3GPP TSG RAN WG2 #130	R2-2503986
St. Julians, Malta, May 19th – 23rd, 2025


Agenda Item:	8.8.5
Source:	Toyota ITC
Title:	Regenerative payload for NTN for NR Ph3
Document for:	Discussion and Decision


1	

Conclusion
In this document, we analyse some remaining issues for regenerative scenario for NTN for NR Ph3, with the following observations and proposals:

Satellite switch with resynch:
Observation 1: In a regenerative payload scenario, for satellite switch with resynch, the two satellites belong to different cells. Due to security reasons, this may lead to additional signalling required for the satellite switch with resynch procedure. It is possible that this may reduce the usefulness of the satellite switch with resynch procedure compared to the L3 handover procedure.
Proposal 1: RAN2 should not pursue the work on satellite switch with resynch for regenerative payload until SA3 has clarified the impact required for the procedure and RAN2 concluded in turn that there are still benefits for this procedure.

Network verified UE positioning:
Observation 2: TRP change for regenerative scenario may have adverse effects on positioning procedure.
Observation 3: In a regenerative scenario which includes gNB change, inter-gNB coordination appears inefficient to reduce positioning procedure interruption effects.
Observation 4: To prevent interruption of positioning procedure, the UE reporting of incoming TRP expiration is useful. Using of relative time compared to the sending of the message appears the most efficient for this.
Proposal 2: The UE indicates incoming TRP expiration to the LMF.
Proposal 3: The UE indicates incoming TRP expiration to the LMF in a relative time compared to the sending of the message.


4.	

3GPP TSG-RAN WG2#130 											      R2-2504033
Malta, MT, May. 19th – 23rd, 2025
Agenda Item:	8.8.5
Source: 	NEC
Title:	        Stage 2 Updates for Regenerative Payload
Document for:	 Discussion
Discussion
Mobility between regenerative mode and transparent mode satellites
UE barely can distinguish regenerative mode and transparent mode, and we also concluded that UE would support regenerative mode without any additional capability. Straightforward, UE shall support mobility between regenerative mode and transparent mode, we propose to make it clear as same as for the mobility between different orbits. 
Proposal 1: clarify UE supports mobility between gNBs operating with transparent and regenerative NTN payloads in section 16.14.3.2


Satellite switch with re-synchronization
RAN2 has discussed several times on supporting satellite switch with re-synchronization in regenerative mode, but could not agree, because satellite switch means gNB changes in regenerative mode, and much more work must be done especially in RAN3. At this point, we can confirm that it will not be supported in Rel19, and hence it should be clarified the section below is only for transparent mode:

Proposal 2: clarify in section 16.14.3.2.3 that satellite switch with re-synchronization is only for transparent mode

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3GPP TSG-RAN WG2 Meeting #130  	                            R2-2504058
St.Julians, Malta, May 19th – 23rd, 2025					                (Resubmission of R2-2502494)		             
Agenda Item:	8.8.5
Source: 	Sony
Title:	Satellite switch with re-sync in regenerative payload
Document for:	Discussion 

Conclusion
We have the observation as following:
Observation 1: It’s difficult to support satellite switch with re-sync in regenerative payload architecture without any changes compared to Rel-18 NTN.  
We propose RAN2 to discuss following proposals:
Proposal 1: Re-sync for regenerative payload will not be supported in Rel-19 NTN.  



  

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