Adaptive Gateway Management in Heterogeneous Wireless Networks

In the recent years, there exist an ever-growing demand for ubiquitous connectivity which requires seamless integration of Mobile Ad hoc Network, Wireless LAN and Cellular networks. Integration of these networks results in a heterogeneous wireless network (HWN) architecture which is capable of providing high data-rate, end-to-end connectivity utilizing the higher bandwidth of multi-hop networks and the wide range communication of 3G Networks. HWN architecture has numerous real-world applications such as communication between spatially-apart military troops in war-front, disaster recovery operations which demand data access from heterogeneous networks. To provide seamless connectivity in HWN architecture, gateway nodes are required in MANET and WLAN to liaison with the cellular network for data communication. In this paper, an Adaptive Gateway Management (AGM) which includes an effective gateway selection mechanism to select an optimal Gateway from the Gateway Candidate Nodes, is proposed using metrics such as residual energy, 3G signal strength and mobility speed. Once a selected gateway loses its optimality due to diminishing energy and dynamic changing topology, makes it unavailable which results in disconnection between networks. In order to sustain the connectivity between networks for a longer time, an Adaptive Gateway Migration mechanism has also been proposed to select an optimal gateway to which the responsibility of the current gateway is migrated, when the above metric values reach to a predefined threshold. This adaptive gateway management scheme has been implemented in a HWN environment using Network Simulator 2. Extensive simulations have been carried out and the results show that the proposed scheme enhances the overall performance in terms of packet delivery ratio, transaction duration and control overhead.