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Author: search.filters.author.Phakphisut, WatidSubject: search.filters.subject.LDPC codes

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    Efficient Design of Read Voltages and LDPC Codes in NAND Flash Memory Using Density Evolution
    (2023-01-01)
    Duangthong, Chatuporn
    ;
    Phakphisut, Watid
    ;
    Wardkein, Paramote
    Low-density parity-check (LDPC) codes play an important role in the reliability enhancement of commercial NAND flash memory. Unfortunately, due to the requirement of the reading speed of NAND flash memory, the LDPC decoder will not obtain precise soft information to achieve high error-correcting capability. In this work, we use a density evolution (DE) algorithm to reveal the decoding threshold of the LDPC decoder affected by the read voltages. We propose the efficient design of read voltages so that the LDPC decoder has the lowest decoding threshold. Therefore, this method can guarantee that the designed read voltages are suitable for a given LDPC code. Moreover, since we found that the designed read voltages are related to the structure of the LDPC code, the joint design of the read voltages and LDPC code is then proposed to achieve the capacity of NAND flash memory. The simulation results demonstrate that our proposed design significantly improves the frame error rate (FER) performance of NAND flash memory.
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    Joint design of channel output quantizer and LUT-Based LDPC decoder
    (2021-05-19)
    Duangthong, Chatuporn
    ;
    Supnithi, Pornchai
    ;
    Phakphisut, Watid
    Recently, the LUT-based LDPC decoder has been designed by maximizing mutual information, where the performances of channel output quantizer and LUT-based decoder are considered separately. In this work, we propose the joint design of the channel output quantizer and LUT-based decoder. Our joint design aims to minimize the error probability of LDPC decoding through the density evolution algorithm. We found that the joint design outperforms the previous work at the waterfall region.
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    EXIT Chart Analysis of Protograph-based LDPC Codes for Unequal Power Two-User Gaussian Multiple Access Channel
    (2020-07-01)
    Khittiwitchayakul, Sirawit
    ;
    Phakphisut, Watid
    ;
    Supnithi, Pornchai
    ;
    Min Myint, Lin Min
    In this work, we analyze the theoretical performances of protograph-based LDPC codes for unequal power two-user Gaussian multiple access channel (GMAC) by using Extrinsic information transfer (EXIT) chart. We show that the decoding performances of LDPC codes for two-users are improved significantly when the transmitted power of user increases. Moreover, we present the design of protograph structures of the LDPC codes for unequal power two-user GMAC by using the differential evolution (DE). The results show that the designed LDPC codes outperform the traditional LDPC codes.
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    Sliding-window processing of turbo equalization for partial response channels
    (2019-04-01)
    Khittiwitchayakul, Sirawit
    ;
    Phakphisut, Watid
    ;
    Supnithi, Pornchai
    Spatially coupled low-density parity-check (SC-LDPC) codes are the attractive candidates for the application requiring a practical constraint on the latency and complexity. In previous works, the turbo equalization consisting the SC-LDPC window decoder and Bahl-Cocke-Jelinek-Raviv (BCJR) detector is used to tackle the inter-symbol interferences (ISIs) in the magnetic recording systems. However, the prior works consider only the SC-LDPC codes which replace the conventional LDPC block codes. In this work, we propose the modification of turbo equalization processing whereby both the SC-LDPC decoder and BCJR detector operate using the sliding window. The results show that the proposed turbo equalization schemes used in the partial response (PR) channel can provide better bit error rate (BER) performances than the conventional turbo equalization.
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    Quasi Cyclic-LDPC codes based on PEG algorithm with maximized girth property
    (2011-12-01)
    Prompakdee, Patanasak
    ;
    Phakphisut, Watid
    ;
    Supnithi, Pornchai
    In this paper, we propose a method to construct parity-check matrices of Quasi Cyclic (QC) LDPC codes based on the progressive edge-growth (PEG) algorithm with maximized girth property. The proposed algorithm can eliminate short cycles and improve the decoding performance. Simulation results illustrate that the codes constructed with the proposed algorithm have superior performance to the previous PEG-QC codes over the additive white Gaussian noise (AWGN) channel. At the BER of 10 <sup>7</sup>, the coding gain of 0.005 dB. © 2011 IEEE.