Niche spectrum and multi-tenant small cells help push the MNO-free 5G model

It is widely acknowledged that, for 5G to succeed, it will have to support a wide variety of use cases with very different network requirements. That also means it will be implemented in a wide variety of spectrum bands, equipment form-factors and devices in order to support all those requirements optimally. The logical assumption to follow from that, is that it must also support a wide variety of service providers, each properly equipped to address one of these wildly diverse applications.

As conventional MNOs publicly struggle to make a strong business case for 5G in the Internet of Things, or in industrial applications which require high availability or very low latency, it is important that alternative providers can step into the breach. Some will operate as vertically specialized MVNOs on the main mobile networks; but some will look to deploy their own equipment, perhaps for a particular location or vertical sector, to add specialized performance to the wide area mobility and broadband access of the MNOs’ national networks.

These will be enabled, in the 5G world, by the same elements that opened up the WiFi ecosystem to a huge variety of providers – shared spectrum, affordable small cells which can be deployed for targeted usage, neutral host models where it makes no sense for multiple physical networks to be built in the same areas.

We have already written about some of the companies driving these trends and showing, even in 4G, what can be done. Airspan is a vendor of small cells which is acquiring spectrum licences in order to build neutral host networks for enterprise services. Quortus and Core Network Dynamics are two of the start-ups which offer low footprint, virtualized packet cores, enabling an enterprise or specialized provider to manage its own subnet independently and control aspects like security.

CBNL, best known for wireless backhaul, has joined this crowd by virtue of a new business activity – building custom wireless equipment for companies which own or can access unusual spectrum bands. Airspan also has a history of doing this going back to WiMAX days. Both firms are prepared to adapt their platforms to support spectrum bands which are valuable to support certain applications, but have not been widely adopted by vendors, operators or regulators, and so lack the economies of scale to attract large OEMs.

This approach tended to focus on niches – spectrum owned by a single country’s utilities, for instance, or a band in which one or two countries had their own peculiar band plan. But in an era when private networks for specialized purposes are on the rise, whether in licensed or unlicensed spectrum, this business model could be far more applicable.

To support all the use cases envisaged, and all the types of service providers, 5G will certainly have to embrace spectrum choices which go well beyond the core, harmonized frequencies adopted by the World Radio Conference and the 3GPP. Those will always be vital for large-scale markets like consumer smartphones, and for international roaming, but the diversity of 5G services will also require that any available piece of spectrum must be used if at all possible.

John Naylon, CTO and founder of CBNL, said that bespoke equipment can give companies that own rare or atypical spectrum the ability to build out their frequencies affordably. That could apply in various scenarios – an organization which wants to use its spectrum to build a network whose behaviour and quality it can control; one which wants to monetize spectrum by selling it, in a readily usable state, to an operator or neutral host; or one which needs to build a network to satisfy regulators.

Of course, these specialized builds will mainly be valuable for services that do not rely on smartphones or other mass consumer devices, which need to be harmonized around a relatively small number of bands to ensure interoperability and avoid having to pack scores of frequencies into one gadget.

Naylon said the business was already “a real success story for us”, because CBNL has designed its equipment so that new bands can be plugged in easily if demand arises. “We’ve always had a modular approach to engineering.”

Early experience came in the US, particularly  with companies that acquired the LMDS licences in 28 GHz and 39 GHz, such as Straight Path and XO. In the early days of the century, those bands were undervalued and there was little attention paid to them by vendors, but now they have become the bedrock of the US’s moves into millimeter wave 5G, and highly strategic, with Verizon and AT&T buying up many of those LMDS operators. CNBL has built bespoke equipment for the 39 GHz and 31 GHz bands, among others.

Many of the initiatives to support certain enterprise and industrial use cases on their own subnets rely on neutral host support. These subnets will typically be based on small cells, in licensed or shared spectrum, covering a limited area such as a city or campus, and users will get national and fully mobile coverage via MVNO agreements with the large MNOs. But while there will be a few completely private networks, perhaps for a safety critical activity such as power plant monitoring, in many cases these subnets will need to support multiple service providers. A smart city platform, for instance, would benefit from being usable by various specialized connectivity providers and by the MNOs themselves. It would need to support consumers whose data plans are with different MNOs. And it makes no sense to build multiple networks in the same location, putting pressure on sites, backhaul and risking congestion.

The slow progress towards neutral host models in small cells, often a result of MNO lethargy or hostility, has been a key factor in the slower than expected deployment of small cells in enterprise and urban settings. But the need for specialized use cases in 5G will unlock those floodgates, and if MNOs are really hostile, shared spectrum technologies like MulteFire and its presumed 5G successor provide an alternative route for a neutral host.

Crown Castle, the US towerco which has been most enthusiastic about expanding its business into small cell sites and services, believes real progress is now being made. The company’s chief commercial officer, Mike Kavanagh, said there are two important developments which have become visible this year – small cell build-outs taking place in tier two markets, not just the big cities which urgently need dense capacity; and support for multiple carriers on some small cell networks.

In the early days of urban small cells, 5-6 years ago, Kavanagh told FierceWireless that a major installation would cover 50 nodes in a city. Today that number is nearer 2,000, and may rise to 7,000 in a dense market. That equates to 2-4 small cells per mile, or 7-12 per mile in those very dense areas.

“You’re utilizing small cells as a much bigger element of the network build,” he said. “You’ve got to have that tower layer. And you’ve got to have small cells.”

It is very important to the towerco model that each site has multiple tenants, and that applies in small cells too. The neutral host company is increasingly likely to deploy a small cell site to support two carriers at once – this is now the case in 30% of its new sites, and it expects to add another tenant typically within five years in small cells, compared to 10 years in macro towers.