A Study on Mutually Compensatory Property of Multimedia QoS

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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.