Performance metrics and configuration strategies for group network communication

There is an increasing number of group-based multimedia applications over the Internet, for example, voice conference or multi-player games. For these applications, it is often necessary to select a strategy to distribute the multimedia streams or mixing the multimedia stream data so as to provide better quality of service (QoS) guarantees. However, there is no appropriate metrics to evaluate the QoS of a group multimedia session, despite abundant literature on how to evaluate the QoS for two-party communication (e.g. MOS, E-Model). In this paper, we propose a new measure which is called the group mean opinion score (GMOS). To leverage on existing work, our definition of GMOS is based on two-party MOS, hence, it can be estimated via measurement of network parameters and fitting these data into the E-Model. We conduct large scale experiments using the latest SKYPE conference software. We first calibrate the GMOS based on the subjective scores of our experiments, then for individual conference sessions, we check whether our approach can pick a server configuration strategy to achieve the best GMOS. The study shows our proposed methodology is very promising and the potential of applying to other group-based applications.