Interworking of WLAN and 3G systems

Interoperation of different fixed and mobile networks is one key feature of systems beyond 3G, specifically between wireless local area networks, covering hot-spots with high data rates, and mobile cellular systems with full coverage. This comprises the vertical handover, i.e. the handover between systems with different air-interfaces, which are investigated in the paper. In contrast to several approaches that investigate solutions for the IP layer, the focus of the paper is on mechanisms on the link layer to improve the handover, respectively scanning other air-interfaces, measurements and appropriate triggers from the link layer that are considered in the handover decision process. Finally, the benefits for the handover performance are indicated and the potential of the proposed new concepts is highlighted.