可提供预约视频点播服务的一种加权入口控制算法

摘要

A new call admission control algorithm with WMQL scheme in a video-on-demand environment is introduced. In making a video selection, the proposed scheme takes into consideration the viewer waiting time and the request queue length of each video. Then, an adaptive algorithm: AWMQL scheme is developed. This policy provides pre-demanding services to viewers and tries to satisfy all the requests before the deadline of viewers’ waiting tolerance. Simulation shows that the proposed scheme performs well in increasing the throughput of the VOD system, meanwhile maintaining better degree of fairness among viewers.%一个视频点播系统需要有大容量的存储空间和高速的输入/输出带宽.在视频点播的高峰时期，经常会出现系统资源供不应求的情况，这就需要有一种策略来决定如何管理用户请求，以及以什么样的顺序为用户提供服务.文中提出了一个新的入口控制算法：WMQL(Weighted Maximal Queue Length)调度，在选择要发送的视频段时，不仅考虑了视频的请求队列长度，还考虑了用户的请求等待时间.接着又提出了一个改进的调度方案：AWMQL(Advanced WMQL)调度，这种调度策略允许用户进行预约，而且尽量在用户的等待容忍度范围内满足用户请求.最后，进行了模拟试验，结果表明，AWMQL调度算法可以有效地增加系统的吞吐量，同时实现了较好的公平性.