VGSN: a gateway approach to interconnect UMTS/WLAN networks

High tier wireless systems such as GPRS and UMTS provide users high mobility but low bandwidth. On the other hand, low tier wireless systems such as wireless LAN offer higher bandwidth with less mobility. To support seamless roaming between. heterogeneous wireless networks is regarded as one of the key issues in the future mobile communication system. The paper presents method and system for seamless roaming between WLAN and UMTS networks. The two networks are assumed to be constructed and to operate independently, but wish to offer roaming services to their customers. A new logical node, called virtual GPRS support node (VGSN), is designed for this purpose to connect UMTS and WLAN core networks. VGSN is a normal GPRS support node (GSN) in a UMTS system and also acts as an access route in a WLAN network. The node converts control signals and routes data packets between two networks for roaming users. With the presented approach, Mobile IP is not required and users can have seamless roaming between networks based on one IP address.