
	Where results make sense

Topic: Low density parity check codes

Related Topics

MTN

Lyndon Baines Johnson Library and Museum

In the News (Thu 17 Dec 09)

Northern Trust

Marvin Harrison

Peter Chernin

Gary Locke

Match Play

Penelope Cruz

Mickey Rourke

AR Rahman

Danny Boyle

Hugh Jackman

	Contents
		The second course was a course on error-correcting codes.
		Cyclic codes are a very broad class of codes which includes, for example Reed-Solomon codes, the codes used on todays CDs.
		Other codes, such as the Goppa codes and the low density parity check codes, do not need group theory but were too advanced to fit naturally into chapter 3.
	web.usna.navy.mil /~wdj/book/node1.html (878 words)

	Low complexity decoding of low density parity check codes patent invention
		The defining characteristic of an LDPC code is that the parity check matrix H is sparse (i.e., is mostly zeros).
		Some LDPC codes are referred to as "regular" codes because they have the same number d.sub.c of non-zero elements in every row of H and have the same number d.sub.v of non-zero elements in every column of H. Such codes are often referred to as (d.sub.v, d.sub.c) LDPC codes.
		The check node output messages tend to reinforce the status quo of the input variable nodes if the check node parity check is satisfied, and tend to flip bits in the input variable nodes if the check node parity check is not satisfied.
	www.freshpatents.com /Low-complexity-decoding-of-low-density-parity-check-codes-dt20060824ptan20060190797.php (2516 words)

	Codes on Graphs and Iterative Decoding Algorithms, Spring Semester 2004
		These exciting developments in coding theory during the last decade did not only revolutionize the field of channel coding, but had also a great impact in other areas, such as channel equalization, lossless and lossy data compression, interference cancellation, multi-user detection etc., where the ``turbo-principle'' can be applied efficiently.
		Asymptotic analysis of LDPC codes on binary, memoryless, symmetric channels: iterative message-passing decoders, density evolution, monotonicity, thresholds, stability, concentration, EXIT charts, the Gaussian approximation for density evolution and approximated threshold transformations.
		Parity-check density versus performance of binary linear block codes over memoryless symmetric channels, the connection between parity-check density and complexity for codes defined by standard Tanner graphs, and capacity-achieving ensembles for the binary erasure channel with bounded complexity.
	www.ee.technion.ac.il /people/sason/codes_on_graphs.html (766 words)

	Low Density Parity Check Codes
		Error-correcting codes are primarily used to correctly transmit data across a noisy channel.
		The length of the code is the integer
		This matrix would not suffice as an adequate Low Density Parity Check matrix because it is not of low density.
	cadigweb.ew.usna.edu /~wdj/mcdonald/mcdonald-honorsthesis (1956 words)

	Low-Density Parity-Check Codes: Constructions and Bounds \| Events \| Computer Science Department, Technion
		In particular, we discuss the decoding of expander codes that are based on a non-bipartite underlying graph.
		We present a new family of generalized expander codes, which is different from all known families of expander codes, and discuss its parameters.
		Finally, we focus on expander codes that use weak constituent codes, and in some cases, we derive lower and upper bounds on the minimum distance of the corresponding expander codes.
	www.cs.technion.ac.il /events/2006/120 (327 words)

	Iterative Probabilistic Decoding of a Low Density Parity Check Code
		Iterative Probabilistic Decoding of a Low Density Parity Check Code
		We have rediscovered Gallager's (1962) low density parity check codes and iterative decoding algorithm.
		For the Gaussian channel this graph shows the performance of rate-1/4 codes developed by Davey and MacKay that are superior to all known rate-1/4 codes.
	www.inference.phy.cam.ac.uk /mackay/codes/gifs (224 words)

	Low-density Parity Check Codes (Site not responding. Last check: )
		We study LDPC codes for channels with non-uniform noise distributions, rate-adaptive coding, and unequal error protection.
		An important property of the proposed technique is the design of the codes that have a low error floor and low variable node degrees, while maintaining performance close to the
		We also show that punctured LDPC codes can be studied as a special case of our design methodology for non-uniform channels.
	users.ece.gatech.edu /~hossein/LDPCresearch.htm (649 words)

