A Study on Mutually Compensatory Property of Multimedia QoS

本课题主要研究IP网络上的音视频传输。本文的研究成果可以分为以下五类：1.综述了基于服务质量映射的用户级服务质量评估的研究现状，找出了该技术领域存在的问题，提出了研究方向。2.作为用户级服务质量的初步研究之一，对三种类型的网络进行了应用级服务质量评估。我们已经在DiffServ网络上用AF服务来处理Web访问和流媒体服务的应用级服务质量，IEEE 802。3.作为第二个初步研究，我们评估了音视频组播中目的地间的同步质量。在分层模型的分层网络和无线自组织网络中，比较了三种目的地间同步方案的质量。4.根据区间尺度对用户级的服务质量进行了评估。我们首先提出了一种通过两种心理测量学方法：配对比较法和比较判断法来获取区间尺度的用户级服务质量参数的方案。接下来，我们考察了端到端延迟的平均值和标准差对实时音视频传输的用户级服务质量的影响。研究了用户级服务质量的连续时间评估及其连续时间映射。5.研究了音视频传输中服务质量的互补性。我们首先使用序数尺度的MOS(平均意见得分)作为用户级的服务质量参数来研究这一特性。通过主成分分析和多元回归分析，得到了应用层和用户层之间的服务质量映射关系。此外，我们还考察了内容对互补性的影响。

This research focuses on audio-video transmission over IP networks. The research results can be classified into the following five categories.1.We have surveyed previous studies on user-level QoS assessment by means of QoS mapping, identified open problems in this technical area and found research directions for them.2.Assessment of application-level QoS has beenmade in three types of networks as one of preliminary studies on user-level QoS. We have treated application-level QoS of Web access and streaming services with AF service on DiffServ networks, that of IEEE 802. 1le wireless LANs, and the effect of segmentation mismatch on the QoS in Bluetooth networks.3.As the second preliminary study, we have assessed inter-destination synchronization quality in audio-video multicasting. The quality of three inter-destination synchronization schemes has been compared in a hierarchical network of a Tier model and in wireless ad hoc networks.4.User-level QoS has been evaluated in terms of the interval scale. We first proposed a scheme for obtaining a user-level QoS parameter of the interval scale by means of two psychometric methods : the methods of paired comparison and the law of comparative judgment. We next examined the effect of the mean and standard deviation of end-to-end delay on user-level QoS of live audio-video transmission. We also studied continuous time assessment of user-level QoS and its continuous time mapping.5.The mutually compensatory property of QoS has been investigated in audio-video transmission. We first studied the property using MOS(Mean Opinion Score), which is an ordinal scale, as the user-level QoS parameter. We then constructed a user-level QoS parameter of the interval scale and obtained QoS mapping relations between application-level and user-level by the principal component analysis and multiple regression analysis. Furthermore, we examined the effect of contents on the mutually compensatory property.