrict our attention to the reading process and ignore the written-in errors in MR systems unless otherwise stated. Hopefully, this survey will inspire more research activities in the area of LDPC-coded MR systems.

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Non-Binary LDPC Codes for Magnetic Recording Channels: Error Floor Analysis and Optimized Code Design

Cited by 33 publications

References 26 publications

LOCO Codes: Lexicographically-Ordered Constrained Codes

LOCO Codes: Lexicographically-Ordered Constrained Codes

The finite length analysis of spatially-coupled codes for 1-D magnetic recording channels

Design Guidelines of Low-Density Parity-Check Codes for Magnetic Recording Systems

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