Warisarn, Chanon

Preferred name

Warisarn, Chanon

Alternative Name

Warisarn, C.

Main Affiliation

Integrated Innovative Technology

chanon.wa@kmitl.ac.th

Now showing 1 - 10 of 14

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Symbol-flipping method for block decoding in bit-patterned magnetic recording
(2021-05-19)
Sokjabok, Siwakon
;
Mattayakan, Mutita
;
Warisarn, Chanon
;
Koonkarnkhai, Santi
;
Kovintavewat, Piya
Bit-patterned magnetic recording (BPMR) technology can provide an areal density (AD) up to 15 Terabit per square inch (Tb/in2). However, the consequence of an increased AD results in severe inter-symbol interference (ISI) and inter-track interference (ITI). In practice, a run-length limited (RLL) code can be used to alleviate this problem. Therefore, this research proposes a symbol-flipping method in an iterative detection scheme between a soft-output Viterbi algorithm (SOVA) detector and an RLL decoder to help reduce errors resulting from these two interferences in a BPMR system. Simulation results reveal that the proposed system performs better than the same system architecture without the symbol-flipping method by 0.5 decibels at an AD of 5 Tb/in2.
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Enhancing Log-Likelihood Ratios with Mutual Information on Three-Reader One-Track Detection in Staggered BPMR Systems
(2025-03-01)
Rueangnetr, Natthakan
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Koonkarnkhai, Santi
;
Kovintavewat, Piya
;
Greaves, Simon John
;
Warisarn, Chanon
Because so much information is currently being shared online, there has been a sharp rise in the need for data storage devices over the past ten years. The main storage option is the hard disk drive (HDD), which is less expensive than some other types of data storage. Physical constraints, such as the superparamagnetic limit, are difficult to overcome using existing HDD technology. Consequently, bit-patterned magnetic recording (BPMR) has emerged as a potential solution, offering higher areal densities whilst maintaining thermal stability. Nevertheless, BPMR poses new challenges, such as inter-symbol interference and inter-track interference. Consequently, a number of approaches, such as staggered island layouts and array-reader magnetic recording, have been proposed to overcome these issues. However, this article proposes a three-reader one-track detection method to enhance data retrieval in a staggered BPMR system. Leveraging three-track reading for one-track detection, we obtain three readback signals that function as mutual data sequences. This substantially enhances the detection process in one-dimensional partial-response maximum-likelihood channels. Next, using these mutual data sequences, four novel techniques are presented to enhance bit-error rate (BER) performance and detection accuracy: hard-information flipping, maximum soft-information finding, bit-summation detection, and multilayer perceptron (MLP). This study shows that these proposed techniques can provide better BER performance compared with conventional methods and that the MLP is the most effective technique in enhancing system performance.
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Three-Track Detection Using a Multi-Layer Perceptron for Dual-Layer Bit-Patterned Magnetic Recording Systems
(2025-01-01)
Koonkarnkhai, Santi
;
Plotchu, Siriphon
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Martnok, Warunee
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Rueangnetr, Natthakan
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Kilaso, Sathapath
This paper proposes a multi-layer perceptron (MLP)-based three-track detection method for dual-layer bit-patterned magnetic recording systems. Three architectures are explored: one MLP for three tracks, two MLPs for upper and lower layers, and three individual MLPs per track. Simulation results show that all MLP-based methods outperform conventional partial response maximum likelihood detection, especially under high areal density and complex interference. Among them, the two-MLP system achieves the best bit-error rate performance by effectively separating detection tasks across layers.
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Soft Information Adjustor for Four-Head/Two-Track (4H/2T) Bit-Patterned Magnetic Recording
(2022-01-01)
Rueangnetr, Natthakan
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Warisarn, Chanon
;
Koonkarnkhai, Santi
;
Kovintavewat, Piya
To mitigate the two-dimensional (2D) interference and track misregistration (TMR) effect, we have previously proposed a TMR correction method combined with the soft-information adjustor (SIA) technique. In practice, the SIA technique uses the advantage of a 2D soft-output Viterbi algorithm (SOVA) detector to improve the reliability of the log-likelihood ratio (LLR) before deciding the estimated user bits. To further improve its performance, this paper proposes a novel SIA scheme by exploiting the advantage of the 2D SOYA detector to improve the LLR reliability of the estimated data bits for the considered upper- and lower-track in four-head/two-track (4H/2T) bit-patterned magnetic recording system. The simulation results indicate that the proposed system can deliver a better BER performance over the conventional SIA system, in particular when the system experiences media noise.
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An Intertrack Interference (ITI) subtraction scheme for bit-patterned media recording
(2021-05-19)
Buajong, Chaiwat
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Warisarn, Chanon
;
Koonkarnkhai, Santi
;
Kovintavewat, Piya
Currently, hard disk drive has been struggled to overcome the super-paramagnetic limit that restricts the density increment. Bit-patterned magnetic recording (BPMR) is a candidate that can increase an areal density (AD) up to 4 Tb/in2. However, inter-track interference (ITI) arising from a narrow track width at high AD severely degrades the system performance. This study proposes the ITI subtraction technique with turbo iteration in a coded BPMR system. This method refines the equalized sequence by subtracting the ITI using an imitated ITI sequence that is generated by the soft information obtained from turbo iteration and ITI coefficients. The refined sequence that contains the partial ITI is sent to the turbo iteration as many rounds as needed. Simulation results indicate that the proposed system outperforms the conventional system whether or not media noise is considered.
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Three-Track Detection Using a Multilayer Perceptron for Dual-Layer Bit-Patterned Magnetic Recording Systems
(2026-01-01)
Koonkarnkhai, Santi
;
Plotchu, Siriphon
