Online Network Coding for the Dynamic Multicast Problem

Many of the multimedia applications such as video broadcasting and teleconferencing require the network to support dynamic multicast sessions when the membership of the multicast group changes over time. In this paper, we study this problem in the context of coded networks. While trying to minimize the cost of the multicast, we also want to minimize the disturbances to existing users when the multicast graph changes. To characterize disturbances to users, we define two types of rearrangements, link rearrangements and code rearrangements. We present four algorithms to solve the non-rearrangeable and rearrangeable versions of the dynamic multicast problem. Simulation results show that the alpha-scaled algorithm we proposed can keep the cost of the multicast close to that of the optimal solution when the multicast subgraph evolves, and, at the same time, causes very few rearrangements during the process