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    Item type:Publication,
    Symbol-flipping method for block decoding in bit-patterned magnetic recording
    (2021-05-19) ;
    Mattayakan, Mutita
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    Koonkarnkhai, Santi
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    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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    Item type:Publication,
    Codeword design of a Rate-5/6 for single-reader two-track reading in BPMR systems
    (2021-05-19)
    Mattayakan, Mutita
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    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.
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    Item type:Publication,
    Simple Soft-Information Developers Based on Parallel Detection Scheme in Bit-Patterned Media Recording (BPMR) Systems
    (2021-06-27)
    Mattayakan, Mutita
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    Warisam, Chanon
    Among the alternate ultra-high density data storage technologies, bit-patterned media recording (BPMR) is one of the mentioned technologies that was proposed to achieve a higher density. Due to the closeness between the magnetic islands, so the readback sequences are disrupted from the effect of two-dimensional (2D) interference, which includes both intersymbol interference (ISI) and intertrack interference (ITI). In this paper; therefore, we propose the simple and effective soft-information developers (SIDs) to improve the soft-information that are obtained from both vertical and horizontal detectors. An optimal weight was optimized under the BPMR channel before multiplying with the horizontal soft-information. The proposed SIDs and conventional 2D detector's performances were carefully compared in the terms of BER. The results show that our proposed methods achieve a gain of approximately 8 dB at a BER of 10-3.