User-Level QoS Assessment of a Multipoint-to-Multipoint TV Conferencing Application over IP Networks

摘要

This paper studies a multipoint-to-multipoint TV conferencing application over IP networks and assesses its user-level QoS with two types of QoS mapping. In utilizing the application, the user perceives quality of the communication with every other conferee; we refer to the quality as individual user-level QoS to a conferee. According to the individual user-level QoS, he/she totally judges the quality of the application, which is refer to as overall user-level QoS for the user. The overall user-level QoS of the application can be affected by the individual one to each conferee; therefore, it is difficult to clarify QoS parameters which affect the overall user-level QoS. This paper tackles the problem by utilizing two types of QoS mapping: mapping between the two kinds of user-level QoS and that between user-level QoS and application-level QoS. In this paper, an experiment with a simple task by three conferees was carried out. The user-level QoS is assessed by one of the psychometric methods. As a result of the two types of QoS mapping, we find two interesting results. First, when a user communicates with the other two conferees, the lower individual user-level QoS has more effect on the overall user-level QoS than the higher one. Second, the individual user-level QoS can depend on not only its application-level QoS but also that of the other conferees.