Exploiting the temporal dimension in QoS-aware multicast routing

We investigate the temporal dimension in dynamic QoS-based multicast routing in order to improve significantly the performance of previous spatial protocols. We describe the design of a new protocol named T-TBP, which is extended from a previously proposed protocol, TBP, that uses a ticket-based directed search framework (see Chen S., and Nahrstedt, K., IEEE J. Sel. Areas Commun., vol.17, no.18, 1999). T-TBP exploits the temporal dimension based on a path residuum mechanism to improve performance in tree cost and success ratio of member joins in a highly dynamic environment. It caches previous search information and may make adjustments to an existing multicast tree to improve the quality of the resulting multicast tree. Through extensive simulation, our proposal is demonstrated to achieve superior performance to the original protocol. Most notably, it is able to construct lower-cost trees with only a minor increase in control overhead when network load is light, and to improve the success rate for finding the feasible path when network load is heavy.