5G is a new network system that has much higher speeds and capacity, and much lower latency, than existing cellular systems. The technologies to be used in 5G are still being defined, but there are many details on which everyone agrees.
5G networks will use a type of encoding called OFDM, which is similar to the encoding that LTE uses. The air interface will be designed for much lower latency and greater flexibility than LTE, though.
The new networks will predominantly use very high frequencies that can transmit huge amounts of data, but only a few blocks at a time. The standard will work all the way from low frequencies to high, but it gets the most benefit over 4G at higher frequencies. 5G may also transmit data over the unlicensed frequencies currently used for Wi-Fi, without conflicting with existing Wi-Fi networks. That's similar to a technology T-Mobile is launching this year called LTE-U.
5G networks are much more likely to be networks of small cells, even down to the size of home routers, than to be huge towers radiating great distances. Some of that is because of the nature of the frequencies used, but a lot of that is to expand network capacity.
So 5G networks need to be much smarter than previous systems, as they're juggling many more, smaller cells that can change size and shape. But even with existing macro cells, Qualcomm says 5G will be able to boost capacity by four times over current systems by leveraging wider bandwidths and advanced antenna technologies.
The goal is to have far higher speeds available, and far higher capacity per sector, at far lower latency than 4G. The standards bodies involved are aiming at 20Gbps speeds and 1ms latency, at which point very interesting things begin to happen.