Avoiding network-wide broadcasting with controlled flooding for on-demand ad hoc routing protocols

Ad hoc routing protocols that use broadcast for route discovery may be inefficient if the path between any pair sourcedestination is frequently broken. In order to efficiently use network resources, this paper proposes to use a controlled flooding (CF) mechanism to replace network-wide broadcast in route discovery procedures. CF is used to build alternative routes around the shortest-path between the source and the destination. With alternative routes, data packets are forwarded to a secondary path without requiring the source to re-broadcast the network. Furthermore, these alternative routes serve as guidelines indicating an approximative direction for future controlled floodings. CF is not orthogonal to the route discovery algorithm, but only complementary. Indeed, CF requires a pre-existing path to operate. The key idea is that the source only performs a new broadcast if all paths (shortest path and alternative paths) are lost. CF can be used for many purposes. We detail in this paper one of the applications of controlled flooding: connectivity maintenance. We show that our proposal reduces the connection disruption probability as well as the need for network-wide broadcasts.