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5G has not been popularized yet. The United States claims to have started research and development of 6G. Is it 5G or 6G?

On February 21, President Trump tweeted, "I hope 5G and 6G will land in the United States as soon as possible." Recently, the Federal Communications Commission of the United States has taken the first step toward a Trump's instructions, deciding to open 95 GHz to 3 THz bands for 6G experiments.

On February 21, President Trump tweeted, "I hope 5G and 6G will land in the United States as soon as possible." Recently, the Federal Communications Commission of the United States took the first step towards Trump's instructions, deciding to open 95 GHz to 3 THz bands for 6G experiments.

"The Federal Communications Commission has launched the 6G competition," New York University professor Ted Rapporter said in a statement. Haven't we enjoyed the dividend of 5G deployment yet, and 6G with faster network speed has come roaring? Is 6G a "small lotus just showing its sharp edge" or "all enchantments are ready to open"? The reporter of Science and Technology Daily interviewed He Jiguang, a postdoctoral and wireless communication expert at Oru University in Finland.

Key technologies are still being explored

"5G networking has not been completed, and even international standards have not been fully developed. 6G is still in its infancy. It has just begun to study and even has no clear concept definition. Its key technology is still in the process of exploration. He Jiguang told reporters that it takes time to start research and mature technology. The European Union launched METIS project in 2013 (information society and mobile wireless communication booster in 2020) to carry out 5G research, but until the end of the project in 2015, the key technologies have not been fully determined. "As a wireless communication researcher, I believe 6G will come one day, but it is still a time to perfect 5G and explore 6G."

"Terahertz is considered by many to be one of the key technologies of 6G. In fact, whether terahertz can be used in wireless communication is still being demonstrated. He Jiguang introduced that before, terahertz was mainly used for radar detection and medical imaging, and its application in wireless communication has only been studied in recent two years. Its characteristics are high frequency and high communication rate, which can theoretically reach terabyte per second (TB/S), but in fact, which application needs such a high network speed is still uncertain. And terahertz has obvious shortcomings, that is, short transmission distance, easy to be interfered by obstacles. Now the communication distance can only be about 10 meters. Only by solving the problem of communication distance, can it be used in the existing mobile communication cellular network. In addition, the higher the communication frequency, the higher the requirement of hardware equipment, the better the performance and processing technology are needed. These technical problems are difficult to solve in a short time.

Route schemes still need to be validated

"At present, international communication technology research and development institutions have proposed a variety of technical routes to achieve 6G, but these schemes are at the conceptual stage, whether they can be implemented still needs to be verified." He Jiguang said that the wireless communication center of Oru University is the first 6G research and development organization in the world. It is currently researching in four areas: wireless connection, distributed computing, equipment hardware and service application.

Wireless connection is the use of terahertz or even higher frequency radio communication; distributed computing is to solve the problem of time delay caused by large amounts of data through artificial intelligence, edge computing and other algorithms; equipment hardware is mainly for terahertz communication, research and development of corresponding antennas, chips and other hardware; service applications are to study the possible response of 6G. Use areas, such as automatic driving. "At present, there are only four directions, and the details are not clear yet."

Reporters learned that in 2018, SK Group Information and Communication Technology Center of Korea put forward the 6G technology scheme of "terahertz + De-Cellular structure + high-altitude wireless platforms (such as satellites)", which not only applies terahertz communication technology, but also thoroughly changes the existing cellular structure of mobile communications, and establishes a Space-earth integrated communication network. 。

He Jiguang pointed out that the de-honeycombing structure mentioned by SK Group is one of the current research hotspots, that is, the base stations are not necessarily arranged in a honeycomb shape, and the terminals may not only communicate with one base station, which can improve the spectral efficiency. The research team of Linxueping University in Sweden first proposed the concept of de-honeycombing structure. But whether this idea can meet the 6G delay, communication rate and other indicators still need to be verified.

In addition to SK Group, Bell Laboratories in the United States has also proposed a "terahertz + network slicing" technology route. These schemes need to be validated by long-term experiments in technical details.

Extension and application costs are high

"With the further development of wireless communication, a large amount of investment is indispensable." He Jiguang said that there are two ways to improve the communication rate: first, base stations are more dense, deployment volume is increased, although the power of base stations can be reduced, but the increase in the number will still lead to increased costs; second, the use of higher frequency communication, such as terahertz or millimeter wave, but high frequency to base stations, antennas and other hardware devices. The requirement of equipment is higher, and the cost of testing terahertz communication hardware has exceeded the affordability of general research institutes. In addition, from the number of base station antennas, there are only 8 antennas in 4 G base station, 64, 128 or even 256 antennas in 5 G base station. The number of antennas in 6 G base station may be more, and the replacement of base station will also increase the application cost.

"Without changing the existing communication frequency band, it is difficult to achieve the envisaged 6G vision by means of algorithm optimization and other measures, and it is unrealistic to replace all base stations." He Jiguang believes that in the future, it is likely to adopt a non-independent networking mode, i.e. deploying 6G devices on the basis of existing base stations and other facilities. 6G coexists with 5G or even 4G or 4.5G networks. 6G is mainly used in densely populated areas or meets the requirements of automatic driving, telemedicine, intelligent factories, etc.