Download or read book An Analog Decoder for Turbo Structured Low Density Parity Check Codes written by Ali Reza Rabbani Abolfazli and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Stochastic Decoding of Low Density Parity check Codes written by Saeed Sharifi Tehrani and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Mixed Signal Implementation of Low Density Parity Check Decoder written by Sanjoy Basak and published by . This book was released on 2018 with total page 190 pages. Available in PDF, EPUB and Kindle. Book excerpt: The receiver side of many communication systems incorporates an error-correction decoder to achieve good bit-error rate (BER) performance. While good BER is a metric of reliable communication, high throughput and energy-efficiency are also desired. Low-density parity-check (LDPC) decoders are able to perform well in term of these metrics. In this thesis, the Modified Differential Decoding Binary Message Passing (MDD-BMP) algorithm of LDPC codes has been chosen to implement in mixed-signal domain. The goal of this research is to achieve energy-efficiency in LDPC decoding while maintaining high-throughput in an implemented design of reasonable effective area. The re-design of some digital parts of the LDPC decoder in analog domain is expected to offer energy-efficiency and high throughput. However, these benefits come at a cost of analog impairments, such as, different random mismatch between similar inverters arising from process variation during fabrication. The comparative contribution of these impairments on the BER performance of the decoder has been investigated. During the design of the decoder, an on-chip calibration scheme has been arranged and global routing of the tuning signals has been maintained to address these random mismatches. Furthermore, modulation of the decoding speed by off-chip tuning has been made possible. For the purpose of high-speed testing of the decoding process, enough on-chip memory has been placed to store 10 codewords and feed them to the decoder through a binary-weighted capacitor-based digital to analog converter. Design and placement of analog MUXes enable us to debug sensitive analog nodes inside the decoder from off-chip. Finally, the full process of the physical design of the decoder in TSMC 65nm has been almost fully automated in Cadence SKILL code. Over 100 simulations including parasitic capacitance of long wires in physical design yield an average decoding speed of approximately 2.04 ns in moderate speed mode, therefore, providing a high throughput of 134 Gb/s. Taking into account the average current drawn by the circuits during both the pre-charge phase and the decoding phase, the calculated average energy per bit consumed by the decoder is 1.267 pJ/bit.

Download or read book Iterative Decoding of Low Density Parity Check Codes and Turbo Codes written by Juntan Zhang and published by . This book was released on 2005 with total page 288 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Flexible Encoder and Decoder Designs for Low density Parity check Codes written by Sunitha Kopparthi and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Future technologies such as cognitive radio require flexible and reliable hardware architectures that can be easily configured and adapted to varying coding parameters. The objective of this work is to develop a flexible hardware encoder and decoder for low-density parity-check (LDPC) codes. The design methodologies used for the implementation of a LDPC encoder and decoder are flexible in terms of parity-check matrix, code rate and code length. All these designs are implemented on a programmable chip and tested. Encoder implementations of LDPC codes are optimized for area due to their high complexity. Such designs usually have relatively low data rate. Two new encoder designs are developed that achieve much higher data rates of up to 844 Mbps while requiring more area for implementation. Using structured LDPC codes decreases the encoding complexity and provides design flexibility. The architecture for an encoder is presented that adheres to the structured LDPC codes defined in the IEEE 802.16e standard. A single encoder design is also developed that accommodates different code lengths and code rates and does not require re-synthesis of the design in order to change the encoding parameters. The flexible encoder design for structured LDPC codes is also implemented on a custom chip. The maximum coded data rate of the structured encoder is up to 844 Mbps and for a given code rate its value is independent of the code length. An LDPC decoder is designed and its design methodology is generic. It is applicable to both structured and any randomly generated LDPC codes. The coded data rate of the decoder increases with the increase in the code length. The number of decoding iterations used for the decoding process plays an important role in determining the decoder performance and latency. This design validates the estimated codeword after every iteration and stops the decoding process when the correct codeword is estimated which saves power consumption. For a given parity-check matrix and signal-to-noise ratio, a procedure to find an optimum value of the maximum number of decoding iterations is presented that considers the affects of power, delay, and error performance.

