Performance analysis of a context aware cross layer scheme for fast handoff in IMS based integrated WiFi–WiMax networks

Providing fast and seamless handoff in a pervasive computing environment is one of the recent research issues. The delay incurred due to IP Multimedia subsystem (IMS) re-registration and session re-setup process during vertical handoff (VHO) is still a major bottleneck for Voice Over IP (VoIP) and interactive multimedia services. In the conventional Session initiation Protocol (SIP), handoff performance is very poor due to high handoff delay and packet loss. In this paper, we propose two SIP based schemes, a Context Awareness (CA)-based Pre-registration approach to reduce the IMS Re-registration delay and a novel scheme called Prior-SIP (P-SIP) with a cross layer scheme utilizing Media Independent Handover (MIH) services to reduce the IMS session re-setup delay in a WiFi/WiMax heterogeneous environment by defining new SIP messages. We have simulated these scenarios using NS2 and the performance characteristics are studied. We have also analyzed the IMS pre-registration delay and IMS session re-setup delay based on Queuing theory. The simulation and analytical results show that, the proposed solution shows an improvement of 44% in terms of handoff delay and packet loss when compared with previous approaches and was able to maintain 90% throughput during handoff and suits well for supporting real-time applications to mobile users.