In order to make it easier for the terminal (UE) to understand which cells are available in the network and which ones are not; 3GPP defines in TS38.304 that wireless cells (Cel) in a 5G (NR) network are categorized according to the services they (can) provide as follows;.
I.Acceptable cell is a cell in which a terminal (UE) can reside to obtain limited services (to initiate emergency calls and receive ETWS and CMAS notifications). This type of cell should meet the following requirements (minimum requirements for initiating emergency calls and receiving ETWS and CMAS notifications in 5G networks); the cell is not prohibited; and it meets the cell selection criteria.
* The subdivision is not prohibited.
* Meets subdivision selection criteria.
II.Suitable cell for a terminal (UE) not operating in SNPN access mode, a cell is considered suitable if the following conditions are met:
* The cell is part of a list of selected, registered, or equivalent PLMNs and for that PLMN;
* The cell broadcasts a PLMN-ID for that PLMN that has no associated CAG-ID and the CAG unique indication for that PLMN in the UE does not exist or is false;
* The list of allowed CAGs for that PLMN in the UE includes the AG-ID broadcast by the cell for that PLMN;
* The cell selection criteria are satisfied.
According to the latest information provided by NAS:
* The cell is not banned;
* The cell belongs to at least one TA that does not belong to the list of "No Tracking Areas", which belongs to the PLMN selection requirements that fulfill the first point above.
For UEs operating in SNPN access mode, a cell is considered suitable if the following conditions are met:
* The cell is part of a UE selected SNPN or registered SNPN;
* The cell selection criteria are met;
According to the latest information provided by NAS:
* The cell is not banned;
* The cell belongs to at least one TA that does not belong to the "No Tracking Area" list, which belongs to the selected SNPN or the SNPN registered by the UE.
III.Barred cell If the system information indicates that the cell is barred, the cell is barred.
IV. Reserved cell (reserved cell) If the system information indicates that the cell is reserved, the cell is reserved, except in the following cases;
If the UE is making an emergency call, all acceptable cells of that PLMN are considered suitable for the duration of the emergency call.
On a cell that belongs to a registration area in which the provision of regional services is prohibited; A cell that belongs to a registration area in which the provision of regional services is prohibited is suitable, but only limited services are provided.
The UE may perform NR Sidelink communication or V2X Sidelink communication if the UE in the RRC_IDLE state satisfies the condition of supporting NR Sidelink communication or V2X Sidelink communication in the limited service state.
NOTE: In the RRC CONNECTED state, the UE is not required to support manual search and selection of PLMN or CAG or SNPN, and the UE can use RRC local release.
