2020 is about to end. With the advancement of 5G network construction and the freezing of the 3GPP R16 version, more and more people will shift their focus to 6G.
On July 14, South Korea’s Samsung Electronics released the white paper “Next Generation Hyper-Connected Experience”. In the white paper, Samsung estimates that the earliest time point for the completion and commercialization of the 6G standard is 2028, and large-scale commercialization may occur around 2030 .
Naijatechnews.com understand that, this forecast time point is very close to the forecast time point given by ZTE at the second global 6G Wireless Summit on March 17th:
From the perspective of social and technological trends, 6G will have the following notable features:
- Both humans and machines will be 6G users (and machines will instead be the primary users of 6G).
- AI will penetrate into various industries, such as finance, health, industrial manufacturing and other fields. 6G will use AI to further improve performance and reduce CAPEX and OPEX.
- 6G will make communication technology more open (such as the O-RAN alliance established in recent years, etc.).
- 6G will play a key role in many social issues. For example, tackling climate change (combined with digital technology to reduce greenhouse gas emissions) and solving education inequality (distance education) and other issues, 5G has provided some help for this. The hyper-connection provided by 6G will further assist in fulfilling the 2030 sustainable development goals proposed by the United Nations.
From a service perspective, what will 6G bring?
Naijatechnews learnt that, 6G will further enhance the eMBB, URLLC, mMTC and other features defined by 5G, and integrate more advanced sensing, imaging, display, and AI technologies to provide a hyper-connected experience, such as:
- Immersive Extended Reality (XR)
- High-fidelity mobile hologram
- Digital Mirror (Digital Twin)
(Extended reading: What is a digital twin?)
▉ Requirements that 6G must meet
To achieve a hyper-connected experience, 6G must meet requirements from three dimensions: performance, architecture, and reliability.
- 6G performance requirements
Compared with 5G, what performance improvement will 6G have? As follows:
- The peak data rate is 1Tbps (1000Gbps), which is 50 times that of 5G
- Air interface delay is less than 100 microseconds (μs), which is one-tenth of 5G
- Reliability reaches 10-7, one hundred times that of 5G
- The device connection density reaches 107/Km2, ten times that of 5G
- Spectrum efficiency reaches twice that of 5G
Draw into a spider web model, roughly as follows:
- 6G architecture requirements
Solve the problems caused by the limited computing power of mobile devices, and realize the true integration of communication and computing, so that various devices of end users can seamlessly use the computing power available in the network, such as the introduction of AI (or AI) from the early stage of technology development. Called native AI).
Flexible integration of new network functions, including integration with non-terrestrial networks, such as aircraft, low-Earth orbit and geostationary orbit satellites, high-altitude platforms, etc.
- 6G credibility requirements
Solve the security and privacy issues caused by the widespread use of user data and AI technology.
▉ Key technology development direction of 6G
Some typical candidate technologies for 6G are as follows:
- Terahertz frequency band (THz)
5G NR has begun to discuss working in the frequency band above 52.6GHz. Following this trend, mobile communications in the 6G era will inevitably use the THz frequency band.
However, in actual use of the THz frequency band, there are some technical challenges that must be overcome, such as:
(1) Its own propagation characteristics (severe path loss and atmospheric absorption): It is necessary to establish a multipath channel model suitable for THz for indoor and outdoor scenarios.
(2) Chips and radio frequency devices: In the past ten years, researchers have devoted themselves to the development of chip-level terahertz technology. Now based on InP, GaAs, SiGe, and even CMOS technologies, there have been some breakthroughs in the lower THz frequency band. But in the higher THz frequency band, further breakthroughs are needed to meet the requirements of high efficiency, low energy consumption and low cost.
(3) Antenna and beamforming: Terahertz means a sharp increase in path loss. Therefore, a very large-scale antenna array is required to compensate for the path loss. On the other hand, this will result in a very narrow beam (similar to a laser beam), so how to optimize the beamforming and improve the performance of the system with reasonable cost and energy efficiency is also very important.
(4) New waveforms, signals, channels and protocols: At present, OFDM will still be a candidate, but it is necessary to explore new candidate waveforms, reduce PAPR, and meet the hardware limitations of THz. In addition, appropriate signals, channels, and protocols need to be developed to effectively adapt to various operations of THz.
- New antenna technology
5G NR already uses Massive MIMO technology, but the THz band requires more antennas than millimeter waves, so there will be greater challenges. Here are some options:
(1) Antenna and RF front-end based on metamaterials
The first method is to apply the metasurface lens as a phase shift structure to the antenna array signal, and apply a DC offset to adjust the beam direction, which helps to sharpen the beam shape.
