the internet and telecommunications networks are changing with each passing day and are developing rapidly. At the end of 2013, the Ministry of Industry and Information Technology announced the issuance of 4G licenses, which brought the transmission rate of the mobile Internet to a higher level. In the 3G era, the demand for information transmission has long been more than low-quality pictures and video information. With the improvement of transmission rate, mobile terminal products have gained vitality, and they have sprung up in daily life. Before 5G officially starts commercial in 2019, 4G communication can meet the daily information transmission service needs of high-definition video communication, mobile payment, e-commerce, common equipment terminals such as mobile phones and tablets. Of course, 4G itself has some limitations.

When multiple mobile terminals gather and need to implement information transmission services at the same time, network congestion will occur, that is, there is a high probability that the crowded local network will be paralyzed. In general, the base station covers an area of one kilometer radius, and users within this range are unlikely to be online at the same time. When a small number of users are served at the same time, the channel resources allocated to each user fully meet the communication needs, and the problem of network abnormality will not occur. Therefore, in most communication situations, 4G systems are able to meet our daily communication needs. The problem is that when each user has multiple mobile terminals and multiple devices need to implement communication services at the same time, the number of users does not decrease but the mobile terminals multiply. Under the premise of ensuring transmission quality, the communication system needs a larger channel capacity, that is, to improve the maximum information rate that can be transmitted by the transmission channel.

The way to improve the channel capacity, Shannon's formula clearly gives three suggestions: For a single channel, to increase the channel capacity, it is necessary to increase the bandwidth, increase the signal power, and reduce the power of noise or interference signals. However, the bandwidth resources are limited, and the power can not be increased indefinitely. The problem of electromagnetic wave interference will only become more and more serious. To address the need to increase the channel capacity by 2 to 3 orders of magnitude, it is far from being possible to simply expand and optimize the layout of the existing system.

In this regard, 5G large-scale MIMO technology gives a more perfect answer. The solution is to increase the bandwidth, using millimeter wave, large-scale multiple input multiple output, 3D beamforming, small base station and other technologies to achieve faster speed, lower delay and larger bandwidth than 4G, and can link hundreds of billions of devices at the same time. The leap in communication quality brought by 3G and 4G depends on MIMO technology. For wireless communication, MIMO refers to the use of more antennas on the base station. This of course means that the channel capacity is increased without increasing the frequency band and power, and 4x 4, 8x 8 multiple input multiple output communication is realized. On the basis of the existing base station network, what 5G needs to do is to further scale up and realize 32x 32, 64x 64 or even larger scale transceiver communication. It is estimated that the communication frequency band will reach 100G, and the download rate will theoretically reach 20 GB/s, which is 20 times that of 4G.

To realize the interconnection of everything and the ubiquitous communication interaction experience, the 5G network currently underway is only a prelude to the curtain of this new era. The blueprint for the interconnection of all things that has been drawn for the world will take a period of time to gradually realize the technology iteration. Before 5G growth, 6G has arrived in a hurry. At the beginning of 2019, the goal of using THz frequency band to realize 1 TB/s/user was proposed. The application to be realized is still the interconnection of everything. The focus here is no longer simply on the information rate, but on the information resources enjoyed by each mobile terminal. The idea is to use satellite communications, drone communications, marine communications and other means to achieve as much as possible seamless interaction of information, and then to achieve a vision of everywhere without connection.

In every era of rapid progress, while technology brings many conveniences to social life, it also does not forget to attach new problems. Social issues such as privacy protection brought about by the development of communications may make us celebrate technological progress while calmly thinking about which directions in the future need to be carefully chosen, which are beyond doubt, and the correctness of our choices. Every communicator can look forward to the future in which all things will shine brilliantly. But at the same time, 4G will not easily withdraw from people's lives. As we all know, Everest has installed 5G base stations, but we still have some areas using 2G/3G networks. It is foreseeable that in the next few years, we will see that 4G is still undertaking basic network construction, and its depth and breadth will still be the cornerstone of the entire era of communication interconnection.

We are very lucky to live in this era. In this era, we understand the size of the universe and the vast nebula. The "where to come from" and "where to go" constantly asked by the sages of the past dynasties have become clearer a little bit. You don't need to shake the feather fan, you can know what's going on in the world and comment on the past and the future without leaving your home. This era is called the information age.

Original article, welcome to reprint

Reprinted please indicate: Reprinted from Rosenberg Mobile Communications