In terms such as 3G, 4G, and 5G, G is an abbreviation for the English word "generaTIon" (xth generation). Therefore, 5G is the fifth generation mobile communication technology.
First, the key point of the development of 5GIn the field of mobile communications:
The first generation is analog technology;
The second generation realized digital voice communication;
The third generation is the well-known 3G technology, characterized by multimedia communication;
The fourth generation is the 4g technology that is being rolled out, and its communication rate is greatly improved, marking the era of entering the wireless broadband.
In simple terms, 5G will be faster and consume less than 4G, bringing a new range of wireless products. Li Zhengmao, vice president of China Mobile, once said that the telecom equipment in the 5G era has been greatly reduced: "In the 4G to 5G era, the transmission cost per bit has been reduced by 1000 times. Then we also hope that the price of telecom equipment will also be reduced by 1000 times. The cost is determined by the operators. The key to profitability in the data age."
1, 5G is actually not a new technologyTwo different perspectives about 5G
There is a view that 5G will be a new technology. The representative of this view is Huawei's wireless network product line CMO Yang Chaobin. In his view, 4G will not become 5G anymore, and 5G will be a new technology.
5G is not just a technical update, it is a very big leap development, it is a change, which means that the network architecture must be improved, 5G's network demand will be completely different from 4G; although the 4G LTE technology still used now Will continue to evolve, but how 4G will evolve will not become 5G, 5G will be a new technology.
But most technical experts are more inclined to the following point: 5G is the inevitable evolution of 4G technology - both evolution and revolution.
Although any generation of technology development cannot be a repetition of the previous generation of technology, if the new generation of technology is the same as the previous generation technology, then what is a new generation, so 3G technology is different from 2G, 4G is different from 3G, its technical principle The way to solve problems, the way to deploy, and the ability to achieve are different, but there is no foundation for the previous generation of technology, or the next generation does not inherit the technology of the previous generation, and the revolutionary upgrade is also a castle in the air.
5G is not an amazing new technology. 5G technology is a new combination of existing technologies and a re-evolution of 4G technology.
Why should we emphasize "re-"? Because the last three letters of 4G LTE mean long-term evolution, 5G should be a re-evolution based on 4G. Regarding the viewpoint of technological evolution, the scientific squirrel member communication professional teacher Occam razor has a popular double hump theory, which can clearly explain that 5G is only a technological evolution.
Okam razor's double hump theory
Occam's razor believes that after the emergence of a new technology concept, there will be a climax of research and discussion in the industry, this is the first hump.
Relevant academic papers will be produced as hotspots. The piles of doctoral masters have completed their graduation thesis with this new technology. Although it is very lively, it is only limited to the level of academic research, and there are still many problems in the implementation of specific technologies. Or because of cost reasons, it is impossible to mass production.
The study discussed the climax of the climax, which is the first hump's whereabouts, followed by low-key and pragmatic technical research. This platform may be a few years or a decade. When the technical problems are solved, the business will be welcomed. Mass production and market enthusiasm, this is the second hump.
According to the International Telecommunication Union's plan for 2020, it will be fully entered into 5G in five years, and the core technology system has not yet been established. Reviewing the history of 3G technology development, the International Telecommunication Union accepted the 3G technology proposal on June 30, 1998, and ushered in the first hump period. Until January 7, 2009, the Ministry of Industry and Information Technology officially issued three 3G license, this only entered the second hump, the platform period lasted for 11 years, especially one of the three licenses of TD-SCDMA, until 2013 is really mature, the platform period is up to 15 years, can just mature 4G era It’s coming. According to the "double hump law", the technology that will be promoted globally after 5 years should usher in the first hump around 2010, and will not be born two or three years before 2020, and then quickly be internationally telecommunication. The alliance is determined to be the global 5G standard, which violates the general rules of technological development and is unlikely to come true.
2. Without the development of 3G and 4G technologies, there will be no 5G.In essence, the roads selected by most R&D institutions in 5G research are also the same, walking on two legs.
In the 5G R&D, two legs are proposed: on the one hand, we continue to promote the evolution based on 4G technology, and on the other hand, we develop 5G new technology, both of which take care of both.
