Improved vertical handoff module for NS2 using IEEE 802.21 MIH for heterogeneous networks

The next generation wireless networks are expected to support the seamless vertical handoff mechanism in which users can maintain the connections even when they switch from one network to another with service continuity. For this, IEEE 802.21 provided a framework which facilitates seamless handoff in heterogeneous wireless networks. The IEEE 802.21 Media Independent Handover has become a standard in 2008. National Institute of Standards and Technology (NIST) developed the IEEE 802.21 add-on modules for network simulator-2, which uses only signal strength and interface type for handoff decision. In this paper we have proposed a method for Vertical Handoff by enhancing the handoff module of NIST´s IEEE 802.21 add-on module. The proposed method takes into account the link layer and application layer information and makes decisions depending on that information. It will allow the mobile terminals to be always best connected and provide seamless mobility in vertical handoff. The simulation result shows better performance over basic IEEE 802.21 add-on module for ns2.