Sliced Terminal AMF and NW Selection in 5G!

I. AMF and NW Slicing Selection The AMF is selected when CN-RAN and NG RAN interact information according to Table 16.3.2.1-1 Terminal (UE) provides Temp ID or NSSAI through RRC.

II.Radio Interface Support When a service is triggered by the upper layer the terminal (UE) transmits the NSSAI via RRC in a format explicitly indicated by the upper layer.

III.Wireless Resource Isolation and Management Resource isolation can be implemented specifically tailored to avoid one slice affecting another. Whereas hardware/software resource isolation depends on the implementation, where each slice can be allocated shared, prioritized or dedicated wireless resources; depending on the RRM implementation and SLAs (as described in TS 28.541 [49]); in order to be able to differentiate traffic with different SLAs for network slices, the NG-RAN will:

• NG-RAN configure a different set of configurations for different network slices via OAM;
• Select the appropriate configuration for each network slice of traffic, and the NG-RAN receives relevant information indicating which configurations apply to this particular network slice.

Slice-based RACH configurations for RA isolation and prioritization can be included in SIB1 messages. The slice-based RACH configuration is associated with a specific NSAG, and if the UE does not provide the NSAG used for selecting the RACH configuration, the UE does not consider the NSAG used for selecting the slice-based RACH configuration.The UE determines the NSAG to be considered during the RA as specified in TS 23.501 [3].The UE will not apply the slice-based RACH configuration when the UE AS does not receive any of the information used for the random access NSAG from the NAS. information, the UE does not apply the slice-based RACH configuration.

IV Slicing Resource Handling NG-RAN nodes can use multicarrier resource sharing or resource reclassification to allocate resources to slices to support slice service continuity in case of slice resource shortage.

• In multicarrier resource sharing, RAN nodes can set up dual connections or carrier aggregations with different frequencies and overlapping coverage where the same slices are available.
• Resource reallocation allows a slice to use resources in a shared or/and prioritized pool when its own dedicated or prioritized resources are unavailable, and the use of unused resources in the prioritized pool is as described in TS 28.541 [49].
• The slicing RRM policy/limit associated with resource reallocation is configured by O&M. Measurements of RRM policy utilization based on resource types defined in TS 28.541 [49] are reported by the RAN node to the O&M and may result in the O&M updating the configuration of the sliced RRM policies/restrictions.

V. Slice-based Cell Reselection Its information may be included in the SIB16 and RRCRelease messages delivered. The slice-based cell reselection information may include: a reselection priority per frequency per NSAG and a corresponding list of cells that support or do not support slicing of NSAGs. the UE determines that the NSAGs and their priorities are to be taken into account during cell reselection (see described in TS 23.501 [3] and TS 38.304 [10]).

When slice-based cell reselection is supported and slice-based cell reselection information is provided to the UE, the UE will use the slice-based cell reselection information.Valid cell reselection information provided in the RRCRelease always takes precedence over the cell reselection information provided in the SIB message. When no slice-based cell reselection information is provided for determining any NSAG to be considered during cell reselection (as described in TS 23.501 [3]), the UE will use the general cell reselection information i.e. without considering the NSAG and its priority.