Low communication latency is why 5G will be radically different from today's mobile networks.
Just about everything you hear about 5G points out how its higher data speeds will let you download videos or update your apps much more quickly. Well, whoop-de-do. Faster data is helpful, but a different 5G benefit could actually be a bigger deal: reducing network communication delays called latency. Latency is the time it takes to get a response to information sent -- for example, the lag between the moment you try to shoot a space invader and the moment the internet server hosting the game tells your app whether you succeeded.
Lower latency could help 5G deliver mobile networks that let us do entirely new things, not just modestly improve what we're already doing now. Possibilities include multiplayer mobile gaming , factory robots , self-driving cars and other tasks demanding quick response -- all areas where today's 4G networks struggle or can't manage at all.
"Latency is really going to open up new real-time experiences we've never had before," said AT&T Chief Technology Officer Andre Fuetsch.
Well, at least it will if it works as promised. The 5G hype has been heavy for years, the truly low 5G latencies won't arrive until 2020 -- and really, how many years have we been hearing about how telemedicine will let surgeons operate on patients in a different time zone?
So sure, some skepticism is in order. But latency profoundly important, and improving it changes how everything works, so don't dismiss the 5G's low latency. Think of how much faster hard drives are than mainframe-era reels of magnetic tape, or how flash memory drives now are replacing pokey hard drives in laptops . When we eliminate delays from a system, it can mean changes like getting eggs on demand from Amazon instead of having to wait for the weekend shopping trip.
Factory automation is a favorite example of low-latency advantages. Fuetsch sees 5G connecting robots so they can coordinate their actions and avoid running into each other. 5G also could let robots communicate wirelessly instead of with network cables, untethering them so a factory can rapidly switch manufacturing jobs.
Drones could get better, too. 5G enables fast links to base stations so computing smarts can be on the ground -- for example for object recognition to aid navigation. Without having to carry as powerful a computer and the battery needed to run it, a drone can fly longer when delivering packages or have more power carry a better but heavier camera. Of course, you'll need a 5G network handy, which could be a problem in rural areas where 5G networks aren't likely to arrive for years.
5G could also help gamers, in particular those outside and away from home broadband connections.
"Action multiplayer games such as Fortnite need a low latency to deliver a good multiplayer experience. Historically, mobile network latencies have been too poor to support action multiplayer gaming well," said OpenSignal analyst Ian Fogg. That's changing with today's 4G, "and as 5G new radio networks launch, latencies will improve even more significantly."
Another way gaming could benefit is similar to the drone example. With 5G, game consoles could rely on fast links to central servers with most of the computing horsepower. "Processing can be done in the cloud because of the high throughput and and low latency," said Dan Mondor, chief executive of Inseego, the company formerly named Novatel that's building the wireless network equipment for Verizon's early 5G broadband service. (Well not quite 5G, since Verizon this year is actually using technology similar to 5G but not the true standard itself, but the point still stands.)
Video chat and even plain old web browsing will benefit, Fogg added. Loading websites requires lots of round-trip communication exchanges between a browser and the servers hosting websites, so low latency can make websites snappier.
Vehicle-to-vehicle (V2V) communication is another latency-sensitive technology. It's not certain yet whether 5G will play a role there, but some think it will, including Jane Rygaard. She's head of 5G marketing for Nokia , one of the world's biggest makers of the mobile network equipment in the cell towers that connect your phone to the internet. 5G could help one car learn from others ahead on the road about potholes or braking. That information would be important to self-driving cars.
Key to V2V is an idea called edge computing that goes hand in hand with 5G. The idea is to move computing smarts from the central servers out to the 5G base stations. That'll mean a faster response time for processing tasks like figuring out which cars nearby need to know about a problem and which aren't affected.
"We need the network to be so good that we can leave space for the IT application to actually run," Rygaard said.
Augmented reality stands to benefit from 5G, too. A low-latency connection can deliver the necessary imagery nearly instantly as you move your phone or headset around, so an AR app doesn't have to deliver all the possible imagery for an AR scene in advance.
Oh, and there's that remote surgery idea. It'll be a long time before people trust robot surgeons commanded by distant humans, Rygaard said. But there are other places for remote-control operators who need real-time interaction -- a robot crawling around the radioactive Fukushima nuclear reactor disaster site, perhaps, or examining a possible bomb.
And there's more to medicine than surgery. Verizon is excited about 5G-linked virtual reality headsets that let a remote physical therapist perform cooperative ball-bouncing exercises with patients.
There's evidence 5G is getting the promised low latency links.
"We are between 1 to 2 milliseconds," Rygaard said of Nokia's tests of latency between phones and cell towers. A millisecond is a thousandth of a second, about the time a baseball is in contact with a bat that's hitting it.
There will be other delays in the system, such as software actually doing something with the data that's traversing the network, but the 5G fundamentals appear to be in place.
"We're seeing the very low single digit milliseconds," Fuetsch said. That's more than the 1-millisecond latency goal 5G proponents have sought for years, but it also includes communications deeper into the network, not just between a phone and cell tower. And it's a big improvement over today's 4G networks with latencies more than 10 times slower, according to real-world measurements from mobile analytics company OpenSignal.
On top of that, future versions of 5G will be able to guarantee that latency.
"In a 5G network, I can determine I want 2 milliseconds, and it should be able to give me 2 milliseconds every single time," Rygaard said. That guarantee doesn't matter much for watching streaming video from a sports game, but it does when you have two factory robots working in sync, she said.
Not everyone is so optimistic, though.
"Even if I reduce the latency to 1 millisecond, that only gets you to the base station. For most normal things you're doing on the phone, it's got to go to the cloud anyway," so latency will still be a problem, said Linley Group analyst Linley Gwennap. You can cache some data and do some processing in base stations themselves, but you can't put all the data and software from all the data centers operated by Google , Netflix, Facebook and others.
And self-driving cars with 5G? "Ridiculous," Gwennap said. There will be lots of areas with no 5G network coverage, he said, and "if my car is on Verizon and yours is on AT&T it's not going to be instantaneous anyway," he said.
OK, so maybe the hype is getting ahead of the reality. The 5G standards for ultra-low latency are still being hammered out and that technology likely won't arrive until 2020, Mobile Ecosystem analyst Mark Lowenstein said.
"We're in a particular period of pre-5G hype cycle, where a dose of reality is needed," he said in an October report. 5G really will be different from 4G today, but it'll arrive only gradually and in phases. So don't expect the self-driving cars or 5G robots quite yet. "Patience and a long view will be needed."
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