For example, if a remotely controlled robot senses its own surroundings but needs to ask the cloud how to respond to things nearby, it had better get nearly instant responses so it can act on time. LTE isn't built for a quick enough turnaround, no matter how many bits per second it can transmit.
The consensus is that 5G should get latency down to 1 millisecond. That's a simple number to remember, but it's also the time it takes for someone to react to an object in front of their eyes, said Professor Gerhard Fettweis of TU Dresden. If a wireless virtual-reality headset can't sync up vision and reaction at least that closely, the user will start to feel sick after a while, Fettweis said at an MWC panel discussion.
Deutsche Telekom's T-Mobile is demonstrating that concept on the show floor with a robotic arm. The arm places two metal balls at the top of a small tower, where they're secured by electromagnets. Then the arm swings past the tower, and when it's detected passing underneath, the balls fall. The ball controlled over a network with some 5G features drops in time to be caught, but the one linked to an LTE network falls too late.
A demonstration of potential 5G technology in the T-Mobile booth at Mobile World Congress 2016, seen on Feb. 24, 2016, used a robot arm to show a benefit of low-latency wireless.
5G is also meant to connect millions of low-power devices like sensors and meters. There won't be much data traversing those links, but the objects at the edge will have to operate for years on the same battery.
5G is expected to go one step further than LTE's emerging low-power system, Narrowband-IoT. NB-IoT can handle about 100,000 devices per cell, 100 times regular LTE's capacity. If IoT proliferates like so many vendors and carriers say it will, there may be a need to support another 100 times as many.
5G will have so many uses that it will need a way for carriers to make the same network perform in different ways for different users. The software that can do this function, called network slicing, is expected to be a key element of 5G. SK Telecom, T-Mobile and others are demonstrating it at MWC.
Network slicing divides the infrastructure into several virtual networks optimized for things like high speed, low latency and low power consumption. Each virtual network gets its share of a pool of computing power, and if one gets overloaded, the others aren't affected.
Now for the bad news. No one's showing 5G handsets yet. The devices that simulate phones in current trials can be as big as an ice cream cart. And the 10-year IoT battery life everyone's talking about assumes batteries that are reliable for a decade.
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