16.14.3.3 Measurements

The same principle as described in 9.2.4 applies to measurements in NTN unless hereunder specified.

The network can configure:

• multiple SMTCs in parallel per carrier and for a given set of cells depending on UE capabilities;
• measurement gaps based on multiple SMTCs;

- assistance information (e.g., ephemeris, Common TA parameters, kmac) provided in SIB19 for UE to perform measurement on neighbour cells in RRC_IDLE/RRC_INACTIVE/RRC_CONNECTED;

• two different SMTC periodicities for SMTCs per frequency layer for UE in RRC_IDLE/RRC_INACTIVE/RRC_CONNECTED;
• up to 7 SMTCs for UE in RRC_IDLE/RRC_INACTIVE for the (quasi-)Earth fixed cells, including the SMTC of the serving cell, where the UE may down-select SMTCs associated with the closest reference locations.

NW-controlled adjustment of SMTCs can be based on UE assistance information reported in RRC_CONNECTED. The UE may be configured to report the closest reference locations to assist configuration of SMTC and measurement gap. A UE in RRC_IDLE/RRC_INACTIVE can adjust SMTCs based on its location and assistance information in SIB19.

UE assistance information consists of the service link propagation delay difference(s) between serving the cell and neighbour cell(s).

For a UE in idle/inactive mode, it is up to UE implementation whether to perform NTN neighbour cell measurements on a cell indicated in SIB3/SIB4 but not included in SIB19.

For a UE in connected mode, it is up to UE implementation whether to perform NTN neighbour cell measurements on a cell included in the measurement configuration, but without corresponding satellite information in measurement configuration or in SIB19.

UE can perform time-based and location-based measurements on neighbour cells in RRC_IDLE/RRC_INACTIVE:

• The timing and location information associated to the serving cell is provided in SIB19;
• Timing information refers to the UTC time when the serving cell stops serving the current geographical area;
• Location information refers:
• In the (quasi-)Earth fixed cell scenario, to the reference location of the serving cell and a distance threshold to the reference location.
• In the Earth moving cell scenario, to the reference location of the serving cell at the epoch time and a distance threshold to the reference location.

The time-based measurement initiation may be applicable for the feeder link switchover case for cell re-selection.

Measurement rules for cell re-selection based on timing information and location information are specified in clause 5.2.4.2 in TS 38.304 [10].