What are the reasons for SCG FAILURE INFORMATION NR (Random Access Problem)?

Hey Experts,
What are the reasons for SCG FAILURE INFORMATION NR (Random access problem) usually?

Means Rach failed on NR cell.
Need to check which exact step of RACH failed.

So could be power issues?

Could be any… including power issue.

Can it be due to a DTCH configuration from SS?

Not really. DTCH has no role in RACH.

Yes, agree.

This means max number of preamble transmissions has been reached.
And UE is sending scgfailureinformationnr-r15 with failure type randomaccessproblem.

Can be either UE side power limitation or gNB side SS beam issue.

Just one more query related to scg failure information NR in EN-DC scenario.
Suppose UE sends NR SCG failure info-NR after addition of PScell(nr1), will that affect addition of nr2?
UE sends reestablishment request with cause reconfig failure when it receives RRC reconfiguration for nr2 addition.

1- B1 threshold is too low
2- LTE has more than one neighbor with same PCI
3- Device issue

Of it occures in good RF than check dedicated bwp parameters. Search spaces are not well configured.
Msg2-msg4 uses SS type1.
Br

Hi All.

For NR, if UE send SCG failure information, then does it indicates drop of MCG and SCG leg with pscell change?

What are possible scenario?

Any of the below types can-be causing scg failure:

  • t310-Expiry
  • synchReconfigFailure-SCG
  • randomAccessProblem
  • rlc-MaxNumRetx
  • srb3-IntegrityFailure
  • scg-reconfigFailure
1 Like

Thanks, that’s clear.

My query is what are procedure after SCG failure once UE declared it?
Where will UEl move?
Will it move to New SCG with same MCG ?

Yes. What I have seen is with same MCG UE will retry either same SCG or new SCG but MCG remains unchanged unless any threshold based HO to new MCG.

I believe after SCG failure, NW needs to configure new or same SCG based on measurement.

UE just follows.

Is it like re-establishment request which can be same on different cell?

Please tell what measurement Indicates here…

Reestablishment is UE initiated procedure, only for primary or master cell.

NW will need to Reconfigure SCG again based on UE provided or blind measurements.

Or just release it!