As 5G planning progresses, we’re getting more information from operators about how they’re seeing things like Open RAN, public-cloud 5G hosting, and new 5G-dependent services. Things are still very preliminary, but one thing that’s already clear is that the high cost of 5G licenses (as reflected in recent auctions) are raising the risk level for operators who simply blunder along into 5G. It’s not business as usual. What might come of the impact of these forces is critical to 5G and to network evolution overall.
The current focus of 5G is the RAN (technically, “New Radio” or NR in 5G terms), for the simple reason that most of the visible aspects of 5G (bandwidth per user and per cell) are created there, and because RAN changes are reflected in 5G devices, which have to get into the pipeline quickly or there’s no user base available for services. As essential as this early RAN-focused stuff is to jump-start the device market, it’s not likely to deliver on tangible differentiators for 5G-specific services that operators could monetize. To understand why, we’ll have to dig a bit into 5G, and perhaps invent some useful terminology.
5G, like all mobile network technologies, creates a kind of functional domain within which it offers specific features to support mobile users. Mobility management, an element of the 4G IMS and evolved packet core (EPC) are examples of this. We have an IP service network (the Internet, VPNs, or whatever), and the 4G functional domain is sort-of-glued onto it, to provide the additional stuff needed to support mobile users. Think of this as a big circle (the public data network, like the Internet) with a bunch of little circles distributed around the edge. At the point of contact, we can imagine a kind of “shim layer”, a broad outline of that central circle. Let’s look at 5G based on this.
The little circles are the metro area RAN and associated “on-ramp” technologies. These include the true 5G NR/RAN implementations, as well as on-ramp facilities for things like WiFi users and (likely) 5G fixed-wireless (5G/FTTN). Within these little circles, it’s important to be able to provide for free mobility of users across 5G cells, and also to other access technologies like WiFi.
The shim-layer outline of the big circle is the control-plane extension and coordination that allows for unification of 5G mobile experiences across the little-circle RAN metro domains. If somebody roams out of one RAN metro domain into another, there has to be a graceful way of coordinating that process so packets are properly delivered. Ideally, sessions should be maintained. The big inner circle, the PDN, has been the historical common connecting point, linking mobile users to the services and sites they want. It’s not currently required to be aware of mobile behaviors.
From a function-and-features perspective, 5G differs from 4G in large part because it offers capabilities beyond mobility. Latency control, for example, is a special feature of 5G, and another might be support for simple devices (IoT), precision location services, and security. Most of these features, which are usually envisioned as being extra-cost options, are implemented through the network slicing capability of 5G, which creates “virtual networks” over common infrastructure.
These added 5G features require 5G control over more of the information flow than simple mobility management would require. Thus, we could visualize their impact as being a “thickening” of our shim-layer outline to extend coordination and data handling directly between metro domains, and likely the introduction of similar features into the big center circle, the core PDN in current terminology. Some might see more and more of 5G information flows staying in the 5G functional domain, making the “shim” outline thicker, to the point where it might end up being much or even most of that central core.
This relates to operator plans for two reasons. First, the standards needed to fully outline the implementation of this added 5G feature set aren’t finalized, and second, the implementation of all of these additional features demands a considerable shift in thinking. If “Open RAN” is a desirable goal for operators, then “Open Core” is mandatory.
We know what the 5G model of what I’m calling “Open Core” would look like. There’s common infrastructure under all the slices, and that infrastructure might be dedicated to a slice, to 5G, or coerced from shared resources. The model the 3GPP promotes is that features are all built on NFV, but this presupposes that NFV actually represents a useful model of function hosting in an age where we already have cloud-native concepts that are far beyond it in utility.
The other challenge here, as operators see it, is just what “Open” means. There is no question that operators believe that mobile services of the kind we’ve had for years must support intercalling across operator boundaries. There’s no question that basic enhancements to our little-circle metro domains like WiFi roaming would have to extend to any roaming user, and also would have to support calls across operator boundaries. But the rest? Do operators want to invest in IoT and network-slicing-based services in cooperation with other operators? That’s not clear to many of them yet.
Operators in areas like the EU tend to believe that they would likely face a regulatory mandate to open 5G-specific features across operator boundaries to create a uniform EU-wide service set. In the US, that seems less likely, and in much of the rest of the world, there’s no clear consensus on the topic at all. The likely outcome, most think, is that operators would decide based on the overlap in service areas between themselves and potential partner operators. Big-overlap plus no-regulatory-mandate equals try an all-on-us solution rather than partnering.
One thing that almost all operators say now is that they would like to see an open 5G Core model, not just Open RAN. Perhaps one in five are suggesting that absent that capability, Open RAN is less useful to them. This seems congruent with the way that the proprietary 5G vendors are positioning; they focus more and more on the concept of “end-to-end” 5G slices and features.
Another area getting some attention is the “federation” of features implemented through NFV (or a cloud-native successor technology). There are no specific standards relating to the way these features would be accessed, even by the operator who deployed them, much less how they’d be shared. Some operators see a value in having “feature brokers” who built useful features and even services and then offered them on a wholesale basis for others to integrate.
Many operators see public cloud hosting of 5G service components as a kind of federation. While there’s certainly interested in using public cloud generalized hosting, especially for 5G services deployed outside operators’ traditional footprints, there’s also interested in a SaaS model where functional elements of 5G are offered, not just hosting of those elements. That same approach could be taken for those above-5G features that build additional service value.
Open RAN could have a direct impact on this, because of the RIC or RAN Intelligent Controller element. This provides orchestration for key 5G components, but it also offers a point of interface between 5G control and higher-layer add-on elements. Thus, how capable, how evolved, the RIC turns out to be could influence how quickly Open RAN could evolve to support NaaS.
That’s where things stand. The Open RAN discussion, the costly spectrum auctions, the continued profit pressure on network operators, and the uncertainties of a future service set that’s not wired into monolithic hardware are unsettling to operators overall, but they’re something they’re increasingly resigned to facing, and hoping to face well. That, of course, may be the big vendor opportunity.