Homophonic Sequence Substitucion

Authors

  • Valdemar C. da Rocha Jr.
  • Hélio M. de Oliveira

DOI:

https://doi.org/10.14209/jcis.1998.12

Keywords:

source coding, homophonic substitution, Markov sources, Huffman coding

Abstract

Homophonic sequence substitution is the name given in this paper to the technique which consists of substituting
one-to-one a given finite (or semi-infinite) sequence of symbols by another finite (or semi-infinite) sequence over the same alphabet but having a higher entropy rate. The output sequence of a given discrete stationary and ergodic source is encoded with a binary lossless source code C. A concatenation of codewords of C is then conveniently parsed and reencoded with a binary lossless source code. By iterating the latter step a number of times, it is proved that the entropy rate of the binary sequence at the output of the last encoder approaches the value 1 asymptotically, therefore performing optimum homophonic sequence substitution. The remaining redundancy, after k consecutive encodings, is 1- H_k(S) bits per binary digit, where H_k(S) is the entropy rate of the binary sequence resulting after the k-th encoding. A Markov source model is presented to describe the binary encoded sequences and to compute their entropy rate.

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Published

2017-04-07

How to Cite

da Rocha Jr., V. C., & de Oliveira, H. M. (2017). Homophonic Sequence Substitucion. Journal of Communication and Information Systems, 13(1). https://doi.org/10.14209/jcis.1998.12

Issue

Vol. 13 No. 1 (1998)

Section

Regular Papers

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Received 2017-04-07
Accepted 2017-04-07
Published 2017-04-07