The Experts below are selected from a list of 228 Experts worldwide ranked by ideXlab platform

Daniel J. Costello - One of the best experts on this subject based on the ideXlab platform.

  • a low cost serial decoder architecture for low density parity check convolutional codes
    IEEE Transactions on Circuits and Systems I-regular Papers, 2008
    Co-Authors: S Bates, Zhengang Chen, L Gunthorpe, Ali Emre Pusane, Sh K Zigangirov, Daniel J. Costello
    Abstract:

    We propose a low-cost serial decoder architecture for low-density parity-check convolutional codes (LDPC-CCs). It has been shown that LDPC-CCs can achieve comparable performance to LDPC block codes with Constraint Length much less than the block Length. The proposed serial decoder architecture for LDPC-CCs uses a single decoding processor. Terminated data frames are sent through the processor iteratively until correctly decoded or a maximum number of iterations is reached. This architecture saves memory consumption and uses a very small number of logic elements, making it especially suitable for strong LDPC-CCs with large code memory. The proposed architecture is realized for a (2048,3,6) regular LDPC-CC on an Altera Stratix FPGA. With a maximum of 100 iterations, the design achieves up to 9-Mb/s throughput using only a very small portion of the field-programmable gate array resources.

  • Probabilistic construction of large Constraint Length trellis codes for sequential decoding
    IEEE Transactions on Communications, 1995
    Co-Authors: Fu-quan Wang, Daniel J. Costello
    Abstract:

    Probabilistic algorithms are given for constructing good large Constraint Length trellis codes for use with sequential decoding that can achieve the channel cutoff rate bound at a bit error rate (BER) of 10/sup -5/-10/sup -6/. The algorithms are motivated by the random coding principle that an arbitrary selection of code symbols will produce a good code with high probability. One algorithm begins by choosing a relatively small set of codes randomly. The error performance of each of these codes is evaluated using sequential decoding and the code with the best performance among the chosen set is retained. Another algorithm treats the code construction as a combinatorial optimization problem and uses simulated annealing to direct the code search. Trellis codes for 8 PSK and 16 QAM constellations with Constraint Lengths v up to 20 are obtained. Simulation results with sequential decoding show that these codes reach the channel cutoff rate bound at a BER of 10/sup -5/-10/sup -6/ and achieve 5.0-6.35 dB real coding gains over uncoded systems with the same spectral efficiency and up to 2.0 dB real coding gains over 64 state trellis codes using Viterbi decoding. >

J H Harris - One of the best experts on this subject based on the ideXlab platform.

  • a Constraint Length based modified viterbi algorithm with adaptive effort
    IEEE Transactions on Communications, 1999
    Co-Authors: C Feldmann, J H Harris
    Abstract:

    A modified Viterbi (1971) algorithm for convolutional codes is described that provides for signal-to-noise ratio (SNR) adaptive computational effort. The algorithm has three levels of prioritized effort. Movement from one level to the next is controlled by parameters that can be selected according to desired output bit error rate performance. For 3-bit soft decision detected signals, a coding gain within 0.06 dB of Viterbi at a 3-dB SNR is achieved for the same Constraint-Length code with modest parameter values and computational effort. At values of SNR above 6 dB, the algorithm decodes with very low computational effort. Effort levels are controlled by spanning the decoding trellis in steps that are one Constraint-Length long.

  • Single-chip design of bit-error-correcting stack decoders
    IEEE Journal of Solid-state Circuits, 1992
    Co-Authors: T.m. Gould, J H Harris
    Abstract:

    The design of a single-chip VLSI system to implement the Zigangirov-Jelinek sequential decoding algorithm for bit-error-correction is described and the dependence of performance on design parameters is discussed. By virtue of being self-contained, having few input and output pins, and processing stack elements once each clock cycle, the system should be capable of high-speed decoding. For Constraint Length 21, rate 1/2 codes, and 3-b soft decision detection, it is found that a system containing approximately 25000 stack cells reduces errors in a 3-dB signal-to-noise level environment, corresponding to 7.8% hard decision error rate, by two orders of magnitude. Higher decoding gain is obtained at lower noise levels through the use of a relatively long Constraint Length. The Constraint Length is not limited by the architecture. Chip area estimates needed to obtain prescribed decoded error rates and average decoding rates are also described and indicate that an effective system is potentially achievable with current technology. >

Brian L. F. Daku - One of the best experts on this subject based on the ideXlab platform.

