Analysis of VR/XR Services Quality of Experience based on Retrial Queueing System with Feedback

In the paper, a model for Virtual Reality (VR) and Extended Reality (XR) service environments is proposed in the form of a retrial queueing system with feedback. In such systems, users may repeatedly attempt to access services when resources are unavailable and may also reinitiate requests due to dissatisfaction, making retrial and feedback mechanisms essential for realistic modeling. Taking into account that user experience is highly sensitive to the service quality (mostly latency), we aim to estimate a proportion of satisfied and unsatisfied requests by the asymptotic analysis approach. An asymptotic analysis under a long retrial delay condition is employed to obtain tractable analytical expressions for system performance. Based on this approach, the analytical expressions for system performance measures, such as probability distributions of the number of customers, waiting and sojourn time, are derived. In addition, a QoE-oriented framework is incorporated by estimating feedback probabilities as a function of customers waiting time, thereby enabling the model to capture user-driven dynamics. Finally, numerical experiments are presented to illustrate the applicability of the model and to validate the accuracy of the asymptotic results.