Measuring Service Continuity in Integrated TN/NTN for 5G-Advanced and 6G

Service continuity has been defined in 3GPP TS 22.261 as the " uninterrupted user experience of a service that is using an active communication when a UE undergoes an access change without, as far as possible, the user noticing the change". Such definition remains open, is not associated with KPIs and thus, cannot be used to compare the many architecture and business options that can be envisaged to deploy and operate 3D networks. In this paper, we propose a generic three-phased approach, with KPIs, to quantify the seamless performance of TN / NTN switching. We also discuss the purpose, applicability and order of magnitude of each KPI, based on concrete examples.