Experts: 6G will be available in 10 years and is expected to be 100 times faster than 5G

5G has not yet been fully rolled out, but 6G is already "eager to try".

Not long ago, Huawei's internal employee community platform "Xinsheng Community" published the minutes of the interview that the company's founder Ren Zhengfei gave to The Economist earlier this month. In the interview, Ren Zhengfei said that Huawei's 6G research is leading the world, but it is expected that 6G will not be put into use until 10 years later.

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So, what exactly is 6G? What stage has the research on 6G progressed to? What are the key core technologies of 6G? Recently, at the 2019 National Communication Theory and Technology Academic Conference and Communication Field Innovation and Development Forum, many industry experts said that 6G research is just getting started and international unified standards need to be established in the field of technology.

Different from 5G, 6G aims to build a network that realizes integrated communication in the air, space, land and sea. The 6G frequency band will be expanded from the millimeter wave band of 5G to the terahertz band. The data transmission rate is expected to be 100 times faster than 5G, and the latency will reach the sub-millisecond level. In the fields of personalized services for users, the Internet of Things, industrial Internet, unmanned driving, smart factories, etc., 6G will have a broad application prospect.

Signals can cover communication "blind spots"

"In the 6G era, perhaps we can surf the Internet on airplanes without affecting flight safety. When mountaineers encounter danger while climbing, they can send location information and distress signals in real time without delay. When sailing at sea, the crew on board do not have to worry about losing contact with the land, as 6G can ensure real-time communication." This is what Wu Qihui, executive vice president of the School of Electronic Information Engineering at Nanjing University of Aeronautics and Astronautics, described to Science and Technology Daily, a communication network connecting air, space, land and sea built with satellites, aviation platforms and ships. The core technology supporting this network is 6G.

The 6G network will be committed to creating a fully connected communication world that integrates ground communications, satellite communications, and ocean communications. Today's "blind spots" of mobile communications, such as deserts, uninhabited areas, and oceans, are expected to be covered by signals.

"The speed of 6G network will be 100 times faster than 5G, almost 1TB per second, which means that downloading a movie can be completed in 1 second, and the control of unmanned driving and drones will be very comfortable, and users will not even feel any delay." Wu Qihui said that nowadays, medium and low radio spectrum resources are very scarce, and the development of high-speed transmission 6G network requires sufficient spectrum resources as support. This means that 6G communication needs to expand to high-frequency spectrum resources, from the millimeter wave (electromagnetic wave with a wavelength of 10 mm to 1 mm) band in the 5G era to the terahertz (electromagnetic wave with a wavelength of 3000 microns to 30 microns) band.

The communication changes brought about by 6G are not only reflected in network speed, but also in the user's interactive experience will be greatly improved. The information transmission capacity per unit time will be larger and the transmission delay will become shorter.

In the view of Zhu Hongbo, chairman of the Communications Branch of the China Electronics Society and dean of the School of Internet of Things at Nanjing University of Posts and Telecommunications, in the 1G to 4G era, communication technologies were still consumer applications, while 5G and beyond will move towards industrial applications, such as industrial Internet and smart transportation.

"There are different views in the academic community on the definition of 6G. 5G is mainly used to provide preliminary infrastructure for Industry 4.0, while the specific application direction of 6G is still in the exploration stage." Zhu Hongbo said that some experts believe that in the future 6G will be used in scenarios such as space communication, intelligent interaction, tactile Internet, emotional and tactile communication, multi-sensory mixed reality, machine collaboration, and fully automatic transportation.

More base stations are needed to complete signal "relay"

From the 1G era to the 5G era, base stations are like a "transportation hub", building "bridges" for information exchange between users and mobile operators. But in the 6G era, the construction of "bridges" may face huge challenges.

"In the future, base station construction will be oriented towards the sky and the ocean. The distance of air transmission is very long, the signal loss of underwater transmission is large, and the communication between drones and ships at sea is dynamic. This requires coordinated deployment and research." Li Jiandong, vice president and professor of Hefei University of Technology, told Science and Technology Daily.

