On optimal multiresolution source-channel coding across degraded broadcast channels

Inspired by a converse result, the concept of "probabilistically matched" sources and channels is extended to sources subject to multiresolution coding and degraded broadcast channels. Unlike in the point-to-point communication scenarios, however, due to the lack of a separation principle or a complete characterization for achievable cost-distortion triplets, matching of the source and the channel constitutes only a sufficient condition for optimality.