Entropy Density and Mismatch in High-Rate Scalar Quantization With Rényi Entropy Constraint

Abstract

Properties of scalar quantization with rth power distortion and constrained Rényi entropy of order α ∈ (0, 1) are investigated. For an asymptotically (high-rate) optimal sequence of quantizers, the contribution to the Rényi entropy due to source values in a fixed interval is identified in terms of the "entropy density" of the quantizer sequence. This extends results related to the well-known point density concept in optimal fixed-rate quantization. A dual of the entropy density result quantifies the distortion contribution of a given interval to the overall distortion. The distortion loss resulting from a mismatch of source densities in the design of an asymptotically optimal sequence of quantizers is also determined. This extends Bucklew's fixed-rate (α = 0) and Gray et al.'s variable-rate (α = 1) mismatch results to general values of the entropy order parameter α.