Distributing Layered Content using Network Coding

Motivated by the application of streaming multimedia to heterogeneous clients, in this paper we examine the problem of distributing layered content in a network. The source content is represented by multiple description layers that provide incremental refinement; a layer is useful only when all previous layers have been received. For such layered content, a distribution method based on linear network coding is presented. This method represents a simplification of the "pollution treatment" approach proposed for the general multi-session network coding problem. In this method, each link is partitioned into a number of pipes. The first pipe is used for transmitting packets that are functions of the base layer only; the second pipe is used for transmitting packets that are functions of the base layer and the first refinement layer, and so on. The capacities of the pipes are treated as optimization variables. We present a sufficient condition (in the form of flow conditions) that characterizes whether a certain traffic demand can be fulfilled in a network.