Caroline Gabriel is the co-founder and Research Director of Rethink Technology Research; Senior Contributor, Analysys Mason, Next Generation Wireless; and a member of the Small Cell Forum. Caroline has been engaged in technology analysis, research and consulting for thirty years and since 2002, has been focused entirely on mobile and wireless. Caroline has led research and consulting projects with a wide range of clients, including mobile infrastructure vendors, large and start-up operators, regulators, trade bodies, government agencies and financial institutions. Her advice and forecasts have helped inform strategic decisions at a wide range of vendors, operators, start-ups and finance houses.
Every year since 2007 has been dubbed ‘the year of the small cell’, with varying degrees of justification. Significant penetration of the residential market in many countries was followed by disappointment with limited expansion in the most heavily scrutinised sector, the urban hotzone. But like most hyped wireless platforms, just when the market watchers start to lose interest, the technology is suddenly there – established in the mainstream when nobody was looking.
Densification is now a common and important element of many operators’ LTE-Advanced plans and 5G roadmaps. It applies to indoor and enterprise locations – often the biggest driver of data traffic and of premium services – as well as the classic network-on-a-lamppost.
Operators’ commercial imperatives are shifting from broad coverage to dense capacity with LTE, and one of the few areas of agreement about 5G is that it will rely heavily on small cells. The use of higher frequency spectrum, from 3.5 GHz to millimeter wave; and the use cases which rely on distributing cloud services very close to the user, will require density. As this happens, the technology will just be part of the accepted toolbox.
Indeed, we will stop referring to ‘small cells’ as though they were a breed apart – already operators (and the Small Cell Forum itself) talk more commonly about heterogeneous networks (HetNets) which integrate any combination of cell domains, base station form factors and spectrum bands.
Several key enablers of these dense, flexible HetNets are currently in the headlines. The US FCC has approved rules for opening up high frequency spectrum in 28 GHz; and Facebook announced an open source small cell design, OpenCellular, last year to try to shake up the cost of deployment.
Another development is LTE in 5 GHz spectrum, with technologies like LTE-LAA (Licensed Assisted Access) and MulteFire. Because of its range and power limitations, 5 GHz is inherently a densification band, whether that is achieved with cellular or Wi-Fi access points, or an integrated mixture.
But there are still significant barriers to deploying large numbers of small cells cost-effectively, and the highest are nothing to do with technology and everything to do with logistics and business habits. The complex and uncoordinated process of acquiring large numbers of sites, negotiating leases and contracts, and ensuring adequate power and backhaul, will only get more daunting as cell numbers rise.
As well as creating more streamlined and repeatable processes for working with cities and landlords, the small cell industry needs to embrace another important remedy; multi-operator networks.
Although there are standardised technologies to enable multi-operator small cells, notably 3GPP’s MOCN and MORAN, these have scarcely been deployed. Mobile operators are concerned about enabling competitors and losing control of infrastructure and network optimisation (even though many have gone through that dilemma and embraced sharing in the macro network). Apathy or hostility from MNOs has limited the vendors’ incentive to prioritise MOCN, as well as the impact of some of the neutral host companies looking to build wholesale networks and provide SCaaS (small cell as a service).
Yet multi-operator is crucial to make small cell economics work – to save cost and to avoid the ridiculous planning, deployment and interference issues of having multiple networks per enterprise or city (and also to avoid the alternative – a single-operator network which only certain visitors and employees can use).
Like most hyped wireless platforms, just when the market watchers start to lose interest, the technology is suddenly there – established in the mainstream when nobody was looking
When it comes to 5G and to Internet of Things applications, neutral host will not just be desirable but essential. It will be the only way to make ultra-dense networks deployable and cost-effective, and it will be crucial to support the wide variety of vertical industry bodies and virtual service providers which will want to harness 5G, as so many daily activities become connected and smart for the first time.
There are two related factors which could be catalysts for making multi-operator small cell networks a reality at last. One is the increasing availability of shared or unlicensed spectrum for LTE – in 5 GHz, or in the US’s 3.5 GHz CBRS flexible spectrum scheme, for instance. Technologies like MulteFire will allow non-MNOs to build small cell networks without needing an anchor network in licensed spectrum, so that a neutral host could create a platform – perhaps for a specific region or vertical sector – without needing the cooperation of the mobile operator. Fees would only be paid to the spectrum owner for wide area mobile roaming.
The other factor is the rising interest of infrastructure companies in expanding their business models into neutral host small cells (providing sites and backhaul, and even active equipment in some cases). The main categories are towercos, cable providers, independent fibre providers and vertical market private network operators, though there have been a few examples of start-ups set up specifically to offer small cells as a service (SCaaS).
Towercos are divided in their approach to small cells. Some are deterred by the very different investment cycles, site valuations, and the dilemma of whether to venture into active equipment and provide neutral host cells, not just backhaul and sites. In the U.S., for instance, SBA remains unconvinced but Crown Castle is bullish, with CEO Jay Brown saying: “We are seeing the business model of small cells play out very similarly to that of towers.”
We will stop referring to ‘small cells’ as though they were a breed apart – already operators talk more commonly about heterogeneous networks (HetNets) which integrate any combination of cell domains, base station form factors and spectrum bands
Brown also put his finger on the main problem with small cells – that networks are not easily and repeatably deployable yet. Lamp posts may be convenient and ubiquitous sites, but they do not necessarily have fibre. He said the “vast majority of this fibre and small cells are purpose-built. They need to be in specific locations, long routes where we can install on poles. … This fibre is very different than what we have seen historically deployed.” This gives the firm an opportunity to differentiate itself and charge a premium, based on its operational expertise and scale, but does not necessarily contribute to the vision of an out-of-the-box network.
Fibre providers, whether wholesale operators like CityFibre or broadband providers such as cablecos, may be better placed to leverage existing infrastructure, and the pay-TV firms understand the logistics of deploying very large numbers of units, especially those which have been rolling out public Wi-Fi at scale.
But there are issues facing each category of small cell provider, and while more flexible spectrum will remove the huge problem of MNO resistance to neutral host, there are still many issues to address before the business case is convincingly made for most players.
