What is 6G ?

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 (For the details of 6G the frequency range being actively discussed, refer to 6G Spectrum page). However, it seems to be clear that the final target is to achieve Tera bps range of data transfer (Refer to 6G KPI page for the details of 6G data rate requirement). 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 ? (For the details of the electronics for 6G implementation, refer to 6G Electronics page)  

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.   There are many documents that defines 6G in various different aspects.  None of them defines better than others. You would not know of the best definition for a while even after 6G realization. The only thing we can do as of now (May 2021) would be to collect as much diverse opinions as possible and try to get another picture of your own.  

Source : The shift to 6G communications: vision and requirements (Dec 2020)    

Following illustrations shows a 6G definition by Huawei. As you see, eMBB, mMTC, URLLC would take evolutionary path into 6G and Network Sensing will become a new pillar in 6G. All the components will be coordinated / controlled by AI in 6G. Source : 6G: The Next Horizon  


Source : 6G: The Next Horizon    


Source : Drawn based on 6G Wireless Systems: Vision,Requirements, Challenges,Insights, and Opportunities      



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