Puttarak, Nattakan
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Puttarak, Nattakan
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Puttarak, N.
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nattakan.pu@kmitl.ac.th
13 results
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Item type:Publication, EXIT chart analysis of nonbinary protograph LDPC codes for partial response channels(2014-11-01); ; Low-density parity-check (LDPC) codes over finite fields GF(q) provide an error correction in the noisy partial response (PR) channels. The extrinsic information transfer (EXIT) chart can be used to predict the threshold decoding of protograph LDPC codes, however, previous works only consider the binary protograph LDPC codes in the PR channels. In this paper, we propose to perform the EXIT chart analysis on the nonbinary protograph LDPC codes for the PR channels. Unlike prior works, the actual extrinsic information of the channel detector is measured, then the extrinsic information to the variable nodes is generated with the measured statistics. Moreover, since the mutual information of the variable nodes depends on GF(q), we use the Monte Carlo method to approximate the mutual information. The analysis on the regular (2,4) code, regular (3,6) code, RA code, and AR3A code on the PR channels reveal that, for the PR1 channel, the RA code outperforms the others for q = 2, 4, and 8, but the regular (2,4) code is the best for q = 16 and 32. For the PR2 channel, the RA code is the best code for q = 2 and 4, but the regular (2,4) code is the best code for q > 4. The simulation of the codes for q = 4 and 16 are then used to confirm the theoretical results. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, An implementation of low-density MDS array codes for data protection in distributed network data storage system(2016-09-07); Kaewprapha, PhisanWe present an implementation of disk arrays(RAIDs) in distributed networked data storage environment by applying an error-correcting to accommodate fault tolerance feature. Any of the current state-of-the-art distributed file systems, such as MooseFS [1], can be used as an underlying data space where low density-MDS (Maximum distance separable-Low density parity check) array codes [3] is used as a logical protection layer implemented through FUSE interface (File System In User Space). The redundancy/parity scheme is based on graph structures leading to an MDS code, then can be simply implemented in a parity matrix (H matrix) of an LDPC code. The ability of error correction and data recovery is shown as the bit-error rate (BER) has been investigated. It achieves the same trend compared to the simulation results in [3]. The low-density MDS array code can mitigate hardware failure at higher disk space efficiency comparing to the repetition code. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Network localization using tree search algorithm(2016-09-06) - 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, Low-density MDS array codes based on rigid graph structure(2014-10-15); Kaewprapha, PhisanIn data communications system including wired and wireless transmissions, the reliability, integrity, speed, and cost efficiency are the main issues that people desire. An error correcting code is one of the efficient and nearly-optimal methods to improve the system performance. Based on the idea of constructing MDS codes called CGR codes in [3] for disk arrays, this paper introduces a new perspective and construction of LDPC codes due to its sparsity and advantage complexity in implementation. The performance of this code in Additive White Gaussian Noise (AWGN) and fading channels gains about 1.0 dB at the 10<sup>-3</sup> of bit error rate (BER) compared with an EVENODD code. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, A short-term rain-induced attenuation model for satellite link quality prediction(2014-01-01); This paper proposes a novel but simple satellite link quality prediction based on the relationship between rainfall rate and satellite signal attenuation. After quantifying their relationship statistically, we describe their contemporaneous variations using a linear dynamical system response model. The expectation-maximization (EM) algorithm is used to obtain the maximum likelihood estimates of the model parameters. Subsequently, the communication link quality is predicted by thresholding the estimated short-term signal attenuation level obtained from the Expectation step of the EM algorithm. The prediction performance of the proposed method is compared against the measured beacon signals from Thaicom-4 (IPSTAR) satellite during rainfalls. Using solely the observed rainfall rates from a tipping bucket rain gauge, the algorithm is able to decently predict the satellite link quality. We believe the proposed model can be modified as a predictive tool for real-time link unavailability monitoring of satellite communication system. © 2014 IEEE. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, An implementation of maximum likelihood decoder for error-file recovery on cloud storage system(2018-07-02) - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Designed MMSE equalizers for nonlinear magnetic recording channels(2014-01-01); Writing process in hard disk drives (HDD) is affected from nonlinearity. Normally, nonlinearity is not easy to be avoided or removed since it is unexpected and caused by various sources. In this paper, we review a description of a nonlinearity behavior by using a Volterra model, and using a random binary number to generate an input data. The Volterra model can describe both linear and nonlinear parts of the read-back signals in terms of the volterra equations. In addition, we propose to use an MMSE method to equalize the read-back signals with nonlinearity using various constraints before applying the Viterbi detector. For a 2nd-order Volterra model, the results show that the equalizer with g<inf>1</inf> =1 constraint gives the lowest MMSE values. Furthermore, as the nonlinearity level increases, the bit error rate (BER) performance degrades. © 2014 IEEE. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, A study on Ka-band site switching using advanced prediction for rain-induced attenuation(2015-01-28); High frequency satellite communications suffers from rain-induced attenuations, which may cause service discontinuity during high-intensity rain events. To combat this, we propose a novel site switching technique that anticipates signal attenuations using a linear dynamical system response model and performs site switching in advance. Using only the rainfall data measured at a ground station for attenuation prediction, we demonstrate that our method is able to lessen signal attenuation while maintaining link availability. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, A smart dialogue box for the hearing impaired(2019-07-01);