Improving delivery ratios for application layer multicast in mobile ad-hoc networks

Abstract — Delivering multicast data using so-called overlay networks offers many advantages. Overlay networks only con-sisting of a multicast group’s members that are connected by means of transport links, non-members (especially routers) no longer need to bother about multicast routing and keeping a group’s state information. While existing application layer multicast protocols mainly were designed for the fixed Internet, first attempts to adapt such protocols for mobile ad-hoc networks start emerging. Because these adaptions however still suffer from a relatively high rate of packet losses, this paper outlines generic mechanisms that improve the overall delivery ratio for application layer multicast protocols. Although the proposed mechanisms are illustrated at the example of the NICE-MAN protocol (which is an adaption of the NICE protocol, originating from the Internet), they may be applied to arbitrary overlays. Furthermore, this paper shows how overlay networks combined with the developed mechanisms can be used, to significantly improve delivery ratios for existing multicast protocols (like ODMRP, M-AODV) that reside on the network layer. I