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Martnok, Warunee
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Rueangnetr, Natthakan
;
Kilaso, Sathapath
This article proposes a multilayer perceptron (MLP)-based three-track detection method for dual-layer bit-patterned magnetic recording (BPMR) systems. Three different MLP architectures are explored and evaluated, namely: 1) a single MLP detecting all three tracks simultaneously; 2) three MLPs, each detecting one track independently; and 3) two MLPs dedicated to upper and lower recording layers. Simulation results show that the proposed MLP-based systems outperform the conventional partial-response maximum-likelihood (PRML) detection scheme, particularly under severe interferences and high areal density (AD). Among the proposed systems, the two-MLP architecture offers the optimal balance between detection accuracy and computational complexity, making it the most promising solution for future high-density magnetic recording systems.
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A Novel ITI Suppression Technique for Coded Dual-Track Dual-Head Bit-Patterned Magnetic Recording Systems
(2020-01-01)
Koonkarnkhai, Santi
;
Warisarn, Chanon
;
Kovintavewat, Piya
Generally, an intertrack interference (ITI) is a critical problem in bit-patterned magnetic recording (BPMR) systems that can attain an areal density (AD) up to 4 Tb/in2. Unavoidably, at high ADs, a very narrow track width must be employed, leading to severe ITI and unacceptable system performance. To tackle the ITI; therefore, this article introduces a novel ITI suppression technique for coded dual-track dual-head (DTDH) BPMR systems. At the first turbo iteration, the weighted readback signal of the adjacent track served as an estimated ITI signal is utilized for subtracting from the target readback signal to subside the ITI effect, before passing the refined readback signal to a turbo equalizer. Nonetheless, for the second turbo iteration onwards, the estimated ITI signal generated by the soft information obtained from a decoder at each turbo iteration will be then employed to subtract from the target readback signal during the turbo decoding process. Computer simulation results demonstrate that the proposed system can provide better performance than the DTDH system using a hard ITI suppression technique as well as the conventional system using one read head to decode one data track for all ADs, because the proposed technique can estimate the ITI signal well. Furthermore, when considering the recording system under the effects of media noise and track mis-registration, we also found that the proposed system is more robust than other systems.
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Neural Networks Input Techniques to Maintain a Small Skew Angle in Bit-Patterned Magnetic Recording with a V-Shaped Read-Head Array
(2023-01-01)
Fatika, Kirana Alif
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Koonkarnkhai, Santi
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Kovintavewat, Piya
;
Warisarn, Chanon
The demand for enormous storage devices has kept increasing, leading to the development of various advanced technologies with a vast storage capacity. Extensive numbers of related research studies have been aiming at optimizing code design and algorithms analytically; however, enacting them on practical devices has been scarce. Achieving this demand might bring some obstacles called two-dimensional interference and skew angle (SA). To meet the challenge of the obstacle, we propose a SA detection method for bit-patterned magnetic recording systems by computing a specific target by three readback sequences before estimating the SA value and detecting the SA amount happening in the system using an application of neural network namely multilayer perceptron. An error correction code, low-density parity-check, is applied, and its decoder outputs a log-likelihood ratio whose probability density distribution is examined. The simulation results show that the sliding window technique can significantly provide a better bit error rate performance.
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A Linear Support Vector Machine Based Detector for Bit-Patterned Magnetic Recording
(2023-01-01)
Khametong, Anawin
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Koonkarnkhai, Santi
;
Kovintavewat, Piya
;
Warisarn, Chanon
The demand for high-capacity storage devices for storing digital information is continuously increasing because of the rapid growth in the number of social media users. Alternative magnetic recording technologies, such as bit-patterned magnetic recording (BPMR), have been proposed in parallel with the current perpendicular magnetic recording technology. However, to increase the areal density in BPMR, we unavoidably encounter the problems of two-dimensional (2D) interference and track mis-registration (TMR). Consequently, to solve these problems, we first present the modified soft-information adjuster (SIA) to mitigate the 2D interference and improve the log-likelihood ratios (LLRs) that were initially produced from the conventional detectors. Then, we propose a linear support vector machine (LSVM)-based detector that works with the modified SIA so as to enhance the reliability of LLRs, which can in turn provide better estimated user bits. Simulation results reveal that the proposed system can yield better bit-error rate performance and is more robust to the TMR effect than the conventional system without the LSVM-based detector.
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A simple 2D modulation code in single-reader two-track reading BPMR systems
(2021-02-01)
Busyatras, Wiparat
;
Warisarn, Chanon
;
Koonkarnkhai, Santi
;
Kovintavewat, Piya
A reduction in the track width of magnetic recording systems results in a welcome increase in Areal Density (AD), but can severely deteriorate system performance in the unfortunate appearance of extreme Inter-Track Interference (ITI). The effect of severe ITI may be mitigated by using coding schemes. In this paper, therefore, we present a rate-5/6 2-Dimensional (2D) modulation code based on a proposed Single-Reader/Two-track Reading (SRTR) technique to cope with this serious problem in staggered Bit-Patterned Magnetic Recording (BPMR) systems. We then evaluate the Bit-Error Rate (BER) performance of the proposed system in the presence of media noises, e.g., position and size fluctuations. Our simulation results indicate that, at the same User Density (UD), the proposed system performs better than an uncoded system by about 1.0 dB at the BER of 10<sup>−5</sup> and is also superior to the conventional recording system.

Warisarn, Chanon

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