一种基于效用最优的分层多播动态层速率分配算法

An Optimal Layer Rate Dynamic Allocation Algorithm Based on Utility in Layered Multicast

分层多播已被认为是在Internet上进行视频多播的一个解决方案 已有的分层多播协议通常在接收方执行层的适应 ,在发送方使用静态的层速率分配技术 首先介绍了分层多播的基本原理 ,讨论了接收方驱动的静态分层与发送方驱动的动态分层技术 ,特别地引入了一种衡量尺度“效用”对多媒体应用满意度进行度量 ;提出了一种效用最优的层速率分配算法ORAU ,并通过推理证明得出了一个求解途径 ;接着给出了ORAU算法的实现 ;最后对ORAU算法在特定的网络环境中进行了实验仿真 ,并对仿真结果与其他算法进行了比较分析 实验结果表明 ,采用ORAU算法的多媒体多播系统能够花费较小的带宽就可以获得相对较高的系统效用 。

Layered multicast has been proposed as a solution to video multicast over Internet. Existing multicast protocols usually perform layer adaptation at the receiver's side,using static layer rate allocation techniques at the sender's side. In this paper,the basic theory of layered multicast is introduced firstly. The technology of receiver-driven fixed layer rate allocation and dynamic sender-driven rate allocation is discussed. Especially,a kind of metric,called utility,is introduced to measure the satisfaction with the multimedia application. An optimal rate allocation algorithm based on system utility,ORAU,is brought forward. Then a solution to the allocation algorithm is found through ratiocinating and proving. Subsequently,the implementation of ORAU algorithm is presented. Finally,ORAU algorithm is simulated in specific network environment. The results of simulation are compared with other algorithms,such as GAU and SLM. They show that the multimedia multicast system adopting ORAU algorithm can gain higher utility with little bandwidth cost. Thus the feasibility and effectivity of the algorithm are verified by the results of experiment and simulation.