Robust Admission Control For Heterogeneous Atm Systems With Both Cell And Call Qos Requirements

The principal goal of call admission control in an ATM system is to simultaneously maintain the Quality of Service (QoS) for several traffic streams with different characteristics. A well-known concept used in designing ATM call admission control schemes is effective bandwidth. However, almost all of the notions of effective bandwidths in the literature are based on cell level QoS alone and the point of view of this paper is that this is not adequate. We propose a new method for ATM call admission control, which is based on the notion of virtual partitioning (VP), where a measure of bandwidth requirement for connections is used that takes into account both cell and call level QoS requirements. This measure can be obtained by analyzing a single class system. The effective bandwidth thus calculated is less conservative than traditionally calculated values, which ignore call dynamics. We describe an asymptotic analysis of a single class system, which combines two qualitatively different scalings associated, respectively, with the cell and call QoS measures. The call admission control policy based on VP reduces to complete sharing when the traffic of all classes are light, and otherwise it gives priority to underloaded classes, i.e., those that are using less than their engineered bandwidth allocations. As a consequence, our call admission control is robust in the face of deviations from engineered load.