If 5G has achieved faster, lower latency and higher network capacity, the goal of 6G will be to achieve full global connectivity. We know that 5G will use millimeter wave for communication, while 6G is expected to use terahertz technology, which will greatly improve the network capacity and network speed of 6G network.
Terahertz may be strange to you, but if you look at the distribution map of different frequencies below, I believe you will have a certain understanding of terahertz.
Terahertz is actually a frequency unit, 1 THz = 1 000 Gh. People's research on terahertz is mainly between 0.65,438+0 THz and 65,438+00 THz. Microwave and infrared rays on both sides of this range have been widely used, so this frequency band has a nickname "terahertz gap". It coincides with millimeter wave (submillimeter wave) in long wave band, while terahertz wave occupies a very special position in electromagnetic spectrum when it coincides with infrared ray in short wave band.
It is worth mentioning that ITU defines the frequency band of 0.3~3THz as terahertz radiation, which is less than the above range, and the current terahertz applications are all in this frequency band.
Terahertz technology is mainly used in spectrum field, imaging, high-speed communication, radar, security inspection, detection, astronomy and so on.
After learning about terahertz, we will show you why terahertz technology can make 6G faster and stronger than 5G. We can recall the 5G spectrum distribution of the three major operators recently announced by the Ministry of Industry and Information Technology. China Mobile has obtained 5G trial frequency resources of 25 15MHz-2675MHz and 4800MHz-4900MHz, China Telecom has obtained 5G trial frequency resources of 3400 MHz-3500 MHz, and China Unicom has obtained 5G trial frequency resources of 3500 MHz-3600 MHz. As we mentioned before, the frequency range of terahertz radiation is 0.3THz~3THz. According to the communication principle, the higher the frequency, the greater the bandwidth allowed to be allocated, and the greater the amount of data that can be transmitted per unit time, which is what we usually call "faster network speed". Therefore, in terms of frequency alone, the network speed of 6G will be about 10 times that of 5G.
Of course, at present, the research on terahertz is only in the exploratory stage, and it will take time for experts to study how to use terahertz. The most important problem to be solved is the short transmission distance of terahertz radiation. If you remember high school physics, you should know this formula: wave velocity = wavelength * frequency. Because the wave speed of electromagnetic waves is fixed at the speed of light, the wavelength of electromagnetic waves is inversely proportional to the frequency. The higher the frequency, the shorter the wavelength, the shorter the wavelength and the shorter the transmission distance. Experts predict that the future 6G network will be a dense network. Only in this way can we achieve wide-area coverage, and how to deploy base stations becomes the primary problem.
The deployment of 6G network goes far beyond these difficulties. Terahertz technology needs further development, which can effectively enrich the application of these frequency bands, so as to truly deploy 6G networks. At present, the application scenarios of terahertz technology mainly include astronomical applications, nondestructive testing, medical imaging, safety inspection and so on. Come and have a look with me.
Astronomical application
Terahertz radio astronomy has become an important astronomical observation method because of the rich background radiation information in the terahertz spectrum. By using terahertz waves to study the background radiation of the universe, we can learn more about our solar system and the evolution of the universe. For example, by studying the terahertz spectrum characteristics of interstellar molecular clouds, we can explore the origin of the universe; By analyzing the spectral information of atomic and molecular scattering, we can study the formation of new galaxies in the universe.
nondestructive test
Terahertz radiation has low photon energy, does not damage armor-piercing projectiles, and can pass through most dielectric substances. Terahertz wave has great development space for detecting hidden defects or special marks in non-conductive materials, which is generally called nondestructive testing, such as detecting oil paintings, spacecraft, semiconductor devices and so on.
Application of life science
Terahertz radiation wave is basically harmless to human body, and water and other tissues have different absorption rates of terahertz wave, so it can be widely used in local imaging of human body and medical diagnosis of diseases, such as skin cancer and breast cancer detection. Terahertz band contains a large amount of spectral information, which shows different absorption and dispersion characteristics for different molecules, especially organic macromolecules. Therefore, it can be effectively used to measure molecular characteristics, and has a wide application prospect in the field of life sciences, such as measuring the binding state of DNA, the characteristics of biological tissues and protein complexes.
Security application
Terahertz wave is penetrating, which can effectively detect hidden objects, and can be applied to national security-related fields, such as hiding explosives, hiding guns, detecting illegal drugs by mail, and rapid airport security inspection. Sun team of Shanghai Microsystems Research Institute developed an imaging system of 0.36 THz, and the team of University of Electronic Science and Technology of China developed a SAR imaging system of 0.34 THz.
High speed communication
Compared with the existing spectrum of microwave and millimeter wave communication bands, THz band has broad spectrum resources, which can be used for ultra-wideband and ultra-high-speed wireless communication, such as 100 Gbps or even higher.