Decoding Speed Research Articles

Quasi-cyclic Expansion Algorithm for Protograph LDPC Codes Based on PEG and PH

One of the important code of modern coding theory, the protograph LDPC code technology has been gained more and more attention due to its low encoding complexity, fast decoding speed, low BER, and simple optimization analysis process etc. the quasi-cyclic expansion algorithm of the protograph LDPC codes, named as PQCE algorithms, can complete the extension of protograph and eventually get the protograph LDPC codes. However, the existing PQCE algorithms may be with a low convergence rate, or exist many short cycles in the check matrix. To solve the above problem, a Quasi-cyclic expansion algorithm for protograph LDPC codes based on PEG and PH is proposed in this paper, referred as PEG-PH-PQCE algorithm. In the proposed algorithm, base matrix is acquired by PEG parallel edges elimination expansion algorithm during the first-step expansion of protograph. Then, the second-step expansion is completed, in which the initial index matrix is obtained by PEG quasi-cyclic expansion algorithm, and the check matrix is acquired by using the Hill Climbing algorithm to optimizing the initial index matrix. Simulation results demonstrate the effectiveness the validity of the proposed algorithm, such as, a small number of short cycles and high convergence rate, etc.

Unsuccessful letter–sound integration in English reading by native Chinese speakers: evidence from an event related potentials study

Integrating letters and sounds are essential for successful reading in alphabetic languages. It remains unclear if native speakers of non-alphabetic languages integrate letters and sounds in reading an alphabetic language in the same way as native alphabetic readers do. Chinese is a morpho-syllabic system (each character corresponds to one syllable) and contrasts sharply with alphabetic languages such as English. Several fMRI studies have shown that native Chinese speakers apply their native language system to read English words. By using the cross-modal mismatch negativity (MMN) paradigm, we directly investigated letter–sound integration for reading in English among native Chinese speakers. To investigate the effect of native language background on letter–sound integration in second language reading, a group of native Korean English learners served as a comparison group. We compared MMN responses between an auditory only condition (only vowels presented) and two audiovisual conditions (AV0, vowel presented synchronously with the corresponding letter; AV200, the letter presented 200ms before the corresponding vowel) for both native Chinese and native Korean speakers. Native Chinese speakers demonstrated significantly attenuated MMN amplitudes in audiovisual conditions compared with the auditory only condition, regardless of their phonological decoding speed. In contrast, native Korean speakers showed amplified amplitude MMN in AV200 compared with that in the auditory only condition. The results suggest that native language may shape the brain responses of second language learners to reading a second language in the early stages. Native non-alphabetic language speakers may be unable to use visual information to facilitate their phonological processing in the early stage while native alphabetic language speakers are capable of integrating letter sounds automatically.

Multiresolution and fast decompression for optimal web-based rendering

Limited bandwidth is a strong constraint when efficient transmission of 3D data to Web clients and mobile applications is needed. In this paper we present a novel multi-resolution WebGL based rendering algorithm which combines progressive loading, view-dependent resolution and mesh compression, providing high frame rates and a decoding speed of million of triangles per second in JavaScript. The method is parallelizable and scalable to very large models.The algorithm is based on the local multi-resolution approaches provided by the community, but ad-hoc solutions had to be studied and implemented to provide adequate performances. In particular, a compression mechanism that reached very high compression rate without impact on rendering performance was implemented. Moreover, the data partition strategy was modified in order to be able to load different types of data (i.e. point clouds) and better adapt to the potentials and limitations of web-based rendering.

Costs and Benefits of Orthographic Inconsistency in Reading: Evidence from a Cross-Linguistic Comparison.

