In this report, we identify various security threats and performance issues in group communications. We propose a solution for efficient key management and distribution for mobile environment using key graph technique. We also propose a solution for providing fault tolerant authentication using hierarchical tree structures. In such a network, mobile nodes are hierarchically organized into groups.
Different groups can have different wireless architectures and different routing protocols.
Mobile nodes communicate with nodes outside their groups through the group leaders. This architecture is flexible and scalable. The groups are highly autonomous. We conduct experiments to compare the new architecture with Ad Hoc networks. The results indicate that the new architecture has a better performance in terms of link change rate.