From 1G to 4G, the core of mobile communication is human-to-human communication, and personal communication is the core business of mobile communication. But 5G communication is not just human communication, but Internet of Things, industrial automation, and driverlessness are introduced. Communication starts from the communication between people and then to the communication between people and things, until the communication between machines and machines.
The fifth generation of mobile communication technology (5G) is the highest peak of the development of mobile communication technology at present, and it is also the important force that human beings hope not only to change their lives but also to change society.
5G is based on 4G, and it puts forward higher requirements for mobile communication. It not only has a new upgrade in speed but also in power consumption and delay. As a result, the business will also be greatly improved, and the development of the Internet will also enter the era of intelligent Internet from the mobile Internet.
3G's three scenes
The International Organization for Standardization 3GPP defines three major scenarios for 5G. Among them, eMBB refers to large-capacity mobile broadband services such as 3D/Ultra HD video, mMTC refers to large-scale Internet of Things services, and URLLC refers to services such as driverless, industrial automation that require low latency and high reliability.
Through the definition of the three major scenarios of 3GPP, we can see that for 5G, the general view of the world communication industry is that it should not only have high speed, but also meet the higher requirements of low latency, although high speed is still a component of it. section. From 1G to 4G, the core of mobile communication is human-to-human communication, and personal communication is the core business of mobile communication. However, 5G communication is not only human communication, but also services such as Internet of Things, industrial automation, and driverless driving. Communication communicates from person to person and begins to communicate between people and things until between machines and machines. Communication.
The three major scenarios of 5G obviously put forward higher requirements for communication, not only to solve the speed problem that has always been solved, but also to provide higher speed to users; and put forward higher requirements on power consumption, delay, etc. The aspect has completely exceeded our understanding of traditional communication and integrated more application capabilities into 5G. This puts higher demands on communication technology. In these three scenarios, 5G has six basic features.
The six basic features of 5G
Compared to 4G, the first problem that 5G has to solve is high speed. As the network speed increases, the user experience and experience will be greatly improved. The network can be faced with unlimited VR/Ultra HD services, and services with high network speed requirements can be widely promoted and used. Therefore, the first feature of 5G defines the speed increase.
In fact, like every generation of communication technology, it is very difficult to say exactly what the speed of 5G is. On the one hand, the peak speed is different from the actual experience speed of the user, and the speed of different technologies will be different. The peak requirement for 5G base station is not less than 20Gb/s. Of course, this speed is the peak speed, not every user experience. With the use of new technologies, there is room for improvement at this speed.
Such a speed means that users can download a high-definition movie every second, or they can support VR video. Such high speeds provide opportunities and possibilities for future businesses that require high speed.
With the development of the business, the network business needs to be all-encompassing and widely existed. Only in this way can we support a richer business and use it in complex scenarios. The ubiquitous network has two levels of meaning. One is extensive coverage and the other is deep coverage.
Broadly refers to the various places in our social life, which need to be widely covered. In the past, the mountain valleys did not necessarily need network coverage, because there are few people living, but if you can cover 5G, you can deploy sensors in large quantities to change the environment, air quality and even landforms. This is very valuable for monitoring earthquakes. 5G can provide a network for more such applications.
Depth refers to the depth of coverage in our lives, although there are already network deployments. We have a 4G network in our home today, but the quality of the bathroom in the home may not be very good. The underground parking garage has basically no signal, and it is now acceptable. With the advent of 5G, the bathrooms and underground parking garages with poor network quality can be widely covered with a good 5G network.
To a certain extent, the ubiquitous network is more important than the high speed. It is only to build a network with a small coverage and high speed. It can not guarantee the service and experience of 5G, and the ubiquitous network is a fundamental guarantee for the 5G experience. There are no ubiquitous networks in the three major scenarios of 3GPP, but the ubiquitous requirements are implicit in all scenarios.
Low power consumption
To support large-scale IoT applications, 5G must have power requirements. In the past few years, wearable products have developed, but many bottlenecks have been encountered. The biggest bottleneck is the poor experience. Take a smart watch as an example. Recharge every day, even less than one day. All IoT products require communication and energy. Although communication can be achieved by various means today, the supply of energy depends on batteries. If the communication process consumes a lot of energy, it is difficult to make the Internet of Things products widely accepted by users.
If you can reduce the power consumption, and let most IoT products charge once a week, or even once a month, you can greatly improve the user experience and promote the rapid spread of IoT products. The eMTC evolved based on the LTE protocol, and the LTE protocol was tailored and optimized for better communication between objects and for lower cost. The eMTC is deployed on a cellular network, and its user equipment can directly access the existing LTE network by supporting 1.4MHz RF and baseband bandwidth. The eMTC supports a peak rate of up to 1 Mbps for both uplink and downlink. NB-IoT is built on a cellular network and consumes only about 180 kHz of bandwidth. It can be deployed directly on GSM networks, UMTS networks or LTE networks to reduce deployment costs and achieve smooth upgrades.
NB-IoT can be deployed based on GSM network and UMTS network. It does not need to rebuild the network like 5G core technology, but although it is deployed on GSM and UMTS networks, it is still a rebuilt network. Its ability to greatly reduce power consumption is also to meet the needs of 5G for low-power IoT applications. Like eMTC, it is an integral part of the 5G network system.
