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Author: Vikram Arkalgud Chandrasetty
Publisher: Academic Press
ISBN: 0128112565
Category : Technology & Engineering
Languages : en
Pages : 192
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Book Description
This book takes a practical hands-on approach to developing low complexity algorithms and transforming them into working hardware. It follows a complete design approach – from algorithms to hardware architectures - and addresses some of the challenges associated with their design, providing insight into implementing innovative architectures based on low complexity algorithms.The reader will learn: Modern techniques to design, model and analyze low complexity LDPC algorithms as well as their hardware implementation How to reduce computational complexity and power consumption using computer aided design techniques All aspects of the design spectrum from algorithms to hardware implementation and performance trade-offs Provides extensive treatment of LDPC decoding algorithms and hardware implementations Gives a systematic guidance, giving a basic understanding of LDPC codes and decoding algorithms and providing practical skills in implementing efficient LDPC decoders in hardware Companion website containing C-Programs and MATLAB models for simulating the algorithms, and Verilog HDL codes for hardware modeling and synthesis
Author: Vikram Arkalgud Chandrasetty
Publisher: Academic Press
ISBN: 0128112565
Category : Technology & Engineering
Languages : en
Pages : 192
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Book Description
This book takes a practical hands-on approach to developing low complexity algorithms and transforming them into working hardware. It follows a complete design approach – from algorithms to hardware architectures - and addresses some of the challenges associated with their design, providing insight into implementing innovative architectures based on low complexity algorithms.The reader will learn: Modern techniques to design, model and analyze low complexity LDPC algorithms as well as their hardware implementation How to reduce computational complexity and power consumption using computer aided design techniques All aspects of the design spectrum from algorithms to hardware implementation and performance trade-offs Provides extensive treatment of LDPC decoding algorithms and hardware implementations Gives a systematic guidance, giving a basic understanding of LDPC codes and decoding algorithms and providing practical skills in implementing efficient LDPC decoders in hardware Companion website containing C-Programs and MATLAB models for simulating the algorithms, and Verilog HDL codes for hardware modeling and synthesis
Author: Kevin Cushon
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
"Low-density parity-check (LDPC) codes are a type of error correcting code that are frequently used in high-performance communications systems, due to their ability to approach the theoretical limits of error correction. However, their iterative soft-decision decoding algorithms suffer from high computational complexity, energy consumption, and auxiliary circuit implementation difficulties. It is of particular interest to develop energy-efficient LDPC decoders in order to decrease cost of operation, increase battery life in portable devices, lessen environmental impact, and increase the range of applications for these powerful codes.In this dissertation, we propose four new LDPC decoder designs with the primary goal of improving energy efficiency over previous designs. First, we present a bidirectional interleaver based on transmission gates, which reduces wiring complexity and associated parasitic energy losses. Second, we present an iterative decoder design based on pulse-width modulated min-sum (PWM-MS). We demonstrate that the pulse width message format reduces switching activity, computational complexity, and energy consumption compared to other recent LDPC decoder designs. Third, wepresent decoders based on differential binary (DB) algorithms. We also propose an improved differential binary (IDB) decoding algorithm, which greatly increases throughput and reduces energy consumption compared to recent decoders ofsimilar error correction capability. Finally, we present decoders based on gear-shift algorithms, which use multiple decoding rules to minimize energy consumption. We propose gear-shift pulse-width (GSP) and IDB with GSP (IGSP) algorithms, and demonstrate that they achieve superior energy efficiency without compromising error correction performance." --
Author: Tinoosh Mohsenin
Publisher:
ISBN: 9781124509181
Category :
Languages : en
Pages :
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Book Description
