On error exponents, coding and feedback for decoding delay constrained communication systems

2002 ◽  
Author(s):  
G. Kaplan ◽  
S. Shamai
Keyword(s):  
Communication Systems ◽  
Error Exponents ◽  
Decoding Delay

Rate and Performance Enhancement of LDPC Codes Using Collection of Punctured Codes Decoding (CPCD)

2021 ◽  
Vol 11 ◽  
Author(s):  
Rana A. Hassan ◽  
John P. Fonseka
Keyword(s):  
Communication Systems ◽  
Ldpc Codes ◽  
Superior Performance ◽  
Low Density ◽  
Parity Check ◽  
Decoding Complexity ◽  
Low Density Parity Check ◽  
Punctured Codes ◽  
Punctured Code ◽  
Decoding Delay

Background: Low-density parity-check (LDPC) codes have received significant interest in a variety of communication systems due to their superior performance and reasonable decoding complexity. Methods: A novel collection of punctured codes decoding (CPCD) technique that considers a code as a collection of its punctured codes is proposed. Two forms of CPCD, serial CPCD that decodes each punctured code serially and parallel CPCD that decodes each punctured code in parallel, are discussed. Results: It is demonstrated that both serial and parallel CPCD have about the same decoding complexity compared with standard sum product algorithm (SPA) decoding. It is also demonstrated that while serial CPCD has about the same decoding delay compared with standard SPA decoding, parallel CPCD can decrease the decoding delay, however, at the expense of processing power. Conclusion: Numerical results demonstrate that CPCD can significantly improve the performance, or significantly increase the code rate of low-density parity-check (LDPC) codes.

scholarly journals A Parallel Turbo Decoder Based on Recurrent Neural Network

2021 ◽  
Author(s):  
Li Zhang ◽  
weihong fu ◽  
Fan Shi ◽  
Chunhua Zhou ◽  
Yongyuan Liu
Keyword(s):  
Neural Network ◽  
Turbo Codes ◽  
Communication Systems ◽  
Turbo Code ◽  
Error Rates ◽  
Learning Ability ◽  
Turbo Decoder ◽  
Lstm Network ◽  
T Distribution ◽  
Decoding Delay

Abstract A neural network-based decoder, based on a long short-term memory (LSTM) network, is proposed to solve the problem of high decoding delay caused by the poor parallelism of existing decoding algorithms for turbo codes. The powerful parallel computing and feature learning ability of neural networks can reduce the decoding delay of turbo codes and bit error rates simultaneously. The proposed decoder refers to a unique component coding concept of turbo codes. First, each component decoder is designed based on an LSTM network. Next, each layer of the component decoder is trained, and the trained weights are loaded into the turbo code decoding neural network as initialization parameters. Then, the turbo code decoding network is trained end-to-end. Finally, a complete turbo decoder is realized. Simulation results show that the performance of the proposed decoder is improved by 0.5–1.5 dB compared with the traditional serial decoding algorithm in Gaussian white noise and t-distribution noise. Furthermore, the results demonstrate that the proposed decoder can be used in communication systems with various turbo codes and that it solves the problem of high delay in serial iterative decoding.

Plant peptide hormone signalling

2015 ◽  
Vol 58 ◽  
pp. 115-131 ◽  
Author(s):  
Ayane Motomitsu ◽  
Shinichiro Sawa ◽  
Takashi Ishida
Keyword(s):  
Communication Systems ◽  
Cell Communication ◽  
Peptide Hormone ◽  
Peptide Hormones ◽  
Target Cells ◽  
Signalling Molecules ◽  
Receptor Complexes ◽  
Environmental Responses ◽  
Plant Life Cycle ◽  
Multicellular Organisms

