Warisarn, Chanon
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Preferred name
Warisarn, Chanon
Alternative Name
Warisarn, C.
Main Affiliation
Email
chanon.wa@kmitl.ac.th
45 results
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Item type:Publication, A Soft ITI Mitigation Method for Coded 2H2T BPMR Systems(2019-06-01); - Some of the metrics are blocked by yourconsent settings
Item type:Publication, A bit-flipping technique based on 2D modulation constraint in BPMR systems(2018-10-24); Inter-track interference (ITI) cancelation is one of the considerable challenges for high areal density (AD) magnetic recording such as in bit-patterned media recording (BPMR) systems. In literature, the two-dimensional (2D) modulation codes have been proposed to cancel the ITI effect [1, 2] which can efficiently improve the overall system performance, e.g., a rate-5/6 2D modulation code [2]. Although the rate-5/6 modulation code ensures that the readback signal of the center track will not be corrupted by severe ITI; however, both the upper and lower tracks can still be interfered by their sidetracks. To improve this shortcoming; therefore, we propose the bit-flipping technique that performs together with the rate-5/6 2D modulation code. Here, the relationship between the data encoding condition and soft-information obtained from the soft output Viterbi algorithm (SOVA) detector is utilized to be a criterion for flipping the ambiguous data bits. Simulation results indicate that the proposed system is better than the conventional coded system under with/without media noise and track mis-registration. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Symbol-flipping method for block decoding in bit-patterned magnetic recording(2021-05-19); ; - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Unbalanced track pitch combined with 2D modulation code in TDMR systems(2018-10-24); Tongsomporn, D.Two-dimensional magnetic recording (TDMR) [1, 2] is a promising high density storage technology, which is expected to increase an areal density (AD) up to 10 terabit per square inch (Tbpsi). This technology is required write narrow-read wide technique that opposite to write wide-read narrow of one-dimensional (1D) read channel. The narrow track writing operated by shingled writing can greatly improve track per inch (TPI) gain. However, the side reading effect of reader is an unwanted situation because the intertrack interference (ITI) from sidetracks, which degrades the overall system bit error rate (BER) performance. Therefore, we introduce the methods to overcome this severe ITI effect. For instance, the two-dimensional (2D) modulation code that designed based on cross-track data dependent readback. The data pattern such as [1 -1 1]<sup>T</sup> and [-1 1 -1]<sup>T</sup> are forbidden to record onto medium. The rate-5/6 2D modulation code will map the 5 user bits into a 6-bits codeword, which are not contained any forbidden patterns. Furthermore, since the recoded bit is protected from severe ITI effect using modulation code, the middle track can provide a very high reliability. Therefore, we present ITI subtraction to improve upper and lower track performance using data from middle track. Moreover, we also propose an unbalanced track pitch technique, which the middle track can be narrower than upper and lower tracks. The utilization from the high reliability of middle track can improve BER performances both of upper and lower tracks. The reason because the ITI effect that interfere from their sidetracks is reduced by using the properly wider track pitch. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Codeword design of a Rate-5/6 for single-reader two-track reading in BPMR systems(2021-05-19); At present, the information storage demand of hard disk drive (HDD) was dramatically increasing every year. However, an increase of an areal density (AD) for bit-patterned media recording (BPMR) seems to be crucial for HDD industry. One of the main problems of BPMR system is two-dimensional interference effect that composes of inter-track interference (ITI) and inter-symbol interference (ISI), which still be the main challenge that we have to flounder to continuously enhance the efficiency of magnetic recording system. Therefore, this paper proposes a rate-5/6 2D modulation code to evolve bit error rate (BER) efficiency of a staggered single-reader two-track reading (SRTR) based BPMR systems. We select all 32 codewords from all 64 considered patterns according to the statistics principle considering. The first 32 patterns that provide the least error-bit number will then be defined as our proposed codewords. These selected patterns can efficiently avoid the forbidden patterns that means it is going to radically suppress both ISI and ITI effects. We simply encode by using a look-up table, while we use the Euclidean distance concept to recover user bits in the decoding process. From the simulation, we found that the proposed method shows a better BER efficiency than both the uncoded and conventional recording systems. Even we add more media noises, this proposed system still provides us with a better performance. Moreover, SRTR scheme offers us more satisfactory capability than the conventional recording systems. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Spinning disk test study on erase band and write width for shingled magnetic recording(2014-05-07); ; Bai, D.Shingled magnetic recording (SMR) has been predicted as one of the novel technologies to extend the areal density beyond 1 Tb/in<sup>2</sup>. It was widely thought by many researchers that very wide writers could be used for SMR, as it involves corner writing and thus writability would no longer be an issue in SMR. However, in our experimental study, we reveal that there exists an optimal write width for a given writer design due to the erase band limitations. Also we propose the optimal write width for a given shingle track pitch condition. © 2014 AIP Publishing LLC. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Three-Track Detection Using a Multi-Layer Perceptron for Dual-Layer Bit-Patterned Magnetic Recording Systems(2025-01-01); Kilaso, SathapathThis 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. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Bi-directional timing recovery for magnetic recording systems(2009-12-01); ; Kovintavewat, PiyaMagnetic recording systems employ conventional timing recovery to synchronize the sampler with the readback signal. However, conventional timing recovery does not perform well when the timing error is large. This paper proposes the bidirectional timing recovery, which utilizes conventional timing recovery to sample the readback signal both in forward direction and in backward direction. The outputs of these two operations are averaged and sent them to the Viterbi detector to determine the most likely input sequence. Results indicate that the bidirectional timing recovery performs better than conventional timing recovery, especially when the timing error is large. ©2009 IEEE. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, A study of multiple reads of target track prior to detection for two-dimensional magnetic recording(2015-07-14); Two-dimensional magnetic recording (TDMR) has recently received wide attention as a good candidate for next generation high-density data storage [1]. However, the read-back signal is subject to the combination of inter-track interference (ITI) and inter-symbol interference (ISI). Therefore, a major challenge to apply TDMR depends on the development of two-dimensional signal processing. It is widely studied in a variety of forms, leading to the compromise between detection performance and computation complexity. Some recent works on TDMR channels are presented in [2]-[4]. In [2], performance is enlarged by using 2D iterative detector. As for [3] and [4], multiple readbacks from array-reader were proposed to detect data bit. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Soft-output decoding of 2D modulation codes for bit-patterned media recording(2015-07-14); Kovintavewat, P.The two-dimensional (2D) interference is a major impairment in bit-patterned media recording (BPMR) systems because of small bit and track pitches, especially at high recording densities [1]. To mitigate this problem, we introduced 2D modulation codes [2-3], which output only the hard decision, for an uncoded BPMR system (i.e., without error-correction codes). To utilize a rate-4/5 constructive inter-track interference (CITI) code [2] in the coded BPMR system, which employs a low-density parity-check (LDPC) code, we propose the log-likelihood ratio (LLR) algebra implementation in Boolean logic mappings for the CITI coding scheme. Then, this soft CITI coding scheme together with a modified 2D soft-output Viterbi algorithm (2D-SOVA) detector [4] and a LDPC decoder will jointly perform iterative decoding.