6th generation mobile networks

6G, the sixth generation mobile communication standard, is a conceptual wireless network mobile communication technology, also known as the sixth generation mobile communication technology.

The transmission capacity of 6G may be 100 times higher than that of 5G, and the network delay may also be reduced from milliseconds to microseconds.

The 6G network will be a fully connected world integrating ground wireless and satellite communications. By integrating satellite communications into 6G mobile communications, global seamless coverage can be achieved, and network signals can reach any remote village, allowing patients in deep mountainous areas to receive telemedicine and children to receive remote education. In addition, with the linkage support of the global satellite positioning system, telecommunications satellite system, earth image satellite system and 6G ground network, the ground-to-air full coverage network can also help humans predict the weather and respond quickly to natural disasters. This is the future of 6G. 6G communication technology is no longer a simple breakthrough in network capacity and transmission rate. It is more to narrow the digital divide and realize the 'ultimate goal' of the Internet of Everything. This is the meaning of 6G.

Related technologies

Terahertz frequency band

6G will use the terahertz (THz) frequency band, and the 'densification' of the 6G network will reach an unprecedented level. By then, we will be surrounded by small base stations. The terahertz frequency band refers to 100GHz-10THz, which is a frequency band much higher than 5G. From communication 1G (0.9GHz) to 4G (above 1.8GHZ), the frequency of the radio electromagnetic waves we use is constantly increasing. Because the higher the frequency, the larger the bandwidth range allowed to be allocated, and the greater the amount of data that can be transmitted per unit time, which is what we usually say 'the network speed has become faster.' However, another major reason for the development of frequency bands to higher places is that the resources of low-frequency bands are limited. Just like a road, no matter how wide it is, the number of vehicles it can accommodate is limited. When the road is not enough, vehicles will be blocked and unable to travel smoothly, and at this time it is necessary to consider developing another road. The same is true for spectrum resources. With the increase in the number of users and smart devices, the limited spectrum bandwidth needs to serve more terminals, which will lead to a serious decline in the service quality of each terminal. A feasible way to solve this problem is to develop new communication frequency bands and expand communication bandwidth. The main 4G frequency bands of the three major operators in my country are located in a part of the frequency band between 1.8GHz and 2.7GHz, while the mainstream frequency band of 5G defined by the International Telecommunication Standards Organization is 3GHz-6GHz, which belongs to the millimeter wave frequency band. When it comes to 6G, it will enter the higher frequency terahertz frequency band, and at this time it will also enter the submillimeter wave frequency band. Gou Lijun, a researcher at the National Astronomical Observatory of the Chinese Academy of Sciences, told 'Internet Weekly' that 'terahertz is called submillimeter in astronomy. The sites of such observatories are generally very high and dry.For example, Antarctica and Chile's Acatama Desert. 'So why is it that in the 6G era, when the network is 'densified', our surroundings will be full of small base stations? This involves the coverage of base stations, that is, the transmission distance of base station signals. Generally speaking, there are many factors that affect the coverage of base stations, such as the frequency of the signal, the transmission power of the base station, the height of the base station, the height of the mobile terminal, etc. In terms of the frequency of the signal, the higher the frequency, the shorter the wavelength, so the diffraction ability of the signal (also called diffraction, when an electromagnetic wave encounters an obstacle during propagation, and the size of the obstacle is close to the wavelength of the electromagnetic wave, the electromagnetic wave can diffract from the edge of the object. Diffraction can help cover shadow areas) is worse, and the loss is greater. The larger the transmission distance, the greater the loss. And this loss will increase with the increase of transmission distance, and the range that the base station can cover will decrease accordingly. The frequency of 6G signals is already at the terahertz level, and this frequency is close to the spectrum of molecular rotation energy levels. It is easily absorbed by water molecules in the air, so the distance it propagates in space is not as far as 5G signals. Therefore, 6G requires more base stations to 'relay'. The frequency band used by 5G is higher than that of 4G. Without considering other factors, the coverage range of 5G base stations is naturally smaller than that of 4G. When it comes to 6G with a higher frequency band, the coverage range of base stations will be even smaller. Therefore, the base station density of 5G is much higher than that of 4G, and in the 6G era, the density of base stations will be unprecedented.

Spatial multiplexing technology

6G will use 'spatial multiplexing technology'. 6G base stations will be able to access hundreds or even thousands of wireless connections at the same time, and their capacity will be 1,000 times that of 5G base stations. As mentioned earlier, 6G will use the terahertz frequency band. Although this high-frequency band has abundant frequency resources and large system capacity, mobile communication systems using high-frequency carriers face severe challenges in improving coverage and reducing interference.

When the signal frequency exceeds 10GHz, diffraction is no longer the main propagation mode. For non-line-of-sight transmission links, reflection and scattering are the main signal propagation modes. At the same time, the higher the frequency, the greater the propagation loss, and the closer the coverage distance, the weaker the diffraction ability. These factors will greatly increase the difficulty of signal coverage. This is not only true for 6G, but also for 5G in the millimeter wave band. 5G solves such problems through two key technologies: Massive MIMO and beamforming. Our mobile phone signals are connected to the operator's base station, or more accurately, the antenna on the base station. Massive MIMO technology is quite simple to say. It actually increases the number of transmitting antennas and receiving antennas, that is, designs a multi-antenna array to compensate for the loss on the high-frequency path. The configuration of MIMO multiple antennas can increase the amount of transmitted data, and this uses spatial multiplexing technology. At the transmitting end, the high-speed data stream is divided into multiple lower-speed sub-data streams, and different sub-data streams are transmitted on different transmitting antennas in the same frequency band. Because the spatial subchannels between the antenna arrays at the transmitting and receiving ends are sufficiently different, the receiver can distinguish these parallel sub-data streams without paying for additional frequency or time resources. The advantage of this technology is that it can increase channel capacity and improve spectrum utilization without occupying additional bandwidth or consuming additional transmission power. However, the multi-antenna array of MIMO will cause most of the transmission energy to be concentrated in a very narrow area. In other words, the more antennas there are, the narrower the beam width. The advantage of this is that there will be less interference between different beams and between different users, because different beams have their own focus areas, which are very small and do not overlap with each other. But it also brings another problem: the narrow beams emitted by the base station are not 360 degrees omnidirectional, so how to ensure that the beams can cover users in any direction around the base station? At this time, it is time for beamforming technology to show its magic. Simply put, beamforming technology is to manage and control the beams through complex algorithms, making them like 'spotlights'. These 'spotlights' can find where the mobile phones are gathered, and then provide more focused signal coverage to them. 5G uses MIMO technology to improve spectrum utilization. 6G is located in a higher frequency band, and the further development of MIMO in the future is likely to provide key technical support for 6G.