Rate-Distortion Optimized Network Communication

Network information multicast has been considered extensively, either as a routing problem or more recently in the context of network coding. Most of the Internet bandwidth, however, is consumed by multimedia contents that are amenable to lossy reconstruction. In this paper, we investigate the following fundamental question: How does one communicate a media content from nodes (servers) that observe/supply the content to a set of sink nodes (clients) to realize the best possible reconstruction of the content in a rate-distortion sense? While this problem remains essentially open, this paper takes the first step by exploring the intricate entanglement of source coding and network communication, within an optimization framework. In particular, we investigate the joint optimization of network communication strategies (e.g., routing or network coding) and common source coding schemes (e.g., progressive coding or more general multiple description coding). We formulate several such problems for which we are able to develop efficient polynomial time solutions. In particular, we consider layered multicast of progressively encoded source code streams using network coding and optimal routing of balanced multiple description codes. Finally, the improvement in the overall quality of source reconstruction by using the proposed schemes is verified through simulations.