5G has not yet been commercialized, the Ministry of Industry and Information Technology has confirmed that it is about to embark on the study of 6G news, which may make people feel caught off guard, but in fact it makes sense. Why? Because the communications industry must be forward-looking, as early as 2009, 4G LTE first version of the completion of the standard, the major equipment manufacturers have begun to study the 5G, so in the completion of the 5G R15 standard, the 6G research is also to be put on the agenda.
If 5G enables faster, lower-latency networks with higher network capacity, then 6G will aim for a fully connected world. We know that 5G will use millimeter waves for communication, and 6G is expected to use terahertz technology, which will greatly increase the network capacity and network speed of 6G networks.
Terahertz, you may be unfamiliar with, but if you look at the following map of the distribution of different frequencies, I believe you will have a certain understanding of terahertz.
Terahertz, in fact, is a unit of frequency, 1THz = 1000GH, people on the terahertz research is mainly in the 0.1THz ~ 10THz between the range of microwave and infrared on both sides of a wide range of applications, so there is a nickname for this band is called "terahertz divide". It is in the long-wave band and millimeter waves (submillimeter waves) overlap, and in the short-wave band, and infrared overlap, terahertz waves in the electromagnetic spectrum occupies a very special position.
It is worth mentioning that the ITU defines the 0.3~3 THz band as terahertz radiation, which is smaller than the range above, and the current terahertz applications are all in the range of this band.
The main applications of terahertz technology are: spectroscopy, imaging, high-speed communications, radar, security, detection, and astronomy.
After understanding terahertz, bring you to understand why terahertz technology can make 6G faster and stronger than 5G. We can recall the recent announcement of the Ministry of Industry and Information Technology of the three major operators of the 5G spectrum allocation, China Mobile to obtain 2515MHz-2675MHz, 4800MHz-4900MHz band 5G test frequency resources, China Telecom to obtain 3400MHz ~ 3500MHz band 5G test frequency resources, China Unicom obtained 3500MHz ~ China Telecom has obtained 5G trial frequency resources in the 3400MHz~3500MHz band, and China Unicom has obtained 5G trial frequency resources in the 3500MHz~3600MHz band. As we mentioned before, the frequency range of terahertz radiation is 0.3THz~3THz, and according to the principle of communication, the higher the frequency, the greater the range of bandwidth allowed to be allocated, and the greater the amount of data that can be transmitted per unit of time, which means that we usually say that "the network speed becomes faster". So in terms of frequency alone, 6G will be about 10 times faster than 5G.
Of course, the current research on terahertz only stays in the exploratory stage, 6G exactly how to use terahertz also need experts to spend time to study, the most important problem is the transmission distance of terahertz radiation is short of the problem. If you remember high school physics, you should know the formula: wave speed = wavelength * frequency. Because the electromagnetic wave speed is fixed speed of light, then the wavelength of electromagnetic waves and frequency is inversely proportional to the higher frequency, the shorter the wavelength, and the shorter the wavelength, the shorter the transmission distance. Experts predict that the future 6G network will be a dense network, the only way to achieve wide-area coverage, how to deploy the base station has become the primary problem.
Deploying 6G networks is much more than just these difficulties. Terahertz technology needs to be further developed in depth, and effectively enriches the application of these frequency bands in order to truly deploy 6G networks. Currently, the applications of Terahertz technology include astronomical applications, non-destructive testing, medical imaging, security checks, and so on.
Astronomical applications
Because the cosmic background radiation in the terahertz spectrum there is a wealth of information, which makes the terahertz radio astronomy as an important means of astronomical observation. By studying the cosmic background radiation using terahertz waves, it is possible to understand more about the solar system in which we live and the evolution of the universe. For example, by studying the spectral properties of interstellar molecular clouds in the terahertz band, the origin of the universe can be investigated; by analyzing the spectral information scattered by atoms and molecules, the formation of newborn galaxies in the universe can be studied.
Non-destructive testing
Terahertz radiation photon energy is low, the penetrating material will not cause damage, and can pass through the majority of dielectric material. This feature of terahertz waves has great potential for detecting hidden defects or special markings in non-conductive materials, generally known as non-destructive testing (NDT), such as the detection of oil paintings, spacecraft, and semiconductor devices.
Life science applications
Because terahertz radiation is essentially harmless to the human body, and because water and other tissues absorb terahertz waves differently, it is widely used for localized imaging of the human body and medical diagnostics, such as the detection of skin cancer and breast cancer. The terahertz band contains a large amount of spectral information, and shows different absorption and dispersion characteristics for different molecules, especially organic macromolecules, which can be effectively used for molecular characterization, and has a wide range of applications in life sciences, such as determining the bound state of DNA, the characteristics of biological tissues, and protein complexes.
Security applications
Terahertz wave penetration enables effective detection of hidden objects, which can be used in national security-related fields, such as the detection of hidden explosives, concealed firearms, illegal drugs in the mail, and rapid security checks at airports. Sun Xiaowei's team at the Shanghai Institute of Microsystems has developed a 0.36 THz imaging system, and Fan Yong's team at the University of Electronic Science and Technology has developed a 0.34 THz SAR imaging system.
High-speed communication
Compared with the existing microwave and millimeter-wave communication band spectrum, the terahertz band has a huge amount of spectrum resources, which can be used for ultra-broadband and ultra-high-speed wireless communications, such as 100 Gbps or even higher.