Collision Case
AMF informs SMF about HO procedure by rejecting the N1N2 Transfer Request with temporary reject cause. Also any other procedure can pre-empt the UE synchronization procedure while it is awaiting N1 update from the UE.

Step |
Description |
---|---|
1 |
If N1N2 Transfer Failure with cause as Temporary Reject Handover Ongoing is received, SMF awaits HO procedure to pre-empt PDU UE Sync Procedure. |
2 |
While awaiting N1 Update or handover from UE, if any procedure (including handover) is triggered then:
|
3 |
In case UE sync procedure is suspended by handover then on expiry of N1N2 Retry Timer, UE sync resumes after handover is processed. |
4 |
On resuming if the UE sync procedure finds that the RAT has changed then it aborts the procedure and stop any timers. |
5 |
On resuming the procedure in the same RAT the UE sync procedure reinitiates N11N1N2Transfer request message. |