Next Generation Core Network

Description

The Next Generation Core Network (NGC), more commonly standardized as the 5G Core Network (5GC), represents a radical architectural shift from the previous Evolved Packet Core (EPC). It is built on a cloud-native, Service-Based Architecture (SBA) where network functions (NFs) are modular software entities that expose their capabilities via HTTP/2-based service interfaces. The core control plane functions interact using these RESTful APIs, allowing for greater flexibility, scalability, and automation. Key Network Functions include the Access and Mobility Management Function (AMF), which terminates NAS signaling and handles mobility; the Session Management Function (SMF), responsible for PDU session establishment, modification, and release, including IP address allocation and QoS policy control; the User Plane Function (UPF), which is the anchor point for data packet routing, forwarding, inspection, and policy enforcement; the Authentication Server Function (AUSF) and Unified Data Management (UDM) for security and subscription data; and the Network Repository Function (NRF) which enables service discovery. The NGC separates the user plane (UPF) from the control plane (CP), a principle known as Control and User Plane Separation (CUPS), which allows for independent scaling and deployment of resources, crucial for edge computing. It introduces the concept of a PDU Session, which is a connection between a UE and a Data Network (DN) that provides a specific service with a guaranteed set of QoS flows. The NGC works by having the UE register with the network via the AMF, which then orchestrates with the SMF and UPF to establish a PDU Session. All policy decisions are centralized in the Policy Control Function (PCF), which provides rules to the SMF and UPF. This architecture natively supports Network Slicing, allowing the creation of multiple logical networks on a common physical infrastructure, each tailored for specific service needs like enhanced Mobile Broadband (eMBB), Massive IoT (mIoT), or Ultra-Reliable Low-Latency Communications (URLLC).

Purpose & Motivation

The NGC was created to address the limitations of the 4G EPC, which was primarily designed for mobile broadband internet access. The explosion of diverse use cases envisioned for 5G—from massive IoT sensors to mission-critical communications and immersive media—required a core network that was far more flexible, scalable, and efficient. The EPC's monolithic architecture and tight coupling of functions made it difficult to deploy new services quickly or to optimize resources for specific latency or bandwidth requirements. The NGC solves these problems through its cloud-native, service-based design, which enables agile deployment, scaling, and lifecycle management of network functions using DevOps principles. It was motivated by the need to support network slicing as a fundamental capability, allowing operators to create virtualized, end-to-end networks for different customers or services on demand. Furthermore, by cleanly separating the user plane, the NGC facilitates the deployment of UPFs at the network edge, drastically reducing latency for applications like autonomous vehicles and industrial automation. Its creation marks the transition of telecom networks into true software-defined platforms capable of supporting the digital transformation of industries.

Key Features

• Cloud-native, Service-Based Architecture (SBA) with HTTP/2 APIs
• Native support for end-to-end Network Slicing
• Control and User Plane Separation (CUPS) for flexible deployment
• Unified policy framework managed by the Policy Control Function (PCF)
• Support for concurrent access types (3GPP and non-3GPP) like Wi-Fi
• Stateless network functions for high resilience and scalability

Evolution Across Releases

Defining Specifications