T07/1

This tutorial presents the principles and technical issues relevant to 4G Cellular/WLAN Interworking at mobile communications, concentrating on UMTS and 802.11. The main motivation regarding this interworking, stems from the fact that these technologies are complementary rather than competitive. It addresses four interworking scenarios between 3G and WLAN networks. The proposed scenarios are namely: open-coupling, loose-coupling, tight-coupling and very-tight coupling. A qualitative analysis among the different scenarios is presented. It also presents the extended functionality of the needed entities in the cellular and WAN architecture for facilitating the authentication mechanism of a cellular user roaming in a WLAN hot spot. Details are presented in a loose-coupling model by utilizing an enhanced HLR and SIM-Access Gateway. An introduction on EAP-SIM authentication, requirements for an authentication translator and an enhanced HLR that accommodates both WLAN as well as cellular user profiles are described. Enhancements made to an HLR emulator to support WLAN user authentication and authorization mechanisms further to 3GPP release features are also presented