Seamless IP Multimedia Service Continuity Support in Inter-worked UMTS and WLAN

The rapid growth of WLANs provides an opportunity for appropriately equipped user terminals to access the evolutionary 3GPP services via high speed WLAN at low cost. Interworking of UMTS and WLANs aims to extend 3 GPP services and functionality to the WLAN environment, thus effectively making it a complementary access technology. One of the research challenges for this interworking is the design of mobility management mechanisms to support seamless service continuity. In this work, first we undertake a holistic review of the mobility problem, considering handovers at different protocol layers. Then we propose a cross-layer mechanism for better coordination between different layers to improve the handover performance and thereby meet the requirements of seamless service continuity. Finally we present the results from an experimental study of the proposed mechanism.