Download or read book High Performance Decoder Architectures For Low Density Parity Check Codes written by Kai Zhang and published by . This book was released on 2012 with total page 244 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: The Low-Density Parity-Check (LDPC) codes, which were invented by Gallager back in 1960s, have attracted considerable attentions recently. Compared with other error correction codes, LDPC codes are well suited for wireless, optical, and magnetic recording systems due to their near- Shannon-limit error-correcting capacity, high intrinsic parallelism and high-throughput potentials. With these remarkable characteristics, LDPC codes have been adopted in several recent communication standards such as 802.11n (Wi-Fi), 802.16e (WiMax), 802.15.3c (WPAN), DVB-S2 and CMMB. This dissertation is devoted to exploring efficient VLSI architectures for high-performance LDPC decoders and LDPC-like detectors in sparse inter-symbol interference (ISI) channels. The performance of an LDPC decoder is mainly evaluated by area efficiency, error-correcting capability, throughput and rate flexibility. With this work we investigate tradeoffs between the four performance aspects and develop several decoder architectures to improve one or several performance aspects while maintaining acceptable values for other aspects ... Layered decoding algorithm, which is popular in LDPC decoding, is also adopted in this paper. Simulation results show that the layered decoding doubles the convergence speed of the iterative belief propagation process. Exploring the special structure of the connections between the check nodes and the variable nodes on the factor graph, we propose an effective detector architecture for generic sparse ISI channels to facilitate the practical application of the proposed detection algorithm. The proposed architecture is also reconfigurable in order to switch flexible connections on the factor graph in the time-varying ISI channels.

Download or read book Reduced Complexity Decoding Algorithms for Low density Parity Check Codes and Turbo Codes written by Chen Jinghu and published by . This book was released on 2003 with total page 234 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Universal Decoder for Low Density Parity Check Turbo and Convolutional Codes written by Ahmed Refaey Ahmed Hussein and published by . This book was released on 2011 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: De nombreux systèmes de communication sans fil ont adopté les codes turbo et les codes convolutifs comme schéma de codes correcteurs d'erreurs vers l'avant (FEC) pour les données et les canaux généraux. Toutefois, certaines versions proposent les codes LDPC pour la correction d'erreurs en raison de la complexité de l'implémentation des décodeurs turbo et le succès de certains codes LDPC irréguliers dans la réalisation des mêmes performances que les codes turbo les dépassent dans certains cas avec une complexité de décodage plus faible. En fait, les nouvelles versions des standards de ces systèmes travaillent côte à côte dans des dispositifs réels avec les plus anciennes qui sont basées sur les codes turbo et les codes convolutifs. En effet, ces deux familles de codes offrent toutes deux d'excellentes performances en termes de taux d'erreur binaire (TEB). Par conséquent, il semble être une bonne idée d'essayer de les relier de manière à améliorer le transfert de technologie et l'hybridation entre les deux méthodes. Ainsi, la conception efficace de décodeurs universels des codes convolutifs, turbo, et LDPC est critique pour l'avenir de l'implémentation des systèmes sans fil. En outre, un décodeur efficace pour les codes turbo et codes convolutifs est obligatoire pour la mise en oeuvre de ces systèmes sans fil. Cela pourrait se faire par l'élaboration d'un algorithme de décodage unifié des codes convolutifs, turbo et LDPC par des simulations et des études analytiques suivies d'une phase de mise en oeuvre. Pour introduire ce décodeur universel, il existe deux approches, soit sur la base de l'algorithme du maximum a posteriori (MAP) ou l'algorithme de propagation de croyance (BP). D'une part, nous étudions une nouvelle approche pour décoder les codes convolutifs et les turbo codes au moyen du décodeur par propagation de croyances (BP) décodeur utilisé pour les codes de parité à faible densité (codes LDPC). En outre, nous introduisons un système de représentation général pour les codes convolutifs par des matrices de contrôle de parité. De plus, les matrices de contrôle de parité des codes turbo sont obtenus en traitant les codes turbo parallèles comme des codes convolutifs concaténés. En effet, l'algorithme BP fournit une méthodologie très efficace pour la conception générale des algorithmes de décodage itératif de faible complexité pour toutes les classes des codes convolutifs ainsi que les turbo-codes. Alors qu'une petite perte de performance est observée lors du décodage de codes turbo avec BP au lieu du MAP, cela est compensé par la complexité moindre de l'algorithme BP et les avantages inhérents à une architecture unifiée de décodage. En outre, ce travail exploite la représentation tail-biting de la matrice de contrôle de parité des codes convolutifs et des codes turbo, ce qui permet le décodage par un algorithme de propagation de croyance unifiée (BP) pour les nouveaux systèmes de communication sans fils tels que le WiMAX (Worldwide Interoperability for Microwave Access) et le LTE (Long Term Evolution). D'autre part, comme solution alternative, une recherche est effectuée sur la façon de produire un décodeur combiné de ces deux familles de codes basé sur l'algorithme MAP. Malheureusement, cette seconde solution nécessite beaucoup de calculs et de capacité de stockage pour sa mise en oeuvre. En outre, ses récurrences en avant et en arrière résultent en de longs délais de décodage. Entre temps, l'algorithme MAP est basé sur le treillis et la structure en treillis du code LDPC est suffisamment compliquée en raison de la matrice de contrôle de parité de grande taille. En conséquence, cette approche peut être difficile à mettre en oeuvre efficacement car elle nécessite beaucoup de calculs et une grande capacité de stockage. Enfin, pour prédire le seuil de convergence des codes turbo, nous avons appliqué la méthode de transfert d'information extrinsèque (EXIT) pour le décodeur correspondant en le traitant comme une concaténation de noeuds de variable et de contrôle.

