A Novel Seamless Handover Scheme for WiMAX/LTE Heterogeneous Networks

Acquiring seamless handover in IP multimedia subsystem (IMS)-based heterogeneous internetworking environment still remains an unsolved issue. It is highly difficult to achieve seamless handover with the conventional session initiation protocol (SIP) due to its poor performance during vertical handover. In this paper, a novel SIP-based scheme called SIP Prior Handover with a cross-layer design utilizing Media Independent Handover Services is modeled to reduce the IMS session re-setup delay in a Worldwide Interoperability for Microwave Access (WiMAX)/Long Term Evolution (LTE) heterogeneous environment. The proposed scheme further reduces the IMS session re-setup delay by reducing the number of SIP messages exchanged during vertical handover. We have developed a simulating environment using NS2 for a WiMAX/LTE interworking architecture and evaluated its performance. We have also developed a mathematical model for the IMS session re-setup delay based on queuing theory. The simulation results are compared for handover delay, packet loss, SINR and throughput. The proposed design shows an improvement of 18 % when compared with previous approaches during vertical handover from WiMAX to LTE and vice versa and suits well for supporting real-time applications to mobile users.