UE to (R)AN: AN message (AN parameters, Registration Request (Registration type, SUCI
, last visited TAI
(if available), Security parameters, Requested NSSAI
, [Mapping Of Requested NSSAI
], UE Radio Capability Update, UE MM Core Network Capability, PDU Session status, List Of PDU Sessions To Be Activated, Follow on request, MICO mode
preference, Requested DRX parameters) and UE Policy Container (the list of PSIs)).
In the case of NG-RAN, the AN parameters include e.g. SUCI
or the 5G‑GUTI
, the Selected PLMN ID and Requested NSSAI
, the AN parameters also include Establishment cause. The Establishment cause provides the reason for requesting the establishment of an RRC connection.
The Registration type indicates if the UE wants to perform an Initial Registration (i.e. the UE is in RM-DEREGISTERED state), a Mobility Registration Update (i.e. the UE is in RM-REGISTERED state and initiates a Registration procedure due to mobility or due to the UE needs to update its capabilities or protocol parameters, or to request a change of the set of network slices it is allowed to use), a Periodic Registration Update (i.e. the UE is in RM-REGISTERED state and initiates a Registration procedure due to the Periodic Registration Update timer expiry, see clause 220.127.116.11.1
) or an Emergency Registration (i.e. the UE is in limited service state).
When the UE is performing an Initial Registration (i.e., the UE is in RM-DEREGISTERED state) the UE shall indicate its UE identity as follows:
If the UE is in RM-DEREGISTERED state, the UE shall include a native 5G‑GUTI assigned by the same or an equivalent PLMN, if available; otherwise, the UE shall include a native 5G‑GUTI assigned by other PLMNs (if available).
If the UE is already in RM-REGISTERED state via another access in the same or equivalent PLMN, it shall indicate a native 5G‑GUTI (if available) allocated by the AMF during the previous Registration procedure.
If the UE is already in RM-REGISTERED state via another access in a PLMN (e.g. PLMN A) not equivalent to the PLMN the UE is trying to register with (e.g. PLMN B), the UE shall include a native 5G‑GUTI (if available) assigned by a PLMN (e.g. PLMN C) that is not the same or equivalent to the PLMN in which the UE is already in RM-REGISTERED state (PLMN A).
Otherwise, the UE shall include its SUCI in the Registration Request as defined in TS 33.501 .
When the UE is performing an Initial Registration (i.e., the UE is in RM-DEREGISTERED state) with a native 5G‑GUTI
then the UE shall indicate the related GUAMI
information in the AN parameters. When the UE is performing an Initial Registration with its SUCI
, the UE shall not indicate any GUAMI
information in the AN parameters.
If the UE previously received a UE Configuration Update Command indicating that the UE needs to re-register and that it shall not provide the 5G‑GUTI
in access stratum signalling when performing the Registration procedure, the UE performs a Mobility Registration and shall not include any GUAMI
information in the AN parameters. For an Emergency Registration, the SUCI
shall be included if the UE does not have a valid 5G‑GUTI
available; the PEI
shall be included when the UE has no SUPI
and no valid 5G‑GUTI
. In other cases, the 5G‑GUTI
is included and it indicates the last serving AMF.
The UE may provide the UE's usage setting based on its configuration as defined in TS 23.501  clause 18.104.22.168
. In case of Initial Registration or Mobility Registration Update, the UE includes the Mapping Of Requested NSSAI
(if available), which is the mapping of each S‑NSSAI
of the Requested NSSAI
to the S‑NSSAI
s of the Configured NSSAI
for the HPLMN, to ensure that the network is able to verify whether the S‑NSSAI
(s) in the Requested NSSAI
are permitted based on the Subscribed S‑NSSAI
In the case of Mobility Registration Update, the UE includes in the "List of PDU Sessions To Be Activated" the PDU Sessions for which there are pending uplink data. In some cases (see TS 24.501
) the UE may include PDU Sessions in the "List of PDU Sessions To Be Activated" even if there are no pending uplink data for those PDU Sessions.
The UE MM Core Network Capability is provided by the UE and handled by AMF as defined in TS 23.501  clause 5.4.4a
The UE includes in the UE MM Core Network Capability an indication if it supports Request Type flag "handover" for PDN connectivity request during the attach procedure as defined in clause 22.214.171.124.1 of TS 23.501
If available, the last visited TAI
shall be included in order to help the AMF produce Registration Area for the UE.
The Security parameters are used for Authentication and integrity protection, see TS 33.501
. Requested NSSAI
indicates the Network Slice Selection Assistance Information (as defined in clause 5.15 of TS 23.501
The PDU Session status indicates the previously established PDU Sessions in the UE. When the UE is connected to the two AMFs belonging to different PLMN via 3GPP access and non-3GPP access then the PDU Session status indicates the established PDU Session of the current PLMN in the UE. The List Of PDU Sessions To Be Activated is included to indicate the PDU Session(s) for which the UE intends to activate UP connections.
A PDU Session corresponding to a LADN shall not be included in the List Of PDU Sessions To Be Activated when the UE is outside the area of availability of the LADN. The Follow on request is included when the UE has pending uplink signalling and the UE doesn't include List Of PDU Sessions To Be Activated, or the Registration type indicates the UE wants to perform an Emergency Registration. In Initial Registration and Mobility Registration Update, UE provides the UE Requested DRX parameters, as defined in clause 5.4.5 of TS 23.501
The UE provides UE Radio Capability Update indication as described in TS 23.501
The UE access selection and PDU session selection identifies the list of UE access selection and PDU session selection policy information stored in the UE, defined in clause 6.6 of TS 23.503
. They are used by the PCF to determine if the UE has to be updated with new PSIs or if some of the stored ones are no longer applicable and have to be removed.