Download or read book Capacity approaching Coding Schemes Based on Low density Parity check Codes written by Jilei Hou and published by . This book was released on 2003 with total page 316 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Study and Design of Turbo and Low density Parity check Codes Decoder Architectures for High rate Flexible Communication Systems written by Giuseppe Gentile and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Low density Parity check Codes with Reduced Decoding Complexity written by Benjamin Smith and published by . This book was released on 2007 with total page 156 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis presents new methods to design low-density parity-check (LDPC) codes with reduced decoding complexity. An accurate measure of iterative decoding complexity is introduced. In conjunction with extrinsic information transfer (EXIT) chart analysis, an efficient optimization program is developed, for which the complexity measure is the objective function, and its utility is demonstrated by designing LDPC codes with reduced decoding complexity. For long block lengths, codes designed by these methods match the performance of threshold-optimized codes, but reduce the decoding complexity by approximately one-third. The performance of LDPC codes is investigated when the decoder is constrained to perform a sub-optimal decoding algorithm. Due to their practical relevance, the focus is on the design of LDPC codes for quantized min-sum decoders. For such a decoder, codes designed for the sum-product algorithm are sub-optimal, and an alternative design strategy is proposed, resulting in gains of more than 0.5 dB.

Download or read book High Speed Decoders for Polar Codes written by Pascal Giard and published by Springer. This book was released on 2017-08-30 with total page 108 pages. Available in PDF, EPUB and Kindle. Book excerpt: A new class of provably capacity achieving error-correction codes, polar codes are suitable for many problems, such as lossless and lossy source coding, problems with side information, multiple access channel, etc. The first comprehensive book on the implementation of decoders for polar codes, the authors take a tutorial approach to explain the practical decoder implementation challenges and trade-offs in either software or hardware. They also demonstrate new trade-offs in latency, throughput, and complexity in software implementations for high-performance computing and GPGPUs, and hardware implementations using custom processing elements, full-custom application-specific integrated circuits (ASICs), and field-programmable-gate arrays (FPGAs). Presenting a good overview of this research area and future directions, High-Speed Decoders for Polar Codes is perfect for any researcher or SDR practitioner looking into implementing efficient decoders for polar codes, as well as students and professors in a modern error correction class. As polar codes have been accepted to protect the control channel in the next-generation mobile communication standard (5G) developed by the 3GPP, the audience includes engineers who will have to implement decoders for such codes and hardware engineers designing the backbone of communication networks.

Download or read book Codes Systems and Graphical Models written by Brian Marcus and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 520 pages. Available in PDF, EPUB and Kindle. Book excerpt: Coding theory, system theory, and symbolic dynamics have much in common. A major new theme in this area of research is that of codes and systems based on graphical models. This volume contains survey and research articles from leading researchers at the interface of these subjects.

Download or read book Decoder Architectures and Implementations for Quasi cyclic Low density Parity check Codes written by Xiaoheng Chen and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Since the rediscovery of low-density parity-check (LDPC) codes in the late 1990s, tremendous progress has been made in code construction and design, decoding algorithms, and decoder implementation of these capacity-approaching codes. Recently, LDPC codes are considered for applications such as high-speed satellite and optical communications, the hard disk drives, and high-density flash memory based storage systems, which require that the codes are free of error-floor down to bit error rate (BER) as low as 10−12 to 10−15. FPGAs are usually used to evaluate the error performance of codes, since one can exploit the finite word length and extremely high internal memory bandwidth of an FPGA. Existing FPGA-based LDPC decoders fail to utilize the configurability and read-first mode of embedded memory in the FPGAs, and thus result in limited throughput and codes sizes. Four optimization techniques, i.e., vectorization, folding, message relocation, and circulant permutation matrix (CPM) sharing, are proposed to improve the throughput, scalability, and efficiency of FPGA-based decoders. Also, a semi-automatic CAD tool called QCSYN (Quasi-Cyclic LDPC decoder SYNthesis) is designed to shorten the implementation time of decoders. Using the above techniques, a high-rate (16129,15372) code is shown to have no error-floor down to the BER of 10−14. Also, it is very difficult to construct codes that do not exhibit an error floor down to 10−15 or so. Without detailed knowledge of dominant trapping sets, a backtracking-based reconfigurable decoder is designed to lower the error floor of a family of structurally compatible quasi-cyclic LDPC codes by one to two orders of magnitudes. Hardware reconfigurability is another significant feature of LDPC decoders. A tri-mode decoder for the (4095,3367) Euclidean geometry code is designed to work with three compatible binary message passing decoding algorithms. Note that this code contains 262080 edges (21.3 times of the (2048,1723) 10GBASE-T code) in its Tanner graph and is the largest code ever implemented. Besides, an efficient QC-LDPC Shift Network (QSN) is proposed to reduce the interconnect delay and control logic of circular shift network, a core component in the reconfigurable decoder that supports a family of structurally compatible codes. The interconnect delay and control logic area are reduced by a factor of 2.12 and 8, respectively. Non-binary LDPC codes are effective in combating burst errors. Using the power representation of the elements in the Galois field to organize both intrinsic and extrinsic messages, we present an efficient decoder architecture for non-binary QC-LDPC codes. The proposed decoder is reconfigurable and can be used to decode any code of a given field size. The decoder supports both regular and irregular non-binary QC-LDPC codes. Using a practical metric of throughput per unit area, the proposed implementation outperforms the best implementations published in research literature to date.

