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Analog iterative LDPC decoder based on margin proplaoration

IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS II-EXPRESS BRIEFS 2007年第12期54卷 1140-1144页

作者： Kong, Chhay Chakrabartty, Shantanu Univ Illinois Dept Elect & Comp Engn Urbana IL 61801 USA Michigan State Univ Dept Elect & Comp Engn E Lansing MI 48824 USA

A margin propagation (MP) algorithm that can be used for implementing analog decoders for low-density parity check (LDPC) codes is presented. Unlike conventional sum-product analog decoders that rely on translinear operation of transistors, MP decoders use addition, subtraction and threshold operations, and therefore can be mapped onto different analog circuit topologies (current-mode, charge-mode, or nonelectronic circuits). This brief describes salient properties of the MP decoding algorithm and compares its performance to the sum-product and the min-sum (MS) decoding algorithms. Simulation results demonstrate that MP based LDPC decoders achieve nearly an identical bit error rate performance as their sum-product counterparts and achieve superior performance as compared to the MS decoding algorithm. Results presented in this brief also demonstrate that, when messages in LDPC decoding are corrupted by additive noise, the MP decoding algorithm delivers superior performance compared to its sum-product and MS counterparts.

关键词： analog decoding error-control coding low-density parity check (LDPC) margin propagation reverse water filling

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High-rate girth-eight low-density parity-check codes on rectangular integer lattices

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IEEE TRANSACTIONS ON COMMUNICATIONS 2004年第8期52卷 1248-1252页

作者： Vasic, B Pedagani, K Ivkovic, M Univ Arizona Dept Elect & Comp Engn Tucson AZ 85721 USA Inst Mat Estat & Comp Cient BR-13083970 Campinas SP Brazil

This letter introduces a combinatorial construction of girth-eight high-rate low-density parity-check codes based on integer lattices. The parity-check matrix of a code is defined as a point-line incidence matrix of a 1-configuration based on a rectangular integer lattice, and the girth-eight property is achieved by a judicious selection of sets of parallel lines included in a configuration. A class of codes with a wide range of lengths and column weights is obtained. The resulting matrix of parity checks is an array of circulant matrices.

关键词： combinatorial designs error-control coding finite geometries graph girth iterative decoding low-density parity-check (LDPC) codes

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Capacity of the wireless packet collision channel without feedback

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IEEE TRANSACTIONS ON INFORMATION THEORY 2000年第3期46卷 1141-1144页

作者： Thomas, G Univ SW Louisiana Dept Elect & Comp Engn Lafayette LA 70504 USA

It is desirable in random-access protocols for wireless mobile communications to avoid the need for feedback and retransmissions. Pure Aloha protocol can use erasure correction coding in place of retransmissions to maintain a throughput of 0.184. We show in this note that if we use error-correction coding (instead of erasure correction coding) throughput levels not less than 0.322 ran be realized for asynchronous random access without feedback or retransmissions.

关键词： error-control coding multiuser communications random access wireless networks

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ROW COLUMN REPLACEMENT FOR THE control OF HARD DEFECTS IN SEMICONDUCTOR RAMS

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IEEE TRANSACTIONS ON COMPUTERS 1986年第11期35卷 996-1000页

作者： FUJA, T HEEGARD, C School of Electrical Engineering Cornell University

We describe and analyze row/column replacement, the technique currently used to control hard cell defects in semiconductor RAM"s during manufacture. This strategy is shown to be asymptotically ineffective; it is ... 详细信息

关键词： error-control coding RAM"s hard defects redundancy reliability row/column replacement yield improvement

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A PARALLEL SYSTEMS-APPROACH TO UNIVERSAL RECEIVERS

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IEEE TRANSACTIONS ON INFORMATION THEORY 1991年第2期37卷 291-306页

作者： MADHOW, U PURSLEY, MB Coordinated Science Laboratory University of Illinois Urbana IL USA

The problem of communication over a channel with unknown characteristics is addressed. The true channel is from a known set of channels, but the transmitter and receiver do not know which of these channels is actually in effect. The goal of a universal receiver is to provide nearly optimal demodulation regardless of the channel that is actually in effect. A parallel receiver implementation is proposed for a universal scheme to cope with such uncertainty. The parallel system consists of a finite number of receivers with the property that, for each channel in the set, the performance of at least one of the receivers is within a specified performance range. Data verification, the process of selecting the receiver output sequences that are "good" for the channel that is in effect, is accomplished by an appropriate coding system. Sufficient conditions for the existence of such a universal receiver for a prescribed set of channels are established, procedures are outlined for the receiver design, and an example is given to illustrate the applicability of the theory. For M-ary signaling it is shown that, from an information-theoretic viewpoint, the data verification can be achieved at no extra cost by use of the intrinsic side information that is provided by an appropriate coding scheme that also provides error correction. For practical codes, there is a cost in code rate for data verification, but Reed-Solomon codes with bounded distance decoding work well in providing both data verification and error correction.

