David G. M. Mitchell

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In this paper, we construct protograph-based spatially coupled low-density parity-check (LDPC) codes by coupling together a series of L disjoint, or uncoupled, LDPC code Tanner graphs into a single coupled chain. By varying L , we obtain a flexible family of code ensembles with varying rates and frame lengths that can share the same encoding and decoding(More)
Mycotoxigenic fungi colonizing food matrices are inevitably competing with a wide range of other resident fungi. The outcomes of these interactions are influenced by the prevailing environmental conditions and the competing species. We have evaluated the competitiveness of F. culmorum and A. carbonarius in the grain and grape food chain for their in vitro(More)
LDPC convolutional codes have been shown to be capable of achieving the same capacity-approaching performance as LDPC block codes with iterative message-passing decoding. In this paper, asymptotic methods are used to calculate a lower bound on the free distance for several ensembles of asymptotically good protograph-based LDPC convolutional codes. Further,(More)
Growth performance, muscle cellularity and flesh quality were investigated in Atlantic salmon (Salmo salar L.) fed either of two diet ranges [high protein (HP), or low protein (LP)], which differed in digestible protein/digestible energy ratios but were of equivalent digestible energy content (21.4 MJ kg À 1 wet weight). Smolts from an early maturing(More)
In this paper, we perform an iterative decoding threshold analysis of LDPC block code ensembles formed by terminating (J,K)-regular and irregular AR4JA-based LDPC convolutional codes. These ensembles have minimum distance growing linearly with block length and their thresholds approach the Shannon limit as the termination factor tends to infinity. Results(More)
Families of asymptotically regular LDPC block code ensembles can be formed by terminating (J, K)-regular protograph-based LDPC convolutional codes. By varying the termination length, we obtain a large selection of LDPC block code ensembles with varying code rates and substantially better iterative decoding thresholds than those of (J, K)-regular LDPC block(More)
Low-density parity-check (LDPC) convolutional codes have been shown to be capable of achieving capacity-approaching performance with iterative message-passing decoding. In the first part of this paper, using asymptotic methods to obtain lower bounds on the free distance to constraint length ratio, we show that several ensembles of regular and irregular LDPC(More)
— In this paper asymptotic methods are used to form lower bounds on the free distance to constraint length ratio of several ensembles of regular, asymptotically good, protograph-based LDPC convolutional codes. In particular, we show that the free distance to constraint length ratio of the regular LDPC convolutional codes exceeds that of the minimum distance(More)
A novel code construction based on spatially coupled low-density parity-check (SC-LDPC) code chains is presented. The proposed code ensembles are described by graphs in which individual SC-LDPC code chains of various lengths serve as edges. We demonstrate that connecting several appropriately chosen SC-LDPC code chains results in improved iterative decoding(More)
Absorbing sets are combinatorially defined objects existing in the Tanner graph of a low-density parity-check (LDPC) code that have been shown to cause failures in the iterative message-passing decoder when transmission occurs over the additive white Gaussian noise channel. In this paper, we study the absorbing set properties of a class of high-rate(More)