Orthogonal layered multicast: Improving the multicast transmission of multimedia streams at multiple data Rates

This paper discusses the aspect of orthogonality in layered multicast schemes, and presents a general framework for the implementation of layered multicast. This framework can be applied to standard IP multicast or to any other multicast technology capable of transmitting a data stream to a group of subscriber nodes. The multirate transmission is accomplished by a multicast group management facility which maps the frames of the multimedia stream into a number of multicast groups according to different data resolutions. The subscriber nodes are then able to directly control the data rate of the stream that they receive by joining different multicast groups, thus eliminating the need of constant data rate negotiation with the sender node.