Video multicast over fair queueing networks
We consider the problem of video multicast over networks that enforce fair bandwidth allocations in the routers. State-of-the-art layered IP multicast systems perform well for moderately sized sessions, but suffer from three basic problems that prevent their massive deployment: (a) lack of fairness among different multicast sessions, (b) lack of fairness to competing TCP flows, and (c) high complexity requirements to scale up to potentially large numbers of users and sessions. In this work we present an entirely different approach to the design of these systems, in which sources obliviously inject packets into the network (disregarding congestion), whereas routers obliviously drop the amount of bandwidth that exceeds the fair share of a flow (disregarding packet contents). We model our system as a broadcast channel, with receivers connected to the source via erasure channels of different capacities, and we design a video coder to operate in this environment. Our results suggest that a combination of fair queueing routers and appropriate coding is indeed able to overcome certain drawbacks of current IP multicast systems. Furthermore, we also find that such systems would benefit significantly from being able to re-encode the video signal at internal nodes of the multicast tree.