Content for  TS 38.304  Word version:  18.2.0

This state is applicable for RRC_IDLE and RRC_INACTIVE state. When camped normally, the UE shall perform the following tasks:

• monitor the paging channel of the cell as specified in clause 7 according to information broadcast in SIB1;
• monitor Short Messages transmitted with P-RNTI over DCI as specified in clause 6.5 in TS 38.331;
• monitor relevant System Information as specified in TS 38.331;
• perform necessary measurements for the cell reselection evaluation procedure;
• execute the cell reselection evaluation process on the following occasions/triggers:
  1. UE internal triggers, so as to meet performance as specified in TS 38.133;
  2. When information on the BCCH used for the cell reselection evaluation procedure has been modified.
  3. When the network slice(s) and/or NSAG information received from NAS changes.

At reception of RRCRelease message to transition the UE to RRC_IDLE or RRC_INACTIVE, UE shall attempt to camp on a suitable cell according to redirectedCarrierInfo if included in the RRCRelease message. If the UE cannot find a suitable cell, the UE is allowed to camp on any suitable cell of the indicated RAT. If the RRCRelease message does not contain the redirectedCarrierInfo, UE shall attempt to select a suitable cell on an NR carrier. If no suitable cell is found according to the above, the UE shall perform cell selection using stored information in order to find a suitable cell to camp on. When returning to RRC_IDLE state after UE moved to RRC_CONNECTED state from camped on any cell state, UE shall attempt to camp on an acceptable cell according to redirectedCarrierInfo, if included in the RRCRelease message. If the UE cannot find an acceptable cell, the UE is allowed to camp on any acceptable cell of the indicated RAT. If the RRCRelease message does not contain redirectedCarrierInfo UE shall attempt to select an acceptable cell on an NR frequency. If no acceptable cell is found according to the above, the UE not in SNPN Access Mode shall continue to search for an acceptable cell of any PLMN in state any cell selection. If no acceptable cell is found according to the above, the UE in SNPN access mode shall continue to search for an acceptable cell of any SNPN in state any cell selection.

This state is applicable for RRC_IDLE and RRC_INACTIVE state. In this state, the UE shall perform cell selection process to find a suitable cell. If the cell selection process fails to find a suitable cell after a complete scan of all RATs and all frequency bands supported by the UE, the UE not in SNPN Access Mode shall attempt to find an acceptable cell of any PLMN to camp on, trying all RATs that are supported by the UE and searching first for a high-quality cell, as defined in clause 5.1.1.2. If the cell selection process fails to find a suitable cell after a complete scan of all frequency bands supported by the UE, the UE in SNPN access mode shall attempt to find an acceptable cell of any SNPN to camp on. The UE, which is not camped on any cell, shall stay in this state.

This state is only applicable for RRC_IDLE state. In this state, the UE shall perform the following tasks:

• monitor Short Messages transmitted with P-RNTI over DCI as specified in clause 6.5 in TS 38.331;
• monitor relevant System Information as specified in TS 38.331;
• perform necessary measurements for the cell reselection evaluation procedure;
• execute the cell reselection evaluation process on the following occasions/triggers:
  1. UE internal triggers, so as to meet performance as specified in TS 38.133;
  2. When information on the BCCH used for the cell reselection evaluation procedure has been modified.
• regularly attempt to find a suitable cell trying all frequencies of all RATs that are supported by the UE. If a suitable cell is found, UE shall move to camped normally state.
• if the UE supports voice services, the UE is not in SNPN access mode, and the current cell does not support IMS emergency calls as indicated by the field ims-EmergencySupport in SIB1 as specified in TS 38.331, the UE shall perform cell selection/reselection to an acceptable cell that supports emergency calls in any supported RAT regardless of priorities provided in system information from current cell, if no suitable cell is found.
• if the UE supports voice services, the UE is in SNPN access mode, and the current cell does not support IMS emergency calls for any SNPN(s) as indicated by the field imsEmergencySupportForSNPN in SIB1 as specified in TS 38.331, the UE shall perform cell selection/reselection to an acceptable cell of any available SNPN that supports emergency calls, if no suitable cell is found.