Towards unifying multi-resolution and multi-description : a distortion-diversity perspective

Abstract

We consider codec structures that exploit diversity in both source coding and channel coding components. We propose to study source-channel schemes using the tradeoff between end-to-end distortion level and the outage probability as our performance metric, namely distortion-diversity tradeoff. In the high SNR regime, within the distortion-diversity tradeoff framework, we are able to differentiate two source-channel schemes, one based on multi-resolution (MR) and the other based on multi-description (MD), that have been previously determined to have the same average distortion exponent. We then propose a triple-level source-channel scheme that unifies the Mr-based and the MD-based schemes. In particular, we demonstrate that the triple-level scheme dominates the MD-based and the MR-based schemes within the distortion-diversity tradeoff framework. We then extend the distortion-diversity tradeoff to the low SNR regime. We compare the distortion performance of the MR-based scheme and MD-based scheme with separate source-channel decoder that achieve constant levels of outage probability. The performance comparison between the two source-channel schemes is mixed, which naturally links the low outage probability and the high outage probability cases. In particular, the MD-based scheme with separate source-channel decoder preserves the interface between source coding component and channel coding component. The fact that MD-based scheme could outperform MR-based scheme while preserving the source-channel interface suggests that bit rates may not be a complete characterization of the source-channel interface.