There are many multicast routing protocols that use the notion of group-shared trees, for example: Protocol Independent Multicast (PIM), Core-Based Tree. As constructing of a minimal-cost spanning tree to all members of the network is nearly impossible due to its excessive cost in terms of convergence time and network overhead, the core-based approach is chosen as a heuristic method to cope with multicast routing. The core node, which is also referred as center node or rendezvous point, is chosen from a selective group by different algorithm. However, most of protocols for core election in static networks are not suitable for mobile ad hoc network, since these algorithms require the knowledge of the whole network, the total number of nodes participating, the network topology, link state,.. Which are not available or too expensive to acquire in mobile ad hoc networks. There are many proposed protocol for multicast routing in mobile ad hoc networks, such as PUMA, ODMRP or MAODV. In those protocols, PUMA (Protocol for unified multicasting through announcements) has shown to outperform others. PUMA uses a single multicast announcement to establish and maintain the mesh. However, there is still a serious drawback, PUMA elects core by selecting the node with the highest ID and the core remains fixed afterwards. In this thesis, we present an improvement of PUMA by integrating an adaptive core selection mechanism into it. The result show that the new PUMA achieves higher packet delivery ratios, lower delivery times than the old one, while incurring only a little control overhead increment.
