Mobility Updating or Periodic Registration without AMF Change Call Flow

This section describes the Mobility Updating or Periodic Registration without AMF Change call flow.

Mobility Updating or Periodic Registration without AMF Change Call Flow
Mobility Updating or Periodic Registration without AMF Change Call Flow Description

Step

Description

1

The UE triggers the Mobility Updating or Periodic Registration procedure under the following conditions:

  1. The Periodic Registration timer in the UE expires. The UE sets up the registration type as Periodic in this case, and the message arrives on the AMF as an Initial UE NGAP message.

  2. The UE is in idle state and moves to an area that is not currently part of its Tracking Area List. In this case, the UE sets the type to Mobility Updating, and the NGAP message is the Initial UE message.

  3. After or during handover, the UE is an area that is not part of the current Tracking Area List. In this case, the UE sets the type to Mobility Updating, and the NGAP message is the Uplink NAS Transport.

2

If the Registration Type is Mobility Updating, the AMF computes a new Tracking Area List for the UE. The AMF then adds this to a Registration Accept and uses a Downlink NAS Transport NGAP message to send it to the UE.

3

If the registration request in the initial UE message registration type is not Mobility Updating, and the FollowOn IE was not set by the UE, the AMF sends a UE Context Release Command to the gNB to release the resources at the gNB.

If the registration type is Mobility Updating, AMF service ignores FollowOn IE and doesn’t initiate UE Context Release Command.

4

The gNB responds with a UE Context Release Complete.