Recent research supports the eventual convergence of wireless LAN (WLAN) and cellular systems in order to achieve the IMT-2000 (3G) requirement for 2 Mbps indoor capacities. The WLAN access point can be enhanced to either incorporate or supplant the transmission and packet data capabilities in the cellular network. This research used OPNET™ to design, implement, and test a network system level simulation environment to allow investigators to study the issues and trade-offs for interworking the infrastructure-based WLAN technologies into 3G mobile subscriber cellular systems. The specific contribution of this research was to augment the current OPNET™ model library by creating an enhanced user equipment node (UW) and an enhanced WLAN access point node (UWLAN_AP).

The UW was augmented with the capability to selectively gain network access through either a UMTS Node-B or through a 3G-aware WLAN access point. The UWLAN_AP was made 3G-aware by augmenting it with the capability to process UMTS control messages in order to build an access control table to support UMTS authentication and access control. Together, the UW and UWLAN_AP create a simulation framework for interworking the WLAN technology into UMTS as an alternate radio access network for supporting "hot spots." This research is the foundation to allow investigators to identify signaling and data transfer mechanisms that leverage the capabilities of WLAN while supporting cellular service provisioning and accountability requirements for current and future systems.