There are many good reasons for operators to deploy a new core network and move to 5G standalone (SA). But offering services linked to new 5G capabilities such as network slicing, edge applications, fixed/mobile convergence and — in time — ultra-reliable low-latency communications (URLLC) is the primary motivation.

However, the transition to 5G SA is also an opportunity for operators to introduce a new operating model that is agile and efficient. By modernizing their core network infrastructure, operators can achieve greater automation, new scaling and resiliency models, and new methods of network and service orchestration. Clearly, advanced services and advanced infrastructure go hand-in-hand.

So how should operators introduce 5G core (5GC) from a network infrastructure perspective?

The 3GPP Service-Based Architecture (SBA) for 5GC specifies a functional architecture and standardized interfaces. And although implementation is the choice of the operator or vendor, in practice, the expectation is that 5GC will be deployed on software-defined infrastructure. It is increasingly clear that this means a "cloud-native" deployment. In broad terms, this means 5GC implementations that use microservices, containers, centralized orchestration, CI/CD, open APIs, service meshes, and so on.

But while the target for 5GC is clear enough, how to make the transition? And what role should operators' existing virtual infrastructure play? The answer to these questions depends on careful calibration of factors such as the commercial launch timeline, the stability of the operator's infrastructure platform, the maturity of the operations team, network vendor product readiness and the penetration of SA-compatible devices in the customer base.

Interim virtual infrastructure platforms to support 5GC…
The following figure shows how today's virtual infrastructure platforms, originally designed for network functions virtualization (NFV), can be used to support 5GC ahead of a transition to cloud-native infrastructure.

Figure 1: Cloud-native 5G core infrastructure Source: Ericsson

To the left, the figure shows the NFV infrastructure stack that, in most advanced operators, is now a mature platform with well-tested operating models and a high degree of availability/reliability. This can run both virtual network function (VNF) and cloud-native apps that make up 4G and 5GC networks. In this scenario, VNFs run, as expected, in virtual machines (VMs). Cloud-native apps run, as expected, in containers; however, these containers are themselves deployed in VMs. On face value, it is less than ideal to deploy apps into containers, which are then deployed in VMs. So why would an operator consider this? If vendors are offering cloud-native 5GC apps, why not go direct to the target platform, shown to the right of the figure, with containers deployed direct to bare metal?

The main reason for this interim phase is that an operator may need to rapidly deploy 5GC but does not yet have a cloud infrastructure platform capable of running containerized workloads that can meet the requirements of mission-critical telecom networks. As an interim step, using the virtualized infrastructure for certain 5GC functions provides assurances that very demanding availability targets will be met. This approach makes it possible to deploy cloud-native 5GC applications (already available from vendors) right away and then migrate rapidly to a cloud-native platform when it is available.

…but rapid progress toward cloud-native
It is also the case that the industry is making rapid progress to the cloud-native architecture shown to the right of the figure. In the case of advanced operators in progressive markets, this transition will be very fast. The infrastructure stack is increasingly mature and hardened, and operators are quickly gaining the skills and operating know-how required to run 5GC on these platforms. Heavy Reading expects cloud-native 5GC deployments to scale rapidly from 2021 onwards.

The move to SA operation using 5GC is clearly of great importance. But to understand how and when this move will affect operators, it must be part of a wider industry transition to 5G networks that incorporates massive investment in radio access network (RAN), transport and cloud infrastructure, with associated management software. To deliver advanced 5G services to business and consumers requires an extraordinary level of systems thinking — and 5GC is a critical component.

— Gabriel Brown, Principal Analyst – Mobile Networks & 5G, Heavy Reading

This blog is sponsored by Ericsson.