Rate-Distortion Function for a Heegard-Berger Problem with Two Sources and Degraded Reconstruction sets

TL;DR

This paper derives the rate-distortion function for a Heegard-Berger problem with two sources and degraded reconstruction sets, considering lossless and lossy reconstructions with correlated side information.

Contribution

It provides a single-letter characterization of the rate-distortion function for a complex multi-source, multi-decoder setting with degraded reconstruction constraints.

Findings

Single-letter rate-distortion characterization established

Highlights benefits of joint source compression

Generalizes to shared reconstruction constraints

Abstract

In this work, we investigate an instance of the Heegard-Berger problem with two sources and arbitrarily correlated side information sequences at two decoders, in which the reconstruction sets at the decoders are degraded. Specifically, two sources are to be encoded in a manner that one of the two is reproduced losslessly by both decoders, and the other is reproduced to within some prescribed distortion level at one of the two decoders. We establish a single-letter characterization of the rate-distortion function for this model. The investigation of this result in some special cases also sheds light on the utility of joint compression of the two sources. Furthermore, we also generalize our result to the setting in which the source component that is to be recovered by both users is reconstructed in a lossy fashion, under the requirement that all terminals (i.e., the encoder and both decoders) can share an exact copy of the compressed version of this source component, i.e., a common encoder-decoders reconstruction constraint. For this model as well, we establish a single-letter characterization of the associated rate-distortion function.