Interworking architecture between 3GPP and WLAN systems

The Third Generation Partnership Project has recently taken the initiative to develop a cellular-WLAN interworking architecture as an add-on to the 3GPP cellular system specifications. The article presents an overall view on an interworking architecture, which enables provisioning by mobile operators of a public WLAN access service for 3GPP system subscribers. The enabling functionalities include the reuse of 3GPP subscription, network selection, 3GPP system-based authentication, authorization and security key agreement using SIM/USIM card, user data routing and service access, as well as end user charging. The interworking functionalities are achieved without setting any 3GPP specific requirements for the actual WLAN access systems, but relying on the existing functionality available in a typical WLAN access network based on IEEE 802.11 standards.