Periodicity Based Gateway DiscoveryAlgorithm in Hybrid Multihop Network

Abstract

Mobile ad hoc networks (MANETs) are autonomous and stand-alone and infrastructure less networks applicable in areas such as disastrous locations or remote geographical areas, where deploying an infrastructure network is neither feasible nor cost effective. In such network, every node is free to move and change its location. The movement of nodes makes the task of routing more complicated and error prone than fixed infrastructure networks. So, in such dynamic environment, a different routing protocol is required. Further, MANET has very limited services and applications running on them, thereby it creates a need to integrate MANET with the Internet. In order to connect with the Internet, mobile nodes need to discover and select an appropriate gateway. A gateway deals with heterogeneous protocols and also provides mapping among them, so it can work with both MANET routing protocol as well as different Internet protocols. Internet gateway sends connectivity parameter in a message to all the nodes in its range periodically and this time period plays a vital role in the performance of the network. There are many approaches to optimize periodicity, but they mostly use statistical method for this purpose. The major drawback of these approaches is using a threshold value to determine the periodicity of advertisement message which provides a limited performance improvement. Therefore, the objective of this paper is to optimize the frequency of MRA (Modified Router Advertisement) message sent by gateway so that it prevents the saturation of MANET with MRA messages as well as preventing obsolete links to a gateway. For this purpose, we use a fuzzy logic based optimization scheme which uses Advertisement Solicitation Ratio (ASR), Active Source Change (ASC) and TTL Change as parameters. Our simulation results demonstrate that our approach outperforms many existing approaches.