You can credit Moore's Law for much of what you now see happening in terms of spectrum policy and access. Shared spectrum in 3.5 GHz (Citizens Broadband Radio Service), the ability to run Long Term Evolution 4G in unlicensed spectrum, use of unlicensed 5-GHz Wi-Fi spectrum as though it were part of an operator's licensed spectrum, and the vast amounts of new 5G spectrum (and also unlicensed spectrum in millimeter ranges), are possible only because continuing advances in signal processing and computation now allow us to do all those things affordably.
source: Electronic Design
Where in the analog domain millimeter waves would have had cost and distance limitations, we now can process signals at low cost, and code and reconstruct signals at distances that are economically useful and realistic.
That is why the Federal Communications Commission is opening up nearly 11 GHz of spectrum (capacity), in the bands above the 24 GHz frequency range, for mobile use. The FCC also currently considering whether to open up even more spectrum in the millimeter wave bands for 5G and other uses, for perhaps a total of 29 GHz of new spectrum (capacity).
"Within living memory, it was thought that spectrum above 3 GHz (frequency) could not be used for mobile communications," said FCC Chairman Ajit Pai. "Today, one can use millimeter wave spectrum to produce multi-gigabit speeds."