Cumulant Generating Function of Codeword Lengths in Variable-Length Lossy Compression Allowing Positive Excess Distortion Probability

TL;DR

This paper establishes a fundamental limit for the cumulant generating function of codeword lengths in variable-length lossy compression, allowing for positive excess distortion probability, using Rènyi entropy-based bounds.

Contribution

It derives a non-asymptotic fundamental limit for the cumulant generating function in lossy coding and provides explicit code construction methods.

Findings

Achievability and converse bounds characterized by Rènyi entropy

Explicit code construction demonstrated in proof

Asymptotic single-letter characterization for stationary sources

Abstract

This paper considers the problem of variable-length lossy source coding. The performance criteria are the excess distortion probability and the cumulant generating function of codeword lengths. We derive a non-asymptotic fundamental limit of the cumulant generating function of codeword lengths allowing positive excess distortion probability. It is shown that the achievability and converse bounds are characterized by the R\'enyi entropy-based quantity. In the proof of the achievability result, the explicit code construction is provided. Further, we investigate an asymptotic single-letter characterization of the fundamental limit for a stationary memoryless source.