If 5G technology will take so long to mature and become available to customers in its most capable form, and to ascertain whether questionable aspects of 5G like low latency edge computing have actual uses, why would anyone even mention 6G?

WIthout the promise of 6G, mobile telecommunications will develop into a price and performance competition that will leave heavily indebted network operators in a squeeze between debt service, capital spending for network upgrades, and unrelenting price pressure. Pretty grim! So, of course there is a 6G.

What is 6G?

Currently, there is no specification for 6G. 6G, such as it is, is a collection of technologies and buzzwords. 6G is mentioned in the names of telecom industry conferences. There is even a Dutch telecom company named 6G Mobile. It has nothing to do with 6G technology. Why not call it 7G? That name would last longer. Something the 20th Century Fox people should have considered.

Prospective technologies that might someday be included in a 6G specification are, nevertheless, real. Human ingenuity when it comes to radio communication is not at an end. Nor are improvements in processing power going to stop soon.

The task at hand is to separate what could be real in a 6G future, and what is unlikely. Having looked fairly closely at what is real and what is a fantasy in 5G, you are now equipped to identify those same patterns in 6G hype.

Radio technology is real

There are two main avenues for continued improvements in communications radio technology: Increasing the amount of data than can be encoded in a radio signal, and making use of higher frequencies in the radio spectrum.

Future mobile radios will support denser encoding of data. That denser encoding will perform better in real-world conditions as radio designers incorporate greater ability to compensate for interference and noise. These improvements will require more sophisticated software and more processing power. That those things are possible is the safest of bets regarding the future of mobile technology.

Mobile devices will make use of even higher frequencies, even though they require higher performance radio hardware. These developments depend on the mass market economics of mobile communication. If you can sell billions of devices, making the parts for those devices will benefit from the scale in which they are made. The manufacturing equipment can be breathtakingly expensive, but the cost spread over those billions of devices will continue to make it possible for mobile devices to benefit from the cutting edge of radio technology.

Some light reading

While computing power, encoding techniques, compensation for noisy and otherwise hostile environments for radio signals, will continue to advance without running into fundamental limitations, the higher frequencies proposed for use in 6G radios are running up against an insuperable limitation: They are getting close to the visible light spectrum.

The electromagnetic spectrum is bounded at one end by the number zero: If your frequency is zero, you can't communicate. Perhaps surprisingly, as soon at your frequency becomes non-zero, you can use electromagnetic waves to communicate. You can't send a lot of data on a 50 hertz (about a billion times lower frequency than 5G millimeter wave bands) signal, but that signal will penetrate deep, even to the bottom of the ocean and beyond. So if you need to send a signal to a fleet of strategic missile submarines, you do it with a low frequency signal transmitted by an antenna that is kilometers long, buried in the ground. It doesn't really matter where you put the antenna. The US put their radios in Wisconsin and Michigan. The signals from these radios penetrate the entire planet.

Let's look at the opposite end of what humans might conceivably use for radio communication: Terahertz waves. These are shorter than millimeter waves, and getting darn close to visible light, which is of course just another electromagnetic wave. In fact another name for the terahertz part of the electromagnetic spectrum is "infrared."

While it is possible to build radios that will modulate and decode signals that carry potentially prodigious amounts of data on terahertz waves, many things, particularly water, will stop those waves. Not just attenuate, but really stop them entirely. All of the engineering problems making it hard to use millimeter waves are compounded for terahertz waves. Nevertheless, it is a good bet that 6G will try to use terahertz waves.

Antennas get smarter

There are other technology improvements coming. While these are smaller improvements than terahertz radio might bring, they are also less likely to run into large problems when put into practice.

Antenna technology as applied to mobile radio will become ever more important. At the center of antenna technology research is MIMO (multiple input/multiple output) antenna systems, especially massively MIMO, 3D MIMO, and lensed MIMO. While MIMO makes things like beam steering possible for 5G, it is vital for terahertz radio, which would be of little practical use without beam forming.

MIMO will continue to improve for 5G, especially in enabling better performance in 5G fixed wireless service. You can read more about how MIMO works here in upcoming additions to this site.