Although the 5G mobile communications standard is still in the early days of its deployment, ideas are starting to come to the fore to consider what the next generation, i.e. 6G mobile communications might look like.

It is perfectly normal to start looking at what 6G technology might include because the technology for 6G will take some while to develop.

If 6G is to be able to meet the needs of the mobile communications when it is launched and for some while afterwards, then it will need to use up to the minute technology - technology which is not available at the moment.

However the has been talk that 5G will be the last mobile standard released as such: this will be updated to provide the required performance improvements and in this way it overcomes the huge investment required to launch a completely new system. If this idea catches hold then 6G will not be named as such, but instead it will be a major improvement in 5G performance to meet the needs of the ongoing mobile communications or wireless communications users.

What is 6G mobile communications technology - definition

In terms of a definition of what 6G technology might be, it is probably a little early to give an exact definition.

What can be said is that 6G, or the sixth-generation wireless communications system is the successor to 5G cellular technology. It is anticipated that 6G networks will be able to use higher frequencies than 5G networks and this will enable higher data rates to be achieved and for the 6G network to have a much greater overall capacity. A much lower latency levels will almost certainly be a requirement.

Overall it is expected that 6G mobile technology will be to support one micro-second or even sub-microsecond latency communications, making communications almost instantaneous.

Timescales for 6G

5G started its deployment in 2019, and it is anticipated that it will be the major mobile communications technology up until at least 2030. Initial 6G deployments might start to appear in the 2030 to 2035 timescales, although this is very much a rough estimate.

However these timescales for 6G roughly fall in line with those for previous generations: 1G was available in approximately the 1980s, 2G in the 90s, 3G started deployment around 2003, and 4G initial deployments started in 2008 and 2009, and finally 5G in 2019.

In order that 6G technology is available in time, initial ideas need to start coming together about now.

6G technology developments

There are already a number 6G technology research projects looking into what might be possible and also what might be needed.

The actual format for 6G will depend on how 5G develops and where its shortfalls appear to be. Currently there are many different use cases that have been put forwards and only time will tell what the uptake is and how 5G is used. It is expected that it will be used increasingly for the Internet of Things, IoT, as well as inter-vehicle communications for autonomous vehicles. The way all of this pans out remains to be seen.

If there are shortfalls in 5G, then these can be included in the 6G proposals.

In addition to this, one of the areas that is expected to be a key element of 6G is TeraHerz communications. Using these exceedingly high frequencies, huge bandwidths will become available, although the technology is not available to make this happen.

6G development projects

There are already a number of 6G technology projects that are under way at the moment, and some organisations are now starting early development.

  • South Korea Electronics and Telecommunications Research Institute:   As might be expected, South Korea is well ahead and this institute is conducting research on Terahertz band technology for 6G. They are hoping to make 6G 100 times faster than 4G LTE and 5 times faster than 5G networks.
  • The Ministry of Industry and Information Technology, MIIT, China: With China investing large amounts into technology, they are keen to gain a lead in 6G. Accordingly MIIT is directly investing and monitoring the research and development process.
  • The University of Oulu, Finland:   This university has started a 6G research initiative known as 6Genesis. The project is expected to run for at least eight years and it will develop ideas that will be suitable for 6G technology almost to 2040.
  • USA initiatives:   The USA is planning to open up 6G frequency spectrum at frequencies at frequencies between 95 GHz and 3 THz for early research and development, although this will require approval from the Federal Communications Commission FCC for frequencies over 95 gigahertz GHz to 3 THz.

Technologies for 6G

6G mobile communications technology will build on that already established for 5G. Some of the existing new technologies will be further developed for 6G

  • Millimetre-Wave technologies:   Using frequencies much higher in the frequency spectrum opens up more spectrum and also provides the possibility of having much wide channel bandwidth. With huge data speeds and bandwidths required for 6G, the millimetre wave technologies will be further developed, possibly extending into the TeraHertz region of the spectrum.
  • Massive MIMO:   Although MIMO is being used in many applications from LTE to Wi-Fi, etc, the numbers of antennas is fairly limited -. Using microwave frequencies opens up the possibility of using many tens of antennas on a single equipment becomes a real possibility because of the antenna sizes and spacings in terms of a wavelength.
  • Dense networks: Reducing the size of cells provides a much more overall effective use of the available spectrum. Techniques to ensure that small cells in the macro-network and deployed as femtocells can operate satisfactorily are required.

Many new technologies will also be introduced. Some candidates that are being talked about could include the following.

  • Future PHY / MAC:   The new physical layer and MAC presents many new interesting possibilities in a number of areas:
    • Waveforms:   One key area of interest is that of the new waveforms that could be used for wireless communications. OFDM has been used very successfully in 4G and 5G mobile communications as well as a number of other high data rate wireless communications systems, but it does have some limitations in some circumstances. Other waveforms could include: GFDM, Generalised Frequency Division Multiplexing, as well as FBMC, Filter Bank Multi-Carrier, UFMC, Universal Filtered MultiCarrier. Each has its own advantages and limitations and it is possible that adaptive schemes may be employed, utilising different waveforms adaptively for the 6G mobile communications systems as the requirements dictate. This provides considerably more flexibility for 6G mobile communications.
    • Multiple Access Schemes:   Again a variety of new access schemes are being investigated for 6G techno
    • Modulation:   Whilst PSK and QAM have provided excellent performance in terms of spectral efficiency, resilience and capacity, the major drawback is that of a high peak to average power ratio. Modulation schemes like APSK could provide advantages in some circumstances. APSK has a much lower peak to average power ratio, PAPR, it lends itself better for mobile communications systems better as the final amplifier can operate more efficiently the lower the PAPR.
  • Duplex methods:   There are several candidate forms of duplex that could be considered for the new 6G wireless communications system. Currently systems use either frequency division duplex, FDD or time division duplex, TDD. New possibilities are opening up for 6G including flexible duplex, where the time or frequencies allocated are variable according to the load in either direction or a new scheme called division free duplex or single channel full duplex. This scheme for 6G would enable simultaneous transmission and reception on the same channel.

Although 6G mobile communications is a very long way off, research and development as well as some thought of what 6G might look like is already starting, and the pace will only continue to increase.

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