Download or read book Low Density Parity Check Decoder Architectures for Integrated Circuits and Quantum Cryptography written by Mario Milicevic and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Forward error correction enables reliable one-way communication over noisy channels, by transmitting redundant data along with the message in order to detect and resolve errors at the receiver. Low-density parity-check (LDPC) codes achieve superior error-correction performance on Gaussian channels under belief propagation decoding, however, their complex parity-check matrix structure introduces hardware implementation challenges. This thesis explores how the quasi-cyclic structure of LDPC parity-check matrices can be exploited in the design of low-power hardware architectures for multi-Gigabit/second decoders realized in CMOS technology, as well as in the design and construction of multi-edge LDPC codes for long-distance (beyond 100km) quantum cryptography over optical fiber. A frame-interleaved architecture is presented with a path-unrolled message-passing schedule to reduce the complexity of routing interconnect in an integrated circuit decoder implementation. A proof-of-concept silicon test chip was fabricated in the 28nm CMOS technology node. The LDPC decoder chip supports the four codes presented in the IEEE 802.11ad standard, occupies an area of 3.41mm^2, and achieves an energy efficiency of 15pJ/bit while delivering a maximum throughput of 6.78Gb/s, and operating with a 202MHz clock at 0.9V supply. The test chip achieves the highest normalized energy efficiency among published CMOS-based decoders for the IEEE 802.11ad standard. A quasi-cyclic code construction technique is applied to a multi-edge LDPC code with block length of 10^6 bits in order to reduce the latency of LDPC decoding in the key reconciliation step of long-distance quantum key distribution. The GPU-based decoder achieves a maximum information throughput of 7.16Kb/s, and extends the current maximum transmission distance from 100km to 160km with a secret key rate of 4.10 x 10^(-7) bits/pulse under 8-dimensional reconciliation. The GPU-based decoder delivers up to 8.03x higher decoded information throughput over the upper bound on secret key rate for a lossy optical channel, thus demonstrating that key reconciliation with LDPC codes is no longer a post-processing bottleneck in quantum key distribution. The contributions presented in this thesis can be applied to future research in the implementation of silicon-based linear-program decoders for high-reliability channels, and single-chip solutions for quantum key distribution containing integrated photonics and post-processing algorithms.

Download or read book High Performance Decoder Architectures for Error Correction Codes written by and published by . This book was released on 2015 with total page 232 pages. Available in PDF, EPUB and Kindle. Book excerpt: Due to the rapid development of the information industry, modern communication and storage systems require much higher data rates and reliability to server various demanding applications. However, these systems suffer from noises from the practical channels. Various error correction codes (ECCs), such as Reed-Solomon (RS) codes, convolutional codes, turbo codes, Low-Density Parity-Check (LDPC) codes and so on, have been adopted in lots of current standards. With the increasing data rate, the research of more advanced ECCs and the corresponding efficient decoders will never stop.

Download or read book Wiley Encyclopedia of Telecommunications Volume 2 written by John G. Proakis and published by Wiley-Interscience. This book was released on 2003 with total page 608 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Contains 275 tutorial articles focused on modern telecommunications topics. The contents include articles on communication networks, source coding and decoding, channel coding and decoding, modulation and demodulation, optical communications, satellite communications, underwater acoustic communications, radio propagation, antennas, multiuser communications, magnetic storage systems, and a variety of standards"--V.1, p. v.