Quality and performance of a desktop video conferencing system in the network of interconnected LANs

Proceedings of 19th Conference on Local Computer Networks Pub Date : 1994-10-02 DOI:10.1109/LCN.1994.386584

J. Harju, Ville Kosonen, Changhong Li

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引用次数: 4

Abstract

We describe the results obtained when using a desktop videoconferencing system for distance learning and, at the same time, doing measurements about its performance. The system hardware is based on a PC with a LAN network controller, and a compression card implementing the CCITT H.261 algorithm. Our network environment consists of a campus network (Ethernets connected with routers and bridges) and a wide area network connection (0.5 Mbit/s frame relay) to another university 150 miles away. In this environment TCP/IP is used as the transport and network protocol suite. The quality of the videoconferencing application is first analysed on a subjective perceptual basis in four different subnetworks. Then, the transmission rate of the application and the number of TCP retransmissions is measured in those subnetworks under varying background traffic load. As one may assume, severe problems with audio appear when the networking environment gets more demanding. With video, the problems are not so evident. Yet, slight degradation of perceptual quality can be observed and related to the increase of load and number of packet switches (routers and frame relay nodes) in the network connection.<>

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局域网互联网络中桌面视频会议系统的质量和性能

我们描述了使用桌面视频会议系统进行远程学习时获得的结果，同时对其性能进行了测量。该系统的硬件是基于一个带有局域网网络控制器的PC机和一个实现CCITT H.261算法的压缩卡。我们的网络环境包括一个校园网(以太网连接路由器和网桥)和一个广域网连接(0.5 Mbit/s帧中继)到150英里外的另一所大学。在这种环境中，TCP/IP被用作传输和网络协议套件。首先在主观感知的基础上分析了四个不同子网的视频会议应用质量。然后，在不同的后台流量负载下，在这些子网中测量应用程序的传输速率和TCP重传次数。正如人们所设想的那样，当网络环境变得越来越苛刻时，音频就会出现严重的问题。对于视频，问题就不那么明显了。然而，可以观察到感知质量的轻微下降，这与网络连接中负载和分组交换机(路由器和帧中继节点)数量的增加有关。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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Proceedings of 19th Conference on Local Computer Networks

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