3GPP TSG-RAN2 Meeting #130	R2-2504335
St Julian’s, Malta, May 19th – 23rd, 2025

Agenda item:		4.1
Source:	Nordic Semiconductor ASA
Title:					Clarification to NTN SI message accumulation over SI-windows
Document for:		Discussion and Decision

Conclusions
Related to SIB31(-NB) and SIB33(-NB) acquisition we also made the following observation and the proposal:
Observation 3: The SI accumulation feature should not be used when acquiring SIB31(-NB) and SIB33(-NB).
Proposal 2: Clarify in the specifications that the SI accumulation shall not be used when acquiring SIB31(-NB) and SIB33(-NB).
Text proposal
3GPP TS36.331 clarification proposal:
5.2.1.2a	Scheduling for NB-IoT

Within the SI-window, the corresponding SI message can be transmitted a number of times over 2 or 8 consecutive NB-IoT downlink subframes depending on TBS. The UE acquires the detailed time/frequency domain scheduling information and other information, e.g. used transport format for the SI messages from schedulingInfoList field in SystemInformationBlockType1-NB. The UE is not required to accumulate several SI messages in parallel but may need to accumulate a SI message across multiple SI windows, depending on coverage condition. For NTN SI messages for which modification period is not applicable the UE is not expected to accumulate SI messages across multiple SI-windows.
SystemInformationBlockType1-NB configures the SI-window length and the transmission periodicity for all SI messages.