用应用层组播技术解决小规模多点视频会议中的关键问题

在因特网上实现小规模多点视频会议需要解决三个关键问题，即端系统带宽不充足、实时传输和临界带宽的使用。采用应用层组播技术，可以设计一种比较合理、适用的组播树构造算法。模拟结果表明该算法较好地解决了以上三个问题。该算法由本地路由算法和组播树优化算法两部分组成，每个与会成员首先利用本地算法结合自身的特点生成一棵基于源的树，然后，再利用生成树优化算法对所有基于源的树从全局的角度进行优化，平衡树与树之间带宽的使用。

Solve the Key Problems in Multi-party Video Conferencing by Using the ALM-technology

Before applying multi - party video conferencing into the Internet, we must resolve three problems, they are insufficiency of end system bandwidth, real transmission and the use of extreme bandwidth. With ALM, we can design a more reasonable and appropriate multicast - tree constructing algorithm. The result of simulation shows that this algorithm can solve all the problems. This algorithm includes a local router algorithm and a multicast - tree optimizing algorithm. Every member makes a source - based tree by using the local router algorithm and considering his own condition, then the optimizing algorithm optimizes all the source -based trees in overall situation in order to balance the usage of bandwidth between trees.