In the face of the thousand-fold speed-up requirement in the 5G era, the evolution of 4G technology is only possible by greatly increasing the bandwidth. Increasing the bandwidth is the starting point, and the resulting millimeter wave, micro base station, high-order MIMO, beamforming, etc. are all logical trends. In the 5G era, the key technology cores for large-scale antenna arrays, millimeter-wave technologies, new network architectures, and new air interface designs are mostly based on the extension of 4G network technology, which can greatly improve performance. Taking soft air interface technology as an example, this technology combines the hardware processing capability of Pre5G, allowing operators to have smooth upgrade capability from 4G to 5G. From 4G to Pre5G, the terminal does not need to be replaced, but from Pre5G to 5G, the base station equipment can also continue to use.
Figure: Micro base station under millimeter wave technology
Understand that 5G is the basic definition of the fifth generation of mobile communication technology. It is understood that it is upgraded from 3G and 4G. Naturally, it is also a technology accumulation and evolution. It can be said that without the development of 3G and 4G technologies, there is no 5G. On the one hand, the evolution of 5G technology is the inevitable result of technology accumulation. Of course, it also requires revolutionary innovation to achieve the goal of evolution. On the other hand, it is also an inevitable requirement for the rapid improvement of human communication demand.
Conversely, the previous 5G has not been popularized. First, technology is not available, and second, there is no demand for application. Now with the demand, there is 5G. What needs? Future networks will face: 1000 times data capacity growth, 10 to 100 times wireless device connectivity, 10 to 100 times user speed requirements, 10 times longer battery life requirements, and more. Frankly speaking, 4G networks may not be able to meet these needs in the next five or six years, so 5G must be launched in advance.
Based on the judgment of technological evolution, reviewing China's arduous struggle through the 3G and 4G eras, we have reason to believe that the improvement of China's industry and technology has also laid a solid foundation for the 5G layout. From the past passive acceptance of technology to the beginning of output technology, China will With the opportunity to develop into one of the leading countries in the world of 5G technology, standards, industry and application services, from the following to lead, China's communications industry has the opportunity to learn Chinese high-speed rail in the 5G era to achieve cornering overtaking. The three major operators, Huawei, Datang, and ZTE have invested in 5G R&D for a long time and are at the forefront of the world.
Second, what are the advantages of 5G?For several consumers, the value of 5G is that it has a faster speed than 4g LTE (peak rate can reach tens of Gbps), for example, you can download a high-definition movie in one second, and 4G LTE may have 10 minute. It is precisely because of this unique advantage that the industry generally believes that 5G will play an important role in the fields of driverless cars, VR and the Internet of Things.
Compared with 4G, the 5G upgrade is comprehensive. According to the definition of 3GPP, 5G has high performance, low latency and high capacity characteristics, which are mainly reflected in millimeter wave, small base station, Massive MIMO, full duplex and beam. Forming these five major technologies.
Millimeter waveIt is well known that as the number of devices connected to wireless networks increases, the problem of scarce spectrum resources is becoming increasingly prominent. At least for now, we can only share limited bandwidth over extremely narrow spectrum, which greatly affects the user experience.
So how do you achieve the dozens of Gbps peak speeds provided by 5G?
As we all know, wireless transmission increases the transmission rate generally in two ways, one is to increase spectrum utilization, and the other is to increase the spectrum bandwidth. The 5G using millimeter wave (26.5-300 GHz) is the second method to increase the rate. In the 28 GHz band, the available spectrum bandwidth reaches 1 GHz, while the available signal bandwidth per channel in the 60 GHz band is 2 GHz.
In the history of mobile communications, this is the first time that new band resources have been opened. Prior to this, millimeter waves were only used on satellite and radar systems, but now operators have begun to use millimeter waves to test between base stations.
Of course, the biggest disadvantage of millimeter waves is that the penetration is poor and the attenuation is large. Therefore, it is not easy to transmit 5G communication in the millimeter wave band in a high-rise environment, and the small base station will solve this problem.