We compared reading acquisition in English and Italian children up to late primary school analyzing RTs and errors as a function of various psycholinguistic variables and changes due to experience. Our results show that reading becomes progressively more reliant on larger processing units with age, but that this is modulated by consistency of the language. In English, an inconsistent orthography, reliance on larger units occurs earlier on and it is demonstrated by faster RTs, a stronger effect of lexical variables and lack of length effect (by fifth grade). However, not all English children are able to master this mode of processing yielding larger inter-individual variability. In Italian, a consistent orthography, reliance on larger units occurs later and it is less pronounced. This is demonstrated by larger length effects which remain significant even in older children and by larger effects of a global factor (related to speed of orthographic decoding) explaining changes of performance across ages. Our results show the importance of considering not only overall performance, but inter-individual variability and variability between conditions when interpreting cross-linguistic differences.

Fast List Decoders for Polar Codes

Polar codes asymptotically achieve the symmetric capacity of memoryless channels, yet their error-correcting performance under successive-cancellation (SC) decoding for short and moderate length codes is worse than that of other modern codes such as low-density parity-check (LDPC) codes. Of the many methods to improve the error-correction performance of polar codes, list decoding yields the best results, especially when the polar code is concatenated with a cyclic redundancy check (CRC). List decoding involves exploring several decoding paths with SC decoding, and therefore tends to be slower than SC decoding itself, by an order of magnitude in practical implementations. In this paper, we present a new algorithm based on unrolling the decoding tree of the code that improves the speed of list decoding by an order of magnitude when implemented in software. Furthermore, we show that for software-defined radio applications, our proposed algorithm is faster than the fastest software implementations of LDPC decoders in the literature while offering comparable error-correction performance at similar or shorter code lengths.

Parallelized deblocking filtering of HEVC decoders based on complexity estimation

This paper proposes a parallelization method for a deblocking filter in a high-efficiency video coding (HEVC) decoder based on complexity estimation. A deblocking filter of HEVC is generally considered to be appropriate for data-level parallelism (DLP) because there are no data-level dependencies among adjacent blocks in the horizontal and vertical filtering processes. However, an imbalanced workload can increase the idle time on some of the threads, and thus, the maximum parallel performance cannot be achieved with only DLP. To alleviate this problem, the proposed method estimates the computational complexity by utilizing the coding unit (CU) segment information and the on/off flag of the deblocking filter in advance. Then, the workload is distributed equally across all threads. The experimental results indicate that the proposed method can accelerate the decoding speed by a factor of 3.97, with six threads on top of the sequential deblocking filtering. In addition, the ratio of the maximum elapsed time to ideal elapsed time is reduced to approximately 21 %, as compared to conventional DLP-based parallel deblocking filtering methods that do not implement a complexity estimation method.

Telerehabilitation in developmental dyslexia: methods of implementation and expected results.

Developmental Dyslexia is a disorder, highly frequent in the school population, for which the recommended rehabilitation procedures are not well defined. This study aimed to automatize reading decoding skills by using an innovative system for rehabilitation, based on a telerehabilitation method. It requires an intensive home-exercise with the supervision, by web, of the clinician. The study had three main aims: to diffuse knowledge on new methods for rehabilitation of reading difficulties; to verify whether an intensive and simplified exercise, targeted to the automation of reading, is suitable for different subgroups of dyslexic children; to define the treatment effects on basic cognitive functions underlying reading. Twenty-five children, grouped according to the neuropsychological and anamnestic profiles, took part to the treatment by the software Reading Trainer®. Both speed and accuracy of reading decoding increased significantly after treatment, independently from the functional neuropsychological profile or the history of oral language delay. These changes were specific to decoding and not associated with improvements in reading comprehension or spelling skills. However, there was a "cascade effect" of the treatment efficacy on those basic cognitive functions considered precursors of the ability to read, with significant improvements in rapid lexical access, phonological processing and visual attention. This study provides information on the efficacy of new tools for telerehabilitation of specific reading disorders.

