5G Core (5GC) network: Get to the core of 5G

5G Core (5GC) is the heart of a 5G mobile network. It establishes reliable, secure connectivity to the network for end users and provides access to its services. The core domain handles a wide variety of essential functions in the mobile network, such as connectivity and mobility management, authentication and authorization, subscriber data management and policy management, among others. 5G Core network functions are completely software-based and designed as cloud-native, meaning that they’re agnostic to the underlying cloud infrastructure, allowing higher deployment agility and flexibility.

With the advent of 5G, industry experts defined how the core network should evolve to support the needs of 5G New Radio (NR) and the advanced use cases enabled by it.

Together, they developed the new 3GPP standard for core networks known as 5G Core (5GC), which includes new network functions (NFs) to the Core Network. The figure below depicts the 5GC network architecture with some of its main NFs associated to the packet core and user data management domains.

3GPP 5G Core architecture

The new 5GC architecture is based on what is called a Service-Based Architecture (SBA), which implements IT network principles and a cloud-native design approach. In this new architecture, each network function (NF) offers one or more services to other NFs via Application Programming Interfaces (API). Each NF is formed by a combination of small pieces of software code called as microservices. Some microservices can even be re-used for different NFs, making implementation more effective and facilitating independent life-cycle management – which allows upgrades and new functionalities to be deployed with zero impact on running services.

Disclaimer and acronyms

This diagram does not include all the network functions (NF) rather than focus on those that are most associated to the packet core and user data management domains.

All NFs shown in this diagram are part of Ericsson’s Cloud Core portfolio except for:

• CHF (Ericsson’s BSS portfolio)
• GMLC and LMF (Ericsson’s OSS portfolio)
• (R)AN (Ericsson’s RAN portfolio)
• AF that is a function outside CSPs’ domain
• DN that is the data network being accessed by the UE (e.g., internet)

Acronyms

5G-EIR
5G Equipment Identity Register
NSSF
Network Slice Selection Function

AF
Application Function
NWDAF
Network Data Analytics Function

AMF
Access and Mobility Management Function
PCF
Policy Control Function

AUSF
Authentication Server Function
(R)AN
(Radio) Access Network

CHF
Charging Function
SMF
Session Management Function

GMLC
Gateway Mobile Location Centre
UE
User Equipment

LMF
Location Management Function
UDM
Unified Data Management

DN
Data Network
UDR
User Data Repository

NEF
Network Exposure Function
UPF
User Plane Function

NRF
NF Repository Function