5G mobile communications

The new 5G mobile communications system will enable many new mobile capabilities to be realised – offering high speed, enormous capacity, IoT capability, low latency and much more it provides the bearer for many new applications.

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The 5G mobile communications system provides a far higher level of performance than the previous generations of mobile communications systems.

The new 5G technology is not just the next version of mobile communications, evolving from 1G to 2G, 3G, 4G, but it provides a new approach giving ubiquitous connectivity.

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5G technology is very different. Previous systems had evolved driven more by what could be done with the latest technology. The new 5G technology has been driven by specific uses ad applications.

5G mobile communications has been driven by the need to provide ubiquitous connectivity for applications as diverse as automotive communications, remote control with haptic style feedback, huge video downloads, as well as the very low data rate applications like remote sensors and what is being termed the IoT, Internet of Things.

5G is able to provide much greater flexibility and therefore it is able to support a much wider range of applications, from low data rate Internet of Things requirements through to very fast data rate and very low latency applications.

5G standardisation

Like all widely used systems, the 5G mobile communications is governed by a series of standards. Building on 2G GSM, 3G UMTS and then 4G LTE, the 5G standard come under the auspices of 3GPP – Third generation Partnership Project.

3GPP has a number of different work groups, each addressing different elements of the required standards. They draw on industry expert who give of their time and are sponsored by relevant mobile communications companies. In this way the standards are written and developed.

By having a main industry organisation that controls the standards, interested parties are able to influence the standards to ensure that the required functionality is obtained. Also as the standard are international not only can different companies work on different elements of the system and know they will interoperate, but also for the user, capabilities like roaming are available, and the cost of phones, calls, etc are reduced as a result of the savings of scale, etc.

The 3GPP standards are updated as specific releases – each release refining elements that have already been described, and introducing new functionality. Previous releases contained the standards for GSM, UMTS and LTE. As 5G started to be developed, it too was incorporated into the standards.

3GPP RELEASES
3GPP RELEASE	RELEASE DATE	DETAILS
Previous releases	—	GSM, UMTS & LTE
Release 14	Mid 2017	Elements on road to 5G
Release 15	End 2018	5G Phase 1 specification
Release 16	2020	5G Phase 2 specification
Release 17	~Sept 2021

5G cellular systems overview

As the different generations of cellular telecommunications have evolved, each one has brought its own improvements. The same is true of 5G technology.

• First generation, 1G:   These phones were analogue and were the first mobile or cellular phones to be used. Although revolutionary in their time they offered very low levels of spectrum efficiency and security.
• Second generation, 2G:   These were based around digital technology and offered much better spectrum efficiency, security and new features such as text messages and low data rate communications.
• Third generation, 3G:   The aim of this technology was to provide high speed data. The original technology was enhanced to allow data up to 14 Mbps and more.
• Fourth generation, 4G:   This was an all-IP based technology capable of providing data rates up to 1 Gbps.
• 5G technology:   When 5G was being first postulated a number of use cases were put forwards: very high speed data transfer as video downloads become larger and more commonplace; remote control with low latency – examples of autonomous vehicles communicating with rad infrastructure to provide safe transport as well as the example of experienced surgeons being able to perform delicate surgery remotely using a 5G link both of these examples require very low latency mobile communications; more capability for general data communications; ability to accommodate the very low data rate and occasional communications for the Internet of Things, IoT where very long battery life is needed.

Rather than just offering more of what was in the previous mobile communications generations, 5G technology needed to offer new capabilities and ubiquitous connectivity. This would require not only the use of existing base stations which could be converted to 5G, but also many more small cells as well.

5G requirements

As the preliminaries for the work for the new 5G mobile communications system, the outline requirements were set in place. These were A defined by the ITU as part of IMT2020. Even now with 5G as an active mobile communications system, it is useful to refer to these requirements.

