基于用户行为特征的SVC分片调度算法

SVC Fragment Schedule Algorithm Based on User Behavior Characteristic

针对异构环境中网络和终端的复杂性,以及用户随机搜索行为造成的视频点播服务中播放进度的突变性,提出一种异构环境中基于用户行为特征的可扩展视频编码分片调度算法。设计2类调度窗口,即根据当前播放时刻保证顺序播放数据持续功能的播放窗口和依据服从Weibull分布的用户随机搜索行为设计的加入数据预取机制的锚点窗口。对播放窗口和第一个锚点窗口采用逐层调度策略,以保证数据的及时性,其余锚点窗口使用rarestfirst策略,以平衡整个系统的分片分布。在Over Sim平台上的仿真结果表明,与现有的逐层调度算法和权值调度算法相比,该算法在发生用户随机搜索行为的应用场景中能提高节点分片调度性能,缩短响应时延,降低服务器负载,提高用户观看视频的质量和流畅度。

In view of the complexity of the network and terminal in heterogeneous environment,and the mutability of playback progress in the video-on-demand service that is caused by user random seeking,an Scalable Video Coding（SVC） fragment schedule algorithm based on user behavior characteristic is proposed.In the proposed algorithm,two types of windows are designed.One is playback window based on current playtime to ensure order data continues,the other one is anchor window designed with data prefetching,which is based on user random seeking following the Weibull distribution.The Layer-by-Layer（LL） schedule strategy is utilized in playback window and the first anchor window to ensure the timeliness of data,and the rarest-first strategy is used in the other anchor windows to balance the fragment distribution of the whole system.Simulation results in OverSim show that,compared with current LL schedule algorithm and weighted schedule algorithm,the proposed algorithm can improve the fragment scheduling performance,shortens the response time delay,reduces the server load,and improves the quality and fluency of the user in watching video.