Study on enhancement of network slicing; Phase 3
The Technical Report studies the gaps and performs evaluations of potential architecture enhancements to support Network Slicing with the following objectives:
1. Study whether and how to address the following scenario in order to provide service continuity: if an existing network slice or network slice instance cannot serve the PDU session, or if the existing network slice instance cannot meet the performance requirements of the applications. The study should investigate whether deployment optimization is sufficient. Minimized system optimisations can be considered if valuable.
2. Study whether and how to initiate a registration for a rejected S-NSSAI that was rejected in a first TA of the RA but may be available in another TA of the RA.
3. Study whether and how to support the following stage one Rel-18 EASNS requirements related to roaming specified in TS 22.261 clause 6.1.2.1, i.e. Requirement on enhancement the information available to the UE in roaming scenarios regarding the availability of network slices in VPLMNs available in the roaming country, in order to allow the UE to select and obtain services from the VPLMN supporting the network slices which UE may wish to use.
4. Study whether and how to enhance the system to ensure network controlled behaviour of network slice usage including UE registration and PDU Session establishment (e.g. so that when performing NSAC the network slice can serve UEs/PDU Sessions with actual activity).
5 Study deployment considerations when a service provided has an area of service that does not overlap with the already deployed Tracking Areas and/or have a limited lifetime and how existing mechanisms including network slicing can help support such scenarios. If existing mechanisms are concluded to be not sufficient to achieve the scenarios, study whether and how additional mechanisms can resolve the analysed gap.
6. Study whether and how to enhance the support of NSAC when more than one NSACF is involved in enforcing a shared maximum allowed number of the UEs or PDU Sessions for a network slice in one PLMN or in roaming, in order to avoid fragmentation of the shared maximum allowed number. This item depends on the outcome of corresponding Rel-17 CRs.