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Author: search.filters.author.Koonkarnkhai, SantiSubject: search.filters.subject.2D modulation code

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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.
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    Modified 2D Viterbi Algorithm using 2D Modulation Encoding Constraints in BPMR Systems
    (2020-06-01)
    Sokjabok, Siwakon
    ;
    Warisarn, Chanon
    ;
    Koonkarnkhai, Santi
    ;
    Lee, Jaejin
    The severity of inter-symbol interference (ISI) and inter-track interference (ITI) effects caused by the reduction of the spacing between bit islands in the along- and across-track directions to acquire ultra-high areal densities (ADs) is the main problem in bit-patterned magnetic recording (BPMR) systems. We call these two effects as two-dimensional (2D) interference, which can degrade the overall system performance. Practically, a one-dimensional (1D) modulation code, e.g., run-length limited (RLL) code, is essentially utilized to prevent the severe ISI effect. The use of 2D detectors is also one of the important ways to cope with the severe ITI; however, its complexity is quite high. To avoid the severe ITI effect and complex 2D detectors; therefore, we propose to apply the 1D RLL code as the 2D modulation code. Then, the 2D modulation encoding constraint is employed to reduce the number of states and branches in the trellis of the proposed modified 2D Viterbi detector. Simulation results reveal that the proposed detector not only delivers a lower complexity but also provides superior bit error rate gain, especially at ultra-high ADs and/or large location fluctuation.