Many emerging and future communication applications require a significant amount of high throughput data processing and operate with decreasing power budgets. This need for greater energy efficiency and improved performance of electronic devices demands a joint optimization of algorithms, architectures, and implementations. Low Density Parity Check (LDPC) decoding has received significant attention due to its superior error correction performance, and has been adopted by recent communication standards such as 10GBASE-T 10 Gigabit Ethernet. Currently high performance LDPC decoders are designed to be dedicated blocks within a System-on-Chip (SoC) and require many processing nodes. These nodes require a large set of interconnect circuitry whose delay and power are wire-dominated circuits. Therefore, low clock rates and increased area are a common result of the codes' inherent irregular and global communication patterns. As the delay and energy costs caused by wires are likely to increase in future fabrication technologies new solutions dealing with future VLSI challenges must be considered. Three novel message-passing decoding algorithms, Split-Row, Multi-Splitand Split-Row Threshold are introduced, which significantly reduce processor logical complexity and local and global interconnections. One conventional and four Split-Row Threshold LDPC decoders compatible with the 10GBASE-T standard are implemented in 65 nm CMOS and presented along with their trade-offs in error correction performance, wire interconnect complexity, decoder area, power dissipation, and speed. For additional power saving, an adaptive wordwidth decoding algorithm is proposed which switches between a 6-bit Normal Mode and a reduced 3-bit Low Power Mode depending on the SNR and decoding iteration. A 16-way Split-Row Threshold with adaptive wordwidth implementation achieves improvements in area, throughput and energy efficiency of 3.9x, 2.6x, and 3.6x respectively, compared to a MinSum Normalized implementation, with an SNR loss of 0.25 dB at BER = 10−7. The decoder occupies a die area of 5.10 mm2, operates up to 185 MHz at 1.3 V, and attains an average throughput of 85.7 Gbps with early-termination. Low power operation at 0.6 V gives a worst case throughput of 9.3 Gbps--above the 6.4 Gbps 10GBASE-T requirement, and an average power of 31 mW.
Author: Ahmad Darabiha
Publisher:
ISBN: 9780494398173
Category :
Languages : en
Pages : 228
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Book Description
Near-capacity performance and parallelizable decoding algorithms have made Low-Density Parity Check (LDPC) codes a powerful competitor to previous generations of codes, such as Turbo and Reed Solomon codes, for reliable high-speed digital communications. As a result, they have been adopted in several emerging standards. This thesis investigates VLSI architectures for multi-Gbps power and area-efficient LDPC decoders. To reduce the node-to-node communication complexity, a decoding scheme is proposed in which messages are transferred and computed bit-serially. Also, a broadcasting scheme is proposed in which the traditional computations required in the sum-product and min-sum decoding algorithms are repartitioned between the check and variable node units. To increase decoding throughput, a block interlacing scheme is investigated which is particularly advantageous in fully-parallel LDPC decoders. To increase decoder energy efficiency, an efficient early termination scheme is proposed. In addition, an analysis is given of how increased hardware parallelism coupled with a reduced supply voltage is a particularly effective approach to reduce the power consumption of LDPC decoders. These architectures and circuits are demonstrated in two hardware implementations. Specifically, a 610-Mbps bit-serial fully-parallel (480, 355) LDPC decoder on a single Altera Stratix EP1S80 device is presented. To our knowledge, this is the fastest FPGA-based LDPC decoder reported in the literature. A fabricated 0.13-mum CMOS bit-serial (660, 484) LDPC decoder is also presented. The decoder has a 300 MHz maximum clock frequency and a 3.3 Gbps throughput with a nominal 1.2-V supply and performs within 3 dB of the Shannon limit at a BER of 10-5. With more than 60% power saving gained by early termination, the decoder consumes 10.4 pJ/bit/iteration at Eb=N0=4dB. Coupling early termination with supply voltage scaling results in an even lower energy consumption of 2.7 pJ/bit/iteration with 648 Mbps decoding throughput. The proposed techniques demonstrate that the bit-serial fully-parallel architecture is preferred to memory-based partially-parallel architectures, both in terms of throughput and energy efficiency, for applications such as 10GBase-T which use medium-size LDPC code (e.g., 2048 bit) and require multi-Gbps decoding throughput.
