Approximating the gaussian multiple description rate region under symmetric distortion constraints

Chao Tian, Soheil Mohajer, Suhas N. Diggavi

Research output: Contribution to journalArticlepeer-review

31 Scopus citations

Abstract

We consider multiple description (MD) coding for the Gaussian source with Κ descriptions under the symmetric mean-squared error (MSE) distortion constraints, and provide an approximate characterization of the rate region. We show that the rate region can be sandwiched between two polytopes, between which the gap can be upper-bounded by constants dependent on the number of descriptions, but independent of the distortion constraints. Underlying this result is an exact characterization of the lossless multilevel diversity source coding problem: a lossless counterpart of the MD problem. This connection provides a polytopic template for the inner and outer bounds to the rate region. In order to establish the outer bound, we generalize Ozarow's technique to introduce a strategic expansion of the original probability space by more than one random variable. For the symmetric rate case with any number of descriptions, we show that the gap between the upper bound and the lower bound for the individual description rate-distortion function is no larger than 0.92 bit. The results developed in this work also suggest that the "separation" approach of combining successive refinement quantization and lossless multilevel diversity coding is a competitive one, since its performance is only a constant away from the optimum. The results are further extended to general sources under the MSE distortion measure, where a similar but looser bound on the gap holds.

Original languageEnglish (US)
Pages (from-to)3869-3891
Number of pages23
JournalIEEE Transactions on Information Theory
Volume55
Issue number8
DOIs
StatePublished - Aug 12 2009

Keywords

  • Multiple descriptions
  • Rate distortion
  • Symmetry

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