Why is 5G SA taking so long?

The deployment of 5G core and the transition to 5G standalone (SA) operation – i.e., 5G without a dependency on 4G – is proving harder and taking longer than many in the industry, including me, had anticipated. In the meantime, 5G non-standalone (NSA) – i.e., where 5G supplements a 4G network – is scaling very rapidly and will support over a billion subscribers by the end of this year.

It is the case that some operators have launched 5G core and SA, albeit in a limited way (e.g., T-Mobile US, Vodafone Germany and Netherlands, Korea Telecom), and more will deploy over the next year or two. But others have reset their schedules (no names), and many more are taking a wait-and-see approach, perhaps running trials and selecting vendors but holding off on the major deployment.

So why is SA taking time to implement and scale?

In a nutshell, in the words of one anonymous operator CTO, "because it's difficult."

5G core remains a critical part of the 5G architecture. But it pays to be realistic, and so in this blog, I set out the major challenges for SA migration. What makes the process harder for operators and vendors is that these challenges are interrelated and require coordination across domains, departments and companies.

Here, then, are the key issues:

1.) Cloud native infrastructure: Developing cloud native infrastructure and the associated operations model is proving harder than most operators had expected. It certainly is not a straight-line evolution from a virtual core, but a re-architecting and re-building of the entire core platform, which in practice often means the wider telco cloud platform. You can do your own math on that.

2.) Implementing the 5G core: This is proving difficult for two reasons: 1) Mapping the 3GPP architecture to a cloud native infrastructure (as above); and 2) all the new interfaces, protocols, network functions, signaling, subscriber databases, monitoring systems, routing technologies and so on and so on, that must be introduced. Kudos to the vendor and operator teams working on this – it is a huge lift.

3.) 5G RAN coverage: To operate an SA network, coverage needs to be good enough to support control plane signaling and uplink traffic, which means a footprint somewhat equivalent to 4G. This, by definition, is a huge investment that takes time. To give them their credit, operators are embracing this challenge with gusto and making great progress. In most cases, SA will require at least one lowband 5G frequency carrier to handle indoor and other cell edge users, aggregated with a midband carrier for capacity.

4.) Carrier aggregation and spectrum refarming: Two carrier aggregation (2CA) is a start, but it is not enough; operators need more. The beauty of 5G NSA is that operators were able to double their capacity overnight. With marketing teams fixated on the latest performance benchmarking report (Yay, we do 1Gbit/s!), operators need to match the amount of spectrum in NSA – and that means more 5G carriers. 4CA is probably a good threshold for mass-market SA, with many and various additional 5G CA combinations to follow. The challenge is that each evolution requires device and RAN vendor support – which often means a new generation of device silicon, new RAN software and perhaps new radio deployments. And then, the operator must think very strategically about spectrum refarming over a multiyear period. This is, to put it mildly, not simple.

5.) SA-capable devices: SA is now available in high-end phones and chipsets, but initially with limited capabilities and not yet in any Internet of things (IoT) modules to speak of. New SA-capable devices will permeate the subscriber base over time, but the mass-market tipping point still looks ways away in many markets. Of course, this is also a device OS issue – anyone heard from Apple lately about its plans to support network slicing?

6.) You need a service differentiator: If your lowest spectrum band is allocated to 5G spectrum, you might need SA for Voice over NR (VoNR), but that is not really going to blow the doors off the marketing department. So what else is there? What is 5G SA for, and will customers notice? Here I am optimistic – I think edge services, network slicing, predictable low latency, cloud integration, XR, metaverse, wearables, industrial IoT, connected car, you name it, have potential. But these SA-enabled services need time and experimentation.

I remain a believer in 5G SA – operators need it, the industry needs it and customers need it (even if they do not know it yet). But, yes, "it's difficult" and takes a lot of work. With all that in mind, my headline is wrong; 5G SA is not taking such a long time – it is tracking in the right direction.

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