Effect of monitor size on user-level QoS of audio-video transmission over IP networks in ubiquitous environments

This paper investigates user-level (or perceptual) QoS of audio-video transmission over IP networks with terminals of different size monitors. As the first step of our research, we treat large-sized monitors. By experiment, we assess the user-level QoS for three monitor sizes (80, 60 and 40 inches) and perform QoS mapping. In our experiment, we changed the monitor size by using a projector. The user-level QoS is assessed by the method of successive categories, which is one of the psychometric methods. Moreover, we performed QoS mapping from application-level to user-level with multiple regression analysis. The experimental result indicates that when the degradation of the quality of the audio-video transmission is not noticeable, the user-level QoS of the large monitor size (i.e., 80 inch) becomes the highest. We also observe that when we can notice a low level of degradation of the transmission, the user-level QoS parameter of the large monitor size becomes the smallest. When the degradation is too much, we hardly notice any difference in the user-level QoS between the monitor sizes. We thus confirmed that the monitor size is one of important application-level QoS parameters we must consider