Multicast routing of hierarchical data

Multicast of real-time data in a heterogeneous network environment, in which links and recipients differ in their bandwidth, is considered. Traditional schemes are designed to deliver the source´s complete data to all recipients, thereby restricting the source´s handling of heterogeneity to either overcompressing to the bandwidth accessible by the least capable user, or excluding those destinations which cannot receive the full signal. The author presents an alternative approach, in which the source encodes its signal hierarchically, and the network delivers subsets of the signal layers in accordance with individual destinations´ bandwidth constraints. This approach allows each user to trade off reception bandwidth for signal quality independently of other users´ selections. In support of such a service, efficient routes that carry the desired bandwidth to all destinations must be computed. Routing algorithms that compute such paths are presented, and their merits are compared