On Additive and Multiplicative QoS-QoE Models for Multiple QoS Parameters

Generic relationships between QoE and QoS have been intensively discussed in literature for single QoS parameters and often found to be logarithmic or exponential. While there are many experimental studies investigating statistically the influence of several parameters on QoE, the generic relationship between them, and how to best model it, have not been discussed so far. For communication networks, however, there is a major interest from different stakeholders to have multi-dimensional QoE models. The contribution of this paper is an analysis of the generic relationship between QoS and QoE for multiple QoS parameters and its implications. We address the question of whether multi-dimensional QoE models for several parameters are additive or multiplicative. In an analytic model and with examples involving HTTP non-adaptive video streaming, we show that a multiplicative model has different properties than the current additive QoE model proposed in ITU-T standards. We want to raise sensitivity in the community on multi-factor QoE models, their properties, and the need for multi-factor studies to confirm the appropriate models.