from5g to 6g

Scoring the Terabit/s Goal: Broadband Connectivity in 6G

From 5G to 6G

Dr. Italo AtzeniSenior Researcher, Adjunct Professor

Some key questions

- What will beyond-5G and the sixth-generation (6G) wireless networks look like?

- Which new technology components will be at their heart?- Will the 1 Tbps frontier be reached in practice?- Will uniform coverage and quality of service be fully achieved?

At the moment, it is very challenging and risky to provide definite answers to these questions.

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Some key answers

A conservative answer:- 6G networks will be based on a combination of 5G with other known

technologies that are not mature enough for being included in 5G.- Example: full MIMO processing with digital signal-space

beamforming to replace traditional codebook-based beamforming.

A more daring answer:- 6G networks will be based on new technologies that were not at all

considered when designing and developing 5G combined with vast enhancements of technologies that were already present in the previous generation of wireless cellular networks.

- Example: advanced massive MIMO schemes together with cell-free and user-centric network deployments.


Some key answers

A confident answer: 6G networks will- Be based on extreme network densification to form a cell-free network

with seamless QoS over the coverage area.- Complement sub-6 GHz carrier frequencies for wide-area coverage

with higher carrier frequencies beyond the mmWave through the THz band and up to visible light (VL) for high-capacity point-to-point links.

- Integrate terrestrial, airborne, and satellite networks to improve coverage and offload the network.

- Make intense use of distributed processing and cache memories, e.g., in the form of cloud-RAN technology.

- Leverage network slicing and multi-access edge computing to support vertical markets.

- Leverage machine learning to improve the efficiency of traditional model-based algorithms for signal processing and resource allocation.


5G today – modulation and coding

The 5G New Radio (NR) standard uses the same waveforms as in 4G.- OFDM mandatory in both the downlink and the uplink; DFT-spread-OFDM

available in the uplink.- Current studies for extending the NR specification to carrier frequencies up to 71

GHz envision the use of the same waveforms with bandwidths up to 2 GHz.

The 5G NR standard currently supports 256-QAM in both the downlink and the uplink.- Support for 1024-QAM in the downlink expected in future releases.- π/2-BPSK supported for the DFT-spread-OFDM in the uplink, which can enable

extreme coverage due to its low PAPR.

The 5G NR standard uses new channel coding schemes with respect to 4G.- LDPC coding for the data channels and polar coding for the control channels.


5G today – multi-antenna techniques

Multi-antenna techniques are ubiquitous in the 5G NR standard (single-user and multi-user MIMO).

3GPP defines massive MIMO as having more than 8 antenna ports: this is already widely supported by the current 5G NR standard.- Nonetheless, there are plenty of commercial products with up to 64 antennas for

use in sub-6 GHz bands.

At mmWave frequencies, the 5G NR standard relies on larger antenna arrays and analog beamforming.- From 8 beams in one dimension at sub-6 GHz frequencies to 64 beams in two

dimensions (vertical/horizontal) at higher frequencies.

Rel. 16 supports transmissions from multiple transmission/reception points and several other enhancements to exploit large antenna arrays.


6G use cases

The emergence and need for 6G technology will be governed by unprecedented performance requirements arising from exciting new applications.Broadband applications will require high data rates in combination with other specialized characteristics.

- Extreme capacity xHaul: fixed high-capacity point-to-point links capable of aggregating the data of many users and providing efficient access to cloud-/edge-computing resources.

- Enhanced hotspot: access points with high downlink rate and short coverage to several low-complexity users.

- Short-range device-to-device communications: high-rate data links between low-energy, low-complexity users with limited or no involvement by the network.


6G use cases

- Connectivity in remote areas: 10 Mbps guaranteed in every populated area of the world by a combination of terrestrial, airborne, and satellite network components.

- High-mobility hotspot: mobile hotspot to fixed infrastructure links with very high data rate, low latency, and close to 100% availability at speeds exceeding hundreds of km/h.

- Multi-sensory extended reality: AR/MR/VR applications capturing multi-sensory inputs and providing real-time user interaction.

- Industrial automation and robotics: industry 4.0 and high-precision manufacturing enabled by very high reliability, low latency, and real-time data transfer.

- Autonomous mobility: fully autonomous smart transportation enabled by very high data rate, high reliability, low latency, and 100% availability at speeds up to 1000 km/h.


6G key performance indicators (KPIs)

6G will likely consider the same KPIs as 5G (plus some additions) but with much higher ambitions. - In the future, we should consider new KPIs driven by

technology/productivity and sustainability/societal aspects.

6G KPIs will be defined based on different groups, with all the indicators in a group fulfilled at the same time.- The requirements of different broadband applications will

become so specialized that their union cannot be simultaneously achieved.


6G key performance indicators (KPIs)


KPIs 5G 6G

Peak data rate 20 Gb/s 1 Tb/s

Experienced data rate 0.1 Gb/s 1 Gb/s

Peak spectral efficiency 30 b/s/Hz 60 b/s/Hz

Experienced spectral efficiency 0.3 b/s/Hz 3 b/s/Hz

Maximum bandwidth 1 GHz 100 GHz

Area traffic capacity 10 Mb/s/m2 1 Gb/s/m2

Connection density 106 devices/km2 107 devices/km2

Energy efficiency Not specified 1 Tb/J

Latency 1 ms 100 µs

Reliability 1 - 10-5 1 - 10-9

Jitter Not specified 1 µs

Mobility 500 km/h 1000 km/h

Thank you!

from5g to 6g

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