Small-cell base stations are finally getting traction, but mainly for improving indoor 4G LTE coverage in offices, while outdoor 5G units are still a ways off. That’s the conclusion of a report from a trade group of OEMs and service providers that make and deploy them.

At an annual event, members of the Small Cell Forum shared successes to date and concerns that technical and especially business challenges could limit future growth. The good news for small-cell deployments is that “we’ve done more in the last 12 months than in the last six years,” said Gavin Jones, a mobile manager for BT, a service provider in the U.K.

By 2025, nearly 10 million small cells will ship a year, according to the Small Cell Forum’s annual forecast. Half of them will be indoor units to business, a market that took the bulk of the less than 4 million units sold last year.

OEMs at the event said that they are still waiting for 5G silicon from Qualcomm for units that they expect to start selling early next year. Only in 2022 will 5G small-cell deployment account for more than one-fifth of the total, but by 2025, 5G cells will make up two-thirds of total sales, the trade group predicted.

In the U.S., infrastructure builder Crown Castle is “rolling out lots of small cells; we are finally starting to see them gain traction,” said Andrea Goldsmith, a Stanford professor and wireless expert who advises the company.

Challenges for operators include deciding how to allocate channel and power resources among small and traditional base stations and how to optimize their connections for data rate, latency, robustness, and energy constraints. Future small cells will use millimeter-wave bands that bring unique coverage challenges, she said.

Small cells also open doors as hosts for smart caching and computing at the edge. Such functions “have tremendous potential to enable new applications, and we don’t understand these issues well at all,” she added.

At the London event, a senior radio planner for Turkcell, Turkey’s main service provider, described its deployments of 4G small cells that extended network throughput up to 40%.

BT has been putting the devices, about the size of a Wi-Fi access point, on streetlights, on payphones, and even under manhole covers, some with backhaul links running up to 100 Gbps. The U.K. alone could deploy three-quarters of a million small cells by 2025, but “we have to improve the processes and speed,” Jones said.

Indeed, the trade group estimated that small-cell shipments might reach only 6 million units/year by 2025 if the industry fails to address a handful of business challenges around making public and private systems easier to deploy.

Small Cell forecast

4G small cells are taking off now, and 5G versions are expected to pick up in 2021. (Source: Small Cell Forum)

Battles over spectrum and small-cell ownership

Stakeholders must collaborate to enable new business models for private cellular networks and open up real estate to deploy small cells for public networks, several speakers said. If that doesn’t happen, it could slash more than 4 million units a year off 2025 sales projections, according to the trade group.

“We need a patchwork of shared providers rather than operators competing with each other,” said Caroline Gabriel of Rethink Research, who helped write the report.

Last year, it took BT an average of 52 days to get approvals needed to deploy small cells for public networks, and some approvals took more than 100 days. Currently, only 60% of all of BT’s base-station sites are profitable given fixed costs of power and site rental.

“We have to change the rules to get better access to sites at lower costs,” Jones said.

Small Cell forecast freq

Today’s small cells are mainly for licensed sub-6-GHz bands, but that’s expected to shift significantly by 2025.(Source: Small Cell Forum)

Meanwhile, cellular and Wi-Fi nets are increasingly projected to share spectrum in bands ranging from 2 GHz to 60 GHz. “Today, most businesses buy their own Wi-Fi networks but not cellular,” said Gabriel, suggesting that they need risk-sharing plans with operators.

“I’m skeptical that LTE or 5G can replace Wi-Fi for normal net access,” said Dean Bubley, a wireless market watcher at Disruptive Analysis, noting a shortage of trained small-cell installers.

He predicted that US regulators will release most 6 GHz spectrum for unlicensed usage. “What’s a bit unclear is if there will be any particular rules that favor Wi-Fi versus cellular” regarding regional licenses or interference between technologies, he added.