Master Thesis - 2007

The spread of broadband access to the Internet means that real-time applications have become commonplace. Video conferencing, communicating interactively in real time at multiple locations, is one such real-time application. For multipoint real-time communication, each member has to transmit information to all of the other members in the multicast delivery. However, there are some problems in multipoint real-time multicasting. Because the network resource of each member is different among multicast members, the maximum quality of the video stream, which each member can receive, is different among multicast members.

In this study, I aim to guarantee the maximum quality of service of each member’s communication according to each network resource, in multipoint real-time communication. I assume that the multicast belongs to shared tree, application-level and layered one. To solve the problems mentioned above, I propose a new control mechanism in the root node of the shared tree. The control mechanism has consist of four phase. The first phase is deciding transmission rate. The second phase is deciding layer information. The third phase is dividing data stream for QoS. The fourth phase is controlling transmission rate based on the core’s capacity. The first and the second phases are base processes, and the third and the fourth phases are extension processes. Thus, the first and the second phases are the essential function of the proposed mechanism, and the third and the fourth phases contribute to improving the quality of communications.

Finally, performance evaluation demonstrates that my proposed system can guarantee the maximum quality of service of each member’s communication according to each network resource.