Adaptive shared tree multicast in mobile wireless networks

Shared tree multicast is a well established concept used in several multicast protocols for wireline networks (e.g. core base tree, PIM sparse mode etc). In this paper, we extend the shared tree concept to wireless, mobile, multihop networks for applications ranging from ad hoc networking to disaster recovery and battlefield. The main challenge in wireless, mobile networks is the rapidly changing environment. We address this issue in our design by: (a) using "soft state"; (b) assigning different roles to nodes depending on their mobility (two level mobility model); (c) proposing an adaptive scheme which combines shared tree and source tree benefits. A detailed wireless simulation model is used to evaluate the proposed schemes and compare them with source based tree (as opposed to shared tree) multicast. The results show that shared tree protocols have low overhead and are very robust to mobility.