On-demand gateway broadcast scheme for connecting mobile ad hoc networks to the Internet

Gateway discovery algorithm is a fundamental protocol for interconnecting mobile ad hoc network (MANET) with the Internet. In most existing schemes, each gateway node broadcasts gateway advertisements to announce its presence. The decision of when to emit advertisements can influence the performance of the network. Traditional gateway discovery schemes adopt the method of periodically emitting advertisements with a time interval. However, this method does not fulfill the actual needs of the source nodes. This paper proposes a novel adaptive scheme for gateway discovery, in which the gateway broadcasts advertisements only on-demand instead of periodic emission. In order to obtain the network´s actual demands for gateway advertisement, routes to the gateway are monitored. In particular, if any route is predicted to be broken, the source node requires fresh gateway advertisements to update routes, and then the gateway will be triggered to broadcast to fulfill such demands. We study the performance of on-demand gateway discovery scheme by a comparison approach. The results show that the proposed adaptive gateway discovery scheme greatly outperforms the conventional solutions: it is capable of achieving higher packet delivery ratio and lower end-to-end delay, while minimizing the routing overhead.