6G ? Home : www.sharetechnote.com
Here goes the list of the items in this page, as the techology grows and my knowledge on this subject gets wide and deep enough I will spin out separate pages for more specific topics.
Simple answer is 'We don't know yet' -:). At least, as of Jul 2019 when I was writing the first note on this topic.
But from various presentations and documents that I've gone through, it seems that we may identify a few pillars as we did at the early stages of 5G as shown below. I tried to set the three pillars as in 5G. It seems that the first two pillars Terahertz and AI/ML seems to the ones that are most commonly mentioned in the early discussion but I am not sure whether the third pillar High Data Rate in eMTC/URLLC can be a clear target for 6G or not.
Teraherz/Tera bps : In many of the documents, this goal is described as Terahertz. The literal meaning of Teraherzh implify that the carrier frequency of the signal is in the range of TeraHz(1000 Ghz). But I would interpret this as a Tera bps rather than Tera Hertz since the carrier frequencies being proposed in various documents are not always in the range of Tera Hz. The frequency range being discussed in those documents are in the range of several hundreds of Ghz or in Tera Hz. However, it seems to be clear that the final target is to achieve Tera bps range of data transfer.
Now you may have some fundamental questions and stick to it for several years. What kind of electronics would be used to achieve this goal ? Would we call this mmWave ? or Optical wave ?
AI(Artifical Intelegence)/ML(Machine Learning) : In 6G, it seems that AI/ML would be a feature that is integrated into the functionality of the radio and core network. It would implie that most of the network component should be virtualizied to apply the flexibility of AI/ML to the network functionality.
I asked the same question when I started looking into things about 5G around mid 2013. 5G activities in some pioneering organizations started even earlier. Now I heard some leading company in 5G has started their research back to 2007 or so.
I would say, "Yes it is too early if you are interested only in solid/determined 3GPP specification". I don't think you would see much formal activities in 3GPP until release 18 or later (probably sometime around 2026 or later ?).
However if you are interested in observing the whole process of how a new technology is being formed and evolved and finally turns into operational products, nothing is too learly. To me, it is always enjoyable to follow something from the very early conception through the full developmental process.
For now (Jul 2019), I am writing comments on this based on the assumption that 6G physical layer will be based on THz(Tera Hertz) technology,
Roughly two major technology of Thz implementation is being discussed. One is based on Optics and the other is based on electronics, but it is highly likely that electonics based technology would be adopted (at least for communication between mobile station and base station).
There are many options to implement this, but preferred one would be transistor based on implementation. Then need to check if a source(osciallator), mixer, power amplifiers can be implemented for the selected technology. I am not the expert on this area, so not in the position to share the latest information on this. If you are interested, you may refer to Ref  as a start and follow through the references listed there. It is published in 2011, so I think the technology has been much more matured by now(Jul 2019).
Once the basic components (e.g, Source, Mixer, Amplifer etc) is developed and commercialized, some pioneering test equipment vendor would come up with signal generator and analyzer. Then the industry or academia would start researching on physical channel properties for the target frequency. This is what had done by 5G several years back (see this as an example).
The result on this physical channel properties and propagation model would be a critical step to determine whether the selected technology can be adopted for the new communication technology or not. Once it is determined to be feasible to use the technology, you may start hearing on possible concepts of physical layer protocol issues like waveform, modulation scheme, frame structure etc.