| Wireless technology is one of the areas receiving most attention and investment. Wireless services are quickly becoming part of people's daily life. This dissertation presents a framework for supporting real-time and multimedia applications in wireless networks. Mobile applications require backbone network support from multiple aspects, including QoS, secure multicast, seamless handoff and others. Included in the framework presented in this dissertation is a set of new mechanisms addressing those requirements.; There are four components in the framework. Different needs of mobile applications are addressed by different component. The first component, Wireless Resource Reservation Protocol (WRSVP), enables wireless devices to reserve necessary resources in wireless networks, which is a necessary condition for QoS. With help of WRSVP, resources can be successfully reserved and refreshed without being affected by poor links and handoffs.; The second component, Handoff Protocol for Overlay Network (HOPOVER), is a handoff protocol designed specifically for overlay networks where multiple wireless networks coexist. With increasing number of high-speed moving wireless devices, smaller cell sizes, and more and more wireless networks being built, handoffs happen at increasingly higher frequency both horizontally and vertically. HOPOVER, enables wireless devices to move freely and smoothly intra- and inter-network.; The third component, Smart Server Selection (S3) helps wireless devices in choosing the best server when they use replicated services. Traditional server selection solutions are hard to use in wireless networks because network topology is unstable from the viewpoint of both the servers and the clients. S3 enables accurate, fast and low overhead server selection by utilizing the client side DNS server and up-to-data routing information from routers.; The last component, Secure Transmission Backbone (STB) enables wireless devices to participate in secure multicast sessions. STB effectively solves the multicast key management problem and addressees the problems caused by handoffs and limited resources in wireless environment.; In summary, with all these components, we have solid support for mobile applications in overlay networks, thus help users to utilize their favorite applications anytime, anywhere. |
