Conditional overflow probability and profile curve for ATM congestion detection

Many systems in ATM environments require the queue to be monitored for impending congestion before it happens. We characterize impending congestion by measuring how long the queue length has exceeded a certain threshold. Based on the idea of the profile curve, we introduce a new performance measure called the conditional overflow probability which gives a quantitative measure on the congestion state. We develop a matrix analytic method to compute the conditional overflow probability and the profile curve, and present a corresponding algorithm to estimate the two measures using real traffic data.