Equipment vendors and carriers have talked a great game about 5G's promise. Its ability to handle the high-density wireless environments created by Internet of Things (IoT) deployments and provide gigabit speeds to smartphones has been trumpeted from the rooftops.
But it's important to realise that the most eye-catching capabilities of 5G technology aren't here yet, as many of them depend on the 5G New Radio (NR) technology operating at high, millimetre-wave frequencies, which isn't yet widely available. Nor are the vast majority of endpoints currently on the market able to communicate on those sorts of networks.
However, private 5G technology – which takes advantage of the new features designed for 5G and deploys them in enterprise networks, rather than as carrier services – is quietly making inroads into the marketplace. 5G mobile backhaul transport equipment is expected to become a $3 billion market by 2024, according to recent research by the Dell'Oro Group.
Backhaul is an overlooked part of the problem set that 5G is designed to solve, since 5G is primarily thought of as an endpoint connectivity technology.
Farpoint Group principal Craig Mathias said that users might be more likely to see 5G backhaul deployed by enterprises as part of a setup where both infrastructure and end users are connected via the same 5G access points. "5G is not about augmenting wire," he said. "It's about replacing it."
Mathias also highlighted that terminology makes talking about the use of 5G as backhaul somewhat awkward, given the fact that many 5G standards have not been finalised, and that many millimetre-wave point-to-point links use similar frequencies and technology to 5G without necessarily falling specifically under the specification.
"The reason you might not see a lot of pure 5G backhaul is that a lot of [those frequencies] are licensed by the carriers," he said.
Hence, there are a lot of enterprise products out there that use frequencies and technologies that are very similar to 5G, but aren't technically under the same standards umbrella. This doesn't stop many of them from labelling themselves as "5G backhaul" for marketing purposes, of course.
The key to 5G's appeal as a backhaul tech, according to Paul Challoner, Ericsson vice president of network products solutions for North America, is bang for your buck.
"In the enterprise WAN market, there's fiber, there's DSL, Ethernet. Where they're not cost-effective or easy to implement, we see using 5G as a WAN connection to the enterprise," Challoner said.
This has let 5G – or, at least, 5G-like – backhaul make headway in the market. There's no typical use case, although connected cameras are particularly well-suited to it.
The upshot is that any application where an organisation would typically need to use a wired connection but doesn't want to for cost or efficiency reasons, could be a good candidate for a 5G backlink, according to Mehmet Yavuz, a former Qualcomm executive and co-founder of private 5G/LTE networking vendor Celona.
"In parking lots, or thinking about big box retail stores, in-store pickup – employees with hand-held devices to scan boxes and so forth, IP cameras – you might not have an LTE chipset in an IP camera," he said. "So you'd connect them back to a gateway that does have one," he said, noting that this would obviate the need for the chipset.
University campuses could use the links to provide basic Internet connectivity to different parts of campus without running a wire there, Yavuz noted. While the type of millimetre-wave frequencies that characterise 5G New Radio products have a difficult time penetrating walls and windows, an exterior antenna with line-of-sight could serve as a backhaul connection between different buildings.
In Houston, Jack Hanagriff, a technology coordinator for the city, said that one of the major advantages that private 5G offers is the use of clear spectrum, when compared to the overload of traffic frequently found on unlicensed bands such as Wi-Fi.
In recent years, Houston needed a wireless way to keep critical smart-city infrastructure like security cameras connected during major sporting events hosted in the city, Hanagriff said. Particularly in media centre areas or in places where large crowds were gathering, those unlicensed bands were heavily congested.
"[The] city of Houston has very little public fibre. There's fibre all over the place but we don't own it," he said. "Prior to the Super Bowl, we had the Final Four, and that's when we discovered that our wireless infrastructure, because of drastic environmental change, all the new people and so on, significantly disrupted the cameras."
The cameras ordinarily used frequencies of around 4.9GHz, squarely in the same range as Wi-Fi. Other, usually uncluttered, frequency bands were suddenly congested by carriers bringing in portable cell towers to help cope with demand.
"We had to put in technology that didn't have infrastructure," Hanagriff said.
So the city used 5G backhaul technology from a company called Siklu as an easy-to-deploy, high-bandwidth link to get the camera feeds backhauled to the main network without having to deploy new cabling or deal with tight spectrum in the more usual places.
A particularly high-demand space during those events was the city's Discovery Green park. A centrally located 12-acre green space in the centre of Houston, the park was used to host festivities and media events before the big game.
The city had servers and network hardware situated in a parking garage beneath Discovery Green, so Hanagriff used a novel solution to link those systems to the park grounds.
"I piped it into a vent shaft," Hanagriff said. Using an antenna at either end of the ventilation system that keeps airflow moving in the garage, he was able to beam the signal from the park proper down into the command centre below.