SCG failures during Random Access Procedure

Hello Experts.

I am facing SCG failures in Nokia (NSA) and majority of the failures are occurring during Random Access Procedure mainly msg2 failures.

Maximum Preamble Transmission Count is N7(20) but majority of the cases RA attempts are even less than this and cause RACH failure and result into SCG fail.

Please advise.

Admin note: this post was updated with image below.

Is it specific for certain FGI?

Not sure about this.

We need to check from other UEs also?

Do you think this issue could be related to UE capability?

Whats your B1 threshold to add the NR?

B1 is -110.

BTW NR rf is better than B1 in all cases.

First thing to check any UL/DL intereference.

RACH failures are also happening when there’s no dominance.

That is no clear best serving PCI.

Yes, interference is there, but competitors have less ratio of these failures despite interference existence.

I think in our case, it appears that dominance is not the issue.

play with raresponsewindow. msg2 failures are happening cuz of 2 reasons, DL interferece and false msg1 (ghost RACH) attempts…

At failure location what is UE RSRP / SINR and UL SINR?
(Need to check at gNB)

For rach failure, be aware in 5G there are 3 types of SINR:


SSB SINR/RSRP is fine.