Iterative reliability-based modified majority-logic decoding for structured binary LDPC codes

In this paper, we present an iterative reliability-based modified majority-logic decoding algorithm for two classes of structured low-density parity-check codes. Different from the conventional modified one-step majority-logic decoding algorithms, we design a turbo-like iterative strategy to recover the performance degradation caused by the simply flipping operation. The main computational loads of the presented algorithm include only binary logic and integer operations, resulting in low decoding complexity. Furthermore, by introducing the iterative set, a very small proportion (less than 6%) of variable nodes are involved in the reliability updating process, which can further reduce the computational complexity. Simulation results show that, combined with the factor correction technique and a well-designed non-uniform quantization scheme, the presented algorithm can achieve a significant performance improvement and a fast decoding speed, even with very small quantization levels (3–4 bits resolution). The presented algorithm provides a candidate for trade-offs between performance and complexity.

Unified Acoustic Modeling using Deep Conditional Random Fields

Acoustic models based on Deep Neural Networks (DNNs) lead to significant improvement in the recognition accuracy. In these methods, Hidden Markov Models (HMMs) state scores are computed using flexible discriminant DNNs. On the other hand, Conditional Random Fields (CRFs) are undirected graphical models that maintain the Markov properties of HMMs formulated using the maximum entropy (MaxEnt) principle. CRFs have limited ability to model spectral phenomena since they have single quadratic activation function per state. It is possible and natural to use DNNs to compute the state scores in CRFs. These acoustic models are known as Deep Conditional Random Fields (DCRFs). In this work, a variant of DCRFs is presented and connections with hybrid DNN/HMM systems are established. Under certain assumptions, both DCRFs and hybrid DNN/HMM systems can lead to exact same results for a phone recognition task. In addition, linear activation functions are used in the DCRFs output layer. Consequently, DCRFs and traditional DNN/HMM systems have the same decoding speed.

The Research on TDMP Merged Decoding Algorithm of LDPC Codes Based on DVB-S2 Standard

DVB-S2 is the second generation of Digital Video Broadcasting-Satellite and LDPC (Low Density Parity Code) is the key technology in which the decoding plays an important role in determining the performance of DVB-S2 system. According to the research on the characteristics of DVB-S2 standard, this paper reports on the improvement of the Turbo Decoding Message Passing (TDMP) algorithm by adopting the idea of merging. The component codes which don’t have public nodes are regarded as a new component. By changing the decoding order of component codes and removing useless waiting time, the message capacity transmitted between two adjacent component codes is increased. The performance of the proposed TDMP merged decoding algorithm is evaluated by simulation experiments. We measure decoding performance, convergence rate and the average decoding time to evaluate the system performance. The results obtained show that the TDMP merged decoding algorithm ensures the performance of decoding and good convergence, and also improves the average decoding speed and throughput.

Hybrid Prediction and Fractal Hyperspectral Image Compression

The data size of hyperspectral image is too large for storage and transmission, and it has become a bottleneck restricting its applications. So it is necessary to study a high efficiency compression method for hyperspectral image. Prediction encoding is easy to realize and has been studied widely in the hyperspectral image compression field. Fractal coding has the advantages of high compression ratio, resolution independence, and a fast decoding speed, but its application in the hyperspectral image compression field is not popular. In this paper, we propose a novel algorithm for hyperspectral image compression based on hybrid prediction and fractal. Intraband prediction is implemented to the first band and all the remaining bands are encoded by modified fractal coding algorithm. The proposed algorithm can effectively exploit the spectral correlation in hyperspectral image, since each range block is approximated by the domain block in the adjacent band, which is of the same size as the range block. Experimental results indicate that the proposed algorithm provides very promising performance at low bitrate. Compared to other algorithms, the encoding complexity is lower, the decoding quality has a great enhancement, and the PSNR can be increased by about 5 dB to 10 dB.

Third graders’ verbal reports of multiplication strategy use: How valid are they?

