A New Vertical Handoff Scheme for UMTS - WLAN Integrated Network

Designing of heterogeneous Networks involves several interworking issues, such as seamless handoff or roaming, mobility management, security and charging problems. Among these interworking items, the issue of seamless handoff is of great importance for guaranteeing service continuity and Quality of Service. In this paper, we propose a seamless handoff scheme with minimum handoff delay and low packet loss during UMTS–WLAN handoff. The proposed handoff scheme separates Layer 2 and Layer 3 handoff processes with help of a new defined signaling message between mobile nodes, called WLAN/UMTS Zone Identification Message and performs pre-registration and preauthentication processes before entering the coverage area of the new Network and before performing layer 2 trigger. Key Words-Interworking, Mobile IP, UMTS, Vertical handoff, WLAN, Interworking.