database the mobile subscription is stored (in the case of UDR, composed of different memory stacks). The hnkey field identifies the key used for the encryption of the SUCI identifier. NG-RAN Network - Functional Architecture The outfield is the result of the encryption of the mobile's IMSI identity (MSIN (Mobile Subscriber Identification Number)) including the message authentication value (MAC (Message Authentication Code)). After authentication, the AMF provides a 5G-GUTI. Each 5G-GUTI is unique. This 5G-TMSI identifier is concatenated with the AMF identifier, in order to constitute the 5G-GUTI identifier (Figure 1.9). The GUAMI identity corresponds to the AMF address. The GUAMI identity is the concatenation of the identity of the PLMN and the identity of the AMF: <GUAMI> = <MCC><MNC><AMF Identifier> The 5G-S-TMSI identifier combines the AMF identity (AMF pool ID and pointer) as well as the 5G-TMSI identifier: <5G-S-TMSI> = <AMF Set <AMF Pointer><5G-TMSI>. The 5G-S-TMSI identifier is used as a radio identification for paging notifications. 5G-GUTI (80 bits) ID PLMN ID AMF 5G TMSI 24 bits 24 bits 32 bits ID region AMF ID pool AMF ID AMF 5G TMSI 12 bits 12 bits 8 bits 10 bits 32 bits GUAMI - 48 bits Figure 1.9. The fields of the 5G-GUTI identifier Once registered, the connection state of the mobile at the AMF level is either the connected state (CM-CONNECTED) or the standby state (CM-IDLE). In the CM-CONNECTED state, a NAS connection is established between the mobile and the AMF function. Because the NAS connection is encapsulated in the RRC message, the mobile is both in the CM-CONNECTED state with the AMF and in the RRC_CONNECTED state with the NG-RAN node. The NG-RAN node creates a UE context with RNTI (Radio Network Temporary Identifier). NG-RAN and 5G-NR After a period of inactivity, the NG-RAN node can: - suspend the radio connection. The mobile goes to the RRC INACTIVE state, the context is kept by the NG-RAN node and the UE context is kept at the AMF level (the mobile is still in the CM-CONNECTED state); 