Service Management Function

In Release 15, the SMF was introduced as a core network function responsible for managing PDU sessions, including QoS mapping and user plane management for EPS interworking. It handles procedures such as validating UE location for LADN PDU session establishment and retrieving SMS management subscription data from the UDM. The release also defined the SMF's role in selecting and combining with the PGW-C, managing service area restrictions, and enforcing user plane security in scenarios like Dual Connectivity.

• Nudm_SDM retrieval of SMS Management Subscription data TS 29.503CR0037
• SMF QoS mapping TS 29.513CR0010
• CR-slice-management-security TS 33.501CR0290
• Configuration information the UE may exchange with the SMF during the lifetime of a PDU Session TS 23.501CR0003
• User Plane management to support interworking with EPS TS 23.501CR0122
• Management of service area restriction information TS 23.501CR0144

+ 55 more changes

In Release 16, key enhancements for the SMF included the introduction of the Intermediate SMF (I-SMF) to control Uplink Classifier/Branching Point (UL CL/BP) and local traffic offload, requiring new service operations for its insertion, change, and context management. The release also expanded SMF capabilities for 5G LAN group management and introduced support for selecting SMFs and UPFs based on ATSSS rules or network analytics. Furthermore, it added procedures for the SMF to handle port management information for Ethernet and TSN bridges, including the exchange of these capabilities during PDU session establishment.

• 5GS Logical TSN bridge management TS 23.501CR1002
• UL CL/BP controlled by I-SMF TS 23.501CR0848
• ATSSS-SMF and UPF selection TS 23.501CR0761
• Use of analytics for SMF selection TS 23.501CR0940
• eSBA communication schemas related to SMF discovery and selection TS 23.501CR0801
• Transfer of N4 information for local traffic switching from SMF to I-SMF TS 23.501CR1050

+ 202 more changes

In Release 17, the SMF saw enhancements for edge computing and mobility, including (I-)SMF discovery based on DNAI and an I-SMF removal procedure for target DNAI. It also introduced support for I-SMF/V-SMF restoration procedures and refined session management, such as providing QoS flow descriptions for PDU sessions used for relaying. Furthermore, updates were made to integrate analytics for Session Management Congestion Control Experience and to clarify mobility management based on NSAC.

• KI #1-1, I-SMF selection TS 23.501CR2634
• Selecting the same PCF for AMF and SMF TS 23.501CR2644
• Adding the usage of Session Management Congestion Control Experience analytics TS 23.501CR2708
• SMF function update to support Edge computing enhancement TS 23.501CR2762
• Support GERAN/UTRAN access in SMF+PGW-C TS 23.501CR2790
• EPS User Plane Integrity Protection using SMF+PGW-C TS 23.501CR3009

+ 137 more changes

In Release 18, the SMF saw enhancements for managing complex 5G Virtual Network (VN) groups, including support for groups with multiple SMF sets and enabling cross-SMF VN group communication. It also introduced new capabilities for optimized session and mobility management for temporarily available network slices and gained the ability to make specific decisions on steering parameters and PDU Set Handling Activation. Furthermore, the SMF's role was extended in event exposure, such as facilitating direct reporting of Time-Sensitive Communication (TSC) management information from the UPF.

• UPF event exposure service for TSC management TS 23.501CR3720
• 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
• KI#1: Support the enhancement of group attribute management TS 23.501CR4086
• Common EAS re-discovery initiated by SMF TS 23.501CR4144
• Support for 5G VN group with multiple SMF(Set)s TS 23.501CR4306

+ 138 more changes

In Release 19, the SMF saw significant enhancements for Local Offloading Management, introducing new I-SMF selection and insertion procedures based on a local offloading allowed indication. Key interfaces, including N11, N16a, and N38, were enhanced to support this management, and the architecture now allows PFCP sessions to be excluded from restoration upon an SMF failure when an SMF set is deployed. Additionally, the SMF gained capabilities for establishing a PDU session in a target PLMN and for including ATSSS status in session management messages.

• P-CSCF triggering SMF/PGW-C failure checking TS 23.380CR0129
• I-SMF selection/insertion based on local offloading allowed indication TS 23.501CR5604
• Local Offloading handling at I-SMF TS 23.501CR5744
• KI#1 Architecture for Local Offloading Management TS 23.501CR5752
• Local Offloading handling at I-SMF TS 23.501CR5825
• PCF's awareness of I-SMF insertion for Local Offloading Management TS 23.501CR5833

+ 98 more changes

In Release 20, the SMF saw enhancements for satellite access scenarios, specifically requiring mobility management to account for satellite radio access networks. Furthermore, the SMF's role was refined to support the management of a 5G satellite network as a radio extension of the terrestrial network with QoS capability. Procedures were also corrected for PDU Session ID handling during V-SMF charging in EPS–5GS interworking scenarios.

• SMF and PCF Selection for UIA_ARC TS 23.501CR6504
• Rel-20 CR 32.255 Correction on PDU Session ID Handling for V-SMF Charging in EPS–5GS Interworking TS 32.255CR0622