The core is the heart of a mobile network: Evolved Packet Core powers 4G LTE networks, the 5G Core powers standalone 5G networks.
The Evolved Packet Core (EPC) converged voice and data by replacing circuit switching with packet switching. That shed a foundational concept in telecommunications: that point-to-point communications required an open circuit. The convergence of voice and data as manageable digital information transformed mobile communications. And 4G LTE has been a driver of global enterprise and consumer telecom demand ever since.
The EPC was introduced by 3GPP in Release 8. The EPC comprises four core elements. The core includes the Serving Gateway (SGW), the PDN Gateway (PGW), the Mobility Management Entity (MME) and the Home Subscriber Server (HSS).
User equipment (UE) connects to the EPC through eNodeB base stations. The SGW manages User Plane (UP) data, while the MME handles Control Plane (CP) functions. The HSS manages User Equipment (UE) authentication. The PGW connects the EPC to external IP networks.
“It was decided to have a ‘flat architecture’. The idea is to handle the payload (the data traffic) efficiently from performance and costs perspective. Few network nodes are involved in the handling of the traffic and protocol conversion is avoided,” said the 3GPP.
5G Non-Standalone Architecture (NSA) pairs a 5G Radio Access Network (RAN) to the EPC. Core network functions remain in the EPC.
5G’s Enhanced Mobile Broadband (eMBB) is the first practical exposure enterprise and consumers have to 5G in most regions. And it’s the tip of the spear of a new generation of 5G services. Those services only work with the transition to a cloud-native core.
“This approach allowed new 5G services to be introduced quickly while maximizing the reuse of existing 4G networks. However, this is also the reason why it’s impossible to unlock 5G’s full potential using these networks to support the vast majority of critical internet of things (IoT) and industrial automation use cases,” said Ericsson.
The transition to cloud-native
Enhanced broadband speeds and better reliability are hallmarks of 5G. But the real meat of the new standard lies in other innovations. Ultra-reliable low latency communications (URLLC), for example. Much greater UE density than ever before, enabling massive machine-type communication (mMTC) and the Internet of Things. Mobile edge computing (MEC) and network slicing, of course. Only the cloud-native 5G core makes and more this possible.
5G NSA gives carriers better operational flexibility to transition to 5G, and it’s already attracting consumers in droves. 4G global network coverage continues to expand in 2021, but 5G on a sharp rise, according to GSMA.
EPC will continue to serve as an engine for mobile telecommunications far into the future. It’s the heart of 4G LTE networks. But the next transition for core network functions comes with the standalone (SA) 5G Core (5GC). 3GPP Release 15 defined the 5GC. The 5GC employs a cloud-native Service-Based Architecture (SBA).
Control and User Plane Separation (CUPS) which began in EPC continues in 5GC. NFs communicate with each other via a Service-Based Interface (SBI). Each NF is containerized and operates independently, and exposes its functionality to other NFs through a SBI.
“The major difference with 5G Core (5GC) compared to EPC is that 5GC’s control plane (CP) functions interact in a Service-Based Architecture (SBA),” said Ericsson.
The 5GC CP separates Access and Mobility Functions (AMF) and Session Management Functions (SMF).
“Other changes include a separate Authentication Server (AUSF) and several new functions, such as the Network Slice Selection Function (NSSF) and the Network Exposure Function (NEF),” said Ericsson.
Cloud-native core
The cloud-native core of 5G enables more granular distribution of NFs. In a cloud-native core, NFs operate as combinations of microservices, with some microservices reused for multiple NFs. Microservices are Cloud Native Functions (CNFs), operating in runtime environments called containers. CNFs can replace and work alongside Virtual Network Functions (VNFs) in the same cloud.
Operating a 5GC telco cloud requires carriers to adopt a DevOps approach to managing cloud-native core network operation. DevOps is a process of continuous integration, development, deployment, testing, and monitoring central to cloud computing. The DevOps lifecycle is a continuous state of flow. Each process is fluid, happening continuously as part of an iterative, constant and repeating system.
“DevOps describes approaches to speeding up the processes by which an idea (like a new software feature, a request for enhancement, or a bug fix) goes from development to deployment in a production environment where it can provide value to the user. These approaches require that development teams and operations teams communicate frequently and approach their work with empathy for their teammates,” said Red Hat.
