6.2.5 AIoT Session Release Procedure

This procedure is used to release the AIoT Session between the NG-RAN and the AIOTF. The AIoT Session release procedure can be triggered by the AIOTF or the NG-RAN node and is specified in TS 38.413 [10].

The initiation of AIoT Session release may be:

• NG-RAN-initiated e.g. if the NG-RAN detects no AIoT Devices responds to the inventory procedure or the command procedure; or
• AIOTF-initiated, e.g. if the AIOTF fails validating the results of AIoT NAS Inventory Report as specified in TS 33.369 [9] in the command procedure.

Both NG-RAN-initiated and AIOTF-initiated AIoT Session Release procedures are shown in Figure 6.2.5-1.

1. NG-RAN may decide to initiate the AIoT Session release procedure. NG-RAN sends an AIoT Session Release Request message (Correlation ID, Cause) to the AIOTF directly (step 1a) or performs steps 2-3 of Message delivery to AIOTF specified in clause 6.2.4.3 (step 1b) when the indirect interface between an AIOTF and NG-RAN is used.

2. If the AIOTF receives the AIoT Session Release request message or the AIOTF decides to terminate all activities related to the AIoT Session, the AIOTF sends an AIoT Session Release Command message (Correlation ID, Cause) to the NG-RAN directly (step 2a) or performs steps 1-3 of Message delivery to NG-RAN specified in clause 6.2.4.2 (step 2b) when the indirect interface between an AIOTF and NG-RAN is used.

3. The NG-RAN node releases the AIoT Session and radio resources related to the AIoT session identified by the Correlation ID provided by the AIOTF, as specified in TS 38.300 [5]. The NG-RAN confirms the AIoT Session Release by sending an AIoT Session Release Complete message (Correlation ID) to the AIOTF directly (step 3a) or performs steps 2-3 of Message delivery to AIOTF specified in clause 6.2.4.3 (step 3b) when the indirect interface between an AIOTF and NG-RAN is used. The AIOTF releases AIoT Session.