This study investigates whether children’s verbal reports accurately represent their thinking processes when solving simple multiplication problems. A total of 106 third graders in Dutch mainstream primary schools solved simple multiplication problems and retrospectively reported how they had done this. The degree to which verbal reports predict children’s problem-solving performance in ways that correspond to known patterns of response latency, accuracy, errors and strategy choice was assessed. The analyses took account of relevant problem characteristics and child cognitive characteristics (i.e., math ability, verbal ability, phonological decoding speed) known to affect the relation between strategy use and multiplication performance. The verbal reports were largely consistent with known patterns, supporting the use of verbal reports in assessing multiplication strategy use. Moreover, verbal reports provide valuable information that can alert teachers and educational researchers to specific issues that students face when solving simple multiplication problems. Considerations for soliciting reliable verbal reports are suggested.

Recursive Construction of n-gonal Codes on the Basis of Block Design

In the article are defined nonlinear n-gonal block codes. The methods of constructing n-gonal codes are considered. Suggest efficient universal recursive methods of constructing codes great length on the basis of block design for error-correcting code. On the basis of these methods can be constructed error-correcting codes for any predetermined number of errors. Among the codes with a predetermined length codeword and a predetermined number of units in the word, these codes will have a maximum number of codewords. Dignity of these codes is speed of encoding and decoding. Also possibility of fast change of a code without change of tables of encoding and decoding. This makes it possible to use these in cryptosystems.

A High-Throughout Design of CAVLC Decoder for H.264/AVC

In this paper, a novel high-throughput method is proposed to improve the decoding efficiency of the context-based adaptive variable length coding (CAVLC) procedure of H.264/AVC. Due to the data dependency among symbols in the entropy decoding flow, the CAVLC decoder requires large computation period, which dominates the overall decoder system performance. To expedite its decoding speed, the critical path in the CAVLC decoder is first analyzed. This paper presents a double level design for H.264/AVC CAVLC decoding. In the proposed design, we exploit a predict strategy to achieve double level decoding. Experimental results show that the operation period of the proposed architecture can be reduced about 28.3% compare with the tradition CAVLC architecture. The maximum frequency can be larger than 120 MHz, which can support the real time requirement.

Construction of Cryptosystem on the Basis of Triangular Codes

In this article the triangular codes found dependence of the power of these codes on the length of codewords in them. The methods of construction codes and some triangular propose an effective general method for constructing such codes based on monotone Boolean functions. Designed with correcting codes cryptosystem on the basis of such a code, which allows one to correct the error. The advantage of this cryptosystem is the speed of coding and decoding, and the ability to quickly change the code without changing tables, coding and decoding. Change the code is implemented using the substitution, and the choice of codes is very large. The number of possible codes is 20! (approximately equal to 2.4*10 18 ) has at length codeword of 20.

1000BASE-T의 4조 PAM-5 신호 상에서 동작하는 비터비 디코더의 구현

LAN 방식은 국내의 초고속 인터넷 서비스에서 가장 널리 사용되며, UHD TV와 같은 고속의 서비스를 제공하기 위하여 100 메가급에서 1 기가급 이더넷으로 빠르게 전환되고 있다. 1000BASE-T 물리계층은 1 Gbps의 전송속도를 달성하기 위해, 4조의 UTP상에서 각 조당 125 MHz의 PAM-5신호로 데이터를 전송한다. 채널 상에서 발생한 오류를 정정하기 위하여 송신측에서는 컨벌루션 부호와 PAM-5신호를 결합한 TCM을 사용하고, 수신측에서는 비터비 복호기를 사용한다. 본 논문에서는 1000BASE-T의 수신측에서 최소 125 MHz 속도와 최대 2조까지 오류 정정 능력을 제공하는 비터비 디코더를 구현한다. 그리고 구현한 디코더를 논리분석기로 이용해서 동작속도와 오류 정정 능력을 검증한다. The LAN method is the most widely used in domestic high-speed internet access and rapidly moving to 1 Gbps Ethernet from 100 Mbps one to provide high-speed services such as UHD TV. The 1000BASE-T PHY with 4 pairs UTP transmits a PAM-5 signal at the 125 MHz clock per each pair to achieve 1 Gbps rate. In order to correct errors over the channel, the transmitter uses a TCM which is combined the convolutional encoder and PAM-5, and the receiver uses the Viterbi decoder. In this paper, we implement a Viterbi decoder which can correct two pair errors and operate at the least 125 MHz clock speed. Finally, we will verify the error correction function and the operating speed of the implemented decoder with a logic analyzer.

