Multi-resolution codes enable multicast at different rates to different
receivers, a setup that is often desirable for graphics or video streaming. We
propose a simple, distributed, two-stage message passing algorithm to generate
network codes for single-source multicast of multi-resolution codes. The goal
of this "pushback algorithm" is to maximize the total rate achieved by all
receivers, while guaranteeing decodability of the base layer at each receiver.
By conducting pushback and code generation stages, this algorithm takes
advantage of inter-layer as well as intra-layer coding. Numerical simulations
show that in terms of total rate achieved, the pushback algorithm outperforms
routing and intra-layer coding schemes, even with codeword sizes as small as 10
bits. In addition, the performance gap widens as the number of receivers and
the number of nodes in the network increases. We also observe that naiive
inter-layer coding schemes may perform worse than intra-layer schemes under
certain network conditions.Comment: 9 pages, 16 figures, submitted to IEEE INFOCOM 201