Admission Control for Integrated Services: Time-scale Decomposition and Insensitivity O. J. Boxma, A. F. Gabor, R. N´ u˜ nez-Queija and H. P. Tan EURANDOM, PO Box 513, 5600 MB, Eindhoven (The Netherlands) Abstract Using time-scale decomposition, we develop approximations to evaluate the performance of an admission control strategy for integrated services in a single UMTS radio cell. Simulation results suggest that the performance is almost insensitive to traffic parameter distributions, and is well estimated by our proposed approximations. I. I NTRODUCTION UMTS is a 3G cellular network that is expected to support a large variety of applications which are commonly grouped into elastic and streaming applications. Elastic applications (e.g., Web pages, emails, stored audio / videos) are characterized by their size. These flows are flexible, or “elastic”, towards rate fluctuations, the total transfer time being a typical performance measure. Streaming flows (e.g., voice, streaming audio / video) are characterized by their duration as well as their transmission rate. For “streaming” applications, stringent rate guarantees are necessary to ensure real-time communication. Various papers that study the integration of elastic and streaming traffic have been published recently [1], [2], [3], [4], [5], [6]. In terms of bandwidth sharing policy, the classical approach is to give head-of-line priority to packets of streaming flows in order to offer packet delay and loss guarantees [1], [2], [4]; alternatively, adaptive streaming flows (that are TCP-friendly and mimic elastic flows) are considered in [3], [5], [6]. In terms of modeling approach, while The support of Vodafone is gratefully acknowledged. This research is partially supported by the Dutch Bsik/BRICKS project and is performed within the framework of the European Network of Excellence Euro-NGI.