Description
The 5G System (5GS) is the comprehensive architectural framework standardized by 3GPP for fifth-generation cellular networks. It is fundamentally structured around two primary domains: the Next Generation Radio Access Network (NG-RAN) and the 5G Core Network (5GC). The NG-RAN consists of gNBs (next-generation NodeBs) and ng-eNBs (evolved LTE eNBs connected to the 5GC), which handle all radio-related functions, including scheduling, radio resource management, and connectivity to user equipment (UE). The 5GC is a cloud-native, service-based architecture (SBA) where network functions (NFs) are implemented as software services that communicate over a common framework, typically using HTTP/2-based service-based interfaces (SBIs). This represents a radical departure from the monolithic, point-to-point interfaces of previous core networks like the Evolved Packet Core (EPC).
At the heart of the 5GC are key Control Plane and User Plane functions. The Access and Mobility Management Function (AMF) terminates the N1 and N2 interfaces, handling registration, connection, and mobility management, but is deliberately separated from session management. The Session Management Function (SMF) is responsible for session establishment, modification, and release, including IP address allocation and policy enforcement for the User Plane. The User Plane Function (UPF) is the packet gateway and router for the data plane, performing packet inspection, routing, forwarding, and applying quality of service (QoS) rules as dictated by the SMF. The UPF also enables local breakout for edge computing and supports network slicing.
Other critical functions include the Unified Data Management (UDM), which stores subscriber data and authentication credentials, the Authentication Server Function (AUSF) for authentication, and the Policy Control Function (PCF) for policy decisions. The Network Exposure Function (NEF) securely exposes network capabilities to third-party applications. The 5GS architecture is designed for flexibility, enabling network slicing—the creation of multiple logical, isolated networks on a shared physical infrastructure—to serve diverse use cases with different requirements on latency, bandwidth, and reliability. The system operates with a clear separation of the Control and User Planes (CUPS), allowing them to scale independently and be deployed closer to the network edge for low-latency services.
Purpose & Motivation
The 5G System was created to address the limitations of 4G LTE and its Evolved Packet System (EPS), which were primarily optimized for mobile broadband. The exponential growth in connected devices, the demand for ultra-low latency applications (like autonomous vehicles and industrial automation), and the need for massive machine-type communications (mMTC) for IoT rendered the previous architecture insufficient. The EPS's monolithic network functions and rigid, point-to-point interfaces made it difficult to innovate, scale efficiently, or rapidly deploy new services.
The primary motivation for 5GS was to build a future-proof, flexible, and efficient network core. By adopting a cloud-native, service-based architecture, 5GS decouples network functions from proprietary hardware, enabling deployment on commercial off-the-shelf servers and in virtualized/containerized environments. This allows for agile scaling, faster service rollout, and reduced operational costs. Furthermore, the explicit design for network slicing is a direct response to the "one-size-fits-all" nature of previous generations, allowing operators to create tailored logical networks for specific vertical industries (e.g., a separate slice for public safety, factory automation, and enhanced mobile broadband) with guaranteed performance characteristics on a common infrastructure.
Classification
Detected Changes Across Releases
from 3GPP Change RequestsSpecific changes extracted from the „Change history“ tables of 3GPP specifications (338 CRs across 6 releases). Complements the general historical overview above with the evidence-based evolution of this function.
In Release 15, the 5G System (5GS) was newly introduced, establishing core capabilities such as initial registration procedures, PDU sessions identified by a PDU session ID, and network slicing via the S-NSSAI parameter. It defined interworking and mobility with the EPS, including mode selection and handling of QoS, S-NSSAI, and the PDU session ID during inter-system changes. The release also specified support for Policy and Charging Control (PCC) over the Rx interface, Public Warning System (PWS) architectures, and various UE configurations, including access selection preferences for MO SMS over NAS and updates to NAS signalling information elements.
