An Investigation Of Adaptive Capacity Control Schemes In A Dynamic Tra c Environment

We consider a dynamically recon gureable network where dynamically changing tra c is o ered. Rearrangement and adjustment of network capacity can be performed to maintain Quality of Service (QoS) requirements for di erent tra c classes in the dynamic tra c environment. In this work, we consider the case of a single, dynamic tra c class scenario in a loss mode environment. We have developed a numerical, analytical tool which models the behavior of the dynamically changing network tra c environment using a time-varying, uidow, di erential equation. An advantage of this approach is that it can be used to study the impact of adaptive capacity adjustment control schemes. We present several capacity adjustment control schemes including schemes that use blocking and system utilization as means to calculate when and how much adjustment should be made. Through numerical studies, we show that a purely blocking-based capacity adjustment control scheme with a preset adjustment value can be very sensitive to capacity changes and can lead to network instability. We also show that schemes, that uses system utilization as a means to calculate the amount of capacity adjustment needed, is consistently stable for the load scenarios considered. Finally, we introduce a minimum time interval threshold between adjustments, which can avoid network instability, in the cases where the results showed that capacity adjustment had been performed too often.