List of all possible 5G NR Handover Scenarios

Mobility
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1

Hi NR Experts.

As HO most important part so trying to list all possible HO scenarios.

Please let me know if I miss any scenario, or any scenario wrong.

For NSA HO:

  1. HO from menb cell 1 to cell 2 without sgnb cell change
  2. HO from menb cell 1 to cell 2 with sgnb cell change from cell 1 to cell 2
  3. HO from sgnb cell 1 to cell 2 with no change in menb cell
  4. Intra gnb ie between cell 1 to cell 2 of same DU ,CU
  5. Inter gnb ie between cell 1 to cell 2 between different DU ,CU
  6. Intra LTE ie between cell 1 to cell 2 of same enb considering no HO at sgnb
  7. Inter LTE ie between cell1 to cell2 of different enb considering no HO at sgnb
  8. intra LTE ie between cell 1 to cell 2 of same enb considering HO at sgnb from cell1 to cell2
  9. Inter LTE ie between cell1 to cell 2 of different enb considering HO at sgnb from cell 1 to cell 2
  10. intra freq sgnb intra gnb no charge in menb cell
  11. inter Freq sgnb intra gnb no change in menb cell
  12. intra freq Sgnb inter gnb no change in menb cell
  13. inter Freq Sgnb inter gnb no change in menb cell
  14. HO from LTE to ENDC with NR cell release during HO
  15. HO from ENDC to LTE with NR cell release during HO

SA HO

  1. NSA to SA HO
  2. SA to NSA HO
  3. SA HO from cell 1 to cell 2 ie intra gnb HO
  4. SA HO from cell 1 to cell 2 ie inter gnb HO

Please Append or delete any scenario needed or not possible in above list.

Admin note: this post was updated with image below.
List of all possible 5G NR Handover Scenarios

2

@ankgitm: Looks it cover all scenario. :wink: I’ll add if i remember another.

3

Make sure there is inter-freq as well in that list.
I would also add inter/intra du/cu if it is the case.

4

Great @marcengo, please help to append point in list. Reply here, and i will consolidate it. Thanks.

For SA to NSA and NSA to SA handover anyone if tested can tell is it like SA cell to NR cell or from SA cell to LTE cell.
As NSA is ENDC so not sure where ue will land up… but it’s required n26 interface for sure.
Concern is that in meas object at SA side we need to define LTE or NR cell Freq mapped with events A3 or A5.
Can it’s like SA to NSA cell HO i.e. intra freq with no change in menb cell.
Or SA to NSA cell inter Freq HO with no change in menb cell.
Other possibility like SA to LTE cell HO i.e. inter Freq with no change in sgnb cell.
Or SA to LTE cell HO i.e. inter Freq with change in sgnb cell.

@ NR experts working hand please comment and share your experience

5

There is no SA to NSA handover.
It is SA to LTE cell HO (IRAT) and then NR addition (NSA).

MO will be LTE frequency.

6

Thanks @sadanandk2 for clearing it :+1:
Got it so it’s SA to LTE standalone HO.
And vice versa.

7

For interworking between NR (SA) and LTE, SIB24 and N26 interfaces both are required.

8

Sib24 for reselection in Idle mode.
N26 for Connected mode.

9

Yes, from LTE → NR.

Yes.

10

For SA to LTE cell reselection which SIB used? Is it SIB5?

Please look for NSA scenario listed. Any correction needed?

11

Yes NR-> LTE SIB5

12

Any 3ggp Spec or call flow for SA intrafrequency and interfrequency HOs

13

Hello NR Experts.

  1. For NSA, if there is inactivity trigger then what will happen? Is it like sgNB release there?

  2. Is it possible to handover from FR1 to FR2 cell?

14

NSA Inactivity - inactivity is detected at SgNB in NSA scenario, post detection SgNB release required message is sent to MeNB with cause ‘user inactivity’ and UE is released from 5G.

It is very well possible to have inter frequency handover between FR1 and FR2 for both NSA and SA scenario.

In NSA some UE have per-FR measurement capability means UE can measure each frequency independently so no coordination required from MeNB. On the other hand there are few UEs which don’t have this capability for them MeNB coordination is required to configure the measurement gaps for measurement of Target FR.

So If UE and Network both support FR1 ↔ FR2 Handover is possible.

15

Thanks! :+1:

For SA in case of inactivity I think gNB will send RRC release.

16

What is the IE on UE capability to support FR1-FR2 handover?

17

UE-MRDC-CAPABILITY IE

IndependentGapConfig= Supported

These UEs will not required MeNB coordination for configuring measurement gap…

If UEs not support this capability then network should support MeNB coordination.

18

If we have SA site only like FR1 and FR2 mixed cells then is it possible considering RJIO case.

19

Yes.

If OEM provides MeNB coordination feature, it is possible for all UEs.

20

Interesting discussion over here between vendors regarding that IE

https://www.3gpp.org/ftp/tsg_ran/WG2_RL2/TSGR2_111-e/Inbox/Drafts/[Offline-041][TEI16]%20Other%20Corrections%20(Huawei)