SUGGESTED 5G WIRELESS PERFORMANCE
PARAMETER	SUGGESTED PERFORMANCE
Peak data rate	At least 20Gbps downlink and 10Gbps uplink per mobile base station. This represents a 20-fold increase on the downlink over LTE.
5G connection density	At least 1 million connected devices per square kilometre (to enable IoT support).
5G mobility	0km/h to “500km/h high speed vehicular” access.
5G energy efficiency	The 5G spec calls for radio interfaces that are energy efficient when under load, but also drop into a low energy mode quickly when not in use.
5G spectral efficiency	30bits/Hz downlink and 15 bits/Hz uplink. This assumes 8×4 MIMO (8 spatial layers down, 4 spatial layers up).
5G real-world data rate	The spec “only” calls for a per-user download speed of 100Mbps and upload speed of 50Mbps.
5G latency	Under ideal circumstances, 5G networks should offer users a maximum latency of just 4ms (compared to 20ms for LTE).

5G communications system

The 5G mobile cellular communications system is a major shift in the way mobile communications networks operate. New network topologies, access networks and the like were defined and implemented.

• 5G New Radio, 5G NR:   5G new radio is the new name for the 5G radio access network. It consists of the different elements needed for the new radio access network. Using a far more flexible technology the system is able to respond to the different and changing needs of mobile users whether they be a small IoT node, or a high data user, stationary or mobile.

• 5G NextGen Core Network:   Although initial deployments of 5G utilised the core network of LTE or possibly even 3G networks, the network needed to move to a much flatter structure to provide the data capability and low latency needed.

5G technologies

5G also incorporates many technologies, many of which are new, to enable the it to provide the very high levels of performance required of it.

The technologies for 5G mobile communications include:

• Waveforms & modulation:   One of the major discussions when 5G was being developed was based around the type of waveform to be used. In the end the scheme was based around OFDM, with actual modulation formats dependent upon the link and these include QPSK, 16QAM, 64QAM, 256QAM and for the uplink when DFT-OFDM is used, π/2-BPSK can be used.
  
  For the future, other forms of waveform may be developed, but currently the waveform is based around OFDM.
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• Multiple Access:   Again, a variety of access schemes were discussed, but for the 5G New Radio, OFDMA was implemented. For the downlink CP-OFDM was used and in the uplink either CP-OFDM or DFT-OFDM could be used.

• Millimetre-Wave communications:   Millimetre wave mobile communications was not implemented for the initial deployments of the 5g mobile communications system as the technology for cost effective millimetre wave communications had not been sufficiently developed. The use of mmWave for 5G mobile communications will require a large number of base stations to give the required coverage.
  
  In preparation for the implementation of mmWave, frequencies are being allocated and fall within the FR2 (Frequency Range 2) set of allocations.

• Massive MIMO with beam-steering:   The antenna technologies for 5G have provided significant opportunities for enhancement of the performance over 4G. Although MIMO was used with 4G LTE, the technology has been taken further.
  
  Beam-steering technology has also been adopted to enable the transmitter and receiver antenna beams to be focussed towards the mobiles with which they are communicating. Each mobile can have its own beam, using advanced antenna technology, and this focussed the transmitted power where it is required and reduces interference between mobiles. This gives a significant improvement in performance.

• Dense networks:   Reducing the size of cells provides a much more overall effective use of the available spectrum. Whilst the large macro cells will be retained for general communications, many more small cells will be deployed to ensure that the data capacity can be provided.
  
  The use of smaller cells gives much greater frequency re-use and as a result the overall network can provide a significantly increased level of data capacity. As data usage is increasing rapidly, this is a clear and pressing requirement.

These are a few of the main techniques being developed and discuss for use within 5G.

 

 

5G timeline & dates

5G technology has developed rapidly. The first real deployments went live in 2019, and further deployments soon followed. Although there were some teething issues, many noticed a significant increase in speed.

New handsets were launched to accommodate the new technology and these enabled users to take advantage of much higher download speeds.

Many countries were keen to deploy 5G technology quickly as effective communications enable economic growth and are seen as an essential element of modern-day life and industry.

5G mobile communications technology is rapidly developing and it is becoming the technology that everyone is moving towards. Not only will it be able to accommodate the super-fast speeds required of it, but it will also be possible to accommodate the low data rate requirements for IoT and IIoT applications. As such 5G mobile communications will be able to encompass a huge number of different applications, and accommodate very many different data types.With the demanding requirements being placed upon the new 5G mobile communications standard, a totally new radio interface and radio access network has been developed. Called 5G New Radio or 5G NR, the new radio interface provides for the growing needs for mobile connectivity.

