5G node where are getting 0% NRleg_RET on 3 sectors

5G NR
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1

Experts,
We are having problem with one 5G node where are getting 0% NRleg_RET on 3 sectors.
SCGBearer_Setup is 100%, SCGBearer_Att is also there but NRleg_Drops 100%.
Ericsson system
NSA NR850.
SW 20.Q4.
Anchoring parameters verified.
Any help would be appreciated before I plan for reconfiguration with new BBU.

2

Seems like it’s UE lost issue.
Have you check nrarfcn value configured at LTE end?
T310, n310, maxretrlc threshold value at NR end.

3

Nrarfcn is same as ssbfrequency.
T310, n310, maxretrlc these are as per gold standard.

4

Please check if is this useful:

5

Can you check SCG failure information message there or not in L3 window?
For RA fail check maxharq parameter for msg3.

6

This is my node:

image

And this for reference node:

image

I’m from integration background.
Not sure how to apply traces.
Can check parameter level.

7

Ok. Any drive test tool there used?
Are you getting RA failed?

8

Yes, 100%.

9

So RACH related parameter need to look like for Ericsson.
Sorry I don’t have idea for exact parameter name but can correlate with preamable max tx power, max harq msg3, etc… parameters.

10

100% failures in RA. Accessibility 0%.
Could you please check LTE towards 5G relation & X2 Link status also?
If SON implemented then check configuration file again.
That’s what I know.

11

Anchoring parameter and relations are good.

12

Isn’t NSA a type of contention-free RA?
I would also recommend to check what RACH parameters is eNB sending to UE for RACH on gNB.

13

I’ve seen examples with non-contention based also.

14

I wouldn’t say NSA is contention free. It can be Contention based or contention free.

15

Thanks. What’s the reason of making it contention based?
Surely eNB has confirmed resources are available at target gNB before sharing details with UE.
So why not make it easier to attach?

16

Not sure, but lot of the networks are using contention based.
I agree with you that is probably better to use contention free.

17

I think it’s like normal handover.
Better to do free of CB .
Bbut nothing restricts to use CB.

18

I think it’s more like an SCell addition type scenario.
So assumed it’s always contention-free.

Interesting, thanks for sharing.

19

I thought even Scell addition can be CB based.

20

Scell addition you are saying for CA?
In CA scell addition doesn’t require RACH.

For SgNB addition, primarily contention free rach is used.
But if gNB is running out of dedicated preamble then it can skip giving dedicated preamble in RRC reconfiguration.
In this case contention based RACH is used.