Improving the Performance of MANET Gateway Selection Scheme for Disaster Recovery Nor Aida Mahiddin School of Engineering, Computer and Mathematical Sciences, Auckland University of Technology Auckland, New Zealand nmahiddi@aut.ac.nz Nurul I Sarkar School of Engineering, Computer and Mathematical Sciences, Auckland University of Technology Auckland, New Zealand nurul.sarkar@aut.ac.nz Abstract—In this paper, we propose an improved MANET gateway selection scheme suitable for disaster recovery applications. Having an infrastructure less and decentralize features, MANET is well suited to bring the network back that has been collapse after a disaster. We focus on improving throughput performance of MANET by designing a better gateway selection scheme. The key idea is to eliminate the congestion at each MANET gateway for improved performance. Simulation results show that the proposed gateway selection scheme can efficiently manage the traffic distribution at each gateway to maximize the network performance. Keywords—MANET; Gateway Selection Scheme; Disaster Recovery Area; Throughput. I. INTRODUCTION A MANET is a group of mobile nodes (MNs) which the communications are performed through multi-hop routing using the multi-hop wireless link. By forwarding packets to the neighbors, each node plays an important role not only as a user but also as a relay. The advantage of MANET is network can be performing without any support from existing infrastructure. It can rapidly form and deform a network without decentralized management. Therefore, MANET is suitable to be one of the solutions for communication after a disaster occurs. In post-disaster areas, collapse building, communication infrastructures damaged and become unworkable, are a common result. We know that natural disasters (e.g., earthquake, tsunami, typhoon and etc.) occur frequently over the years in the worldwide, which cause the destruction of a large number communication equipment's (e.g., base station, wireless router). It is extremely expensive and time-consuming to replace or repair if major installations such as cell towers or fiber optic cables are involved. Thus, to keep communication alive in a disaster recovery area, MANET features and advantages are very feasible for disaster recovery area. However, victims seek to contact family and friends cause to a high level of data traffic which leads to network congestion. To allow communication between MANET nodes and the outside network, it requires a gateway as a door to let entry and exit packets from the network. This gateway is the Internet Gateway (IG) which will route all packets to and from the Internet. A gateway is also a node in MANET networks. The main task of a gateway is to control network traffic between two or more different networks. In one network it can have more than one gateway. As shown in Fig. 1. each gateway has an average queue size to monitor. On the other hand, congestion may occur when the number of packets being transmitted to the gateway exceeded pre-set threshold queue size. Therefore, how MNs choose a gateway has been a key issue in recent years as it affects the network throughput performance. Fig. 1. Gateway selection scheme plays an important role to achieve better network performance. In traditional wireless network algorithm, MNs will choose the nearest gateway to send data packet regardless of the heavy traffic load[1]. The bottleneck queuing at gateway leads to congestion and packet loss [2]. Imbalance traffic distribution among MANET gateways causes network performance degradation. Therefore, in this paper, we would like to introduce an enhancement of gateway selection scheme in disaster recovery areas to maintain the throughput performance in MANET. The main contribution of this research is to optimize the throughput for MANET performances by developing a gateway selection schemes with consideration of nodes mobility. The remainder of this paper is organized as follows: In section II we introduce briefly about MANET gateway on previous research and the challenge of nodes mobility. In section III, we discuss in details a gateway selection method.