School of Specs 24.501v20.0.0

3GPP 24.501 v20.0.0 — the document's own text

5.4.2.6 Abnormal cases in the UE

Taught in 4. Inside TS 24.501, the document at the centre (CT1 — the group that writes what your phone says, overview).

The following abnormal cases can be identified:

  • Transmission failure of SECURITY MODE COMPLETE message or SECURITY MODE REJECT message indication from lower layers (if the security mode control procedure is triggered by a registration procedure).

The UE shall abort the security mode control procedure and re-initiate the registration procedure.

  • Transmission failure of SECURITY MODE COMPLETE message or SECURITY MODE REJECT message indication with change in the current TAI (if the security mode control procedure is triggered by a service request procedure).

If the current TAI is not in the TAI list, the security mode control procedure shall be aborted and a registration procedure shall be initiated.

If the current TAI is still part of the TAI list, the security mode control procedure shall be aborted and it is up to the UE implementation how to re-run the ongoing procedure that triggered the security mode control procedure.

  • Transmission failure of SECURITY MODE COMPLETE message or SECURITY MODE REJECT message indication without change in the current TAI (if the security mode control procedure is triggered by a service request procedure).

The security mode control procedure shall be aborted and it is up to the UE implementation how to re-run the ongoing procedure that triggered the security mode control procedure.

  • NAS security mode command not accepted by the UE as specified in clause 5.4.2.5 and there is an ongoing:
    • service request procedure for emergency services fallback the UE shall abort the service request procedure, stop timer T3517, locally release the N1 NAS signalling connection and locally release any resources allocated for the service request procedure and enter state 5GMM-REGISTERED; or
    • registration procedure for mobility and periodic registration update triggered upon a request from the upper layers to perform an emergency services fallback procedure the UE shall abort the registration procedure for mobility and periodic registration update, stop timer T3510, locally release the N1 NAS signalling connection and locally release any resources allocated for the registration procedure for mobility and periodic registration update and enter the state 5GMM-REGISTERED; and

the UE shall attempt to select an E-UTRA cell connected to EPC or 5GCN according to the domain priority and selection rules specified in 3GPP TS 23.167 [6]. If the UE finds a suitable E-UTRA cell, it proceeds with the appropriate EMM or 5GMM procedures. If the UE operating in single-registration mode has changed to S1 mode, it shall disable the N1 mode capability for 3GPP access.