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Signal Processing Techniques for Enhancing an Areal Density in Two-Reader/Three-Track Detection of Staggered Bit-Patterned Magnetic Recording Systems
(2026-03-01)
Rueangnetr, Natthakan
;
Wattanaphol, Satra Tor
;
Kankhunthod, Kittipon
;
Greaves, Simon J.
;
Warisarn, Chanon
As the demand for digital storage capacity continues to grow, bit-patterned magnetic recording (BPMR) has emerged as a promising technology to overcome the superparamagnetic limit of conventional recording methods. Nevertheless, the extremely close spacing of magnetic islands in BPMR can result in significant signal corruption, particularly due to inter-track interference. This paper presents robust signal-processing schemes for a two-reader, three-track detection system in a staggered BPMR configuration to address these challenges. The first proposed method employs a sum-soft-information technique, which combines log-likelihood ratios from two detectors to maximize mutual information. This approach significantly improves the reliability of middle-track detection. We also propose the inter-track interference subtraction technique, in which the highly reliable data recovered from the middle track are used to reconstruct the interference signal, which is then subtracted from the upper and lower tracks using an optimized weighting factor. Simulation results at an areal density of 3.0 Tb/in<sup>2</sup> demonstrate that an optimized weighting factor of 1.78 effectively cancels interference. Moreover, the results indicate that our proposed scheme achieves a bit-error rate (BER) comparable to that of the three-reader, one-track detection BPMR systems. Furthermore, our method also demonstrates a lower BER for both adjacent tracks when compared to the conventional single-reader, two-track reading system, even in the presence of 10% 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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Inter-Layer Interference (ILI) Suppression in Dual-Layer Bit-Patterned Magnetic Recording Systems
(2026-01-01)
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 (ADs). 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 ILI suppression method to enhance detection reliability. The SSI technique is initially used to improve the reliability of the log-likelihood ratio (LLR) for the bottom layer signal by leveraging the mutual information derived from a staggered array reader configuration. The enhanced data sequence of the bottom layer is subsequently utilized to suppress ILI by applying a weighting before being removed from the mixed readback signal. The separated readback signal of the top layer is then processed using well-predesigned equalizers and detectors. Simulation results demonstrate that the proposed method significantly improves bit error rate (BER) performance compared to conventional single-layer and DL-BPMR systems, particularly at a user density of 4.0 Tb/in2, making it a promising approach for next-generation high-density magnetic recording.
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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
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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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Feasibility Study of Implementing Simple Dual-bit Detection in Dual-Layer Bit-Patterned Magnetic Recording Systems
(2025-09-01)
Rueangnetr, Natthakan
;
Greaves, Simon John
;
Warisarn, Chanon
Dual-layer bit-patterned magnetic recording (DL-BPMR) systems, which combine bit-patterned magnetic recording (BPMR) and multi-layer magnetic recording technologies, are expected to increase the areal density (AD) of data storage up to 10 Terabits per square inch. However, to achieve this goal, several challenges must be overcome, including low response signals from the lower layer and interlayer interference. Therefore, this work proposes a signal processing technique to reduce the number of erroneous bits at the receiver. A simple dual-bit detection (SD-BD) method is proposed. Simulation results comparing the performance of a single-layer BPMR system with that of a DL-BPMR system using the SD-BD signal processing technique show that the latter can effectively reduce the bit error rate. The results indicate that the SD-BD technique has the potential to improve the read accuracy of the DL-BPMR system and is an essential step towards the future development of data recording technologies with higher AD.
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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
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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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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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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
;
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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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.

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