To provide statistical guarantees of QoS, the Internet requires a measurement infrastructure for estimating available resources from actual tra c. In this paper, we outline an algorithm that collects a histogram of the occupancy of a single-server FCFS queue at packet arrival times, and infers the loss rate and delay distribution from such measurements. Direct estimation of such QoS parameters typically leads to estimators with a large variance. To reduce this variance, we t a bu er occupancy model, a sum of exponentials, to the histogram using a weighted least-squares algorithm. Furthermore, we compute batch means to minimize the bias due to the positive correlation between measurements. In this manner, we provide an e cient and robust approach to QoS estimation.
