School of Specs 24.501v20.0.0

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

5.4.3.6 Abnormal cases on the network side

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:

  • Lower layer failure.

Upon detection of a lower layer failure before the IDENTITY RESPONSE is received, the network shall abort any ongoing 5GMM procedure.

  • Expiry of timer T3570.

The network shall, on the first expiry of the timer T3570, retransmit the IDENTITY REQUEST message and reset and restart the timer T3570. This retransmission is repeated four times, i.e. on the fifth expiry of timer T3570, the network shall abort the identification procedure and any ongoing 5GMM procedure.

  • Collision of an identification procedure with a registration procedure for initial registration.

If the network receives a REGISTRATION REQUEST message indicating either "initial registration" or "emergency registration" in the 5GS registration type IE before the ongoing identification procedure has been completed and no registration procedure is pending on the network (i.e. no REGISTRATION ACCEPT/REJECT message has still to be sent as an answer to a REGISTRATION REQUEST message), the network shall proceed with the registration procedure for initial registration.

  • Collision of an identification procedure with a registration procedure for initial registration when the identification procedure has been caused by a registration procedure for initial registration.

If the network receives a REGISTRATION REQUEST message indicating either "initial registration" or "emergency registration" in the 5GS registration type IE before the ongoing identification procedure has been completed and a registration procedure for initial registration is pending (i.e. a REGISTRATION ACCEPT/REJECT message has to be sent as an answer to an earlier REGISTRATION REQUEST message), then:

    • If one or more of the information elements in the REGISTRATION REQUEST message differ from the ones received within the previous REGISTRATION REQUEST message, the network shall proceed with the new registration procedure for initial registration; or
    • If the information elements do not differ, then the network shall not treat any further this new REGISTRATION REQUEST message.
  • Collision of an identification procedure with a registration procedure for mobility and periodic registration update.

If the network receives a REGISTRATION REQUEST message indicating either "mobility registration updating" or "periodic registration updating" in the 5GS registration type IE before the ongoing identification procedure has been completed, the network shall progress both procedures.

  • Collision of an identification procedure with a UE initiated de-registration procedure.

If the network receives a DEREGISTRATION REQUEST message with "switch off" indication in the De-registration type IE before the ongoing identification procedure has been completed, the network shall abort the identification procedure and shall progress the UE-initiated de-registration procedure;

Else the network shall complete the identification procedure and shall respond to the UE-initiated de-registration procedure as described in clause 5.5.2.2.

  • Lower layers indication of non-delivered NAS PDU due to handover.

If the IDENTITY REQUEST message could not be delivered due to an intra AMF handover and the target TA is included in the TAI list, then upon successful completion of the intra AMF handover the AMF shall retransmit the IDENTITY REQUEST message. If a failure of handover procedure is reported by the lower layer and the N1 NAS signalling connection exists, the AMF shall retransmit the IDENTITY REQUEST message.