The Emerging Technologies Shaping Future 5G Networks | MIT Technology Review: "...So it’s natural to look at the longer wavelengths and higher frequencies of millimetre wave transmissions ranging from 3 to 300 GHz. This should provide orders of magnitude increases in bandwidth.
But it won’t be entirely smooth going. The main problem with these frequencies is their propagation characteristics—the signals are easily blocked by buildings, heavy weather and even by people themselves as they move between the device and the transmitter.
But it should be possible to mitigate most problems using advanced transmission technologies, such as directional antennas that switch in real time as signals become blocked. “Propagation is not an insurmountable challenge,” they say.
Next is the rapidly developing multiple input-multiple output or MIMO technology. Base stations will be equipped with multiple antennas that transmit many signals at the same time. What’s more, a device may have multiple antennas to pick up and transmit several signals at once. This dramatically improves the efficiency with which a network can exploit its frequencies...."