Multipath routing for video unicast over bandwidth-limited networks

Video applications such as video-on-demand systems in general have bandwidth and delay constraints. Such QoS requirements can no longer be guaranteed when video is transmitted with the traditional shortest-path routing over a bandwidth-limited network such as the Internet. In this paper, we propose multipath routing algorithms for video unicast so as to meet a certain bandwidth requirement with minimum start-up delay (and hence low user buffer requirement). We first formulate the problem which in its most general form is difficult to solve. However, for the special case where the network links are of unit capacity, we present an exact solution using k-shortest-disjoint paths algorithm with video rescheduling in the source. For the most general case, we propose an efficient heuristic based on max-flow and shortest path algorithms. The complexity of such algorithm is only O(\V\(3)), where \V\ is the number of nodes in the network. Extensive simulation results show that the multipath approach meets the bandwidth requirement with a delay close to the shortest-path routing.