Directed broadcast: a MAC level primitive for robust network broadcast

Network wide broadcast (NWB) is a common and important operation in mobile ad hoc networks (MANETs). NWBs are used to propagate routing requests and/or state in routing protocols as well as application data in group communication protocols. NWB rely on MAC level broadcast which is unreliable. In the presence of shadowing or collisions, this leads to loss of coverage, especially in low density networks or for optimized NWB algorithms with limited redundancy. In this work, we propose a new MAC level primitive, directed broadcast, which significantly improves the reliability of link level broadcast. In particular, directed broadcast is especially suited for optimized NWB algorithms that build a virtual backbone because it allows full reliability for the messages as they cross the backbone. We show that using directed broadcast can significantly improve the reliability of NWB operation.