It's only been five years since 4G mobile broadband came along and made it possible to browse the internet and stream videos on your phone at a decent speed. 4G speeds are already faster than lots of home broadband connections, but the tech world is already wondering what comes next.
The promise of 5G is powerful internet speeds around ten times faster than what's possible now with no lag, providing a new wireless infrastructure for our future smart homes, wearables, driverless cars, and virtual reality. Everyone is super excited about it. But 5G doesn't actually exist—yet.
Researchers, policymakers, and the wireless industry are busy trying to figure out how to make the next-gen protocol a reality, tossing around an optimistic deadline of 2020. On Tuesday, CTIA, a wireless lobbying group, hosted a forum to discuss the road to 5G, keynoted by Senator John Thune, who said he will introduce a mobile expansion bill this week. There was much gushing over the benefits of 5G, but until a bunch of global nations and telecom firms come together and agree on a standard definition, we can only speculate on what 5G will look like and how it will work.
What most everyone does agree on is that the current 4G network is not up to the task of supporting the demand the hyperconnected Internet of Things and Bandwidth-guzzling video will put on wireless networks. Cisco predicts mobile data use will increase tenfold in the next few years as some 50 billion smart things connect to mobile networks. As internet starts flowing through everything from your toaster to your socks, we're going to need a bigger pipe to handle the flow.
But the 4G network is already clogged with too much traffic, with carriers mandating data caps and throttling heavy users. To support the demand for gigabit speeds and mounting data use, we'll have to grab bandwidth from higher up in the electromagnetic spectrum, pushing up into the "extremely high frequency" range at 30-300 GHz—wedged right between microwaves and infrared light.
To support the demand for gigabit speeds and mounting data use, we'll have to grab bandwidth from higher up in the spectrum
Most phones using 4G operate in the 700-800 megahertz (MHz) range of the spectrum, with some LTE as high as 3,500 MHz, or 3.5 gigahertz (GHz). While the 4G network infrastructure is continuing to be built out—"there's some gas left in that tank," said one person at Tuesday's event—the band is increasingly strained.
The radio waves in the extremely high frequency band have 1-10 millimeter wavelengths (versus tens of centimeters in the lower range where 4G lives), so they're also called "millimeter-wave" frequencies. Since the higher the frequency, the more data can be squeezed into a signal, so millimeter-wave speeds are faster by an order of magnitude, with potential for speeds at 10 gigabits per second (Gbps) or more, depending on who you ask.
The wireless industry has been slinging around a bunch of different figures, predicting 5G would be fast enough to download a full-length ultra HD movie in a matter of seconds, versus the several minutes it takes now. (Current 4G speeds hover around 5-100 Mbps.) Early 5G tests were able to transmit data at peak speeds of 7.5 Gbps.
This is good news for playing 8K video or interactive video games on your phone, but most of the buzz around 5G is about enabling the IoT, enabling a network where everything being connected to everything and sending signals betwixt in true real-time—5G is expected to cut latency to under a millisecond.
Picture a scenario where sensors on the road could instantly tell driverless cars or smart cars about an accident up ahead, while at the scene of the crash a person's smartphone or watch could relay their health information to an ambulance en route. Smart cities could solve traffic congestion by getting real-time data and automating flow. And eliminating lag time is obviously key for virtual reality and augmented reality getting good enough for mainstream adoption. (Samsung demoed a wireless-enabled VR headset at Tuesday's event.)
This most likely requires dipping into the huge swath of bandwidth in the extremely high frequency range of the radio spectrum that's sitting mostly unused, because electronics can't currently send and receive transmissions at these frequencies, something chipmakers are working to develop.
It's like discovering a new continent of uncharted wilderness. The radio spectrum is extremely valuable: There's a limited amount of space and ever-increasing demand, and when the government starts doling out new spectrum space we can almost certainly expect a frenzied frequency land grab.
In the US, the government regulates the airwaves, licensing certain frequency bands to private companies and reserving sections for public use. There's fierce competition for the chunks of airwaves the government puts up for auction, with wireless carriers spending billions for prime real estate on the spectrum. The 700 MHz band auctioned off in 2008—freed up because it was being underused by analog TV—was considered "beachfront property" for broadband wireless and spurred a debate over making the open band public access. New frequencies up for grabs would be a chance to allocate public networks or for small carriers to snatch up some bands, though big telco will likely walk away with the lion's share.
While there's more space available in the upper part of the spectrum, the drawback is that airwaves travel shorter distances the higher their frequency. 5G signals would only propagate a couple hundred meters before being absorbed by the gases in the atmosphere, and the narrow waves can't pass through walls or window glass; even leaves can interfere with the signal.
So while 4G mobile is great for providing coverage to a whole house, 5G would require a whole new wireless architecture, with cell bases every 100-200 meters—meaning thousands of antennas and transmitters installed in rooms, lamp posts, street signs and so on. Higher frequencies can be transmitted by smaller antennas, so the industry is focused on "small cell" architecture: microcells, femtocells and picocells.
"Terms like 'beamforming,' 'MIMO,' 'millimeter-wave,' 'small cells,' and others will likely become part of the official lexicon"
Another area of research is "beamforming," which is concentrating the energy of a signal to steer it in a certain direction, aimed right at its target. So you could potentially put an antenna in a device and direct the signal to follow a user around as they move, which could help get around obstacles and interference. "Terms like 'beamforming,' 'MIMO,' 'millimeter-wave,' 'small cells,' and others will likely become part of the official lexicon the wireless industry," said Sen. Thune at Tuesday's event.
Because of these infrastructure requirements, 5G will most likely be rolled out in densely populated cities first. Short-range signals aren't great for servicing rural areas; instead, 5G may fill in the last bits to supplement a fiber internet backbone, and will need to be compatible with low and mid-range spectrum bands as well as 4G and 3G networks. The standard will also have to take into concern a better security protocols, as billions of sensors and everyday objects connected to the internet creates basically a playground for hackers.
Developing an international standard for the 5G network is likely to be a herculean task tangled in red tape, but the deadline in sight is 2020, just four years from now. Japan would like to have 5G up and running by 2020 Olympics in Tokyo, as would South Korea for the 2018 Games. In the US, the Federal Communications Commission proposed making spectrum bands above 24 GHz available for mobile. Senator Thune's new legislation, the Mobile Now Act, will ask the government to free up more airwaves for commercial use and examine millimeter-wave frequencies for 5G.
Meanwhile the group overseeing wireless development, the International Telecommunication Union (ITU), a branch of the United Nations, is also eyeing the 2020 timeline and released a roadmap for progress. It also gave the new mobile standard an official name: IMT-2020. Though something tells me "5G" is going to stick.