6.2.4.3 Message delivery to AIOTF

When the AMF receives an NGAP message from NG-RAN, for example, responses to a procedure or events like Inventory Reports, the AMF determines which AIOTF to send a Namf_AIoT_Notify to and sends the information from NG-RAN to that AIOTF. The additional steps used for an indirect interface from NG-RAN towards an AIOTF is shown in Figure 6.2.4.3-1.

1. Before any NGAP messages can be routed from NG-RAN to the AIOTF, the AMF needs routing information to be able to route them, see clause 6.2.4.2. The same context created in clause 6.2.4.2 includes such routing information and can be used to route multiple NGAP messages from NG-RAN.

2. NG-RAN sends an NGAP message (AIOTF ID, Correlation ID, NGAP AIoT information, [RAN AIoT Device NGAP ID]) to an AMF. NGAP AIoT information is determined by NG-RAN depending upon the operation the NGAP message relates to.

3. AMF determines the Notification endpoint from the context using the AIOTF ID, the Correlation ID, the NG-RAN ID and optionally the RAN AIoT Device NGAP ID received in step 2 from NG-RAN, and then sends the Namf_AIoT_Notify message (AIoT NGAP Message Type, NGAP AIoT information) to the AIOTF.

Step 2 and step 3 are repeated for each NGAP message received from NG-RAN.

If the message received from NG-RAN is an Inventory Failure indicating an error or an AIOT Session Release Complete, then the AMF releases the context which is associated with the NG-RAN ID, the AIOTF ID and the Correlation ID, after sending the Namf_AIoT_Notify message to the AIOTF.