Signalling for NR event A3

Cris3 · August 2, 2022, 8:08am

Hi experts,

I have a question on event A3 for NR. I am under EN-DC access and I have two cells with different PCI for N78 band. So, if I start a download file and move from cell1 to cell2 and vice versa I can see the PCI change and data traffic does not stop! I think it’s good!
My doubt is about the related signalling: after the MR and the ULInformationTransferMRDC messages, I see a RRCConnectionReconfiguration that contains

endc-ReleaseandAdd-r15: true

after that, I see another RRCConnectionReconfiguration that contains

endc-ReleaseandAdd-r15: false.

So, what happens? NR leg is released and then added again?Is this the correct signalling? And is it possible that some months ago this procedure was managed in a different mode?
In particular, at that time when the telephone moved from cell1 to cell2 I did not see the message with endc-ReleaseandAdd-r15: true.

I don’t find the 3gpp spec in wich the entire procedure is explained.

Thank you

aliasgherman · August 2, 2022, 5:33pm

The process is in TS 37.340.

In general, vendors have both options available. I mean that in NSA networking, you can first release the NR leg and then add another one OR just like the one shown in image below, you can send a RRC reconfiguration asking the UE to directly perform a SCG change without an explicit release-and-add procedure.