The second method: as a resonant antenna, the metamaterial antenna radiates a directional beam by itself. Unlike a metasurface lens, it does not require an independent antenna array with a phase shifter.
The third method: Reconfigurable Smart Surface (RIS). In layman’s terms, smart surfaces can change the electromagnetic characteristics of electromagnetic waves, thereby affecting the surrounding propagation environment.
(2) Orbital angular momentum (OAM)
In 1992, scientists confirmed through experiments that photons have the basic property of orbital angular momentum OAM.
The core of OAM communication research is to use orbital angular momentum, an unused electromagnetic wave parameter, for communication. Naijatechnews know that OAM is the characteristic of electromagnetic waves representing phase rotation on the vertical plane in the propagation direction, and the number of phase rotations is called OAM mode. Different OAM modes are orthogonal to each other, and multiple orthogonal signals can be transmitted on the same frequency point, thereby improving spectrum efficiency and channel capacity. This is the OAM multiplexing technology:
In May 2018, NTT of Japan successfully demonstrated 100Gbps wireless transmission for the first time in the world using Orbital Angular Momentum (OAM) multiplexing, and the laboratory designed OAM-MIMO multiplexing transmission. The results show that the system can significantly increase the transmission capacity.
This technology still seems quite promising, but the laboratory has only conducted a ten-meter transmission experiment, and there must be many problems to be solved in the actual implementation and operation.
- Full duplex technology
5G NR introduces dynamic TDD technology to improve duplex flexibility, so that the time slot ratio between downlink and uplink can be dynamically adjusted according to traffic.
Full-duplex technology may be applied in 6G, thereby lifting the traditional duplex mechanism’s limitation on the use of transceiver spectrum resources, and helping to further improve spectrum efficiency (in theory, simultaneous same-frequency full-duplex can double the spectrum efficiency ) And the flexibility of the system.
When the uplink and downlink transmit signals at the same frequency, there will be serious self-interference and cross-interference problems, and certain interference suppression and elimination measures need to be taken during equipment and network deployment.
- Spectrum sharing technology
In line with the idea of paying equal attention to open source and throttling, how to make full use of existing spectrum resources is extremely important (especially in low frequency bands).
Thus, the dynamic spectrum sharing (DSS) technology made its debut.
It allows networks of different standards to share and use the same spectrum resources, which is equivalent to decoupling spectrum and standards. For example, the current dynamic spectrum sharing technology can dynamically allocate spectrum between 4G and 5G.
In the 6G era, dynamic spectrum sharing technology will obviously continue to develop on the original basis, and it may be called “smart” spectrum sharing technology.
- Evolution of network topology
A notable trend in network topology evolution is to use non-terrestrial network NTN, such as satellite and HAPS, to provide coverage even where there is no terrestrial network.
The realization of NTN technology needs to consider new aspects that are not available in terrestrial networks, including support for mobile cells, cells with hundreds of kilometers, large propagation delay, large Doppler shifts and large Doppler shifts caused by NTN’s high-speed movement. Path loss etc.
At present, it is still in the initial stage of developing technology to support NTN. 3GPP R17 will complete the first phase of support for NTN network, let us wait and see.
PS: At this stage, if you want to know more about NTN, it is recommended to refer to 3GPP TR38.811.
- AI technology
The 3GPP 5G standard has introduced the NWDAF network function in the core network to collect and analyze network data. It is believed that this function will continue to evolve in subsequent versions, and 3GPP will also conduct related technical research on the wireless side. In the 6G era, the application of AI technology will be everywhere.
For example, local AI technology provides a brand-new solution for channel coding research, which makes it no longer dependent on traditional coding theory for design. Through learning, training, and searching, the best modulation suitable for the current transmission environment can be found. Encoding. An example of joint AI is prediction-based handover optimization, and end-to-end AI can identify or predict abnormalities in network operation and propose corrective solutions.
▉ Afterword: Is it too early to talk about 6G?
The commercialization of 5G is still in its infancy, and it is time to start preparing for 6G. Because it usually takes about 10 years from the beginning of research to the commercialization of a new generation of communication technology.
As early as March 2019, Finland hosted the world’s first 6G summit. Communication experts from various countries discussed and drafted the world’s first 6G white paper: The key drivers and research challenges of 6G ubiquitous wireless intelligence.
In the past year, countries all over the world have formulated their own 6G development plans and implemented them.
It was previously reported that the actual transmission rate of South Korea’s 5G network is only more than three times that of 4G, far below the standard of 20 times. It can be seen from this that the first task on a global scale is to fully stimulate the potential of 5G, so that enterprises and individuals can fully feel the true value of 5G. Otherwise, talking about 6G is meaningless.
If you summarize it in one sentence, it would be–
Both look up at the stars (6G) and stand down to the ground (5G).