  • A modular bit-serial architecture for large-Constraint-Length Viterbi decoding
    IEEE Journal of Solid-State Circuits, 1992
    Co-Authors: M.a. Bree, David E. Dodds, R.j. Bolton, S. Kumar, Brian L. F. Daku
    Abstract:

    A node-parallel Viterbi decoding architecture and bit-serial processing and communication are presented. An important aspect of this structure is that short-Constraint-Length decoders may be interconnected, without loss of throughput, to implement a Viterbi decoder of larger Constraint Length. The convolutional encoder trellis is modeled by appropriate wiring of decoder processing nodes: a variety of generating codes can be accommodated. Bit-serial communication links between nodes require only a single wire each and thus interconnection area is relatively small. During each decoding cycle, more than 50 b need to be communicated on each serial link and thus the technique is limited to moderate bit rate applications. A Constraint Length K=4 'proof of concept' chip was developed using 9860 transistors in 3 mu m CMOS on a 4.51-mm*4.51-mm die size. The complete circuit operates at 280 kb/s and supports any rate 1/2 or 1/3 code with eight-level soft decision. >

Marco Baldi - One of the best experts on this subject based on the ideXlab platform.

  • design and analysis of time invariant sc ldpc codes with small Constraint Length
    arXiv: Information Theory, 2017
    Co-Authors: Massimo Battaglioni, Giovanni Cancellieri, Alireza Tasdighi, Franco Chiaraluce, Marco Baldi
    Abstract:

    In this paper, we deal with time-invariant low-density parity-check convolutional (LDPCC) codes, which are a subclass of spatially coupled low-density parity-check (SC-LDPC) codes. Classic design approaches usually start from quasi-cyclic (QC) low-density parity-check (LDPC) block codes and exploit suitable unwrapping procedures to obtain LDPCC codes. We show that the direct design of the LDPCC code syndrome former matrix or, equivalently, the symbolic parity-check matrix, leads to codes with smaller syndrome former Constraint Lengths with respect to the best solutions available in the literature. We provide theoretical lower bounds on the syndrome former Constraint Length for the most relevant families of LDPCC codes, under Constraints on the minimum Length of local cycles in their Tanner graphs. We also propose new code design techniques that approach or achieve such theoretical limits.

  • Time-invariant spatially coupled low-density parity-check codes with small Constraint Length
    2016 IEEE International Black Sea Conference on Communications and Networking (BlackSeaCom), 2016
    Co-Authors: Marco Baldi, Massimo Battaglioni, Franco Chiaraluce, Giovanni Cancellieri
    Abstract:

    We consider a special family of spatially coupled low-density parity-check (SC-LDPC) codes, that is, time-invariant low-density parity-check convolutional (LDPCC) codes, which are known in the literature for a long time. Codes of this kind are usually designed by starting from quasi-cyclic (QC) block codes, and applying suitable unwrapping procedures. We show that, by directly designing the LDPCC code syndrome former matrix without the Constraints of the underlying QC block code, it is possible to achieve smaller Constraint Lengths with respect to the best solutions available in the literature. We also find theoretical lower bounds on the syndrome former Constraint Length for codes with a specified minimum Length of the local cycles in their Tanner graphs. For this purpose, we exploit a new approach based on a numerical representation of the syndrome former matrix, which generalizes over a technique we already used to study a special subclass of the codes here considered.

  • time invariant spatially coupled low density parity check codes with small Constraint Length
    arXiv: Information Theory, 2016
    Co-Authors: Marco Baldi, Massimo Battaglioni, Franco Chiaraluce, Giovanni Cancellieri
    Abstract:

    We consider a special family of SC-LDPC codes, that is, time-invariant LDPCC codes, which are known in the literature for a long time. Codes of this kind are usually designed by starting from QC block codes, and applying suitable unwrapping procedures. We show that, by directly designing the LDPCC code syndrome former matrix without the Constraints of the underlying QC block code, it is possible to achieve smaller Constraint Lengths with respect to the best solutions available in the literature. We also find theoretical lower bounds on the syndrome former Constraint Length for codes with a specified minimum Length of the local cycles in their Tanner graphs. For this purpose, we exploit a new approach based on a numerical representation of the syndrome former matrix, which generalizes over a technique we already used to study a special subclass of the codes here considered.

