Markov model aided decoding for image transmission using soft-decision-feedback

TitleMarkov model aided decoding for image transmission using soft-decision-feedback
Publication TypeJournal Article
Year of Publication2000
AuthorsLink, R., and S. Kallel
JournalImage Processing, IEEE Transactions on
Pagination190 -196
Date Publishedfeb.
Keywords3 bit, 3-bit DPCM picture transmission, Bahl algorithm, binary symmetric channel, channel bit error rate, combined source-channel coding, complexity, computational complexity, computational requirement, differential pulse code modulation, image coding, image transmission, joint source/channel decoding, JSCD, Markov model aided decoding, Markov processes, maximum likelihood decoding, modulation coding, one-dimensional data, redundancy, residual redundancy, row-by-row decoding, sheet decoding, soft-decision-feedback MAP decoders, source redundancy, trellis codes, trellis decoding, two-dimensional data, two-dimensional sources, vertical depth, visual communication

Soft-decision-feedback MAP decoders are developed for joint source/channel decoding (JSCD) which uses the residual redundancy in two-dimensional sources. The source redundancy is described by a second order Markov model which is made available to the receiver for row-by-row decoding, wherein the output for one row is used to aid the decoding of the next row. Performance can be improved by generalizing so as to increase the vertical depth of the decoder. This is called sheet decoding, and entails generalizing trellis decoding of one-dimensional data to trellis decoding of two-dimensional data (2-D). The proposed soft-decision-feedback sheet decoder is based on the Bahl algorithm, and it is compared to a hard-decision-feedback sheet decoder which is based on the Viterbi algorithm. The method is applied to 3-bit DPCM picture transmission over a binary symmetric channel, and it is found that the soft-decision-feedback decoder with vertical depth V performs approximately as well as the hard-decision-feedback decoder with vertical depth V+1. Because the computational requirement of the decoders depends exponentially on the vertical depth, the soft-decision-feedbark decoder offers significant reduction in complexity. For standard monochrome Lena, at a channel bit error rate of 0.05, the V=1 and V=2 soft-decision-feedback decoder JSCD gains in RSNR are 5.0 and 6.3 dB, respectively


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