- new annex to 23.228 for 5GS support TS 23.228CR1174
- Adaptation to TS 23.228 due to 5GS TS 23.228CR1175
- Supporting 3GPP PS Data Off in 5GS TS 23.501CR0141
- Support of tracing in 5GS signalling: overview TS 23.501CR0474
- Handling of S-NSSAI and PDU session ID during mobility between EPS and 5GS TS 24.301CR2965
- QoS provision for interworking with 5GS TS 24.301CR2977
+ 66 more changes
In Release 16, the 5G System introduced several major enhancements focused on industrial IoT and network efficiency. These included new capabilities such as Integrated CAPIF for network exposure, 5GS Logical TSN bridge management for time-sensitive networking, and support for IAB (Integrated Access and Backhaul). The release also expanded CIoT optimizations with features like eDRX, data transfer in Control Plane, and Stateless IPv6 Address Autoconfiguration, while adding mechanisms for Service Gap control and Reliable Data Service.
- Integrated CAPIF with 3GPP EPS and 5GS network exposure TS 23.222CR0021
- 5GS Logical TSN bridge management TS 23.501CR1002
- Introduction of eDRX in 5GS TS 23.501CR0768
- Introduction of data transfer in Control Plane CIoT 5GS Optimisation TS 23.501CR0889
- External parameters provisioning to the 5GS TS 23.501CR0898
- User Plane Forwarding with Control Plane CIoT 5GS Optimisation TS 23.501CR0916
+ 95 more changes
In Release 17, the 5G System introduced support for new access technologies, specifically integrating satellite access as a new RAT. It also expanded capabilities for Proximity Services (5G ProSe) and Multicast/Broadcast Services (MBS) with the definition of a TMGI. Furthermore, the release added comprehensive support for Multi-USIM devices, introducing new procedures, indications, and handling for paging, registration, and service requests for MUSIM-capable UEs.
- Definition of TMGI for MBS in 5GS TS 23.003CR0617
- Add general 5G ProSe support to 5GS TS 23.501CR2673
- Support of new RATs in 5GS integrating satellite access TS 23.501CR2781
- 4G <-> 5GS mobility corrections to cope with areas of GERAN/UTRAN-only coverage TS 23.501CR2970
- 5GS Connection release support for 5GC/NR TS 23.501CR3088
- Interworking to 5GS with N26 when N1 mode is disabled and re-enabled TS 24.301CR3579
+ 92 more changes
In Release 18, the 5G System introduced several new capabilities including IPv6 prefix delegation, enhanced support for Service Function Chaining, and the exposure of 5GS information and Packet Delay Variation monitoring data to Application Functions. It also expanded interworking with EPS for services like Vehicle-to-Everything (A2X) communications and lawful interception during handovers, and improved access for User Equipment behind a 5G Residential Gateway via both trusted and untrusted non-3GPP networks. Furthermore, the release added support for counting UEs with active PDU sessions and introduced foundational work for 5GS assistance to application-level AI/ML operations.
- Identifier availability for Lawful Interception during Inter-MME/ MME-5GS handover TS 23.401CR3720
- VAL service over 5GS supporting EPS interworking TS 23.434CR0141
- PCF support of 5GS Packet Delay Variation monitoring based on QoS monitoring mechanism and exposed to AF TS 23.501CR3792
- IPv6 prefix delegation in 5GS TS 23.501CR3859
- Introduction of 5GS Information Exposure TS 23.501CR3887
- 5GS Assistance for Application AI/ML operation: General clause TS 23.501CR3968
+ 38 more changes
In Release 19, the 5G System introduced several new capabilities and clarifications, including support for Mobile Wireless Access Backhaul, enhanced control of UE Radio Access Technology utilization, and the introduction of no-transmit zone restrictions. The release also added initial paging with priority, integrated the GMLC into the charging architecture, and provided a 5GS common time reference traceable to UTC. Furthermore, it included specific enhancements for CIoT optimizations and V2X communications, alongside various corrections to procedures like PDU session modification during mobility and forbidden tracking area list handling for roaming.
