An effective gateway discovery mechanism in an integrated Internet-MANET (IIM)

Ad hoc networking allows portable devices to establish communication independent of a central infrastructure. The Integration of the MANETs and infrastructure networks such as Internet extends the network coverage and increases the application domain of the MANET. Communication between a mobile device in an ad hoc network and a fixed device on the Internet is achieved using gateways, which acts as a bridge between them. The ad hoc routing protocol AODV is extended and used to achieve interconnection between a MANET and the Internet. In the existing approaches of gateway discovery either interface queue length or the minimum hop metric criteria or a combination is used for selecting the gateway by the mobile nodes. In the proposed approach, an efficient proactive gateway discovery algorithm is devised that takes into account the length of the routing queue in addition to the minimum hop count metric for selecting an efficient gateway and also selecting the routes to other mobile nodes. This is a novel strategy of gateway discovery. This approach is implemented by calculating the load along a path and updating the routing entry as the route requests are processed from one mobile node to the other. This allows usage of updated routes without waiting for the gateway advertisements for updating the routing entries. It also reduces the delay along the path for the packets traversing within the ad hoc network. The use of this concept increases the throughput by choosing the less congested paths and reduces the routing overhead. In this paper the impact of this new approach is investigated. Simulation results indicate that our protocol outperforms other approaches.