Ubiquitous Wireless Connectivity across Cellular and Wireless Local Area Networks*

Future generation wireless networks are expected to support multiple wireless ac-cess technologies, each with different access bandwidth and coverage range. Two of these technologies include Universal Mobile Telecommunications System (UMTS) and IEEE 802.11 Wireless Local Area Networks (WLANs). Provision of real time ubiquitous communication to mobile users, anywhere, anytime through these heterogeneous net-works remains a challenge. This paper proposes an end-to-end mobility management solution that enables mobile users to maintain seamless connectivity while moving across such heterogeneous access networks. The continuous network connectivity is obtained through the use of mobile devices equipped with dual network interfaces and the capa-bility to switch data transmission between these interfaces depending upon the availabil-ity of the access network. We present and discuss the design of such a dual- mode radio access device and propose a simple inter-technology handoff technique. We evaluate the performance of our proposed architecture by conducting experimental simulation tests using OPNET