Supnithi, Pornchai
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Supnithi, Pornchai
Alternative Name
Supnithi, P.
Supnithi, Pomchai
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pornchai.su@kmitl.ac.th
19 results
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Item type:Publication, Reliability Ratio-Based Serial Algorithm of LDPC Decoder for Turbo Equalization Schemes(2022-02-01); Serial decoding algorithms of low-density parity-check (LDPC) code converge efficiently with low errors. Previously, a serial decoding algorithm, named a shuffled belief-propagation (SBP), was applied in turbo equalization of bit-patterned magnetic recording (BPMR) systems. With the SBP algorithm, an LDPC decoder converged twice as fast as one using conventional BP algorithms. We further improved the convergence speed of SBP by updating the messages in an adaptive order, which played a flexible role throughout decoding. We proposed two adaptive-serial algorithms for LDPC codes in turbo equalization. One updated the messages using the extrinsic loglikelihood ratio (LLR) and the result of the parity-check equation checking. The second contained an additional rule that tracked the LLR sign changes in each iteration. Both algorithms converged faster and with lower bit error rates (BERs) than the SBP and previous adaptive-serial algorithms in a BPMR system with media noise. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Construction of punctured polar codes based on genetic algorithm(2021-05-19); In this work, we propose a new construction of punctured polar codes, which provides a good error-correcting performance at arbitrary code lengths and code rates. We exploit the density evolution to evaluate the error probability of punctured polar codes. Then, the puncturing pattern and frozen bit positions are selected by genetic algorithm to construct a punctured polar code with low error probability. The results show that the proposed technique provides superior block error rate performance than the quasi-uniform puncturing technique at a high code rate. At a low code rate, the proposed technique can show the better performance than the shortening technique. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Improvement of Kalman Filter for GNSS/IMU Data Fusion with Measurement Bias Compensation(2020-07-01); ; The ASEAN IVO project currently supports the research related to GNSS and ionospheric data products for disaster prevention and aviation in low-latitude regions. In vehicle navigation, Real Time Kinematic (RTK) positioning distorted from the environment often contaminates the measurement vectors (such as position or speed of a rover). In this situation, the conventional Kalman filter with a linear motion model could not reduce positioning errors sufficiently due to existing bias. Hence, the measurement bias compensation method based on the mean of residual vectors is proposed. We modify the conventional Kalman filter by including this compensation in the estimation step. We test the algorithm in both of the simulations and actual experiments. From the results, the proposed method outperforms the baseline method in terms of positioning error by 60% and 12% for the simulation test and the field test respectively. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Performances of GAGAN Satellite-Based Augmentation System in Thailand Region(2020-07-01); - 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, An early termination technique of polar codes for IR-HARQ scheme(2020-10-08); ; In this work, we focus on polar codes in mobile communication systems where a retransmission strategy, namely, the incremental redundancy hybrid automatic repeat request (IR-HARQ) scheme, is performed. We propose an early termination (ET) of polar codes using the interleaved cyclic redundancy check (CRC) codes and the parity check (PC) codes. The parity-check equations of CRC and PC codes are used to detect the incorrectly decoded bits during the polar decoding. The simulation results verify that the proposed ET techniques can detect the erroneous bits in initial transmission and retransmission. The proposed technique provides the ET rate about 4-90%, and the block error rate (BLER) performance degradation is less than 2 dB. - 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); ; - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Improvement of single point positioning accuracy by using GAGAN satellite-based augmentation system in Thailand Region(2021-05-19); - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Real-time jamming detection and position estimation via software-defined radio (SDR)(2021-05-19); Global Navigation Satellite System (GNSS) is widely used in position, navigation and time in applications such as exploration, military, aviation, navigation, and time identification. However, the GNSS signals may be unavailable due to the jammers which disrupt or mislead the positioning. Current jamming detection methods do not estimate the distances from jammers to users nor store spectrum images for later retrieval. Therefore, in this paper, the real-time jamming detection is proposed by using the signal powers from Software Defined Radio (SDR). The proposed jamming detection not only detects jamming occurrences, but also estimate the position of jammers via Friis equation.