ATM networking and video-coding techniques for QOS control in B-ISDN

摘要

Integration of video services are addressed. The view that various types of end-to-end quality of service (QOS) for video communications, ranging from videophone to high-definition television (HDTV), should be supported to utilize broadband integrated services digital network (B-ISDN) services and video data is expressed. End-to-end QOS is recognized as a function of terminal capability and network performance. The key feature of B-ISDN is that both terminal capability and network performance are selectable and controllable. In order to capture the basic characteristics of end-to-end QOS, it is necessary to conduct experiments using a prototype system. A prototype system comprising an asynchronous transfer mode (ATM) switch and video codecs is presented. The ATM switch is based on distributed-memory-switch architecture and it will provide for nonblocking cell-switching capability with a very low cell-transfer delay. Developed codecs conform to H.261 with an additional function of controlling average coding bit rate. The coding bit rate is chosen as a parameter of terminal capability and the cell-loss ratio is chosen as a parameter of network performance. From experiments using a prototype system, a relationship between coding bit rate and cell-loss ratio is obtained.