Usefulness of QoS in Multidimensional QoE Prediction for Haptic-Audiovisual Communications

This article investigates prediction of Quality of Experience (QoE) by comparing borrowing-from-neighbor situations and isolated ones. We demonstrate that joint utilization of multiple QoE measures enhances the accuracy of QoE prediction compared to that by a collection of individual QoE measures each regressed on Quality of Service (QoS) parameters, while the accuracy improvement with additional usage of QoS information in the former is limited. As an example of system that needs multidimensional QoE representation, the article gives haptic audiovisual interactive communications. We employ QoE and QoS data taken previously in an experiment, where 13 QoE measures (a five-point score each) and 12 QoS parameters (nonnegative continuous values each) are available at three average rates of load traffic. We build two kinds of Bayesianmodels for QoE prediction; one is a logistic regression model of a single QoE measure as the response variable and QoS parameters as predictors, which is a typical traditional method of discrete QoE prediction and isolated in a sense. The other is a structural equation model (SEM) with latent constructs (i.e., factors) of audiovisual quality, haptic quality, and user experience quality; the original SEM, which contains only QoE indicators of three constructs (audiovisual quality (AVQ), haptic quality (HQ), and user experience quality (UXQ)), was proposed in one of the author's previous studies. This article extends the SEM to accommodate QoS parameters. We develop two kinds of new SEMs with QoS parameters: One has three extended constructs referred to as eAVQ, eHQ, and eUXQ, each of which has both QoE and QoS indicators, and the other has separate constructs for QoE and QoS, which lead to totally six constructs (AVqoe, Hqoe, UXqoe, AVqos, Hqos, and UXqos). We performed Markov chain Monte Carlo simulation of the Bayesian models with the JAGS software in an R environment. For comparison of QoE prediction accuracy, we adopt the 10-fold cross validation method and in part widely applicable information criterion. We then found that the three-construct models outperform the logistic regression models with respect to all subjective QoE measures and that the two kinds of the models are comparable as for the objective measure. The six-construct model exhibits almost the same accuracy as that of the three-construct one unless the number of QoE measures (nqoe) in the model is small. When the number nqoe is small, single-construct models may be a better choice. We have thus learned that multiple QoE measures should be utilized jointly (i.e., borrowing from neighbor) in QoE prediction rather than resorting to QoS information only.