AbstractWith the rapid development of Cloud computing technologies and wideadopt of Cloud services and applications, QoS provisioning in Clouds be-comes an important research topic. In this paper, we propose an admis-sion control mechanism for Cloud computing. In particular we considerthe high volume of simultaneous requests for Cloud services and developadmission control for aggregated trac ows to address this challenge. Byemploy network calculus, we determine e ective bandwidth for aggregateow, which is used for making admission control decision. In order toimprove network resource allocation while achieving Cloud service QoS,we investigate the relationship between e ective bandwidth and equiva-lent capacity. We have also conducted extensive experiments to evaluateperformance of the proposed admission control mechanism. 1 Introduction Recently the emerging Cloud computing has been developing very quickly[1, 2, 3]. With the rapid development of Cloud computing technologies and wideadoption of Cloud-based applications, the huge amount of trac generated bya large number of users for accessing Cloud services bring in a series challengeto the Internet. The best-e ort service model in the current Internet cannotmeet users’ requirements for Quality of Service (QoS). Call Admission Control(CAC) o ers an e ective approach to controlling network trac and avoiding1
 This paper presents a novel approach for stream-based admission control and job scheduling for video transcoding called SBACS (Stream-Based Admission Control and Scheduling). SBACS uses queue waiting time of transcoding servers to make admission control decisions for incoming video streams. It implements stream-based admission control with per stream admission. To ensure efficient utilization of the transcoding servers, video streams are segmented at the Group of Pictures level. In addition to the traditional rejection policy, SBACS also provides a stream deferment policy, which exploits cloud elasticity to allow temporary deferment of the incoming video streams. In other words, the admission controller can decide to admit, defer, or reject an incoming stream and hence reduce rejection rate. In order to prevent transcoding jitters in the admitted streams, we introduce a job scheduling mechanism, which drops a small proportion of video frames from a video segment to ensure continued delivery of video contents to the user. The approach is demonstrated in a discrete-event simulation with a series of experiments involving different load patterns and stream arrival rates. Network Calculus.- Application of Network Calculus to the Internet.- Basic Min-plus and Max-plus Calculus.- Min-plus and Max-plus System Theory.- Optimal Multimedia Smoothing.- FIFO Systems and Aggregate Scheduling.- Adaptive and Packet Scale Rate Guarantees.- Time Varying Shapers.- Systems with Losses.