Role of S-turn2 in the Structure, Dynamics, and Function of Mitochondrial Ribosomal A-Site. A Bioinformatics and Molecular Dynamics Simulation Study

The mRNA decoding site (A-site) in the small ribosomal subunit controls fidelity of the translation process. Here, using molecular dynamics simulations and bioinformatic analyses, we investigated the structural dynamics of the human mitochondrial A-site (native and A1490G mutant) and compared it with the dynamics of the bacterial A-site. We detected and characterized a specific RNA backbone configuration, S-turn2, which occurs in the human mitochondrial but not in the bacterial A-site. Mitochondrial and bacterial A-sites show different propensities to form S-turn2 that may be caused by different base-pairing patterns of the flanking nucleotides. Also, the S-turn2 structural stability observed in the simulations supports higher accuracy and lower speed of mRNA decoding in mitochondria in comparison with bacteria. In the mitochondrial A-site, we observed collective movement of stacked nucleotides A1408·C1409·C1410, which may explain the known differences in aminoglycoside antibiotic binding affinities toward the studied A-site variants.

Real-time Implementation of a xAVS Video Decoder

AVS video decoder consumes a huge number of computation, so real-time implementation of an AVS decoder has some challenging on x86 computing platform. This article describes a xAVS open source project to solve this problem. First of all, the reason for the low efficiency of the code of the existing AVS video decoder open source reference software RM52J_r1 is analyzed according to the description of AVS key technologies and decoding principles in the official documentation. Then according to the main problems of the reference software, re-design the optimized xAVS decoder architecture, and real-time property significantly improved with C code. Finally, use the x86 platform multimedia instruction sets to further optimize xAVS semantic processor. The experimental results show that, under the precondition of ensuring the quality of decoding, the decoding speed of the xAVS decoder for D1 has increased more than 14 times, to fully meet the needs of real-time decoding. DOI : http://dx.doi.org/10.11591/telkomnika.v12i6.5473 Full Text: PDF

Design of a Playback Control System for Flight Parameter Recorder

A play-back controller was designed for a certain series of aircraft. The XC866 MCU was used as the main controller unit, and an 8051 MCU as the assistant control unit. It achieved the function of channel selection, channel switching, signal filtering, signal decoding and tape speed controlling. Compared with other play-back controllers this instrument is more superior in control precision, reliability, use of flexibility and simple of structure.

Early Decoding Speed and Later Reading Competencies in Children with German as a Second Language

In Germany, 35 % of children under the age of five have a migration background. Many of them acquire German as a second language (GSL). Until today, little is known about the development of early reading skills in these children. The aim of the present study was to compare the development of decoding speed and reading comprehension from Grade 1 to Grade 3 in GSL and native German speaking children. The study especially focused on children who showed poor decoding speed in Grade 1. Results indicated an increase in the achievement gap in measures of reading comprehension between the two language groups. In decoding speed, GSL children showed a tendency toward improving less than their native German speaking peers. In Grade 1 as well as in Grade 3, a large proportion of GSL children showed reading performances which placed them in the lowest 15 % of the test norms: At each of the measurement points, the proportion of GSL poor decoders and GSL poor reading comprehenders was twice as high as expected by test norms and substantially higher than in native German speaking children. Furthermore, results indicated that the discrepancy between measures of nonverbal intelligence and reading performance is not a reliable indicator for specific reading disabilities in GSL children.