The term "killer application" is supposed to mean its success is a dead certainty, not that someone actually dies. The 5G service demonstrated in BT's latest commercial looks far from irresistible and potentially fatal. It features someone receiving a remote shave on what appears to be the summit of Snowdon, the highest mountain in Wales. A robotic arm wielding a razor is operated by a modern-day Sweeney Todd from his shop in London, where actor Kevin Bacon tries to reassure. "Are you sure this is a good idea because I do need this face?" asks the quivering victim.

The intended message, of course, is that BT has a pervasive mobile network you can rely on – not that remote shaving is the next big thing. After plenty of 5G noise from UK rivals Virgin Media O2 and Vodafone in recent weeks, the UK incumbent is desperate to show evidence of its network leadership. Hence the latest update including lots of bold statements about 5G coverage and the importance of fixed.

On the face of it, the headline announcement – that BT will provide a near-nationwide 5G service by 2028 – sounds rather underwhelming. EE, the mobile bit of BT, hit 90% population coverage with 4G just two years after launching its service. A new mobile generation tends to arrive once every nine or ten years, which suggests 6G will be taking baby steps in 2028 (BT launched 5G in mid-2019). In other words, some UK residents will get their first taste of 5G from BT around the time an even more advanced technology turns up.

Bringing home the 5G bacon

No other UK operator has been this upfront about its targets, though, and BT is now the only one to have been transparent about its 5G coverage. Today, it claims to provide a service to about 40% of the UK population, mainly in densely populated areas. Its interim goal is to reach more than 50% of the country by the end of 2023.

Until today, the approach taken by all the UK's operators was to list the cities and towns where 5G is partly available. Even then, BT could boast greater transparency. Locations are only named by the incumbent if they meet three criteria: there is a population of more than 10,000 people, BT has at least one mast in the city or town center, and its 5G network covers at least 35% of the local population. Any rival can be accused of claiming 5G coverage after erecting a solitary mast.

The 5G rollout still seems to be happening at a much slower pace than EE's deployment of 4G, though. "COVID has definitely made it harder for us," says Neil McRae, BT's chief network architect. The ongoing, government-ordered swap-out of Huawei, a Chinese vendor previously used across about two-thirds of the radio access network, is another obstacle EE did not encounter with 4G.

But in the absence of a safe killer application, there also seems to be a recognition that 4G is still good enough for most users. "You have to reflect on what was there," says McRae. "3G and HSPA was a poor substitute for 4G and 5G. Moving from 4G to 5G is not that kind of packet-based improvement and we've done that piece of it. In some respects, we are matching demand with capacity and where we are able to build. In my mind, we are charging ahead."

The accusation stands that UK operators, along with others in Europe, have neglected to invest in mid-band 5G services; instead, they're relying on lower frequency ranges that provide good coverage but a user experience that is not much different from 4G. And the accusation comes from none other than Ericsson, a supplier that BT has introduced alongside Nokia to help replace Huawei. Data the Swedish vendor previously shared with Light Reading shows that 5G speeds are much slower in Europe than in markets such as China and South Korea, where operators have quickly taken advantage of spectrum in and around the 3.5GHz band.

Figure 1: (Source: Ofcom, companies)

It is a charge McRae shrugs off. BT, he insists, has not really seen the need for dynamic spectrum sharing, the technology some operators appear to have relied on heavily to split lower bands between 4G and 5G services. "When I look at our spectrum assets, which are pretty substantial against the competition, I think over time we'll migrate to those mid-band frequencies that we've got for 5G at a point in time where it's right." Already, though, services are markedly better than 4G, he says.

Third-party data does seem to back up the BT claims. RootMetrics, one of several companies that assesses network performance, has just ranked BT ahead of all three mobile network rivals on median 5G download speeds and 5G coverage in the major cities of Leicester, Liverpool, Manchester and Newcastle.

Want to know more about 5G? Check out our dedicated 5G content channel here on Light Reading.

One problem for UK and European operators generally is fewer mobile sites than counterparts have in the most advanced Asian markets. Korea Telecom, for instance, claimed to have 81,000 5G sites in operation last August, meaning there were then 15 5G sites for every 10,000 people. BT has only about 20,000 mobile sites altogether. Regardless of the mobile generation, the best equivalent ratio it could manage without adding new sites is three.

On the need for densification, BT appears undecided at this stage. "It is too early to tell because there is not enough understanding of what demand is going to be," says McRae. Nevertheless, the opportunity to refresh sites with the Huawei swap-out means the operator is assessing whether old sites still make sense and where new ones may be needed.

A big question mark hangs over millimeter wave, frequencies around the 28GHz range (or even higher) that provide superfast connections but lousy coverage. "If you look at the US, they are very spectrum-constrained and hence they have had to go down the millimeter wave route, which has proved to be not as successful as they might have hoped," says McRae. "I think there will be locations where it can deliver use cases." One could be to support video analytics services in the manufacturing sector, he says, with millimeter wave used to provide a high-speed indoor network.

Shaving latency

Shutting down older networks should certainly help to free up resources (including spectrum) and eliminate complexity. BT has now announced it will "sunset" its 3G network by 2023 and decommission 2G later in the decade. And underpinning all this mobile infrastructure is the country's most extensive fixed-line network and what executives insist is the country's largest core deployment, too.

"You can see traffic peaking at 22 Tbit/s on regular times at the moment, but we've also ensured we can scale that," said Howard Watson, BT's chief technology officer, during a press conference this morning. "We've refreshed large amounts of it, and it can cope with up to 57 Tbit/s at each of our key 106 core nodes. We use multiple 100Gbit/s links to interconnect those nodes and can scale that even further to 400 Gbit/s."

Figure 2: (Source: BT)

Investment in a "standalone" 5G core, independent of the 4G network and scheduled to go live next year, is similarly important. Supplied by Ericsson, that core network is intended to support all customers by 2023, when an older core from Huawei can finally be switched off (to the satisfaction of the government). Sitting on top of BT's distributed cloud infrastructure, it will, promises Watson, allow the operator to launch new services "not even contemplated today."

That could be critical if BT wants to support the kind of low-latency applications that someone would need to enjoy a remote shave, or a far likelier session of online gaming. But Watson's ultimate vision, articulated numerous times in the past, is of a properly converged network that would allow a user to jump from 5G to public Wi-Fi to residential fiber without even noticing the hop. The network relay team is taking shape. Proving it can perform handovers without dropping the baton will be the next big challenge.

Related posts:

— Iain Morris, International Editor, Light Reading