The development of the 5G NR or 5G New Radio is key to enabling the 5G mobile communications system to work and it provides a number of significant advantages when compared to 4G.

5G NR has been developed from scratch taking the requirements and looking at the best technologies and techniques that will be available when 5G starts to be deployed.

5G NR utilises modulation, waveforms and access technologies that will enable the system to meet the needs of high data rate services, those needing low latency and those needing small data rates and long battery lifetimes amongst others.

The first iteration of 5G NR appeared in 3GPP Release 15. The draft specifications for Release 15 were approved in December 2017 and are expected to be finalized in mid-2019. Release 15 forms phase one of a 5G mobile communication standard. Release 16 will provide specifications for the second phase and this is expected to be finalized in December 2019.5G radio access network gNB

5G New Radio, 5G NR Basics

The 5G New Radio has been developed to provide a significant enhancements in areas like flexibility, scalability and efficiency, both in terms of power usage and spectrum.

The 5G New Radio is able to provide communications for very high band with transmissions like streaming video as well as low latency communications for remote control vehicle communications as well as low data rate low bandwidth communications for machine type communications.

There are several cornerstones to the new radio used for 5G:

• New radio spectrum:   Mobile communications usage is rapidly increasing, and the introduction of 5G will accelerate this trend with many more applications being accommodated by the technology. Whilst improvements in spectrum efficiency will be made these will not be able to accommodate the huge increases in usage, so more spectrum is needed.
  
  Release 15 also outlines several groups of new spectrum specifically for NR deployments. These range in frequency from 2.5 GHz to 40 GHz. Two bands being targeted for more immediate deployment are in the regions of 3.3 GHz to 3.8 GHz and 4.4 GHz to 5.0 GHz.
  
  The 3.3 GHz to 3.8 GHz spectrum has already been released in countries like the USA< Europe and certain Asian countries and they could see deployment as early as 2018. Other higher frequency bands but below 40 GHz are also being reserved for 5G but this is only the beginning as there is talk of usage of frequencies up to 86 GHz.
  
  The advantage of the higher frequency bands is that they are much wider and they will be able to allow much higher signal bandwidths and hence support much higher data throughput rates. The disadvantage in some aspects is that they will have a much shorter range, but this is also an advantage because it will also allow much greater frequency re-use.
• Optimised OFDM:   An early decision was taken to use a form of OFDM as the waveform for phase one of the 5G New Radio. It has been very successfully used with 4G, the more recent Wi-Fi standards and many other systems and came out as the optimum type of waveform for the variety of different applications for 5G. With the additional processing power available for 5G, various forms of optimisation can be applied.
  

Basic concept of OFDM, Orthogonal Frequency Division MultiplexingThe specific version of OFDM used in 5G NR downlink is cyclic prefix OFDM, CP-OFDM and it is the same waveform LTE has adopted for the downlink signal.

• Beamforming:   Beamforming is a technology that has become a reality in recent years and it offers to provide some significant advantages to 5G. Beamforming enables the beam from the base station to be directed towards the mobile. In this way the optimum signal can be transmitted to the mobile and received from it, whilst also cutting interference to other mobiles.
  

Concept of antenna beamforming used with 5G NRThe move to higher frequencies allows for much smaller antennas and the possibility of programmable high directivity levels.

On frequencies above 24 GHz where antennas are smaller, there is the possibility of having high performance beam steering antennas that are able to accurately direct the power to the mobile in question, and also provide receiver gain in this direction.

• MIMO:   MIMO, multiple input multiple output has been employed in many wireless systems from Wi-Fi to the current 4G cellular system and it provides some significant improvements. Within 5G, MIMO will be one of the mainstay technologies.
  
  5G will take full advantage of Multi-User- MIMO, MU-MIMO where it will provide multiple access capabilities to MIMO by utilising the distributed and uncorrelated spatial location of the various users.
  
  In implementing this the gNB (5G base station) sends a CSI-RS (Channel State Information Reference Signal) to the different user equipment’s and then dependent upon the responses, the gNB computes the spatial information for each user. It uses this information to compute the required information for the pre-coding matrix (W-Matrix) where the data symbols are constructed into the signals for each of the elements of the gNB antenna array.
  
