Enhance Internet Access Ability for Ad Hoc Network with On-Demand Gateway Broadcast Strategy

摘要

Gateway discovery is a fundamental process in interconnecting mobile ad hoc network with the Internet. Traditional gateway discovery algorithms adopt the method of periodically broadcast advertisements with a time interval. However, this method does not fulfill the actual requirements from the source nodes and produces some unnecessary overhead. To solve this problem, this paper adopts a novel adaptive scheme, in which every gateway broadcasts advertisements only on demand instead of simultaneous periodic emissions of all gateway nodes. To support the on-demand gateway broadcast strategy, the network's actual demands for advertisements are obtained by monitoring the status of routes to the gateway. In particular, if a route is going to break, the corresponding gateway will be triggered to broadcast in order to help the source nodes update routes. Furthermore, we propose another strategy of deferring each gateway broadcast operation, comprising a route stability evaluation model. Stable routes can defer route breakage and consequently further reduce the frequency of gateway broadcast. This paper also designs a new gateway selection method to cope with the problems caused by asynchronous on-demand broadcast strategy. The performance of the proposed scheme is studied by a comparison approach. The results show that the proposed scheme significantly outperforms the conventional solutions: it is capable of achieving higher packet delivery ratio and lower end-to-end delay, while minimizing the routing overhead.