Study and Design of Turbo and Low-density Parity-check Codes Decoder Architectures for High-rate Flexible Communication Systems PDF Download
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Author: Giuseppe Gentile
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Author: Giuseppe Gentile
Publisher:
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Category :
Languages : en
Pages :
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Author: Kai Zhang
Publisher:
ISBN:
Category :
Languages : en
Pages : 244
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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.
Author: Aliazam Abbasfar
Publisher: Springer Science & Business Media
ISBN: 1402063911
Category : Technology & Engineering
Languages : en
Pages : 94
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This book introduces turbo error correcting concept in a simple language, including a general theory and the algorithms for decoding turbo-like code. It presents a unified framework for the design and analysis of turbo codes and LDPC codes and their decoding algorithms. A major focus is on high speed turbo decoding, which targets applications with data rates of several hundred million bits per second (Mbps).
Author: Sunitha Kopparthi
Publisher:
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Category :
Languages : en
Pages :
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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.
Author: Keattisak Sripimanwat
Publisher: Springer Science & Business Media
ISBN: 140203685X
Category : Technology & Engineering
Languages : en
Pages : 393
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Turbo Code Applications: a journey from a paper to realization presents c- temporary applications of turbo codes in thirteen technical chapters. Each chapter focuses on a particular communication technology utilizing turbo codes, and they are written by experts who have been working in related th areas from around the world. This book is published to celebrate the 10 year anniversary of turbo codes invention by Claude Berrou Alain Glavieux and Punya Thitimajshima (1993-2003). As known for more than a decade, turbo code is the astonishing error control coding scheme which its perf- mance closes to the Shannon’s limit. It has been honored consequently as one of the seventeen great innovations during the ?rst ?fty years of information theory foundation. With the amazing performance compared to that of other existing codes, turbo codes have been adopted into many communication s- tems and incorporated with various modern industrial standards. Numerous research works have been reported from universities and advance companies worldwide. Evidently, it has successfully revolutionized the digital commu- cations. Turbo code and its successors have been applied in most communications startingfromthegroundorterrestrialsystemsofdatastorage,ADSLmodem, and ?ber optic communications. Subsequently, it moves up to the air channel applications by employing to wireless communication systems, and then ?ies up to the space by using in digital video broadcasting and satellite com- nications. Undoubtedly, with the excellent error correction potential, it has been selected to support data transmission in space exploring system as well.
Author: Zhiqiang Cui
Publisher:
ISBN:
Category : Decoders (Electronics)
Languages : en
Pages : 218
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Low-Density Parity-check (LDPC) codes have attracted considerable attention due to their capacity approaching performance over AWGN channel and highly parallelizable decoding schemes. They have been considered in a variety of industry standards for the next generation communication systems. In general, LDPC codes achieve outstanding performance with large codeword lengths (e.g., N>1000 bits), which lead to a linear increase of the size of memory for storing all the soft messages in LDPC decoding. In the next generation communication systems, the target data rates range from a few hundred Mbit/sec to several Gbit/sec. To achieve those very high decoding throughput, a large amount of computation units are required, which will significantly increase the hardware cost and power consumption of LDPC decoders. LDPC codes are decoded using iterative decoding algorithms. The decoding latency and power consumption are linearly proportional to the number of decoding iterations. A decoding approach with fast convergence speed is highly desired in practice. This thesis considers various VLSI design issues of LDPC decoder and develops efficient approaches for reducing memory requirement, low complexity implementation, and high speed decoding of LDPC codes. We propose a memory efficient partially parallel decoder architecture suited for quasi-cyclic LDPC (QC-LDPC) codes using Min-Sum decoding algorithm. We develop an efficient architecture for general permutation matrix based LDPC codes. We have explored various approaches to linearly increase the decoding throughput with a small amount of hardware overhead. We develop a multi-Gbit/sec LDPC decoder architecture for QC-LDPC codes and prototype an enhanced partially parallel decoder architecture for a Euclidian geometry based LDPC code on FPGA. We propose an early stopping scheme and an extended layered decoding method to reduce the number of decoding iterations for undecodable and decodable sequence received from channel. We also propose a low-complexity optimized 2-bit decoding approach which requires comparable implementation complexity to weighted bit flipping based algorithms but has much better decoding performance and faster convergence speed.
Author: Xiaoheng Chen
Publisher:
ISBN: 9781124906669
Category :
Languages : en
Pages :
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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.
Author:
Publisher:
ISBN: 9781321895544
Category :
Languages : en
Pages : 232
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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.
Author: Thierry Lestable
Publisher: John Wiley & Sons
ISBN: 0470977590
Category : Technology & Engineering
Languages : en
Pages : 263
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Covering the fast evolving area of advanced coding, Error Control Coding for B3G/4G Wireless Systems targets IMT-Advanced systems to present the latest findings and implementation solutions. The book begins by detailing the fundamentals of advanced coding techniques such as Coding, Decoding, Design, and Optimization. It provides not only state-of-the-art research findings in 3D Turbo-codes, non-binary LDPC Codes, Fountain, and Raptor codes, but also insights into their real-world implementation by examining hardware architecture solutions, for example VLSI complexity, FPGA, and ASIC. Furthermore, special attention is paid to Incremental redundancy techniques, which constitute a key feature of Wireless Systems. A promising application of these advanced coding techniques, the Turbo-principle (also known as iterative processing), is illustrated through an in-depth discussion of Turbo-MIMO, Turbo-Equalization, and Turbo-Interleaving techniques. Finally, the book presents the status of major standardization activities currently implementing such techniques, with special interest in 3GPP UMTS, LTE, WiMAX, IEEE 802.11n, DVB-RCS, DVB-S2, and IEEE 802.22. As a result, the book coherently brings together academic and industry vision by providing readers with a uniquely comprehensive view of the whole topic, whilst also giving an understanding of leading-edge techniques. Includes detailed coverage of coding, decoding, design, and optimization approaches for advanced codes Provides up to date research findings from both highly reputed academics and industry standpoints Presents the latest status of standardization activities for Wireless Systems related to advanced coding Describes real-world implementation aspects by giving insights into architecture solutions for both LDPC and Turbo-codes Examines the most advanced and promising concepts of turbo-processing applications: Turbo-MIMO, Turbo-Equalization, Turbo-Interleaving
Author: Ali Reza Rabbani Abolfazli
Publisher:
ISBN:
Category :
Languages : en
Pages :
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