Intra-layer network coding for lossy communication of progressive codes

In this paper we discuss layered multicast (LM) of progressive source codes using network coding. LM is absolutely optimal if different sinks in the network are satisfied up to their max-flow. Since absolutely optimal intra-layer network strategies might not exist for general networks, we present conditions under which an absolutely optimal, intra-layer multicast strategy exists for a given network and how that strategy may be efficiently constructed. We also discuss the problem of designing optimal intra-layer multicast strategies for general directed networks.