Rueangnetr, Natthakan

Preferred name

Alternative Name

Rueangnetr, N.

Main Affiliation

Integrated Innovative Technology

natthakan.ru@kmitl.ac.th

Now showing 1 - 10 of 19

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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
;
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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Reliability Test Techniques in Tabu Search Detection for Enhancing BER Performance of Array Reader Bit-Patterned Magnetic Recording Systems
(2026-01-01)
Mattayakan, Mutita
;
Rueangnetr, Natthakan
;
Kankhunthod, Kittipon
;
Warisarn, Chanon
Bit-patterned magnetic recording (BPMR) at ultra-high densities is strongly affected by inter-track interference (ITI). To cope with severe ITI, we introduce a reliability-testing mechanism with adaptive symmetric thresholding based on the distribution of log-likelihood ratios (LLRs) to effectively identify unreliable bits while controlling the computational complexity of the Tabu search (TS) detector. Additionally, the selected bits identified from the TS detection are employed to refine the original LLR values through a proposed soft-information adjustment (SIA) process. Moreover, we also present an LLR weighting scheme to further enhance the refined LLRs produced by the SIA process, thereby improving the performance of low-density parity-check decoding. Results indicate that our proposed technique can reduce the complexity of the TS detector by using a reliability-testing mechanism. The SIA can be effectively combined with an LLR weighting scheme, thereby improving bit-error rate performance over conventional BPMR systems.
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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
;
Martnok, Warunee
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Rueangnetr, Natthakan
;
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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Inter-Layer Interference (ILI) Suppression in Dual-Layer Bit-Patterned Magnetic Recording Systems
(2025-01-01)
Rueangnetr, Natthakan
;
Koonkarnkhai, Santi
;
Greaves, Simon John
;
Warisarn, Chanon
Dual-layer bit-patterned magnetic recording (DL-BPMR) systems are promising for achieving higher areal densities. However, they face significant challenges, including inter-symbol interference (ISI), inter-track interference (ITI), and inter-layer interference (ILI). To address these issues, this work proposes integrating a sum-soft-information (SSI) technique and an ITI suppression method to enhance detection reliability. The SSI technique is initially used to improve the reliability of the log-likelihood ratio for the bottom layer signal by leveraging the mutual information derived from a staggered array reader configuration. The enhanced data sequence from the bottom layer is subsequently utilized to suppress ILI by applying a weighting before it is subtracted from the top layer readback signals. Simulation results demonstrate that the proposed method significantly improves bit error rate (BER) performance compared to conventional single-layer and dual-layer BPMR systems, particularly at a user density of 4.0 Tb/in<sup>2</sup>, making it a promising approach for next-generation high-density magnetic recording.
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Soft Information Adjustor for Four-Head/Two-Track (4H/2T) Bit-Patterned Magnetic Recording
(2022-01-01)
Rueangnetr, Natthakan
;
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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Three-Track Detection Using a Multilayer Perceptron for Dual-Layer Bit-Patterned Magnetic Recording Systems
(2026-01-01)
Koonkarnkhai, Santi
;
Plotchu, Siriphon
;
Martnok, Warunee
;
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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Enhancing Signal Processing With Multilayer Perceptron Utilization for Bit-Patterned Magnetic Recording
(2025-01-01)
Rueangnetr, Natthakan
;
Greaves, Simon John
;
Warisarn, Chanon
Bit-patterned magnetic recording aims to overcome the superparamagnetic limit and achieve higher areal density in magnetic recording, with improved thermal stability and reduced transition noise. However, the inter-symbol interference and inter-track interference effects remain crucial problems that must be addressed. This work introduces a multilayer perceptron-based equalizer operating in conjunction with an adaptive target scheme. Furthermore, we also propose using a multilayer perceptron-based detector to improve the overall recording performance. We evaluated our enhanced processing methods using regular and staggered bit-island arrangements. The simulation results indicate that the multilayer perceptron-based equalizer achieves lower mean square error values across all signal-to-noise ratio levels when compared to the conventional minimum mean square error equalizer. Additionally, the proposed multilayer perceptron-based detector performs slightly better than the multilayer perceptron-based equalizer. Also, these proposed techniques demonstrate superior bit error rate performance, even when considering bit-island position fluctuations.
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Combining Unequal Bit Islands and Coding Design for Areal Density Enhancing in Dual-Layer Bit-Patterned Magnetic Recording Systems
(2026-01-01)
Sriyapai, R.
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Rueangnetr, N.
;
Koonkarnkhai, S.
;
Warisarn, C.
In this work, we propose an alternating media structure for a dual-layer bit-patterned magnetic recording (DL-BPMR), in which the diameters of the bit islands in the bottom and top layers differ, with the bottom diameter 4 times that of the top. We then propose an encoding scheme that uses the larger bit island in the bottom layer for a parity bit to detect errors during decoding. Moreover, we suggest the log-likelihood ratio (LLR) flipping technique to improve decoding capability, which operates jointly during decoding. Simulation results show that at the same user density (UD), our proposed systems outperform the conventional single-layer (SL) BPMR. For instance, at a bit-error rate of 10<sup>-3</sup> and total UDs of 2.0 or 3.2 Terabit per square inch, the proposed systems provide approximately 0.8 dB and 1.2 dB, respectively, over the conventional SL-BPMR systems.
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Multilayer perceptron-based array reader optimization for ultra-high density magnetic recording
(2024-01-01)
Rueangnetr, N.
;
Warisarn, C.
We have previously presented a utilization of a long-short-term memory (LSTM) network to improve the reliability of the log-likelihood ratios (LLRs) in a coded three-head/three-track bit-patterned magnetic recording (BPMR) system. To continuously enhance a bit error rate (BER) performance; therefore, this article introduces a novel LLR flipper utilizing a multilayer perceptron (MLP), which operates under the optimization of input numbers of array reader positions. We first optimize an input number of MLP-based soft-information flippers with varying the number of recording bits in various data patterns. Then, the right positions of an array reader under the operation of our proposed MPL flipper are also optimized to obtain better BER performance. The simulation results demonstrate that the proposed MLP flipper significantly improves BER performance compared to the previous LSTM flipper using the same input number. Moreover, our proposed system still provides superior performance when it is operated under an optimal input number and can be higher when working with the right array reader positions.
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Optimization of Layer Thicknesses for Dual-Layer Bit-Patterned Media Recording (BPMR) Systems
(2024-01-01)
Rueangnetr, Natthakan
;
Warisarn, Chanon
;
Greaves, Simon John
To increase the areal density (AD) of magnetic recording, we have investigated the effect of the thicknesses of the individual layers in dual-layer bit-patterned media recording (BPMR) systems. The recording media consisted of two, discrete recording layers, separated by a non-magnetic spacer layer. The bottom, or lower, recording layer thickness and the head-medium spacing (HMS) were fixed, while the top, or upper, recording layer thickness was varied to adjust the spacing between the reader and the bottom layer. By varying the layer thicknesses, together with arranging the bit islands in a staggered, overlapping manner, the readback signal strengths from the upper and lower layers could be adjusted and balanced. To determine the bit-error-rate improvement needed to reach a target AD of 4.0 terabits per square inch (Tbits/in2), i.e., 2.0 Tbits/in2 per layer, the readback signal was processed using an iterative method. The results showed that the proposed design could outperform a single-layer (SL) BPMR system.

Rueangnetr, Natthakan

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