3GPP 38.300 v19.3.0 — the document's own text
9.2.1.2 Cell Reselection
Taught in 6. The three states a device sits in (TSG RAN — the group that specifies the radio, in depth).
A UE in RRC_IDLE performs cell reselection. The principles of the procedure are the following:
- Cell reselection is always based on CD-SSBs located on the synchronization raster (see clause 5.2.4).
- The UE makes measurements of attributes of the serving and neighbour cells to enable the reselection process:
- For the search and measurement of inter-frequency neighbouring cells, only the carrier frequencies need to be indicated.
- Cell reselection identifies the cell that the UE should camp on. It is based on cell reselection criteria which involves measurements of the serving and neighbour cells:
- Intra-frequency reselection is based on ranking of cells;
- Inter-frequency reselection is based on absolute priorities where a UE tries to camp on the highest priority frequency available;
- A Neighbour Cell List (NCL) can be provided by the serving cell to handle specific cases for intra- and inter-frequency neighbouring cells;
- Exclude-lists can be provided to prevent the UE from reselecting to specific intra- and inter-frequency neighbouring cells;
- Allow-lists can be provided to request the UE to reselect to only specific intra- and inter-frequency neighbouring cells;
- Cell reselection can be speed dependent;
- Service specific prioritisation;
- Cell-type-specific prioritisation, e.g., HSDN cell and mobile IAB cell;
- Slice-based cell reselection information can be provided to facilitate the UE to reselect a cell that supports specific slices.
In multi-beam operations, the cell quality is derived amongst the beams corresponding to the same cell (see clause 9.2.4).