NSA Handover steps sequence

Mobility
,
1

Hi Experts
I have a NSA scenario where :

  1. We have LTE1 cell.
  2. UE attaches to this LTE1 cell.
  3. Now network has to configure UE for A3 event (as it may have to handover to LTE2 cell in step6).
  4. Now network configures UE for B1 event to add the NR1 cell.
  5. UE measures and upon receiving report, NR1 is added .
  6. Now upon A3 event triggered, UE does handover to LTE2 from LTE1 + NR1.

Can we do steps 3 and 4 in sequence as measurement gap for step 3 is running and measurement is not released?

2

I think mgap is common for LTE and NR in case of NSA FR1.
What gap you used here?

3

Did not understand question here, kindly expalin again.

4

step4 ie measurement config for b1 event is failing due to reconfig failure when we do step3 ie meas config for a3 event.
When step 3 is bypassed there is no issue.

Gp0 ,0

5

For NSA, SMTC is configured for measuring NR.

In the step3 , mgap for LTE is also included along with A3?

6

Basically, UE attaches to LTE1 cell.
Network configures A3 event for UE to handover to LTE2.
Then network configures b1 event to add NR1 cell.

Yes we configure gp0,0 in measgapconfig

7

And when eNb send RRC Reconf for B1, the reconf fail is /RLF happening right?

8

Exactly :+1:t3:

9

It means UE is not complying to some content for that RRC reconf.
It may be due to m-gap issue or anything else.
Check content of that RRC reconf in detail.
And issue is happening with any particular device or all the devices?

10

In all devices.

11

I feel there might be some configuration issue from eNB side.

12

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13

Yes this is correct.
I am saying for measuring NR, SMTC is configured by eNB.
SMTC gives exact time when UE has to scan for NR SSB.

What I am trying to say is, MGL and SMTC should be overlaped in order to scan NR carrier (SMTC is confine din MGL).
If SMTC parameters are wrongly defined, or timing of LTE and NR are not alligned, UE cannot measure NR.
RRC Reconf failure can also happen in this case.

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14

Thank you @sadanandk2, got it :+1:t3: