Mobility Management in Heterogeneous Wireless Networks

Ever increasing demands of users and rapid development of telecommunication technologies have led to the evolution of 4G heterogeneous wireless network. Further, 4G with heterogeneous network environment will provide features such as seamless internet connectivity between different wireless networks, “Always Best Connected” service and “Anywhere Anytime Service”. Due to the different characteristics of heterogeneous wireless networks such as network coverage, bandwidth, data rate etc designing an efficient vertical handoff is the most challenging issue. To provide a seamless connectivity to the mobile users, there is a strong demand for the integration of different wireless access networks. The Worldwide Interoperability for Microwave Access (IEEE 802.16 WIMAX) networks has the capability to provide global network coverage with high data rate, but their deployment cost is high. The Wireless Local Area Network (IEEE 802.11 WLAN) has the capability to provide high data rate at a very low cost but their services are limited to a very small geographical region. By integrating these two challenging technologies WIMAX and WLAN several benefits can be achieved, i.e. increased network coverage, load balancing and better Quality of Service (QoS). Therefore, the integration of WLAN and WIMAX provides seamless internet connectivity and high data rate at low cost to the wireless mobile users. In this paper different integration mechanisms of WIMAX and WLAN are investigated. To be more precise, an internetworking mechanism for the integration of WLAN and WIMAX based on two different types of coupling, i.e loose coupling and tight coupling are implemented. Also an efficient vertical handoff based on IEEE 802.21 Media Independent Handoff approach is implemented on different interworking architecture of WLAN and WIMAX. The simulated results shows that the tight coupling is better than the loose coupling for the applications implemented using Opnet . And also it is found that an efficient handover can be achieved when handover is done based on signal strength and bandwidth.