The ligand–receptor-based cell-to-cell communication system is one of the most important molecular bases for the establishment of complex multicellular organisms. Plants have evolved highly complex intercellular communication systems. Historical studies have identified several molecules, designated phytohormones, that function in these processes. Recent advances in molecular biological analyses have identified phytohormone receptors and signalling mediators, and have led to the discovery of numerous peptide-based signalling molecules. Subsequent analyses have revealed the involvement in and contribution of these peptides to multiple aspects of the plant life cycle, including development and environmental responses, similar to the functions of canonical phytohormones. On the basis of this knowledge, the view that these peptide hormones are pivotal regulators in plants is becoming increasingly accepted. Peptide hormones are transcribed from the genome and translated into peptides. However, these peptides generally undergo further post-translational modifications to enable them to exert their function. Peptide hormones are expressed in and secreted from specific cells or tissues. Apoplastic peptides are perceived by specialized receptors that are located at the surface of target cells. Peptide hormone–receptor complexes activate intracellular signalling through downstream molecules, including kinases and transcription factors, which then trigger cellular events. In this chapter we provide a comprehensive summary of the biological functions of peptide hormones, focusing on how they mature and the ways in which they modulate plant functions.

Instruction Using Augmentative and Alternative Communication Supports: Description of Current Practices by Speech-Language Pathologists Who Work With Children With Autism Spectrum Disorder

2020 ◽  
Vol 29 (2) ◽  
pp. 586-596 ◽  
Author(s):  
Kaitlyn A. Clarke ◽  
Diane L. Williams
Keyword(s):  
Autism Spectrum Disorder ◽  
Augmentative And Alternative Communication ◽  
Communication Systems ◽  
Diagnostic Category ◽  
Children With Autism ◽  
Autism Spectrum ◽  
Spectrum Disorder ◽  
Alternative Communication ◽  
Speech Language Pathologists ◽  
Processing Differences

Purpose The aim of this research study was to examine common practices of speech-language pathologists (SLPs) who work with children with autism spectrum disorder (ASD) with respect to whether or not SLPs consider processing differences in ASD or the effects of input during their instruction. Method Following a qualitative research method, how SLPs instruct and present augmentative and alternative communication systems to individuals with ASD, their rationale for method selection, and their perception of the efficacy of selected interventions were probed. Semistructured interviews were conducted as part of an in-depth case report with content analysis. Results Based on completed interviews, 4 primary themes were identified: (a) instructional method , (b) input provided , (c) decision-making process , and (d) perceived efficacy of treatment . Additionally, one secondary theme, training and education received , was identified . Conclusions Clinicians reported making decisions based on the needs of the child; however, they also reported making decisions based on the diagnostic category that characterized the child (i.e., ASD). The use of modeling when teaching augmentative and alternative communication to individuals with ASD emerged as a theme, but variations in the method of modeling were noted. SLPs did not report regularly considering processing differences in ASD, nor did they consider the effects of input during instruction.

Thoughts on Grammar Intervention in AAC

2008 ◽  
Vol 17 (2) ◽  
pp. 43-49 ◽  
Author(s):  
Marc Fey
Keyword(s):  
Language Impairment ◽  
Specific Language Impairment ◽  
Augmentative And Alternative Communication ◽  
Communication Systems ◽  
Target Language ◽  
Alternative Communication ◽  
Physical Limitations ◽  
Communication Needs ◽  
Communication Interventions ◽  
Planning Intervention

Abstract In this article, I propose that, for several reasons, grammar should be an early focus of communication interventions for young children using augmentative and alternative communication (AAC) systems. The basic goals for such programs should be to facilitate the child's comprehension of the language of the community, or the target language, thus leading the way to literacy, and to foster the child's use of symbol combinations that mirror the grammatical patterns of speaking children acquiring the target language, even if they cannot be fully grammatically complete. I introduce five principles that underlie most successful approaches to grammar interventions with children with specific language impairment. My initial attempts to apply these principles to interventions with children with complex communication needs indicate that they may be of considerable value to clinicians planning intervention programs. On the other hand, the challenges posed by the intellectual and physical limitations of many AAC users and their communication systems make it necessary to modify at least Principle 5 if the basic goals of intervention are to be met.

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