Application-level Fair Multicasting Scheme Suitable for Multipoint Real-time Communication

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 real-time multicasting. Specifically, end-to-end delay and packet loss rate differ among multicast members. In this study, we aim to achieve fairness of time and quality among multicast members in multipoint realtime communication. In this paper, we assume that the multicast is of the application-level shared-tree type. To solve the problems mentioned above, we propose a new control mechanism in the root node of the shared tree. This mechanism consists of a proposed scheduling algorithm and a proposed discarding discipline. To make end-to-end delay among members uniform, the packet transfer order from the buffer is scheduled by considering the packet´s generation time and the delay from the root node to the receiver. On the other hand, to make the packet loss rate among members uniform, the discard probability of packets that have arrived at the root node is decided by considering the packet loss rate in the network from the sender to the root node. Experimental performance evaluation demonstrates that our proposed system can achieve fairness in time and quality.