  The multiple data streams have their own weightings which includes phase offsets to each stream to enable the waveforms to interfere constructively at the receiver. This maximises the signal strength to the user whilst also minimising the signal and hence interference to other users.
  
  In this way the gNB is able to talk to multiple devices concurrently and independently by using spatial information. This means that 5G MU-MIMO enables the UEs to operate without need for knowledge of the channel or additional processing to obtain the data streams.
  
  MU-MIMO on the downlink significantly improves the capacity of the gNB antennas. It scales with the minimum of the number of gNB antennas and the sum of the number of user devices multiplied by the number of antennas per UE device. This means that using 5G MU-MIMO the system can achieve capacity gains using gNB antenna arrays and much simpler UE devices.
• Spectrum sharing techniques:   Much of the radio spectrum, although allocated, is not used in an efficient manner. One of the techniques being proposed is for spectrum sharing.
• Unified design across frequencies:   With the 5G New Radio utilising a wade variety of frequencies, possibly 3.4 to 3.6 GHz below 6GHz and then 24.25 to 27.5 GHz, 27.5 to 29.5 GHz, 37 GHz, 39 GHz and 57 to 71 GHz range as possibilities for the mmWave radio. It is important to have a common interface across these frequencies.
• Small cells:   As network densification is required to provide the required data capability more use of small cells and small cell networks are being proposed. A small cell network is a group of low power transmitting base stations which uses millimetre waves to enhance the overall network capacity. The 5G small cell network operates by coordinating a group of small cells to share the load and reduce the difficulties of physical obstructions which become more important at millimetre waves.

By utilising these techniques and many others, the 5G New radio, 5G NR will be able to significantly improve the performance, flexibility, scalability and efficiency of current mobile networks. In this way 5G will be able to ensure the optimum use of the available spectrum, whether it is licensed, shared or unlicensed, and achieve this across a wide variety of spectrum bands.

With the demanding requirements being placed upon the new 5G mobile communications standard, a totally new radio interface and radio access network has been developed. Called 5G New Radio or 5G NR, the new radio interface provides for the growing needs for mobile connectivity.

The development of the 5G NR or 5G New Radio is key to enabling the 5G mobile communications system to work and it provides a number of significant advantages when compared to 4G.

5G NR has been developed from scratch taking the requirements and looking at the best technologies and techniques that will be available when 5G starts to be deployed.

5G NR utilises modulation, waveforms and access technologies that will enable the system to meet the needs of high data rate services, those needing low latency and those needing small data rates and long battery lifetimes amongst others.

The first iteration of 5G NR appeared in 3GPP Release 15. The draft specifications for Release 15 were approved in December 2017 and are expected to be finalized in mid-2019. Release 15 forms phase one of a 5G mobile communication standard. Release 16 will provide specifications for the second phase and this is expected to be finalized in December 2019.5G radio access network gNB

5G New Radio, 5G NR Basics

The 5G New Radio has been developed to provide a significant enhancement in areas like flexibility, scalability and efficiency, both in terms of power usage and spectrum.

The 5G New Radio is able to provide communications for very high band with transmissions like streaming video as well as low latency communications for remote control vehicle communications as well as low data rate low bandwidth communications for machine type communications.

There are several cornerstones to the new radio used for 5G:

• New radio spectrum:   Mobile communications usage is rapidly increasing, and the introduction of 5G will accelerate this trend with many more applications being accommodated by the technology. Whilst improvements in spectrum efficiency will be made these will not be able to accommodate the huge increases in usage, so more spectrum is needed.
  
  Release 15 also outlines several groups of new spectrum specifically for NR deployments. These range in frequency from 2.5 GHz to 40 GHz. Two bands being targeted for more immediate deployment are in the regions of 3.3 GHz to 3.8 GHz and 4.4GHz to 5.0GHz.
  
  The 3.3 GHz to 3.8 GHz spectrum has already been released in countries like the USA< Europe and certain Asian countries and they could see deployment as early as 2018. Other higher frequency bands but below 40 GHz are also being reserved for 5G but this is only the beginning as there is talk of usage of frequencies up to 86 GHz.
  