	CommsDesign - LDPC: Another Key Step Toward Shannon
		Encoding is done by using equations derived from the H matrix to generate the parity check bits.
		This is a result of having a low number of ones in the H matrix and as such the number of columns of H required to sum to zero tends to be high even for randomly constructed codes.
		In the code example above, columns n0 through n8 represent the message part of the encoded block, while columns n9 through n15 represent the (n-k) parity bits and form a submatrix that is lower triangular in nature further simplifying the encoding process.
	www.commsdesign.com /design_center/broadband/design_corner/showArticle.jhtml?articleID=49901136 (1840 words)

	A Practical Analysis of Low-Density Parity-Check Erasure Codes for Wide-Area Storage Applications
		However, more recently Low-Density Parity-Check (LDPC) codes have arisen as alternative codes that trade off vastly improved decoding performance for inefficiencies in the amount of data that must be acquired to perform decoding.
		The scores of papers written on LDPC codes typically analyze their collective and asymptotic behavior.
		We employ simulation to generate a huge variety of individual codes, and then analyze their behavior in order to address several important heretofore unanswered questions about employing LDPC codes in real-world systems.
	www.cs.utk.edu /~plank/plank/papers/DSN-2004.html (295 words)

	SPIRAL Project: Home Page
		For practical purposes, structured LDPC codes have been considered that allow for encoding and decoding with low complexity.
		With this structure, the position of 1’s in the parity check matrix can be stored in the decoder as the amount of shifts in each permutation matrix, which we call an S-matrix.
		We have developed a generator for FPGA implementations of the entire class of CPA structured LDPC codes to enable the analysis of these codes in low BER regions.
	www.spiral.net /hardware/ldpc.html (465 words)

	Daniel A. Spielman: Research on Error-Correcting Codes
		In Constructing Error-Correcting Codes from Expander Graphs, (IMA '96) we survey the constructions of expander codes and the linear-time encodable and decodable codes.
		In, Improved Low-Density Parity-Check Codes Using Irregular Graphs and Belief Propagation (ISIT '98) we simulated the performance of the codes from the "Efficient Erasure Correcting Codes" paper on the Gaussian channel using belief propagation decoding.
		In, Analysis of Low Density Codes and Improved Designs Using Irregular Graphs, (STOC '98) we extend the approach introduced in the erasure code paper to the design and analysis of codes correcting errors.
	www-math.mit.edu /~spielman/Research/ECC.html (823 words)

	Low Density Parity Check Codes
		Low density parity check (LDPC) codes were introduced along with an iterative probability-based decoding algorithm by Gallager in the early 1960's.
		These codes were constructed using sparse random parity check matrices and showed promising distance properties.
		However, they went largely unnoticed until the advent of turbo codes, where they were “rediscovered” by MacKay, who showed that they perform almost as close to capacity as turbo codes.
	www.csee.wvu.edu /wcrl/ldpc.htm (197 words)

	System and method for generating low density parity check codes using bit-filling (US6789227)
		One aspect of the invention includes a method for generating high rate LDPC codes that first constructs a matrix (H) of size mxn having m rows of check nodes and n columns of bit nodes.
		comprises a set of i check nodes such that i is greater than or equal to 0 and i is less than a
		"Low Density Parity Check Codes: Construction Based on Finite Geometries", Yu Kow et al., IEEE Conference on Global Communications, Nov. 27 to Dec. 1, 2000, vol.
	www.delphion.com /details?pn=US06789227__ (663 words)

	Low-Density Parity-Check Codes - The MIT Press (Site not responding. Last check: )
		Low-density coding is one of the three techniques thus far developed for efficient communication over noisy channels with an arbitrarily low probability of error.
		A principal result of information theory is that if properly coded information is transmitted over a noisy channel at a rate below channel capacity, the probability of error can be made to approach zero exponentially with the code length.
		Any practical use of this theorem, however, requires a coding scheme in which the cost of storage and computation equipment grows slowly with code length.
	mitpress.mit.edu /catalog/item/default.asp?ttype=2&tid=9845 (180 words)