At present, my country has more than 6 million 4G base stations, and the number of 5G base stations is expected to be 10 times that of the former. 6G base stations may be built even denser. At present, most ground base stations are set up on the top of buildings. If the 6G network is to realize the communication between ground base stations and drones and satellites, then the base stations must not only face the ground, but also face the air for signal transmission.

"The channel models on the ground, in the air, and in the ocean are all different." Wu Qihui said that ground base stations transmit signals along the surface of the earth. Due to the obstruction of buildings, mountains, and rivers, the signals will be severely attenuated during the transmission process, and sometimes clutter and noise will appear. Although the ground-to-air channel will not encounter the various obstacles that plague ground transmission, the channel has a large elevation angle, and the propagation characteristics at each angle will also be different. At the same time, when transmitting signals in the air, on the ground, and on the ocean, the 6G network will use different frequencies, which may interfere with each other. How to make them "work together" is also a technical problem that needs to be solved.

In addition, because 6G communications need to expand to high-frequency spectrum resources and are affected by high frequencies, more base stations may be needed in the 6G era to "relay" signal transmission.

Zhang Xiaofei, a professor at the School of Information Engineering of Nanjing University of Aeronautics and Astronautics, explained to Science and Technology Daily: "6G networks will use high-frequency spectrum resources - the terahertz band, with frequencies as high as 100GHz to 10THz. The higher the signal frequency, the shorter the wavelength, and the smaller the signal transmission range, which means that the coverage range of the base station will be reduced. In addition, the higher the signal frequency, the easier it is to be absorbed by water molecules in the air. In rainy and snowy weather, 6G signals are more susceptible to interference, so the propagation distance of 6G signals will not be as far as 5G signals, which requires more base stations to complete the 'relay' transmission of signals."

Chip technology and algorithms need to be improved

With the emergence of application scenarios such as industrial Internet, unmanned driving, and telemedicine, as well as the increase in the number of users and smart devices, limited bandwidth has to carry more and more terminals, and increasing bandwidth has become an urgent problem for 6G technology developers. In Wu Qihui's view, in order to increase bandwidth, we must rely on the development of chip technology and radio frequency circuit technology.

At the same time, some experts pointed out that the heat dissipation problem of terahertz chips also needs to be solved urgently. Nowadays, chips are getting smaller and smaller, and the increase in transmission power will make the chips more likely to "heat up", so micro-heat dissipation technology also needs to be improved urgently.

In addition, the amount of data transmitted is large, and in order to achieve low-latency and high-reliability transmission, the 6G network system must be more intelligent. Wu Qihui introduced that his team is currently studying the intelligent information processing algorithms of 6G networks, including intelligent cloud computing, edge computing, terminal intelligent applications, and how intelligent algorithms at all levels can work together.

"But no intelligent algorithm can meet all the needs of 6G communications. For example, we use the 'deep learning' algorithm for image recognition, but this algorithm may not be applicable in the highly dynamic field of wireless communications. In comparison, the 'reinforcement learning' algorithm may be more suitable." Wu Qihui said that, like the 5G era, the 6G era also needs to build an "algorithm library" to intelligently schedule various systems and use the right algorithm to solve the corresponding problems according to the scenario.

"For example, after receiving a fire alarm signal, the 6G network system must be able to quickly identify the scene and transmit the signal. The intelligent algorithm must make information transmission decisions based on the needs of the application scenario," said Wu Qihui.

From 3G to 4G and then to 5G, each generation of communication technology has gone through a development cycle of about 10 years. In the interview, many experts told reporters that it will take at least another 10 years for 6G to truly "enter the homes of ordinary people."

"At present, 6G research at home and abroad has just started, but there is an urgent need to establish relevant international technical standards, including 6G spectrum, network architecture, multiple access, wireless energy transmission, intelligence and other aspects of the technology." Zhang Xiaofei said.