- Adding support of Mobile Wireless Access Backhaul in 5GS TS 23.501CR5596
- Control of UE RAT utilization by 5GS TS 24.501CR6343
- List of USS addresses in 5GS TS 24.501CR6450
- No-transmit zone restriction in 5GS TS 24.501CR6451
- Initial paging with priority in 5GS TS 24.501CR6948
- Introduction of GMLC in charging architecture for 5GS TS 32.240CR0491
+ 16 more changes
In Release 20, a specific enhancement was introduced to improve charging functionality during inter-system mobility. The release corrected the handling of the PDU Session ID for the Visited Session Management Function (V-SMF) in EPS-5GS interworking scenarios. This update ensured accurate charging records when a user equipment moves between 4G EPS and 5G 5GS networks.
- Rel-20 CR 32.255 Correction on PDU Session ID Handling for V-SMF Charging in EPS–5GS Interworking TS 32.255CR0622
Explore further
Broader topics and technologies where 5GS plays a role.
Defining Specifications
3GPP specifications that define or reference 5GS, with the latest known release. Sourced from the 3GPP document catalog — see methodology.
| Specification | Title | Release |
|---|---|---|
| TR 21.905 vj00 | 3GPP Technical Terms and Definitions | Rel-19 |
| TR 21.916 vg20 | Rel-16 Description Summary | Rel-16 |
| TS 23.003 vj50 | Numbering, addressing and identification in 3GPP | Rel-19 |
| TS 23.041 vj30 | Cell Broadcast Service and Public Warning System | Rel-19 |
| TS 23.222 vj80 | Common API Framework for 3GPP Northbound APIs | Rel-19 |
| TS 23.228 vj50 | IMS Stage-2 Service Description | Rel-19 |
| TS 23.286 vj00 | V2X Application Enabler Architecture | Rel-19 |
| TS 23.401 vj50 | Evolved Packet System (EPS) Stage 2 Description | Rel-19 |
| TS 23.434 vk00 | Service Enabler Architecture for Verticals | Rel-20 |
| TS 23.501 vk00 | 5G System Architecture Stage 2 | Rel-20 |
| TS 23.554 vj70 | MSGin5G Service Application Architecture | Rel-19 |
| TS 23.632 vj10 | 5G User Data Interworking and Migration | Rel-19 |
| TR 23.732 vg00 | User Data Interworking, Coexistence, Migration Study | Rel-16 |
| TR 23.745 vh00 | Study on App Layer Support for Factories of the Future in 5G | Rel-17 |
| TR 23.758 vh00 | Study on Edge Application Architecture | Rel-17 |
| TR 23.764 vh10 | Study on V2X Application Layer Enhancements | Rel-17 |
| TR 23.794 vh00 | Study on enhanced IMS to 5GC integration | Rel-17 |
| TS 23.795 vg10 | V2X Application Architecture Study | Rel-16 |
| TR 23.973 vj00 | Separate HSS/UDM Deployment Scenarios & Solutions | Rel-19 |
| TS 24.229 vj50 | IMS call control protocol based on SIP and SDP | Rel-19 |
| TS 24.301 vj60 | NAS protocol for Evolved Packet System | Rel-19 |
| TS 24.483 vj20 | Mission Critical Services Management Object | Rel-19 |
| TS 24.484 vj30 | MCS Configuration Management | Rel-19 |
| TS 24.501 vj50 | 5G NAS Protocols Specification | Rel-19 |
| TS 24.502 vj20 | 5G Core Access via Non-3GPP Networks; Stage 3 | Rel-19 |
| TS 24.519 vh10 | TSN AF to DS-TT/NW-TT Protocol Aspects | Rel-17 |
| TS 24.526 vj30 | UE Policies for 5GS; Stage 3 | Rel-19 |