	On the design of low-density parity-check codes within 0.0045 dB of the Shannon limit (ResearchIndex) (Site not responding. Last check: )
		For rate 1/2, the best code found has a threshold within 0.0045 dB of the Shannon limit of the binary-input additive white Gaussian noise channel.
		Simulation results with a somewhat simpler code show that we can achieve within 0.04 dB of the Shannon limit at a bit error rate of 10 6 using a block length of 10 7.
		189 Iterative decoding of binary block and convolutional codes (context) - Hagenauer, er et al.
	citeseer.ist.psu.edu /496330.html (365 words)

	DigitalCommons@University of Nebraska - Lincoln \| Algebraic constructions of low-density parity check codes
		Coding theory is the study of efficient ways of encoding information so that error-detection and correction may be achieved.
		Using Ramanujan graphs and introducing the notion of a graph splitting, we describe a new construction to obtain families of LDPC codes.
		Two important properties of the Tanner graph of an LDPC code are girth and expansion factor.
	digitalcommons.unl.edu /dissertations/AAI3176790 (236 words)

	Course #09, Turbo Codes and Low-Density Parity-Check Codes: Analysis, Design, Iterative Decoding and Applications
		After slightly more than a decade from their discovery, turbo and LDPC codes have been accepted as coding standard for 3G wireless communications systems, like CDMA2000 and UMTS, for satellite and deep space applications as the new CCSDS telemetry channel coding standard, for the new digital video broadcasting by satellite DVBS-2, and many others.
		Both classes of codes rely on the application of soft, decentralized decoding algorithm, like the BCJR for turbo codes and the "message passing" for LDPC codes.
		Explanation of the maximum-a-posteriori algorithms, which form the core of the iterative decoding algorithms, extensive analytical and simulation results, and a comparative analysis of the implementation complexity are also presented.
	www.cei.se /009.htm (683 words)

	[Abstract] Rate-compatible Low Density Parity Check Codes for Capacity-approaching ARQ Schemes in Packet Data ...
		Strong rate-compatible codes is important to achieve high throughput in hybrid automatic repeat request with forward error correction (ARQ/FEC) systems in packet data trans mission.
		Analysis on the code ensemble and the asymptotic performance shows that it works well only at high rates and only when the amount of puncturing is small.
		To extend the dynamic rate range, a special ap proach of extending is proposed and is shown to produce good RC-LDPC codes at low rates.
	www.actapress.com /Abstract.aspx?paperId=24350 (226 words)

	The Error Correcting Codes (ECC) Page
		This BCH code is used in control channels for cellular TDMA in the U.S. Since this code has only two-error correcting capability, fast decoding is done by pre-solving a system of two equations (the syndromes) in two unknowns (the error positions), see MacWilliams and Slone's book, chapter 3.
		This is a C++ program (compiled for Sparcs) that computes properties of binary codes, from more basic items such as minimum distance and dimension to more complicated properties such as trellis decoding complexity and whether the Tanner graph of the code is cycle-free.
		The purpose of this tutorial is to introduce the reader to a forward error correction technique known as convolutional coding with Viterbi decoding.
	eccpage.com (1019 words)

	Error Correction
		The Turbo Codes algorithms can be used on squared and non-squared QAM constellations and include both Full-Turbo coding and Multi-level Turbo Coding.
		The process of encoding is simpler than decoding; for this reason, this technique is very suitable for asymmetrical coding (where different coding is used in each direcction of the communication system).
		Technical whitepapers on Reed-Solomon Codes, Turbo Codes, and LDPC codes, as well as other signal processing algorithms, are also available.
	www.vocal.com /advanced_coding.html (345 words)

	Iterative Probabilistic Decoding of a Low Density Parity Check Code (Site not responding. Last check: )
		The transmitted vector consists of these bits and about three times as many parity bits, shown in the lower part of the image.
		At the 16th iteration, the guess violates no parity checks, and the decoder halts.
		For comparison, the Shannon limit for a code of this rate is a s.n.r.
	wol.ra.phy.cam.ac.uk /mackay/codes/gifs/demo2.html (221 words)

