Study on Multimedia Networking in ATM Networks

1实时视频传输的网络服务我们研究了适合实时视频传输的网络服务。通过对基于带宽预留的业务（ATM网络中CBR业务类）和统计复用业务（VBR业务类）的比较，表明前者可以实现高质量、高效率的视频传输。此外，为了公平地共享用户之间的带宽，我们提出了基于效用的带宽分配方案。2 MPEG编码系统的实时视频传输考虑到所需的带宽不一定被保留的视频传输的事实，我们提出了MPEG编码系统，它为用户提供了尽可能高的质量的视频流的可用带宽。此外，为了同时满足多个用户的QoS要求，我们提出了分层编码算法，产生多层的视频流。3视频多播与各种QoS要求的考虑在分布式多媒体系统中，QoS要求不同的用户之间，因为用户的环境的异构性。我们提出的视频组播协议，为用户提供高质量的视频流考虑到用户的QoS要求和可用的带宽。4多媒体应用系统与QoS的分布式多媒体系统需要在系统内的每个实体的QoS保证。我们介绍的QoS控制方法，使有效的资源利用和最大限度地提高提供的视频质量相结合的带宽预留为基础的网络服务和实时操作系统。

1 Network service for real-time video transferWe investigate the network service suitable for the real-time video transfer. Comparing the band- width reservation based service (CBR service class in ATM networks) and the statistical multiplexing service (VBR service class), it is shown that the high quality and effective Video transfer can be achieved by the former class. Further, to fairly share the bandwidth among users, we propose the utility-based bandwidth allocation scheme.2 MPEG coding system for real-time video transferConsidering the fact that the required bandwidth cannot necessarily be reserved for the video transfer, we propose the MPEG coding system which provides a user with the video stream of as high quality as possible on the available bandwidth. Further, to satisfy the QoS requirements of a number of users simultaneously, we propose the hierarchical coding algorithm which produces the video stream of multiple layers.3 Video multicasting with consideration on various QoS requirementsIn the distributed multimedia system, the QoS requirement differs among users because of the heterogeneity of user's environment. We propose the video multicast protocol which provides users with the high quality video stream taking account of the user's QoS requirement and the available bandwidth.4 Multimedia application system with QoS guaranteesThe distributed multimedia system requires QoS guarantees in each entity within the system. We introduce the QoS control method which enables the effective resource usage and maximizes the provided video quality by combining the bandwidth reservation based network service and the real-time Os.