Evaluation and Development of Traffic Control Methods for Very High Speed Communication Networks

在这个项目中，我们评估和开发适用于高速网络，特别是专用于ATM网络的流量控制方法。本文首先讨论了当网络中同时存在语音、视频和文件传输等多种业务时，统计复用增益的影响。我们进一步解决了优先级控制的有效性时，不同的服务质量的多媒体业务在网络中处理。然后，我们评估了高可靠性的数据传输协议，使用FEC（前向纠错）的方法。通过这项研究，它表明，FEC可以适合作为未来的数据传输协议，以达到非常低的信元丢失概率。基于速率的拥塞控制被应用于未来ATM网络的数据传输。我们的下一个贡献是基于速率的拥塞控制的分析方法的发展。通过数值算例，展示了其实现方法对ATM交换机进行有效而简单的流量控制的方法。在交换机上观察到的最大队列长度的分析结果可用于ATM交换机设计中的缓冲器尺寸。在未来的高速网络中，除了数据传输之外，还应该支持诸如运动视频的真实的时间业务。在这种情况下，媒体间的同步机制就显得尤为重要，本文提出了三种媒体间的同步机制，并在基于UNIX工作站的超媒体系统Harmony上实现了这三种同步机制。虽然所提出的机制在应用程序级得到支持，但当系统用作表示系统时，它是有用的。

In this project, we evaluate and develop the traffic control methods suitable to high speed networks, especially dedicated to ATM networks. We first discuss on the effect of statistical multiplexing gain when the multiple traffic classes including voice, motion video and file transfer co-exist in the network. We further address the effectiveness of priority control when the multimedia traffic with different quality of service are handled in the network. Then, we evaluate the highly reliable data transport protocol using FEC (Forward Error Correction) method. By this study, it is demonstrated that FEC can be suitable as a future data transport protocol to attain the very low cell loss probabilities. The rate-based congestion control is applied to data transfer in the future ATM-based betworks. Our next contribution is that the analysis method for the rate-based congestion control is developed. Through the numerical examples, we show its implementation method of the ATM switch for effective and simple traffic control method. The analysis result for maximum queue length observed at the switch can be used for buffer dimensioning in designing the ATM switch. In the future high speed networks, the real time traffic such as motion video should also be supported in addition to the data transfer. In the case, the synchronization mechanisms among the media becomes important.We have poposed three synchronization mechanisms and implemented all of these methods on Harmony, which is our hyper-media system running on the UNIX-based workstation. While the proposed mechanisms are supported at the application level, it is useful when the system is used as the presentation system.