Optimum multicast of multimedia streams

In a VOD system, multicast is a preferred method for saving network bandwidth. That is, customers requesting the same video program over a small time interval can be arranged in a multicast tree (group), and then the video server sends a video stream via this tree to customers. In this research, we considered how to arrange a set of multicast trees such that the number of customers served is maximized and the link capacity constraint is maintained. For a directed acyclic graph (DAG), we proposed a branch-and-bound algorithm to solve this problem and the solution method is illustrated by example. Next, we extended the algorithm to find an approximate solution for a general graph case. It is shown, through simulations on randomly generated graphs that the solution for our approximation method is very close to the optimal solution.