2. Small base stationThe above mentioned millimeter wave has poor penetration and a large attenuation in air, but because the frequency of the millimeter wave is very high and the wavelength is short, this means that the antenna size can be made small, which is small deployment. The basis of the base station.
It is foreseeable that in the future, 5G mobile communication will no longer rely on the deployment structure of large base stations, and a large number of small base stations will become a new trend, which can cover the peripheral communication that cannot be touched by large base stations.
Because of the large size reduction, we can set up a small base station around 250 meters. In this way, operators can deploy thousands of small base stations in each city to form a dense network. Each base station can receive signals from other base stations. And send data to users in any location. Of course, you don't have to worry about power consumption. The small base station is not only smaller than the large base station in terms of scale, but also greatly reduced in power consumption.
In addition to millimeter-wave broadcasting, 5G base stations will have many more antennas than current cellular base stations, namely Massive MIMO technology.
3.Massive MIMOThe existing 4G base station has only a dozen antennas, but the 5G base station can support hundreds of antennas. These antennas can form a large-scale antenna array by Massive MIMO technology, which means that the base station can transmit and receive signals from more users at the same time. Thereby increasing the capacity of the mobile network by dozens of times or more.
MIMO (MulTIple-Input MulTIple-Output) means multiple input and multiple output. In fact, this technology has been applied to some 4G base stations. But so far, Massive MIMO has only been tested in the lab and in several field trials.
Lund University professor Ove Edfors once pointed out that "Massive MIMO opens up a new direction for wireless communication. When traditional systems use time or frequency domain for resource sharing between different users, Massive MIMO imports a spatial domain (spaTIal domain). The way to use a large number of antennas at the base station and to synchronize them, so that it can achieve several times the gain in spectrum efficiency and energy efficiency."
Undoubtedly, Massive MIMO is the key technology for 5G commercialization, but multi-antenna is bound to bring more interference, and beamforming is the key to solve this problem.
4. BeamformingThe main challenge of Massive MIMO is to reduce interference, but it is because Massive MIMO technology integrates more antennas per antenna array. If these antennas can be effectively controlled, the space of each electromagnetic wave it emits cancels or enhances each other. A narrow beam can be formed instead of omnidirectional transmission. The limited energy is concentrated in a specific direction for transmission, not only the transmission distance is further, but also the signal interference is avoided. This wireless signal (electromagnetic wave) is pressed. The technique of propagating in a particular direction is called beamforming.
The advantage of this technology is not only that, it can improve spectrum utilization. With this technology, we can send more information from multiple antennas at the same time; in large-scale antenna base stations, we can even calculate the signal transmission through signal processing algorithms. The best path, and ultimately the location of the mobile terminal. Therefore, beamforming can solve the problem that the millimeter wave signal is blocked by the obstacle and the long distance is attenuated.
In addition, the last big feature of 5G is the mention of full-duplex technology.
5. Full duplexFull-duplex technology means that the transmitter and receiver of the device occupy the same frequency resources and work at the same time, so that both ends of the communication can use the same frequency at the same time in the uplink and downlink, breaking the existing frequency division duplex (FDD). And Time Division Duplex (TDD) mode, which is one of the keys to communication nodes to achieve two-way communication, and is also a key technology for high throughput and low latency required by 5G.
Simultaneous reception and transmission on the same channel greatly increases spectral efficiency. However, 5G's use of this disruptive technology is also facing no small challenge. According to the information released before Mobile Communications, there are three major challenges:
1. Circuit board design, self-interference cancellation circuit needs to meet the conditions of wide frequency (more than 100MHZ) and multiple MIMO (more than 32 antennas), and requires small size, low power consumption and low cost.
2. Optimization design issues of the physical layer and the MAC layer, such as coding, modulation, synchronization, detection, interception, collision avoidance, ACK, etc., especially for physical layer optimization of MIMO.
3. Control plane optimization for dynamic switching between full-duplex and half-duplex, and optimization of existing frame structure and control signaling.
Therefore, although the momentum of 5G far exceeds the previous 4G, the future of 5G is still full of uncertainty, and now we need to wait for these technologies to move from experimental to practical.
(Electronic enthusiasts edited)
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