关键词： UNIVERSAL COMMUNICATION RECEIVERS error-control coding DEMODULATION

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Performance bounds for coded free-space optical communications through atmospheric turbulence channels

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IEEE TRANSACTIONS ON COMMUNICATIONS 2003年第8期51卷 1233-1239页

作者： Zhu, XM Kahn, JM Univ Calif Berkeley Dept Elect Engn & Comp Sci Berkeley CA 94720 USA

error-control codes can help to mitigate atmospheric turbulence-induced signal fading in free-space optical communication links using intensity modulation/direct detection (IM/DD). error performance bound analysis can yield simple analytical upper bounds or approximations to the bit-error probability. In this letter, we first derive an upper bound on the pairwise codeword-error probability for transmission through channels with correlated turbulence-induced fading, which involves complicated multidimensional integration. To simplify the computations, we derive an approximate upper bound under the assumption of weak turbulence. The accuracy of this approximation under weak turbulence is verified by numerical simulation. Its invalidity when applied to strong turbulence is also shown. This simple approximate upper bound to the pairwise codeword-error probability is then applied to derive an upper bound to the bit-error probability for block codes, convolutional codes, and turbo codes for free-space optical communication through weak atmospheric turbulence channels. We also discuss the choice of interleaver length in block codes and turbo codes based on numerical evaluation of our performance bounds.

关键词： atmospheric turbulence error-control coding free-space optical communication interleaver length pairwise error probability (PEP) performance-bound analysis

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Performance of multilayered video encoding and delivery over lossy channels using a joint source-channel coding approach

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WIRELESS PERSONAL COMMUNICATIONS 2006年第2期36卷 113-128页

作者： Pei, Y Modestino, JW Wright State Univ Dept Comp Sci & Engn Dayton OH 45435 USA Univ Miami Dept Elect & Comp Engn Coral Gables FL 33124 USA

In this paper, the performance of selected error-control schemes based on forward error-control (FEC) coding for H.263+ video transmission over an additive white Gaussian noise (AWGN) channel is studied. Joint source and channel coding (JSCC) techniques that employ single-layer and 2-layer H.263+ coding in conjunction with unequal error protection (UEP) to combat channel errors are quantitatively compared. Results indicate that with appropriate joint source and channel coding, tailored to the respective layers, FEC-based error control in combination with 2-layer video coding techniques can lead to more acceptable quality for wireless video delivery in the presence of channel impairments.

关键词： video transport video over wireless channels error-control coding unequal error protection scalable video coding joint source-channel coding

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CCK Modulation: Beyond Wi-Fi

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IEEE COMMUNICATIONS LETTERS 2009年第1期13卷 31-33页

作者： Pursley, Michael B. Royster, Thomas C. Clemson Univ Dept Elect & Comp Engn Clemson SC 29634 USA

The full-rate IEEE 802.11b standard for wireless local area networks, also known as Wi-Fi, employs 256-ary complementary code keying (CCK). For applications that do not require adherence to the standard, it may be desirable to use forward error correction coding with CCK, but the bit-to-symbol mappings used in IEEE 802.11b degrade the performance of most standard binary codes. We show that a standard binary convolutional code performs much better with alternative bit mappings, and we demonstrate that chip scrambling gives additional improvement.

关键词： Complementary code key error-control coding IEEE 802.11b Wi-Fi

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Reliability-based hybrid ARQ

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ELECTRONICS LETTERS 2002年第13期38卷 644-645页

作者： Shea, JM Univ Florida Dept Elect & Comp Engn Gainesville FL 32611 USA

A new hybrid automatic repeat request (ARQ) scheme that utilises reliability estimates generated by soft-input, soft-output (SISO) decoders is proposed. The proposed ARQ scheme transmits additional information for the unreliable bits, and this information is used to perform additional decoding. Results are presented that show this ARQ technique can provide performance close to the channel capacity.

关键词： Protocols reliability theory SISO decoders turbo codes ARQ technique error-control coding Codes iterative decoding soft-input soft-output decoders channel capacity reliability estimates hybrid automatic repeat request scheme turbo coding scheme automatic repeat request decoding

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A generalized reverse jacket transform

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IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS II-EXPRESS BRIEFS 2001年第7期48卷 684-690页

作者： Lee, MH Rajan, BS Park, JY Chonbuk Natl Univ Inst Informat & Commun Chonju 560756 South Korea Indian Inst Sci Dept Commun Engn Bangalore 560012 Karnataka India Seonam Univ Dept Elect & Elect Engn Namwon City 590711 Chonbuk South Korea

Generalization of the well-known Walsh-Hadamard transform (WHT), namely center-weighted Hadamard transform (CWHT) and complex reverse-jacket transform (CRJT) have been proposed and their fast implementation and simple index generation algorithms have recently been reported. These transforms are of size 2(r) x 2(r) for integral values or r, and defined in terms of binary radix representation of integers. In this paper, using appropriate mixed-radix representation of integers, we present a generalized transform called general reverse jacket transform (GRJT) that unifies all the three classes of transforms, WHT, CWHT, and CRJT, and also applicable for any even length vectors, that is of size 2r x 2r. A subclass of GRJT which includes CRJT (but not CWHT) is applicable for finite fields and useful for constructing error control codes.

关键词： error-control coding image-coding reverse-jacket transform Walsh-Hadamard transform

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