Phakphisut, Watid
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Preferred name
Phakphisut, Watid
Alternative Name
Phakphisut, W.
Main Affiliation
Email
watid.ph@kmitl.ac.th
68 results
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Item type:Publication, Reduced-complexity window decoding of spatially coupled LDPC codes for magnetic recording systems(2018-10-24); In channel coding theory, the performance of error correcting codes (ECCs) approaching the Shannon limit can be achieved through increasing code lengths. Unfortunately, the complexity of ECCs will be increased as the code length increases. Nowadays, the magnetic recording (MR) system takes advantage of powerful ECCs by using 4 Kbytes sector. Among the advanced ECCs, the spatially coupled LDPC (SC-LDPC) codes (also known as a LDPC convolutional code) [1] are shown to have the decoding latency and complexity lower than those of the underlying LDPC block codes (LDPC-BC). Moreover, the SC-LDPC codes with threshold decoding outperform the LDPC-BC codes [2]. Hence, the SC-LDPC codes are the strong candidate for the future MR systems, when the sector size is increased beyond 4 Kbytes. An SC-LDPC decoder can use sliding window decoding [3] whereby the received signals are decoded by sliding window along the bit sequence. The window decoder is called "uniform window decoding (U-WD)", when all variable nodes (VNs) within a window are updated. In order to reduce the complexity of window decoding, some researchers proposed the non-uniform window decoding (N-WD) [4], which do not update the VNs with no improvement in the bit error rate (BER). This approach provides about 35-50% reduction in complexity compared to U-WD. In this work, we consider the application of SC-LDPC codes in MR systems, whereby SC-LDPC decoder cooperates with BCJR detector to encounter inter-symbol interference (ISI). We propose the dynamic shifting of window decoding (DS-WD) to reduce the complexity of SC-LDPC codes. Herein, the number of shifted bits is defined according to their soft BERs which are estimated at each decoding position. In addition, we modify the N-WD [4] to reinforce our proposed algorithm called "dynamic-shifting non-uniform window decoding (DS-N-WD)." The DS-WD and DS-N-WD achieve the complexity reduction of 7% and 25% without any loss in performance compared to the N-WD algorithms. i - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Jamming Detection and Distance Calculation of L1 and E1 Frequencies(2020-07-01); GNSS jammers in the form of small portable devices are able to transmit the interference signals to GNSS receivers with the goal of misleading or disrupt the positioning. The interference or jamming can be detected from the carrier-tonoise (C/N0) values. In this work, we apply the Moving Variance (MV) to detect the occurrence of jamming from L1, E1 frequencies of GPS, Galileo satellites. In addition, we use Friis equation and random variable matching to calculate the distance between the GNSS receiver and jammer. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Clustering Technique for Constructing Path Loss Model in Bangkok Metropolis(2022-01-01); - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Learning Polar Codes using Python Program with Graphical User Interface(2019-06-01) - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Quasi Cyclic-LDPC codes based on PEG algorithm with maximized girth property(2011-12-01); 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. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, 5G Channel Coding Tool: Learning and Performance Evaluation(2023-01-01) - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Reduced Complexity Window Decoding of Spatially Coupled LDPC Codes for Magnetic Recording Systems(2018-11-01); Spatially coupled low-density parity-check (SC-LDPC) codes have emerged to possess capacity-approaching performance. The SC-LDPC codes can be decoded by a sliding window, therefore, the decoding latency and complexity of SC-LDPC codes are lower than those of underlying LDPC codes when the codeword length is very large. In this paper, the SC-LDPC decoder with the sliding window is employed in turbo equalization of magnetic recording systems. We examine the bit error rates (BERs) of the output of the sliding window during the iterative decoding, and then observe that the consecutive code blocks have approximately the same BERs. Herein, to reduce decoding complexity of SC-LDPC codes, the consecutive code blocks can be considered as the output of SC-LDPC codes. In addition, the non-uniform schedule update is adopted in the window decoding to avoid unnecessary updates within a window. The simulation results show that the proposed decoding algorithms applied in bit-patterned media magnetic recording systems can achieve a significant reduction in complexity compared to the traditional decoding without any loss in BER performance. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Serial belief propagation for the high-rate LDPC decoders and performances in the bit patterned media systems with media noise(2011-01-01); ; - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Design of partition decoding for polar codes in 5G new radio(2020-10-08); - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Spread-F prediction model for the equatorial Chumphon station, Thailand(2020-01-01); ;