面向宽带流媒体的接入汇聚路由器中缓冲区容量的选取研究

Research on buffer size selection of access convergence router oriented to broadband streaming media application

根据宽带流媒体的突发性和自相似特点及接入汇聚路由器(ACR)对预留宽带的严格控制,建立了用分形布朗运动(FBM)来表示输入流量模型的自相似模型,用其定量分析了ACR中缓冲区容量与分组丢失率的关系.分析结果表明,为支持其有良好服务质量的宽带流媒体业务,必须确保每路视频流的丢失率小于一个定值,在此条件下,所需缓冲压的容量与媒流体的自相似系数及链路平均利用率成正比,在实际工程实践中可以根据系统丢失率的要求计算需要预留的缓冲区容量,以此来保证视频传输的服务质量.

Focused on the burst traffic and serf-similar character of wide band streaming media and the rigid control of reserved bandwidth on access convergence router（ACR）, this paper built a model which uses fractional Brownian motion （FBM） to describe the input traffic＇ s serf-similarity and analyzed the relation between the reserved buffer size of ACR and packet loss quantitatively. In the interest of guaranteeing the quality of video services system, the system must ensure the packet loss probability less than a threshold fore each stream flow. Under this condition, the modal reveal the mutual relation between the reserved buffer size, the self-similar coefficient of media stream and average utilization rate of link. This relationship formula can be used to compute the real reserved buffer size on ACR in an engineering project, so guarantee the quality of wide band streaming media system.