Adaptive group multicast with time-driven priority

This paper shows how to provide an adaptive real-time group multicast (many -to-many) communication service, Adaptive means that the number of nodes th at transmit to the multicast group is continuously changing, In order to me et deterministic quality-of-service (QoS) requirements of a real-time group multicast, some communication resources are reserved. In this work we show 1) how bandwidth is reserved for each multicast group and 2) how an active source can dynamically share the bandwidth allocated to this multicast gro up with other active group members, Quality-of-service support for a real-time multicast group is based on time -driven priority [9]. In this scheme the time is divided into time frames o f fixed duration, and all the time frames are aligned by using a common glo bal time reference, which can be obtained from the global positioning syste m. Bandwidth is allocated to a multicast group as a whole, rather than indi vidually to each user. The allocation is done by reserving time intervals w ithin time frames in a periodic fashion, This type of allocation raises two problems that are studied in this paper: 1) scheduling: how time intervals are reserved to each multicast group and 2) adaptive sharing: how the active (transmitting) participants can dynami cally share the time intervals that have been reserved for their multicast group. The proposed approach is based on the embedding of multiple virtual rings, one for each multicast group. By using the virtual rings, it is simp le to route messages to all the participants while minimizing the bound on the buffer sizes and queueing delays. The finalpart of this paper introduce s a scalable growth of the multicast group by adding multiple subtrees to t he virtual ring.