5G has not yet become popular, and the United States claims to start developing 6G. Should we early try 5G, or wait for 6G on earth?

On February 21st, US President Trump sent a twitter “I hope that 5G and even 6G will land in the United States as soon as possible.” A few days ago, the US Federal Communications Commission took the first step toward Trump’s instructions and decided to open the 95 GHz to 3 terahertz band for use in 6G experiments.

New York University professor Ted Rappaport issued a statement: “The Federal Communications Commission has launched a 6G competition.” We have not yet enjoyed the bonus of 5G deployment, the faster 6G has already roared? Is 6G “small lotus only show sharp points” or “the enchanting is all when you want to open” on earth? The Science and Technology Daily reporter interviewed He Jiguang, a wireless communication expert and postdoctoral fellow at the University of Oulu in Finland.

Key technologies are still being explored

“The 5G network has not been completed yet, and even the international standards have not been fully developed. 6G is still in its infancy, just starting research, and even without a clear definition of concepts, its key technologies are still being explored.” He Jiguang told reporters that from the beginning it takes time to study the maturity of technology. In 2013, the EU launched the METIS project (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 were not completely determined. “As a wireless communication researcher, I believe that 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 for wireless communication is still being demonstrated.” He Jiguang introduced that terahertz was mainly used for radar detection, medical imaging, and wireless communication. The application has only begun to study in the past two years. It is characterized by high frequency, high communication rate, and theoretically can achieve terabytes per second (TB/S), but in fact which application requires such a high network speed is inconclusive. Moreover, terahertz has obvious shortcomings, that is, the transmission distance is short, and it is easily interfered by obstacles. The communication distance that can be achieved now is only about 10 meters, and only the communication distance problem can be solved for the existing mobile communication cellular network. In addition, the higher the communication frequency, the higher the requirements for hardware devices, and the better performance and processing techniques are required. These technical problems are difficult to solve in a short time.

The route plan still needs to be verified

“At present, international communication technology research and development institutions have successively proposed a variety of technical routes to achieve 6G, but these programs are in the concept stage, and verification is still necessary.” He Jiguang said that the University of Oulu Wireless Communication Center is the first in the world to start 6G. Research and development institutions are currently working on four areas: wireless connectivity, distributed computing, device hardware, and service applications.

Wireless connection is the use of terahertz or even higher frequency radio wave communication; distributed computing is to solve the delay problem caused by a large amount of data through artificial intelligence, edge calculation and other algorithms; equipment hardware is mainly for terahertz communication, research and development of corresponding antenna Hardware such as chips; service applications are to study possible applications of 6G, such as automatic driving. “There are only these four directions at present, and the details are not clear.”

The reporter learned that the SKG Information and Communication Technology Center of South Korea proposed the 6G technology solution of “THz/Decellularized Structure and High-altitude Wireless Platform (such as satellite)” in 2018, which not only applies terahertz communication technology, but also thoroughly Transform existing cellular architectures for mobile communications and establish a communications network that integrates space and space.

He Jiguang pointed out that the decellularization structure mentioned by SK Group is one of the current research hotspots, that is, the base station does not necessarily follow the cellular arrangement, and the terminal does not necessarily only communicate with one base station, which can improve the spectrum efficiency. The research team of Linköping University, Sweden The idea of decellularization was first proposed.

However, whether this concept can meet the 6G delay, communication rate and other indicators needs to be verified.

In addition to the SK Group, Bell Labs of the United States also proposed the technical route of “Tertz and Network Slice”. These solutions require long-term experimental verification in technical details.

Promotional applications are costly

“Wireless communication is further developed, and a large amount of investment is indispensable.” He Jiguang said that there are two options for increasing the communication rate: First, the base station is denser and the deployment amount is increased. Although the base station power can be reduced, the increase in the number will still bring the cost. The second solution is to use higher frequency communication, such as terahertz or millimeter wave, but the high frequency requires higher hardware devices such as base stations and antennas. Now the cost of terahertz communication hardware test has exceeded the cost of general research institutions. Affordability. In addition, from the point of view of the number of base station antennas, the number of 4G base station antennas is only 8 and that 5G can be 64, 128 or even 256. The number of 6G antennas may be more, and the replacement of base stations will also increase the application cost.

“Without changing the existing communication frequency band, it is difficult to achieve the envisaged 6G vision by relying on algorithm optimization and other measures. It is not realistic to replace all base stations.” He Jiguang believes that it is very likely that the future will adopt a non-independent networking method. 6G equipment is deployed on the basis of existing base stations and other facilities. 6G and 5G or even 4G and 4.5G networks coexist. 6G is mainly used in densely populated areas or for high-end applications in vertical industries such as autonomous driving, telemedicine, and smart factories.

In fact, ordinary people do not have too high a demand for dozens of G, or even terabytes per second. Moreover, if 6G uses millimeter wave or terahertz as the communication frequency, the price of its mobile terminal is bound to be high.

“6G may have a breakthrough in technology in the next few years, but it is far from fashion application.” He Jiguang predicts that on the one hand, there are fewer research institutions engaged in 6G research and development, and technology development still takes time; Post-standardization also takes time.

From the perspective of technological development, 6G will definitely arrive. However, there is demand for technology, 5G technical indicators can meet most of the industry applications for a long time, and the investment in popularizing 5G is also very high. Unless social development has a very urgent need for 6G, it will not replace 5G with 6G in a very short time.