Myint, Lin Min
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Myint, Lin Min
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Myint, L. M.
Myint, L.
Myint, Lin Min Min
Myint, Lin M.
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linminmin.my@kmitl.ac.th
11 results
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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, Study of Detectors with Noise Predictor for High Areal Density BPMR Systems(2019-04-10); In this paper, we study the performance of Viterbi detectors embedded with noise predictor for the 2-D interference channel of high areal density bit patterned media recording (BPMR) system. After the readback signal is processed by a equalizer, the received signal at the input of detector is corrupted by the colored/correlated noise. Therefore, the noise whitening process using a noise predictor is required to improve the performance of the detector. When the noise predictor is incorporated into the detector, it needs to extend the structure of trellis in the detector. For the 2-D interference channel of BPMR system, the complexity of the detector will grow beyond the practical level. Therefore, we design a detector embedded by a noise prediction technique without extending the trellis. In the proposed technique, the most likely noise samples generated from the branch metric calculation are stored along the surviving path of the trellis in Viterbi algorithm. The proposed technique requires less number of memory and arithmetic operations at each state of the trellis compared to conventional technique. We consider both finite impulse response (FIR) filter and infinite impulse response (IIR) filter for the noise prediction filter. The simulation results show that the proposed noise prediction can improve the performance of detector, especially for the high areal density at 4 Tbit/in<sup>2</sup>. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Track mis-registration detection using correlation functions in magnetic recording(2012-12-01); ; Track mis-registration (TMR) causes the asymmetric inter-track interference which degrades the system performance. In this work, we propose a TMR detection method based on the cross-correlation functions in bit patterned media (BPM) recording systems. Firstly, the coefficients of the channel are predicted with the cross-correlation functions between the readback signals and the recorded bit sequences on the main track as well as the interfering tracks. Using the ratio of the channel coefficients, the presence and direction of TMR and can be predicted more accurately. © 2012 DSI. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Off-track detection based on the readback signals in magnetic recording(2012-10-29); Off-track condition in magnetic recording systems degrades the system performance. It is typically detected and adjusted by the servo control loop. In this work, we propose an off-track detection based on the readback signals and improve the bit error performance using an asymmetric target depending on the detected off-track direction. Specifically, we investigate the effects of off-track events on the target-shaping equalizer coefficients when the generalized partial-response target (GPR) is fixed. For a 3 × 3 channel matrix of bit patterned media recording (BPMR) system, the asymmetric targets offer the gain of about 1 to 2 dB at BER = 10 <sup>-4</sup> for the TMR level of 20% to 25%. © 2012 IEEE. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Modified graph-based detection methods for two-dimensional interference channels(2012-10-29); ; Two-dimensional (2-D) interference channels with inter-symbol interference (ISI) and inter-track interference (ITI) exist in the magnetic recording systems at high areal density. A number of 2-D detection methods have recently been proposed for the multi-track processing of the 2-D channels. Graph-based detector with the belief propagation algorithm appears as an alternative method, but at a degraded performance and high complexity level. In this work, we propose two methods to modify the graph-based (GB) detector. One applies a serial scheduling to the GB detector, while the other modifies the GB detection by ignoring some connections during one direction of the reliability updates in the factor graph leading to the reduction of short cycles. The simulation results show that the proposed GB detectors give better bit error rate performances than the other GB detectors. © 2012 IEEE. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, A TMR mitigation method with 3-track data detection for multi-track multi-head BPMR system(2017-08-10); ; - Some of the metrics are blocked by yourconsent settings
Item type:Publication, A simple crossover-based coding technique for ITI mitigation in bit-patterned media recording(2014-02-12); ; Kovintavewat, PiyaDue to bits being recorded at ultra-high density, a bit-patterned media recording (BPMR) system is faced with two-dimensional (2D) interference, namely inter-symbol interference (ISI) and inter-track interference (ITI), which degrades the overall performance of a recording system. One solution to avoid the 2D interference effect is to apply a modulation code to forbid some specific data patterns leading to severe 2D interference. Nonetheless, this method usually requires either many redundant bits or additional memory. Thus, this paper proposes a simple technique to encode an input data sequence to mitigate the 2D interference effect before recording them onto a magnetic medium. The proposed technique shows the improvement in reducing complexity and additional memory using a crossover-based technique when comparing to other existing methods. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Single-track equalization method with TMR correction system based on cross correlation functions for a patterned media recording system(2017-01-01); ; - Some of the metrics are blocked by yourconsent settings
Item type:Publication, A study of iterative detection method for four-grain based two-dimensional magnetic recording(2012-12-01); ; Two-dimensional magnetic recording (TDMR) is one of the novel magnetic recording technologies for the future ultra-high storage density beyond 10 Tb/in<sup>2</sup> [1]. However, due to the high areal density, the readback signal is extremely corrupted by the inter-symbol interference (ISI) and the inter-track interference (ITI) in the recorded data retrieving. This problem can be alleviated by utilizing an advanced iterative decoding technique. This paper proposes a novel iterative decoding technique incorporating the iterative detectors and an iterative decoder to combat the severe ISI/ITI. Simulation results show that the proposed technique can reduce the ISI/ITI effect and provides a significant performance improvement in terms of bit-error rate if compared to the conventional receiver, which employs a non-iterative detector. © 2012 DSI. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Sidetrack data estimation using multi-track joint 2-D viterbi detector in bit patterned media storage(2018-07-02); In the high areal density, bit patterned media recording (BPMR) system, the inter-track interference (ITI) effects become severe when the areal density is increased. In the literature, a multi-track joint 2-D detector with the aid of a multi-reader array technology is proposed to mitigate the ITI effect in BPMR systems because of its significant performance gains achieved by processing the multiple readback signals concurrently. In practice, the multi-track joint 2-D detector can estimate the recorded data from not only the detecting tracks, but also the sidetracks when the ITI effect is considerably high. Although the estimates of the data on the sidetracks are not as good as those on the detecting tracks, they can be applied in or improved by further coding process. In this work, we study the performance of a multi-track joint 2-D Viterbi detector for estimating the data on the sidetracks by adjusting the offset position of heads in the multi-head multi-track (MHMT) BPMR system. The detector recovers the recorded data on the detecting and sidetracks by processing the readback signals from the detecting tracks. We also investigate the performance changes due to the head offsets. The results show that the performance of detector for estimating the data on the sidetracks can be improved by adjusting the head offsets well.