Author: Zuber Patel
Publisher: Springer Nature
ISBN: 9811562296
Category : Technology & Engineering
Languages : en
Pages : 299
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Book Description
This book presents select peer-reviewed proceedings of the International Conference on Advances in VLSI and Embedded Systems (AVES 2019) held at SVNIT, Surat, Gujarat, India. The book covers cutting-edge original research in VLSI design, devices and emerging technologies, embedded systems, and CAD for VLSI. With an aim to address the demand for complex and high-functionality systems as well as portable consumer electronics, the contents focus on basic concepts of circuit and systems design, fabrication, testing, and standardization. This book can be useful for students, researchers as well as industry professionals interested in emerging trends in VLSI and embedded systems.
Author: Pascal Giard
Publisher: Springer
ISBN: 3319597825
Category : Computers
Languages : en
Pages : 108
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Book Description
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.
Author: Xiaoheng Chen
Publisher:
ISBN: 9781124906669
Category :
Languages : en
Pages :
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Book Description
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: Yuta Toriyama
Publisher:
ISBN:
Category :
Languages : en
Pages : 133
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Book Description
Binary Low-Density Parity-Check (LDPC) codes are a type of error correction code known to exhibit excellent error-correcting capabilities, and have increasingly been applied as the forward error correction solution in a multitude of systems and standards, such as wireless communications, wireline communications, and data storage systems. In the pursuit of codes with even higher coding gain, non-binary LDPC (NB-LDPC) codes defined over a Galois field of order q have risen as a strong replacement candidate. For codes defined with similar rate and length, NB-LDPC codes exhibit a significant coding gain improvement relative to that of their binary counterparts. Unfortunately, NB-LDPC codes are currently limited from practical application by the immense complexity of their decoding algorithms, because the improved error-rate performance of higher field orders comes at the cost of increasing decoding algorithm complexity. Currently available ASIC implementation solutions for NB-LDPC code decoders are simultaneously low in throughput and power-hungry, leading to a low energy efficiency. We propose several techniques at the algorithm level as well as hardware architecture level in an attempt to bring NB-LDPC codes closer to practical deployment. On the algorithm side, we propose several algorithmic modifications and analyze the corresponding hardware cost alleviation as well as impact on coding gain. We also study the quantization scheme for NB-LDPC decoders, again in the context of both the hardware and coding gain impacts, and we propose a technique that enables a good tradeoff in this space. On the hardware side, we develop a FPGA-based NB-LDPC decoder platform for architecture prototyping as well as hardware acceleration of code evaluation via error rate simulations. We also discuss the architectural techniques and innovations corresponding to our proposed algorithm for optimization of the implementation. Finally, a proof-of-concept ASIC chip is realized that integrates many of the proposed techniques. We are able to achieve a 3.7x improvement in the information throughput and 23.8x improvement in the energy efficiency over prior state-of-the-art, without sacrificing the strong error correcting capabilities of the NB-LDPC code.
Author: Radivoje Zarubica
Publisher:
ISBN: 9780549797418
Category :
Languages : en
Pages : 372
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Book Description
Low density parity check (LDPC) codes have garnered much attention in the error control coding field recently, due to the ability to implement soft-decision decoders that perform near the Shannon bound (for long blocklengths). The decoding algorithm is iterative and allows parallel, or semi-parallel, processing; hence, LDPC decoders are perfect candidates for high throughput applications. LDPC codes often are designed to achieve certain properties such as bit error rate and frame error rate, but without implementation issues in mind. Our study focuses on joint LDPC code/decoder design that take implementation issues into account and make the implemented decoder more efficient. Efficient code/decoder design refers to the idea of designing an LDPC code with specified properties in such a way that, when implemented in hardware (FPGA/ASIC), the designed code allows an efficient implementation. Our results indicate that smart code design can improve many parameters of the decoder such as error performance, maximal clock speed, and die area.
Author: Kai Zhang
Publisher:
ISBN:
Category :
Languages : en
Pages : 244
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Book Description
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.
