Arstechnica has a good article on why buying a 5G smartphone may not be a good move for a while. One of the main ideas to get in your head is 5G is has multiple spectrums.
Below is a graphic from the Arstechnica article showing the millimeter wave spectrum that 5G adds on top of 4G.
So sounds good lots more spectrum, but you thought you had problems with 4G LTE coverage. mmwave 5G is going to be worse for coverage in a building or in a car. To get 5G coverage you will need an antenna outside or an internal antenna system connected to the network.
Still a big confused?
How about this as a way to understand 5G. The 4G LTE spectrum will reach you from 10 miles away. mm microwave can be as short as 1,000 ft of an antenna. Handing off between that many antennas on a voice call would be hard.
One study I haven’t seen yet even though the 5G latency is dramatically better than 4G what is the latency and throughput impact when you jump from one 5G antenna to another?
5G will cover LTE, 802.11, and mmMicrowave technologies. Do you think will be addressed in 2019. I don’t think so.