Efficient Design and Decoding of the Rate-compatible Low-density Parity-check Codes - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook Efficient Design and Decoding of the Rate-compatible Low-density Parity-check Codes write by . This book was released on . Efficient Design and Decoding of the Rate-compatible Low-density Parity-check Codes available in PDF, EPUB and Kindle. HKUST Call Number: Thesis ECED 2009 WuXX.
Design of Rate-compatible Structured Low-density Parity-check Codes
Design of Rate-compatible Structured Low-density Parity-check Codes - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook Design of Rate-compatible Structured Low-density Parity-check Codes write by Jaehong Kim. This book was released on 2006. Design of Rate-compatible Structured Low-density Parity-check Codes available in PDF, EPUB and Kindle. The main objective of our research is to design practical low-density parity-check (LDPC) codes which provide a wide range of code rates in a rate-compatible fashion. To this end, we first propose a rate-compatible puncturing algorithm for LDPC codes at short block lengths (up to several thousand symbols). The proposed algorithm is based on the claim that a punctured LDPC code with a smaller level of recoverability has better performance. The proposed algorithm is verified by comparing performance of intentionally punctured LDPC codes (using the proposed algorithm) with randomly punctured LDPC codes. The intentionally punctured LDPC codes show better bit error rate (BER) performances at practically short block lengths. Even though the proposed puncturing algorithm shows excellent performance, several problems are still remained for our research objective. First, how to design an LDPC code of which structure is well suited for the puncturing algorithm. Second, how to provide a wide range of rates since there is a puncturing limitation with the proposed puncturing algorithm. To attack these problems, we propose a new class of LDPC codes, called efficiently-encodable rate-compatible (E2RC) codes, in which the proposed puncturing algorithm concept is imbedded. The E2RC codes have several strong points. First, the codes can be efficiently encoded. We present low-complexity encoder implementation with shift-register circuits. In addition, we show that a simple erasure decoder can also be used for the linear-time encoding of these codes. Thus, we can share a message-passing decoder for both encoding and decoding in transceiver systems that require an encoder/decoder pair. Second, we show that the non-systematic parts of the parity-check matrix are cycle-free, which ensures good code characteristics. Finally, the E2RC codes having a systematic rate-compatible puncturing structure show better puncturing performance than any other LDPC codes in all ranges of code rates.
Efficient Analysis, Design and Decoding of Low-density Parity-check Codes [microform]
Efficient Analysis, Design and Decoding of Low-density Parity-check Codes [microform] - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook Efficient Analysis, Design and Decoding of Low-density Parity-check Codes [microform] write by Masoud Ardakani. This book was released on 2004. Efficient Analysis, Design and Decoding of Low-density Parity-check Codes [microform] available in PDF, EPUB and Kindle. This dissertation presents new methods for the analysis, design and decoding of low-density parity-check (LDPC) codes. We start by studying the simplest class of decoders: the binary message-passing (BMP) decoders. We show that the optimum BMP decoder must satisfy certain symmetry and isotropy conditions, and prove that Gallager's Algorithm B is the optimum BMP algorithm. We use a generalization of extrinsic information transfer (EXIT) charts to formulate a linear program that leads to the design of highly efficient irregular LDPC codes for the BMP decoder. We extend this approach to the design of irregular LDPC codes for the additive white Gaussian noise channel. We introduce a "semi-Gaussian" approximation that very accurately predicts the behaviour of the decoder and permits code design over a wider range of rates and code parameters than in previous approaches. We then study the EXIT chart properties of the highest rate LDPC code which guarantees a certain convergence behaviour. We also introduce and analyze gear-shift decoding in which the decoder is permitted to select the decoding rule from among a predefined set. We show that this flexibility can give rise to significant reductions in decoding complexity. Finally, we show that binary LDPC codes can be combined with quadrature amplitude modulation to achieve near-capacity performance in a multitone system over frequency selective Gaussian channels.
Efficient Low-density Parity-check Codes for Cooperative Communication
Efficient Low-density Parity-check Codes for Cooperative Communication - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook Efficient Low-density Parity-check Codes for Cooperative Communication write by Osso Vahabzadeh. This book was released on 2014. Efficient Low-density Parity-check Codes for Cooperative Communication available in PDF, EPUB and Kindle. In this dissertation, we address code design problem for cooperative communication over different channel models with emphasis on low complexity designs and structured codes that are attractive for practical implementation. We start with the problem of designing efficient codes for the relay node in Gaussian relay channels. For a class of capacity approaching codes for this channel model, called bilayer lengthened LDPC (BL-LDPC) codes, we calculate a measure of decoding complexity as a function of the number of decoding iterations and propose a technique to design complexity-optimized BL-LDPC codes by minimizing the complexity measure of these codes. This is made possible by generalizing the EXIT charts to the case of BL-LDPC codes. Motivated by the fact that there are usually stricter hardware restrictions at the relay node, our technique targets minimizing the decoding complexity of the relay code. Furthermore, excessive delay due to decoding high rate codes at the relay results in additional delay at the destination. Using our technique, we design bilayer codes with noticeable reduction in decoding complexity and delay compared to the rate-optimized codes reported in the literature. Next, we study the achievable rates for the decode-and-forward (DF) relaying strategy for the Rayleigh fading relay channel where the links have independent normalized Rayleigh fading coefficients and the channel side information is perfectly known at the corresponding receivers but not at the transmitters. We design BL-LDPC codes for this scenario for the case when the source-relay link is much stronger than the source-destination link as well as for the case when these two links have comparable SNRs. We also propose a novel two-user cooperation scheme for the block fading channel model that employs protograph-based LDPC codes. The proposed scenario is based on time division where each user transmits its message to the base station (BS) in two successive frames. Cooperation is performed by employing the Alamouti scheme Whenever it is possible. Additionally, the users encode their information over protograph-based LDPC codes that allow flexible selection of rates and code lengths. Finally, we introduce rate-compatible protograph-based root LDPC (RCPB-R-LDPC) codes for cooperative communication over block fading channels and propose two methods to construct these codes. The proposed techniques are based on the extension technique and offer broad design rates resulting in high flexibility. Furthermore, they are based on protograph constructions with minimum distance growing linearly with the block length, a property that improves the error floor performance of the designed codes. The outage probability limit under BPSK modulation is obtained for the cooperative scheme employed in this work and was used to evaluate the WER performance of the designed codes.
Energy-efficient Decoding of Low-density Parity-check Codes
Energy-efficient Decoding of Low-density Parity-check Codes - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook Energy-efficient Decoding of Low-density Parity-check Codes write by Kevin Cushon. This book was released on 2014. Energy-efficient Decoding of Low-density Parity-check Codes available in PDF, EPUB and Kindle. "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." --
