Admission control algorithms for multicast sessions with multiple streams

摘要

Real-time multicast communication is considered, in which each destination makes an individual bid for delivery of a subset of real-time hierarchically encoded streams that are offered to the session by the source. The objective is to customize stream delivery to destinations, based on their requests and network constraints. Admission control procedures, which consider requests for multiple streams from multiple destinations and resolve contention when users' requests exceed available network resources, are presented. Specifications for four admission control procedures are presented and their properties analyzed. A performance measure for admission control is defined to be the total gain for the source that equals the sum of bids by the users taking delivery of the streams they ordered. Simulation results of the performance of the procedures are presented and compared to the performance of an optimal, but highly complex, admission control algorithm. In this paper the assumption is that the routing tree is already in place and the focus is on managing users' requests and deciding on which stream to deliver to each destination. This is done by signaling protocols that transfer messages containing users' requests and resource allocation commands between a source and the destinations. In addition, admission control protocols take users' requests and network resources as their input and issue as outputs the decisions on which request to admit (and allocate resources for) and which to reject.