	Low density - Software for Parity Check (LDPC) codes
		Trudy Forte and Mina Nikanjam of Berkeley Lab and Children's Hospital Oakland Research Institute (CHORI) have developed a synthetic nano-
		Summary:, parity check (LDPC) codes were introduced along with an iterative probability-based decoding algorithm by Gallager in the early 1960's
		This software is meant for supporting research into Parity Check (LDPC) codes.
	webinfofeed.com /wifd/low-density.htm (396 words)

	Research Grants - Research - Advanced Communication Center (ACC), Tel Aviv University
		Low density parity check (LDPC) codes are the current state of the art in channel coding, due to their ability to closely approach channel capacity, using practical iterative decoding algorithms.
		Turbo and LDPC codes have already been implemented in various advanced communication standards.
		These codes have been considered both in point to point as well as in multi-user communications.
	www.tau.ac.il /institutes/acc/LDPC_WS.html (199 words)

	Decoding Low-Density Parity-Check Codes With Probabilistic Scheduling
		In this letter, we present a new message-passing schedule for the decoding of low-density parity-check (LDPC) codes.
		This work also suggests that scheduling plays an important role in iterative decoding and that a schedule that matches the structure of the TG is desirable.
		F. Kschischang and B. Frey, "Iterative decoding of compound codes by probability propagation in graphical models", IEEE J. Select.
	www.comsoc.org /comml/private/2001/oct/414_05comml10-mao.html (297 words)

	vsevcosmos: Estimation of Bit and Frame Error Rates of Low-Density Parity-Check Codes on Binary Symmetric Channe
		A method for estimating the performance of low-density parity-check (LDPC) codes decoded by hard-decision iterative decoding algorithms on binary symmetric channels (BSC) is proposed.
		Based on the enumeration of the smallest weight error patterns that can not be all corrected by the decoder, this method estimates both the frame error rate (FER) and the bit error rate (BER) of a given LDPC code with very good precision for all crossover probabilities of practical interest.
		Through a number of examples, we show that the proposed method can be effectively applied to both regular and irregular LDPC codes and to a variety of hard-decision iterative decoding algorithms.
	vsevcosmos.livejournal.com /22821691.html (181 words)

	Abstract for ``Near Shannon limit performancd of low density parity check codes'' (Site not responding. Last check: )
		Near Shannon limit performancd of low density parity check codes
		The authors report the empirical performance of Gallager's low density parity check codes on Gaussian channels.
		They show that performance substantially better than that of standard convolutional and concatenated codes can be achieved; indeed the performance is almost as close to the Shannon limit as that of turbo codes.
	www.cs.utoronto.ca /~radford/ldpc.abstract.html (81 words)

	Iterative Probabilistic Decoding of a Low Density Parity Check Code (Site not responding. Last check: )
		The figure shows the performance of various codes with rate 1/4 over the Gaussian Channel.
		JPL's code for Galileo: a concatenated code based on constraint length 15, rate 1/4 convolutional code (in 1992, this was the best known code of rate 1/4); blocklength about 64,000 bits;
		Regular binary LDPC [similar to the one shown in Demonstration 2]: blocklength 40000 bits (MacKay, 1999).
	wol.ra.phy.cam.ac.uk /mackay/codes/gifs/GC-survey2.R0.25.html (150 words)

	Rate Compatible Low-Density Parity-Check Codes Based on Progressively Increased Column Weights -- ZHENG et al. E89-A ...
		Rate Compatible Low-Density Parity-Check Codes Based on Progressively Increased Column Weights -- ZHENG et al.
		low complex adaptive communication systems, such as wireless
		Key Words: LDPC codes, rate compatible, parity check matrix, puncturing, progressively increased column weights
	ietfec.oxfordjournals.org /cgi/content/abstract/E89-A/10/2493 (266 words)

	IEEE Transactions on Information Theory: February 2001
		Introduction to the special issue on codes on graphs and iterative algorithms
		Analysis of sum-product decoding of low-density parity-check codes using a Gaussian approximation
		An analysis of belief propagation on the turbo decoding graph with Gaussian densities
	www.cparity.com /it/demo/journals/ieee/it/it/2001047/2001_02.htm (176 words)

Try your search on: Qwika (all wikis)