Access and Mobility Management Function

In Release 15, the AMF was newly introduced as the core network function responsible for Access and Mobility Management within the 5G System (5GS). Key introductions included its role in network slice management interactions, handling mobility event notifications, and managing UE-specific DRX parameters. It also gained capabilities for inter-system mobility with EPS, including support for the N26 interface and storage of EPS NAS security contexts.

• AMF congestion when receiving NAS message TS 24.502CR0051
• Add Network slice subnet management use case with assigned priority TS 28.531CR0009
• Add network slice management interactions with NFV MANO for network service priority TS 28.531CR0010
• UDM receives notification of target/new AMF after AMF planned removal TS 29.503CR0001
• Nudm_SDM retrieval of SMS Management Subscription data TS 29.503CR0037
• Introduce EFs that contain NAS full native security context from 5G Mobility Management Information. TS 31.102CR0776

+ 153 more changes

In Release 16, the AMF saw enhancements for new access types and mobility scenarios, including specific support for mobility to and from NB-IoT and the management of wireline access mobility restrictions. It also gained new capabilities for group management, such as further detailing of 5G LAN group management, and introduced functions like Service Gap control enforcement and AMF overload control for trusted non-3GPP access. Furthermore, the AMF's role expanded in service-based architecture through updated procedures for third-party trust domains and eSBA communication schemas related to AMF discovery and selection.

• Updates to AMF procedures for 3rd party trust domain TS 23.222CR0056
• 5GS Logical TSN bridge management TS 23.501CR1002
• Introduction of Inter-RAT mobility support to and from NB-IoT TS 23.501CR0895
• Mobility restrictions for wireline access TS 23.501CR0745
• eSBA communication schemas related to AMF discovery and selection TS 23.501CR0804
• Use of analytics for UE mobility procedures TS 23.501CR0900

+ 190 more changes

In Release 17, the AMF saw enhancements for mobility and network support, including specific functionality for satellite access and improved handling for mobility between Standalone Non-Public Networks (SNPNs) and between SNPNs and PLMNs. Furthermore, updates were made to AMF behaviors during registration for disaster roaming and to its exposed events as specified in TS 23.501. The release also introduced clarifications and support for mobility management based on Network Slice Admission Control (NSAC) per access type independently and for roaming cases.

• Adding the usage of extended UE Mobility analytics for LADN service TS 23.501CR2582
• Selecting the same PCF for AMF and SMF TS 23.501CR2644
• Adding the usage of Session Management Congestion Control Experience analytics TS 23.501CR2708
• Updating AMF exposed events in TS 23.501. TS 23.501CR2758
• KI#1 - T5, Enable mobility between networks TS 23.501CR2815
• Mobility support between SNPNs and between SNPN and PLMN TS 23.501CR2826

+ 173 more changes

In Release 18, the AMF saw enhancements for managing group services, including service area and LADN provisioning for enhanced group management, and for supporting non-terrestrial networks with procedures for provisioning and transferring satellite coverage data. It also introduced new failure recovery mechanisms for multicast MBS sessions and TSS monitoring, and clarified behaviors for EPS to 5GS mobility and UE policy handling.

• UPF event exposure service for TSC management TS 23.501CR3720
• Reporting the RAN timing synchronization status change from AMF to TSCTSF TS 23.501CR3807
• Service area provisioning and LADN aspects for enhanced group management TS 23.501CR3914
• Considering ML model management capability during ADRF discovery and selection TS 23.501CR3929
• Transfer of Satellite Coverage Data to a UE and AMF TS 23.501CR3956
• Clarification of AMF behaviour when it receives RFSP Index in Use Validity Time from MME during UE mobility from EPS to 5GS TS 23.501CR3991

+ 171 more changes

In Release 19, the AMF introduced enhancements for event exposure, including new capabilities for on-demand broadcast of LCS assistance data and bulk subscriptions at the AMF Set level. It also gained new parameters for the LMF data collection procedure and saw enhancements to its Namf_Communication service to improve UE positioning support. Furthermore, the release defined specific AMF behaviors for scenarios where the AM Policy Association is deleted or does not exist.

• Mobility of UEs served by MWAB TS 23.501CR5469
• AMF event exposure for supporting on-demand broadcast of LCS assistant data TS 23.501CR5580
• KI#1 Architecture for Local Offloading Management TS 23.501CR5752
• PCF's awareness of I-SMF insertion for Local Offloading Management TS 23.501CR5833
• MWAB-gNB configuration during MWAB mobility TS 23.501CR5845
• MWAB-UE Mobility Restriction TS 23.501CR5998

+ 88 more changes

In Release 20, the AMF's role was enhanced with new management capabilities, including the management of the XRM Service and WAB-gNBs as introduced in TS 28.540. Furthermore, its mobility restriction policies were extended to incorporate Forbidden EPS Areas specifically for mobility from NR to LTE.

• Inclusion of Forbidden EPS Areas in mobility restriction for NR to LTE mobility TS 23.501CR6459
• Rel-20 CR TS 28.540 Add Stage 1 for Management of XRM Service TS 28.540CR0044
• Rel-20 CR TS 28.540 Add requirements for WAB-gNB management TS 28.540CR0053
• Add CA management use case and requirement TS 28.540CR0057
• Rel-20 CR Update to management of IAB-node for NCI reconfiguration TS 28.540CR0052
• Rel-20 CR TS 28.540 add missing concepts and backgrouds of management of NG-RAN and 5GC TS 28.540CR0055