自相似业务下视频服务器的接纳控制_戚伟世.pdfVIP

2004 年10 月 通 信 学 报 Vol.25 No.10 第25 卷第10 期 JOURNAL OF CHINA INSTITUTE OF COMMUNICATIONS October 2004 自相似业务下视频服务器的接纳控制1 戚伟世，蔡安妮，孙景鳌 （北京邮电大学电信工程学院，北京100876） 摘 要：VOD 系统中，有限的磁盘I/O 带宽或缓存空间往往成为系统的瓶颈。针对这一问题，提 出了自相似业务下视频服务器的接纳控制算法。该算法运用等效带宽理论，通过在线测量系统所 剩资源和周期容限的幅度变化来实时调节调度周期的大小，使得系统所剩资源达到动态的“等量” 平衡。仿真结果表明，该算法不但简化了接纳过程，节约了系统资源，提高了算法的可实现性， 而且系统的接纳率比Lee ，Yeom 所提算法的接纳率提高了 15%，并且还可根据系统的QoS 参数 灵活调整接纳率。 关键词：接纳控制；自相似；动态调度周期；等效带宽 中图分类号：TP368.5 文献标识码：A 文章编号：1000-436X(2004)10-0148-07 Admission control on video servers under self-similar traffic QI Wei-shi, CAI An-ni, SUN Jing-ao (School of Telecommunications Engineering, Beijing University of Posts and Telecommunications, Beijing 100876, China) Abstract: In VOD systems, the limited disk I/O bandwidth and buffer space frequently causes system bottleneck, therefore, an admission control algorithm about self-similar video traffic is proposed. Based on effective bandwidth theory, the length of scheduling period is on-line adjusted according to current residual system resources and variable range of period tolerance. As a result, residual system resources are in a dynamic ‘equal quantity’ balance. The simulation results show the proposed algorithm has a simplified admission process, low resource consumption and better realizability. The admission rate of the system increases by 15% compared with that of the algorithm proposed by Lee and Yeom, while keeping a flexible adjustment between desired QoS and admission rate. Key words: admission control; self-similar; dynamic scheduling period; effective bandwidth 1 引言 [1] 自从Leland 等 首次明确地提出了以太网中存在自相似通信量以来，网