5G IDENTIFIERS : GUTI, SUPI, SUCI, AMF NAME, GUAMI

5G Identifiers:

As similar to LTE architecture , 5G architecture contained identifiers which helps to identify the user uniquely.

However along with IMSI there are few new identifier has been introduced in 5G system.

Subscriber Permanent Identifier(SUPI):
SUPI is an unique ID allocated to each subscriber in 5G system used inside 3GPP system.
SUPI may contain following details:
- IMSI
- network specific identifier used for private networks which is derived from Network Access Identifier
- Line ID and an operating identifier of the operator administrating the Line ID value, used for supporting FN-BRGs
- HFC_Identifier and an operator identifier of the operator administrating the HFC_Identifier value, used for supporting FN-CRGs and 5G-CRG

When UE registers to 5G system, it does not provide SUPI directly, instead UE provides the SUPI in concealed form.
For interworking with EPC, SUPI allocated to UE is based on IMSI which is the primary identifier for EPC system.

SUBSCRIPTION CONCEALED IDENTIFIER(SUCI):
It is a privacy preserving identifier which contains the concealed SUPI.

PERMANENT EQUIPMENT IDENTIFIER(PEI):
PEI is similar to IMEI in EPC system.
UE will inform the PEI to the network together with an indication of the PEI format being used.
If the UE supports at least one 3GPP access technology (i.e. NG-RAN, E-UTRAN, UTRAN or GERAN), the UE must be allocated a PEI in the IMEI or IMEISV format.

5G GLOBALLY UNIQUE TEMPORARY IDENTIFIER:
This is similiar to GUTI in EPC system.
5G-GUTI consturcted as below:

5G-GUTI = GUAMI + 5G-TMSI

When the GUAMI identifies only one AMF, the 5G-TMSI identifies the UE uniquely within the AMF.
However, when AMF assigns a 5G-GUTI to the UE with a GUAMI value used by more than one AMF, the AMF shall ensure that the 5G-TMSI value used within the assigned 5G-GUTI is not already in use by the other AMF(s) sharing that GUAMI value.

GLOBALLY UNIQUE AMF ID(GUAMI):
GUAMI consists of MCC, MNC, AMF Region ID, AMF Set ID , AMF pointer as below.

GUAMI = MCC + MNC + AMF REGION ID + AMF SET ID + AMF POINTER

AMF Region ID : Region ID
AMF Set ID : Uniquely identifies the AMF Set within the AMF Region
AMF Pointer : one or more AMFs within the AMF Set.

5G-S-TMSI:
It is the shortest form of GUTI which helps in more efficient radio signalling procedure.
5G-S-TMSI = AMF SET ID + AMF POINTER + 5G-TMSI

AMF NAME:
Its a FQDN which uniquely identify an AMF.
The AMF Name FQDN for an AMF within an operator's PLMN shall be constructed as follows:
"<A MF-id>.amf.5gc.mnc<MNC>.mcc<MCC>.3gppnetwork.org"

For more information related to system architecture and identifiers  please refer 23.501 3gpp spec.