In LTE what could be the reason for No RACH Attempts?

Hi Experts.
In LTE what could be the reason for No RACH Attempts?
UE normally can read PCI and TAC but no visible any msg3 att in DU?
All config looks like for the good working cells…

Is the cell selection too not happening?
Wrong PLMN may be.
Or if SSS and PSS collide with RACH then too it won’t happen.

PLMN is fine.

Access class could be one of the reason?

Is the cell in barred state?
If not, have you already tried to perform a cell restart (cold with test)?
Maybe it is a cell sleeping.
Is the TAC OK?

No. But UE is sending rrcconnectionrequest.
But eNB has no any msg3 received.
So, UE pass successful RACH and sending msg3 but for some reason eNB doesn’t have any msg3 ATT.

Is it LTE issue? Contention resolution done after msg3?

No, there is no rrcconnsetup at all.
And on the eNB no any msg3 att at all.

Yes it can be issue for RACH fail.
Contention resolution getting failed.

Check msg3harq and contention resolution timer.
It shoulf be atleast 5 and sf64.
There is RRC request and then fail then this might help to have RRC setup from eNodeB to UE.

MaxHarqmsg3= 4 and cont_rez_timer=64
It should be enough.

Then there should be msg4.
What bt t302?
But sf is failing then this not useful.
t300 value?
So there is no mgs3 happening?

Yes, but for some reason eNB doesn’t have msg3 att counter paged at all, so if doesn’t read msg3 there can’t be msg4.

t300 =2000ms

Correct, from eNB point of view, no msg3.
Maybe is something with RRU.

Are RACH response happening?
What is RACH success rate?

Yes, RRH reset you can do.

And is this cell barred in sib1?
Can you check cell barred status?

Need to check this but UE wouldn’t send msg3 if not pass RACH anyway.

No, it is not.

May be cell reserved mode you have kept.
ra response can be done if not msg3.
Cell is reserved or unreserved too with RACH success rate?

Cell is not reserved.

Rach contention resolution after msg3.

Yes, that is correct.

It was RRU issue

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