1,721,034 research outputs found
Extended Hamming Product Codes Analytical Performance Evaluation for Low Error Rate Applications
Full text linkIn this paper, we study product codes based on extended Hamming codes. We focus on their performance at low error rates, which are important for wireless multimedia applications. We present the basis and a complete set of techniques which allows one to analytically evaluate this performance without resorting to extremely long simulations. We present new theoretical results concerning the popular approximation where the bit error rate is nearly equal to the frame error rate times the ratio of the minimum distance to the codeword length. We prove that: 1) binary codes with a transitive automorphism group satisfy this approximation with equality; and 2) extended Hamming product codes belong to this class. Closed-form expressions for their dominant multiplicity values are derived. Analytical curves are plotted, discussed, and validated by comparison with iterative decoding. This analytical approach is then extended to both shortened and punctured codes, which are important for practical design. The first case is solved by applying the extended MacWilliams identity to the dual codes. For punctured codes, we present a new analytical approach for estimating their average performance using a "random" puncturer
Design and comparison of turbo codes under frame-length and code-rate constraints
No full textWhen the performances of error-correcting codes for space communications are investigated, with the aim to translate them into practical recommendations, comparison among different schemes is usually a very difficult task. As a matter of fact, these comparisons rarely yield general conclusions. On the other hand,
most practical space applications impose strong constraints on the code parameters, which have important effects on code selection. In this paper, we show a methodology and several examples of design and comparison, derived under fixed constraints imposed by the system application on the frame-length and the code-rate. CCSDS Earth observation missions requiring both large coding gains and high spectral efficiency are considered as a case study. Though referred to this specific space mission framework, the presented study is quite general and applies to many other digital communication systems; e.g. for wireless or wired applications where similar constraints exist but are often not taken in due consideration by the designer of the error-correcting schemes
On a family of circulant matrices for quasi-cyclic low-density generator matrix codes
No full textWe present a new class of sparse and easily invertible circulant matrices that can have a sparse inverse though not being permutation matrices. Their study is useful in the design of quasi-cyclic low-density generator matrix codes that are able to join the inner structure of quasi-cyclic codes with sparse generator matrices, so limiting the number of elementary operations needed for encoding. Circulant matrices of the proposed class permit to hit both targets without resorting to identity or permutation matrices that may penalize the code minimum distance and often cause significant error floors. © 2011 IEEE
3rd Distributed Ledger Technology Workshop
No full textThis book contains the contributions which were selected for publication at the third edition of the Distributed Ledger Technology Workshop (DLT 2020), which has been held in conjunction with ITASEC20 at Ancona, on February 4, 2020. This event follows the first two editions of the workshop held at Perugia in 2018 and at Pisa in 2019, respectively, and represents the annual meeting of the Italian DLT group.
The last years have witnessed an impressive and increasing interest around Distributed Ledger Tech- nology. A huge number of application fields, including finance, academics, IoT, industries, just to mention some of the most popular ones, are experiencing the advantages of reliable and unalterable information storage and exchange without any trusted third party. Despite this, several issues are still open and deserve discussion in the scientific and professional community. Among them, a prominent role is played by privacy and security. While some security properties (e.g., countering double spending in cryptocur- rencies) have been extensively studied, other aspects need to be deepened, ranging from software security to scalability, dependability, up to new challenges, like post-quantum blockchains. Similarly for privacy, where the DLT paradigm also has to coexist with current regulations.
The DLT workshops are meant as a forum for researchers, developers, and users to discuss issues related to Distributed Ledger Technology and its adoption in research and business scenarios. The primary goal is to foster discussion and cross-fertilisation of ideas among experts in different fields related to DLTs, and thus advance the national and international state-of-the-art. Research, applications, case studies, and experiences concerning DLT are debated.
Similarly to the previous editions, the DLT 2020 workshop solicited two kind of contributions: re- search papers and oral communications. Both types of contribution entailed an oral presentation at the workshop, but only the former ones are reported in this book. In particular, the workshop accepted 9 research papers and 12 oral contributions.
We would like to express our thanks to the authors who submitted their papers to the workshop, and to the members of the Technical Program Committee for their valuable work in evaluating the submitted papers
3rd Distributed Ledger Technology Workshop
No full textThis book contains the contributions which were selected for publication at the third edition of the Distributed Ledger Technology Workshop (DLT 2020), which has been held in conjunction with ITASEC20 at Ancona, on February 4, 2020. This event follows the first two editions of the workshop held at Perugia in 2018 and at Pisa in 2019, respectively, and represents the annual meeting of the Italian DLT group.
The last years have witnessed an impressive and increasing interest around Distributed Ledger Tech- nology. A huge number of application fields, including finance, academics, IoT, industries, just to mention some of the most popular ones, are experiencing the advantages of reliable and unalterable information storage and exchange without any trusted third party. Despite this, several issues are still open and deserve discussion in the scientific and professional community. Among them, a prominent role is played by privacy and security. While some security properties (e.g., countering double spending in cryptocur- rencies) have been extensively studied, other aspects need to be deepened, ranging from software security to scalability, dependability, up to new challenges, like post-quantum blockchains. Similarly for privacy, where the DLT paradigm also has to coexist with current regulations.
The DLT workshops are meant as a forum for researchers, developers, and users to discuss issues related to Distributed Ledger Technology and its adoption in research and business scenarios. The primary goal is to foster discussion and cross-fertilisation of ideas among experts in different fields related to DLTs, and thus advance the national and international state-of-the-art. Research, applications, case studies, and experiences concerning DLT are debated.
Similarly to the previous editions, the DLT 2020 workshop solicited two kind of contributions: re- search papers and oral communications. Both types of contribution entailed an oral presentation at the workshop, but only the former ones are reported in this book. In particular, the workshop accepted 9 research papers and 12 oral contributions.
We would like to express our thanks to the authors who submitted their papers to the workshop, and to the members of the Technical Program Committee for their valuable work in evaluating the submitted papers
On the Autocorrelation Properties of Truncated Maximum-Length Sequences and Their Effect on the Power Spectrum
No full textTruncated maximum-length binary sequences are studied in this paper. The impact of truncation on their autocorrelation properties and power spectral density is investigated. Several new analytical results are given and validated through simulation. The first- and second-order statistics of the periodic autocorrelation function and the spectral peak amplitudes over the ensemble of all possible starting seeds are analyzed. Explicit bounds are found for the mean square of the periodic autocorrelation function. An analytical technique for evaluating the maximum spectral peak values is derived. As a case study, high data rate space links using LFSR randomizers are considered. Truncation may induce high peaks in the spectrum, requiring suitable margins to comply with power flux density constraints. The new results allow to analytically estimate the margin, providing useful information for the link desig
Low-Lee-Density Parity-Check Codes
No full textWe introduce a new family of linear block codes over \mathbb{Z}-{q} that we name low-Lee-density parity-check (LLDPC) codes. These codes, which are embedded with the Lee metric, are characterized by a parity-check matrix whose rows and columns have low Lee weight. We propose general constructions of LLDPC codes and devise an efficient iterative decoding algorithm for them, with complexity that grows linearly with the code length. We assess the error rate performance of these codes through numerical simulations
A new chaotic algorithm for video encryption
No full textWe present a new encryption algorithm for the video signal that, employing suitably arranged chaotic functions, allows to increase the security level while maintaining acceptable processing times. We analyze the performance of the new scheme either though simulation or via practical implementation, thus demonstrating its efficiency, also in comparison with previous proposals
Performance of DCSK in Multipath Environments: AComparison with Systems Using Gold Sequences
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