  The advantage of the higher frequency bands is that they are much wider and they will be able to allow much higher signal bandwidths and hence support much higher data throughput rates. The disadvantage in some aspects is that they will have a much shorter range, but this is also an advantage because it will also allow much greater frequency re-use.
• Optimised OFDM:   An early decision was taken to use a form of OFDM as the waveform for phase one of the 5G New Radio. It has been very successfully used with 4G, the more recent Wi-Fi standards and many other systems and came out as the optimum type of waveform for the variety of different applications for 5G. With the additional processing power available for 5G, various forms of optimisation can be applied.
  
  
• Basic concept of OFDM, Orthogonal Frequency Division Multiplexing The specific version of OFDM used in 5G NR downlink is cyclic prefix OFDM, CP-OFDM and it is the same waveform LTE has adopted for the downlink signal.

• Beamforming:   Beamforming is a technology that has become a reality in recent years and it offers to provide some significant advantages to 5G. Beamforming enables the beam from the base station to be directed towards the mobile. In this way the optimum signal can be transmitted to the mobile and received from it, whilst also cutting interference to other mobiles.

• 
  

Concept of antenna beamforming used with 5G NRThe move to higher frequencies allows for much smaller antennas and the possibility of programmable high directivity levels.

On frequencies above 24 GHz where antennas are smaller, there is the possibility of having high performance beam steering antennas that are able to accurately direct the power to the mobile in question, and also provide receiver gain in this direction.

• MIMO:   MIMO, multiple input multiple output has been employed in many wireless systems from Wi-Fi to the current 4G cellular system and it provides some significant improvements. Within 5G, MIMO will be one of the mainstay technologies.
  
  5G will take full advantage of Multi-User- MIMO, MU-MIMO where it will provide multiple access capabilities to MIMO by utilising the distributed and uncorrelated spatial location of the various users.
  
  In implementing this the gNB (5G base station) sends a CSI-RS (Channel State Information Reference Signal) to the different user equipment’s and then dependent upon the responses, the gNB computes the spatial information for each user. It uses this information to compute the required information for the pre-coding matrix (W-Matrix) where the data symbols are constructed into the signals for each of the elements of the gNB antenna array.
  
  The multiple data streams have their own weightings which includes phase offsets to each stream to enable the waveforms to interfere constructively at the receiver. This maximises the signal strength to the user whilst also minimising the signal and hence interference to other users.
  
  In this way the gNB is able to talk to multiple devices concurrently and independently by using spatial information. This means that 5G MU-MIMO enables the UEs to operate without need for knowledge of the channel or additional processing to obtain the data streams.
  
  MU-MIMO on the downlink significantly improves the capacity of the gNB antennas. It scales with the minimum of the number of gNB antennas and the sum of the number of user devices multiplied by the number of antennas per UE device. This means that using 5G MU-MIMO the system can achieve capacity gains using gNB antenna arrays and much simpler UE devices.
• Spectrum sharing techniques:   Much of the radio spectrum, although allocated, is not used in an efficient manner. One of the techniques being proposed is for spectrum sharing.
• Unified design across frequencies:   With the 5G New Radio utilising a wade variety of frequencies, possibly 3.4 to 3.6 GHz below 6GHz and then 24.25 to 27.5 GHz, 27.5 to 29.5 GHz, 37 GHz, 39 GHz and 57 to 71 GHz range as possibilities for the mmWave radio. It is important to have a common interface across these frequencies.
• Small cells:   As network densification is required to provide the required data capability more use of small cells and small cell networks are being proposed. A small cell network is a group of low power transmitting base stations which uses millimetre waves to enhance the overall network capacity. The 5G small cell network operates by coordinating a group of small cells to share the load and reduce the difficulties of physical obstructions which become more important at millimetre waves.

By utilising these techniques and many others, the 5G New radio, 5G NR will be able to significantly improve the performance, flexibility, scalability and efficiency of current mobile networks. In this way 5G will be able to ensure the optimum use of the available spectrum, whether it is licensed, shared or unlicensed, and achieve this across a wide variety of spectrum bands.

The 5G NextGen, NG core network will play a key role in enabling the performance of the 5G mobile communications system.

