Why 5G and Why Not 10G?
Why mobile networks are developed in phases like 1G after 2 years 2G and then like wise every 2 years next G? What is stopping us from deploying 10G right now?
You should look at the standard body 3GPP, a consortium of standard bodies, it has releases, not generations and releases come every year or so:
http://www.3gpp.org/specifications/releases
Releases are proposals that are realistic, not only technologically but also economically and that make sense in the telecom ecosystem. For example as you say, one can dream of a 300GHz, 256 antennas phone transmitting data at 3,200 GBits/sec, but actually no phone CPU or hardware would be fast enough to keep up with such a wild beast (they already have difficulties to cope with the current gigabit/sec rates).
In addition the higher frequency you go to escape the spectrum regulation, the greater attenuation there is in the medium, so at 300GHz you can may expect a path of only a few meters.
Reference: http://www.rfwireless-world.com/Terminology/4G-vs-5G-differe...
'The goals of 5G technology can be summarized in the following value points:
1,000x increase in capacity Support for 100+ billion connections Up to 10Gbit/s speeds Below 1ms latency'
Specifically the difference in 4G and 5G. 4G was mostly about increasing speeds and bandwidth in terms of increasing efficiency, using MIMO (multiple input and multiple output) strategies, duplexing, carrier aggregation ...
'5G is aiming on providing pervasive connectivity to lay grounds for fast and resilient access to the Internet users, whether they are on a top of a skyscraper or down under a subway station.' As you've alluded to there have been a number of advancements since 4G was released to the public. To implement 5G it will leverage the latest research in the area including beamforming, vRan and bunch more.
So as you can see mobile communications standards are more than just about frequency bands and includes improving technology for end to end communication. Hope that helps!
Ref: http://www.androidauthority.com/4g-and-5g-wireless-how-they-... Ref: https://www.ericsson.com/research-blog/5g/massive-beamformin... Ref: https://insight.nokia.com/how-vran-helping-future-proof-mobi...