A framework for seamless roaming across cellular and wireless local area networks

In the future, wireless and mobile users will have increased demands for seamless roaming across different types of wireless networks, quality of service guarantees, and support for a variety of services. This awareness has led to research activities directed toward intersystem and global roaming, and can be noticed in numerous products like multimode handsets, interworking gateways, and ongoing standards and research work on intersystem roaming. The authors of this article proposed a global mobility management framework to support seamless roaming across heterogeneous wireless networks. In this article we provide details on the use of the framework to support roaming across cellular and wireless local area networks. Highlights of the framework include a robust architecture for mobility management for varying user mobility spans, provisioning for QoS mapping, intersystem message translation, and mechanisms in the WLAN to support user-subscribed services. Performance aspects related to handoff delays, data redirection, and processing overheads are presented and discussed. Performance comparison of intersystem roaming between cellular and WLAN with and without the framework is presented.