  • Low-rate LDPC convolutional codes with short Constraint Length
    2015 23rd International Conference on Software Telecommunications and Computer Networks (SoftCOM), 2015
    Co-Authors: Marco Baldi, Giovanni Cancellieri
    Abstract:

    We study a family of LDPC convolutional codes having code rate of the type 1/a, and analyze their minimum distance and local cycles Length properties. We consider some low weight codewords that are known from the literature, and are easily obtained from the symbolic parity-check matrix of these codes. Starting from the structure of such codewords, we follow a twofold approach: i) we exploit graph-based techniques to design these codes with the aim to maximize their minimum distance while keeping the syndrome former Constraint Length as small as possible and ii) we provide a simple form for their generator matrices that allows to perform exhaustive searches through which we verify that the code design actually reaches its target. We also estimate the normalized minimum distance multiplicity for the codes we consider, and introduce the notion of symbolic graphs as a new tool to study the code properties.

Giovanni Cancellieri - One of the best experts on this subject based on the ideXlab platform.

  • design and analysis of time invariant sc ldpc codes with small Constraint Length
    arXiv: Information Theory, 2017
    Co-Authors: Massimo Battaglioni, Giovanni Cancellieri, Alireza Tasdighi, Franco Chiaraluce, Marco Baldi
    Abstract:

    In this paper, we deal with time-invariant low-density parity-check convolutional (LDPCC) codes, which are a subclass of spatially coupled low-density parity-check (SC-LDPC) codes. Classic design approaches usually start from quasi-cyclic (QC) low-density parity-check (LDPC) block codes and exploit suitable unwrapping procedures to obtain LDPCC codes. We show that the direct design of the LDPCC code syndrome former matrix or, equivalently, the symbolic parity-check matrix, leads to codes with smaller syndrome former Constraint Lengths with respect to the best solutions available in the literature. We provide theoretical lower bounds on the syndrome former Constraint Length for the most relevant families of LDPCC codes, under Constraints on the minimum Length of local cycles in their Tanner graphs. We also propose new code design techniques that approach or achieve such theoretical limits.

  • Time-invariant spatially coupled low-density parity-check codes with small Constraint Length
    2016 IEEE International Black Sea Conference on Communications and Networking (BlackSeaCom), 2016
    Co-Authors: Marco Baldi, Massimo Battaglioni, Franco Chiaraluce, Giovanni Cancellieri
    Abstract:

    We consider a special family of spatially coupled low-density parity-check (SC-LDPC) codes, that is, time-invariant low-density parity-check convolutional (LDPCC) codes, which are known in the literature for a long time. Codes of this kind are usually designed by starting from quasi-cyclic (QC) block codes, and applying suitable unwrapping procedures. We show that, by directly designing the LDPCC code syndrome former matrix without the Constraints of the underlying QC block code, it is possible to achieve smaller Constraint Lengths with respect to the best solutions available in the literature. We also find theoretical lower bounds on the syndrome former Constraint Length for codes with a specified minimum Length of the local cycles in their Tanner graphs. For this purpose, we exploit a new approach based on a numerical representation of the syndrome former matrix, which generalizes over a technique we already used to study a special subclass of the codes here considered.

  • time invariant spatially coupled low density parity check codes with small Constraint Length
    arXiv: Information Theory, 2016
    Co-Authors: Marco Baldi, Massimo Battaglioni, Franco Chiaraluce, Giovanni Cancellieri
    Abstract:

    We consider a special family of SC-LDPC codes, that is, time-invariant LDPCC codes, which are known in the literature for a long time. Codes of this kind are usually designed by starting from QC block codes, and applying suitable unwrapping procedures. We show that, by directly designing the LDPCC code syndrome former matrix without the Constraints of the underlying QC block code, it is possible to achieve smaller Constraint Lengths with respect to the best solutions available in the literature. We also find theoretical lower bounds on the syndrome former Constraint Length for codes with a specified minimum Length of the local cycles in their Tanner graphs. For this purpose, we exploit a new approach based on a numerical representation of the syndrome former matrix, which generalizes over a technique we already used to study a special subclass of the codes here considered.

  • Low-rate LDPC convolutional codes with short Constraint Length
    2015 23rd International Conference on Software Telecommunications and Computer Networks (SoftCOM), 2015
    Co-Authors: Marco Baldi, Giovanni Cancellieri
    Abstract:

    We study a family of LDPC convolutional codes having code rate of the type 1/a, and analyze their minimum distance and local cycles Length properties. We consider some low weight codewords that are known from the literature, and are easily obtained from the symbolic parity-check matrix of these codes. Starting from the structure of such codewords, we follow a twofold approach: i) we exploit graph-based techniques to design these codes with the aim to maximize their minimum distance while keeping the syndrome former Constraint Length as small as possible and ii) we provide a simple form for their generator matrices that allows to perform exhaustive searches through which we verify that the code design actually reaches its target. We also estimate the normalized minimum distance multiplicity for the codes we consider, and introduce the notion of symbolic graphs as a new tool to study the code properties.