UMTS-WLAN Service Integration at Core Network Level

The integration of wireless LANs (WLANs) and 3G systems performed at core network level requires very little modifications to the current 3GPP architecture and provides a large set of benefits: seamless service integration, exploration of user mobility by applications, seamless use of different radio access network (RANs), easy availability of current services such as Short Message Service (SMS) in other RANs, etc. This paper describes an architecture that has the GPRS as the primary network. Each of the other networks has a core-level component to manage it and to perform the integration. Vertical handovers between RANs are not needed and secondary networks are used on an availability basis. Users can have at least one session per RAN that is maintained even when they are moving in dark areas of that RAN (and the communication is still possible via the primary network). Our proposal does not require the system to be all-IP, but simply IP-enabled.