| TS 24.535 vj00 | TS 24535: (g)PTP Message Delivery Protocol | Rel-19 |
| TS 24.539 vj30 | NW-TT Protocol Aspects | Rel-19 |
| TS 24.571 vj20 | Control Plane LCS Procedures | Rel-19 |
| TS 24.623 vj00 | XCAP Protocol for Supplementary Services | Rel-19 |
| TS 24.890 vg00 | 5G NAS Protocol for 5GS Stage 3 | Rel-16 |
| TS 26.501 vj30 | 5G Media Streaming (5GMS) Architecture | Rel-19 |
| TS 26.847 vj00 | AI/ML Evaluation in 5G Media Services | Rel-19 |
| TR 26.927 vj00 | AI/ML in 5G Media Services Study | Rel-19 |
| TS 27.007 vj40 | AT Command Set for UE | Rel-19 |
| TS 28.203 vi10 | Charging management | Rel-18 |
| TS 28.204 vi11 | Charging management | Rel-18 |
| TS 28.540 vk10 | 5G Network Resource Model (NRM) Management | Rel-20 |
| TS 28.707 vj00 | EPC NRM IRP Requirements | Rel-19 |
| TR 28.816 vh00 | Charging for 5G Cellular IoT | Rel-17 |
| TR 28.839 vi10 | Technical Report | Rel-18 |
| TR 28.840 vi10 | Technical Report | Rel-18 |
| TS 28.849 vj10 | CAPIF Phase2 Charging Study | Rel-19 |
| TS 29.165 vj10 | Inter-IMS Network to Network Interface (NNI) | Rel-19 |
| TS 29.214 vj20 | Policy and Charging Control over Rx | Rel-19 |
| TS 29.507 vj40 | 5G Access & Mobility Policy Control Service | Rel-19 |
| TS 29.518 vj50 | AMF Service Based Interface Protocol | Rel-19 |
| TS 29.549 vj40 | SEAL API Specification for Vertical Applications | Rel-19 |
| TS 29.585 vj00 | TSN Interworking Protocol for 5G System | Rel-19 |
| TS 31.111 vj30 | USIM Application Toolkit (USAT) Specification | Rel-19 |
| TS 32.240 vj40 | Charging Management Architecture & Principles | Rel-19 |
| TS 32.255 vk10 | Telecom Management; Charging for 5G Data Connectivity | Rel-20 |
| TS 32.256 vj40 | 5G Connection & Mobility Charging Spec | Rel-19 |
| TS 32.260 vj10 | IMS Charging Management | Rel-19 |
| TS 32.274 vj10 | SMS Charging Management Specification | Rel-19 |
| TS 32.279 vj00 | 5G MBS Session Converged Charging | Rel-19 |
| TS 32.282 vi20 | Charging management; Time Sensitive Networking | Rel-18 |
| TS 32.290 vj50 | 5G Charging for Service Based Interface | Rel-19 |
| TS 32.298 vj30 | Charging Data Record (CDR) Parameter Specification | Rel-19 |
| TS 32.299 vj00 | Diameter Charging Applications for 3GPP | Rel-19 |
| TS 32.404 vj00 | Performance Management Definitions & Template | Rel-19 |
| TR 32.846 vh00 | Charging for ProSe in 5GS | Rel-17 |
| TS 33.127 vj50 | Lawful Interception Architecture and Functions | Rel-19 |
| TS 33.514 vk00 | 5G Security Assurance for UDM | Rel-20 |
| TS 33.545 vj20 | Security for NR Femto Subsystem | Rel-19 |
| TS 33.814 vg01 | Security aspects of enhanced Location Services (eLCS) | Rel-16 |
| TS 33.835 vg10 | Study on authentication and key management for apps | Rel-16 |
| TR 33.851 vh10 | Security for Industrial IoT in 5G | Rel-17 |
| TS 38.171 vj10 | 5G A-GNSS UE Positioning Requirements | Rel-19 |
| TS 38.300 vj00 | NG-RAN Overall Description | Rel-19 |
| TS 38.305 vj00 | NG-RAN UE Positioning Stage 2 | Rel-19 |
| TS 38.508 vj11 | 5G NR UE Radio Transmission & Reception | Rel-19 |
| TS 38.522 vj11 | UE Conformance Test Applicability Statement | Rel-19 |