Defining the next-generation architecture is the responsibility of the 3GPP’s System Architecture (SA) Technical Specification Group on Service and System Aspects.

The study phase, completed in 2016 and outlined what this new core network, known as NG Core, or NextGen core network, will look like.

considerations

Within the overall waveform format, different types of carrier modulation can be used. Within the 5G communications system, these are variants of phase shift keying and quadrature amplitude modulation.

There are several considerations when using the different modulation formats:

• Peak to average power ratio, PAPR:   The peak to average power ratio is one aspect of performance that needs to be considered for any 5G communications modulation scheme. The peak to average ratio has a major impact on the efficiency of the power amplifiers. For 2G GSM, the signal level was constant and as a result it was possible to run the final RF amplifier in compression to obtain a high level of efficiency and maximise the battery life.
  
  With the advent of 3G, then it’s HSPA enhancements and then 4G LTE, the modulation schemes and waveforms have meant that the signals have become progressively more’peaky’ with higher levels of peak to average power ratio. This has meant that the final RF amplifiers cannot be run in compression and as the PAPR has increased, so the efficiency of the RF amplifiers has fallen and this is one factor that has shortened battery life.
  
  The order of the modulation is one factor that has a major impact upon the PAPR: the greater the level of “peakyness” the lower the efficiency that can be achieved by RF power amplifier efficiency, although schemes like envelope tracking and Doherty amplifiers enable improvements to be made.
• Spectral efficiency:   One of the key issues with any form of 5G modulation scheme is the spectral efficiency. With spectrum being at a premium, especially in frequencies below 3 GHz, it is essential that any modulation scheme adopted for 5G is able to provide a high level of spectral efficiency.
  
  There is often a balance between higher orders of modulation like 64QAM as opposed to 16QAM for example and noise performance. Thus, higher order modulation schemes tend to be only used when there is a good signal to noise ratio.

5G modulation: PSK & QAM

A variety of different modulation formats are used for 5G technology.

• Phase shift keying:   5G technology implements quadrature phase shift keying, QPSK as the lowest order modulation format. Although this will provide the slowest data throughput it will also provide the most robust link and as such it can be used when signal levels are low or when interference is high.
  
  Another form of PSK called π/2BPSK is used in conjunction with DFT-s-OFDM on the up link.

What is PSK! – Phase Shift Keying:

Phase shift Keying, PSK is a form of modulation used particularly for data transmissions. If offers an effective way of transmitting data. By altering the number of different phase states which can be adopted, the data speeds that can be achieved within a given channel can be increased, but at the cost of lower resilience to noise an interference.

• Quadrature amplitude modulation:   Quadrature amplitude modulation enables the data throughput to be increased. Formats used within 5G mobile communications system include 16QAM, 64QAM and 256QAM.
  
  The higher the order of modulation, the greater the throughput, although the penalty is the noise resilience. Therefore 256AM is only used when link quality is good, and it reduces to 64QAM and then 16QAM etc, as the link deteriorates. It is a balance between data throughput and resilience.

What is QAM! – Quadrature Amplitude Modulation:

Quadrature amplitude modulation, QAM is widely sued for data transmission as it enables better levels of spectral efficiency than other forms of modulation. QAM uses two carriers on the same frequency shifted by 90° which are modulated by two data streams – I or Inphase and Q – Quadrature elements.

The waveform and modulation types used with 5G technology has been chosen to provide spectral efficiency, data throughput and resilience needed for the new mobile communications system.

5G mobile communications is able to provide very high data throughput, and therefore the waveforms and modulation need to be able to support this and provide reliable service for the users.

What is 6G Mobile Communications Technology

Even before the 5G mobile communications standard was fully deployed, the eyes of many started to turn towards the next generation: the 6G wireless communications system.

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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 2025. Initial 6G deployments might start to appear in the 2025 to 2030 timescales, although this is 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 TeraHertz*communications. Using these exceedingly high frequencies, huge bandwidths will become available, although the technology is not available to make this happen. *TeraHertz defined as one trillion (10¹²) cycles per second or 10¹² hertz.

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 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.https://spectrum.ieee.org/the-truth-about-terahertz

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, R & D as well as some thought of what 6G might look like is already starting.