On Technologies for Ubiquitous Multimedia Communication

The proliferation of multimedia and deployment of wireless networks over the last decade have made it possible for users to communicate and share information using e-meeting services from almost any location at anytime. While these new services offer new ways to communicate, they are not always easy to use because of the heterogeneity of networks and devices, which must be managed by the users to take full advantage of the possible benefits. Switching to another communication service running on another terminal requires even more configuration efforts. In addition, it is expected that the configuration efforts required by the users will become more time-consuming in the future as the need for richer communication grows and the diversity of services and networks increases. This doctoral thesis proposes and evaluates new methods to create a ubiquitous multimedia communication system, which makes it easier for users to participate in online e-meetings using the most suitable network or terminal. The thesis makes several contributions related to mobility and bandwidth management. One contribution is a new mobility protocol called the Resilient Mobile Socket and an algorithm called Competition-based Soft-Handovers Management designed to manage host mobility and seamlessly migrate media streams between different network connections. To deal with bandwidth variation, the thesis proposes a method based on microeconomic theory to adapt and share bandwidth efficiently between media within an application, thereby relieving the users from manually adjusting bandwidth utilization after switching network. In regards to switching terminals, the thesis proposes a concept called media resources, and a framework for managing media resources using context-awareness. The most beneficial media resource is automatically selected using an algorithm, which is also presented in the thesis. The proposed methods, frameworks, and algorithms have been evaluated through a combination of theoretical analysis, controlled laboratory experiments, user studies, and exploratory experiments using prototypes. The results from these investigations show that it is possible to create a ubiquitous multimedia communication system that enables richer communication in mobile settings by better utilizing available networks and combining multiple terminals. A final conclusion is that it is crucial to minimize configuration efforts, but the user should always have the final decision if a configuration procedure cannot be automated with complete accuracy.