Brace yourself—the debate over what should and shouldn’t count as 5G has only begun. Defining the next generation of wireless networks is complicated, partly because engineers are developing so many exciting technologies at once and have yet to agree on the standards by which they will operate.
Within that murkiness is plenty of room for disagreement over how and where 5G will emerge. Stéphane Téral, an analyst at IHS Markit, recently weighed in by criticizing the use of “5G” to describe sub-6 gigahertz developments in a research note.
Radio waves in the sub-6 GHz range are considered the most desirable among carriers for delivering cellular signals because they can penetrate materials such as concrete and glass. Two ranges in particular—frequencies around 800 megahertz and 1.9 GHz—have long dominated the U.S. cellular landscape.
But these frequencies are becoming crowded as more users consume more data on more devices. And a bevy of other consumer technologies including Wi-Fi, Bluetooth, microwave ovens, and satellite radio operate at frequencies between 1.9 GHz and 6 GHz. So carriers have begun to browse higher frequencies for open bands that they can co-opt for cellular use.
Many have set their sights on much shorter millimeter waves that fall between 30 and 300 GHz. There are plenty of frequencies available in the millimeter-wave range, because they’ve been used only for specialized applications such as remote sensing and military radar. But waves at these frequencies can’t travel as far or make it through as many obstacles, so companies and researchers are still figuring out what it would mean to integrate them into future 5G networks.
“Obviously, the low latency and high bandwidth stuff like AR and VR will definitely benefit from millimeter wave,” says Anshel Sag, a 5G analyst for Moor Insight & Strategy. “But the way the technology works right now, it’s still pretty power hungry and requires a complicated array of antennas.”
Given the situation, Téral says it’s not surprising that carriers are also focused on finding more efficient ways to deliver data on lower sub-6 GHz frequencies. They’re improving their networks through technologies such as multiple input and multiple output (MIMO), in which carriers add antennas to existing 4G base stations to handle more traffic from more users at once.
In fact, some companies have begun to concentrate their 5G efforts on these kinds of sub-6 GHz improvements. Chinese smartphone manufacturer Huawei has said that sub-6GHz bands will be “the primary working frequency” for 5G, and Qualcomm recently announced a new 5G radio prototype focused on the same batch of frequencies.
But Téral is irked by companies who dub these developments 5G. He says only advancements at higher frequencies (those above 6 GHz) should count as “real 5G,” because they would represent a paradigm shift for improving data rates and latency on future wireless networks. He argues that sub-6 GHz improvements incorporated into existing 4G and 4G LTE networks are simply business as usual.
“The cellular guys want to use that spectrum to make a 5G claim, but this is not a dramatic move from where cellular is, from 700 MHz to 2.6 GHz,” he says. “You really want to call that 5G? It doesn't justify a generational jump.”
However, other experts say the importance of millimeter waves to 5G has been overstated, and key developments at lower frequencies, including the repurposing of TV white space, will play a significant role in enabling faster mobile connections, connected cars, and the Internet of Things.
Sag thinks it’s a mistake to rule out anything other than millimeter waves as true 5G. He says 5G New Radio, a wireless standard defined by the global wireless standards group 3GPP, should count as 5G no matter which frequencies it handles. Many others also envision future 5G networks as a blend of millimeter waves and sub-6 GHz technologies.
“I'm in the camp that doesn't believe that millimeter wave is the only way to do 5G,” Sag says. “In fact, I think it's the wrong way of doing 5G if you think of it as the only way of doing it.” Instead, Sag believes 5G will permeate every swatch of spectrum from the low frequencies used for NarrowBand IoT all the way up to high-frequency millimeter waves.
Téral admits progress in the sub-6 GHz range is an important first step in the “pre-5G” evolution of wireless. He also acknowledges that many of the potential uses that experts have dreamt up for 5G can and will be achieved through incremental improvements to 4G LTE networks. But he says he’d prefer to call those improvements “transitional 4G” instead. “There’s nothing new, and that’s the whole point,” he says.
To Sag, the matter of what counts as 5G is not just a theoretical debate: It could have a real impact on the trust that consumers place in carriers. “My biggest concern is kind of the same concern with 4G, in that the definitions get muddled and the consumers get confused,” he says.