Group-based multicast and dynamic membership in wireless networks with incomplete spatial coverage

In this paper we examine the problem of group-based multicast communication in the context of mobile computing with wireless communication technology. We propose a protocol in which group members may be mobile computers and such that the group membership may change dynamically. Multicasts are delivered in the same order at all group members (totally-ordered multicast). Mobile computers are resource-poor devices that communicate with a wired network through a number of spatially limited cells defining wireless links. The spatial coverage provided by wireless links may be either complete or incomplete, which makes the overall system model both general and realistic. The proposed protocol is simple and does not require any hand-off in the wired network upon movements of group members. Moreover, there is no part of the protocol requiring that group members do not move during its execution. This feature leads to mobility assumptions that are practical because they involve only the global movement of group members, e.g., assumptions of the form “a group member does not move very fast all the time”.