In Networked virtual-reality system, it is critical factor of realism that interaction among participants. Interaction among participants is accomplished by exchanging information via network, so real-time communication method is essential for realistic interaction. Furthermore, this has to be many-to-many communication method. It is not applicable that using general point-to-point protocol for many-to-many communication, because of large number of connections or bottleneck at server.
In this paper, our goal is developing communication structure tailored for networked virtual reality system. We define structure of multi-participants networked virtual reality system. To archive collaboration and coordination among participants, every module exchanges information each other. We define requirement for information exchange; reliability and time-criticality. And, we test characteristic of target network; campus wide network. From this, we implement communication structure based on IP-multicast. In a general way, multicast is defined as "send-once-receive-many". But IP-multicast has no faculty of reliability. The implemented structure has faculty of sending packet with specification of reliability and/or time-criticality. We prove implemented structure useful by apply it to multi-participant real-time combat game application.
