A time-scale decomposition approach to measurement-based admission control

We propose a time-scale decomposition approach to measurement-based admission control (MBAC). We identify a critical time-scale <(T-h)over tilde> such that: 1) aggregate traffic fluctuation slower than <(T-h)over tilde> can be tracked by the admission controller and compensated for by flow admissions and departures; 2) fluctuations faster than <(T-h)over tilde> have to be absorbed by reserving spare bandwidth on the link. The critical time-scale is shown to scale as T-h/root n where T-h is the average flow duration and n is the size of the link in terms of number of flows it can carry. A MBAC design is presented which filters aggregate measurements into low and high frequency components separated at the cutoff frequency 1/<(T-h)over tilde>, using the low frequency component to track slow time-scale traffic fluctuations and the high frequency component to estimate the spare bandwidth needed. Our analysis shows that the scheme achieves high utilization and is robust to traffic heterogeneity, multiple time-scale fluctuations and measurement errors. The scheme uses only measurements of aggregate bandwidth and does not need to keep track of per-flow information.