A new scene for 5G is a highly reliable connection for driverless, industrial automation. Information exchange between people, a delay of 140 milliseconds is acceptable, but if this delay is used for driverless, industrial automation is unacceptable. The minimum requirement for 5G for latency is 1 millisecond or even lower. This puts a harsh demand on the network. And 5G is an inevitable requirement for the application of these new fields.
Driverless cars need to be interconnected by the central control center and the car. The car and the car should also be interconnected. In high-speed operation, a brake needs to send information to the car in an instant to react, about 100 milliseconds. Time, the car will rush out a few tens of meters, which requires the information to be sent to the car in the shortest delay, braking and vehicle control reaction.
This is especially true for drones. If hundreds of unmanned formations fly, very small deviations can lead to collisions and accidents, which requires information to be transmitted to the flying drone in a very small time delay. In the process of industrial automation, the operation of a mechanical arm, if it is to be extremely refined, to ensure the high quality and precision of the work, it also requires minimal delay and the most timely response. These characteristics are not so high in traditional human-to-human communication, even when people communicate with machines, because people's reactions are slower and do not require the efficiency and refinement of machines. Whether it is a drone, a driverless car or industrial automation, it is operated at a high speed, and it also needs to ensure timely information transmission and timely response at high speed, which imposes extremely high requirements on time delay.
To meet the requirements of low latency, we need to find various ways to reduce the delay in the construction of 5G networks. Techniques such as edge computing will also be adopted in the 5G network architecture.
Internet of Everything
In traditional communication, the terminal is very limited. In the fixed telephone era, the telephone is defined by the crowd. In the era of mobile phones, the number of terminals has exploded, and mobile phones are defined by personal applications. In the 5G era, terminals are not defined by people, because each person may have several, and each family may have several terminals.
In 2018, China's mobile terminal users have reached 1.4 billion, of which mobile phones are the mainstay. The communication industry's vision for 5G is every square kilometer, which can support 1 million mobile terminals. In the future, access to the terminals in the network is not only our mobile phone today, but also more and more strange products. It can be said that every product in our life is likely to access the network through 5G. Our glasses, mobile phones, clothes, belts, and shoes all have access to the Internet and become smart products. Doors and windows, door locks, air purifiers, fresh air blowers, humidifiers, air conditioners, refrigerators, and washing machines in the home are all likely to enter the era of intelligence. Through 5G access to the network, our family has become a smart home.
In the social life, a large number of devices that were previously impossible to connect to the Internet will be networked and smarter. Public facilities such as cars, manhole covers, utility poles, and trash cans have been difficult to manage in the past, and it is difficult to be intelligent. And 5G can make these devices become smart devices.
Security issues do not seem to be a fundamental issue discussed by 3GPP, but it should also be a fundamental feature of 5G.
The traditional Internet has to solve the problem of information speed and unimpeded transmission. Freedom, openness and sharing are the basic spirit of the Internet. However, based on 5G, the intelligent Internet is established. The intelligent Internet is not only to achieve information transmission, but also to establish a new mechanism and system for society and life. The basic spirit of intelligent Internet is security, management, efficiency and convenience. Security is the first requirement of the intelligent Internet after 5G. Assuming that 5G is built but it is impossible to rebuild the security system, it will cause tremendous destructive power.
If our driverless system is easy to break, it will be like the movie shows that the car on the road is controlled by hackers, the intelligent health system is broken, the health information of a large number of users is leaked, the smart family is broken, and there is no security at home. Guarantee. This situation should not occur, and the problem is not solved by tinkering.
In the 5G network construction, the security problem should be solved at the bottom. From the beginning of network construction, security mechanisms should be added, information should be encrypted, the network should not be open, and special security mechanisms need to be established for special services. . The network is not completely neutral and fair. To give a simple example: on the network guarantee, ordinary users access the Internet, and there may be only one system to ensure that their network is unblocked, and users may face congestion. However, the intelligent transportation system requires multiple systems to ensure its safe operation and ensure its network quality. When the network is congested, the network of the intelligent transportation system must be ensured. And this system is not the general terminal can access management and control.
5G key technology
As a new generation of mobile communication technology, 5G's network structure, network capabilities and requirements are very different from the past, and a large number of technologies are integrated into it. The core technology is briefly described as follows:
OFDM-optimized waveform and multiple access
5G uses OFDM-based waveform and multiple access technology because OFDM technology is widely adopted in today's 4G LTE and Wi-Fi systems, because it can be extended to large bandwidth applications with high spectral efficiency and low data complexity Sex, can meet the 5G requirements very well. The OFDM family of technologies enables a variety of enhancements, such as enhanced frequency localization through windowing or filtering, increased multiplexing efficiency between different users and services, and the creation of single-carrier OFDM waveforms for efficient energy-efficient uplink transmission.
Implement scalable OFDM interval parameter configuration
With a 15 kHz spacing between OFDM subcarriers (fixed OFDM parameter configuration), LTE can support up to 20 MHz carrier bandwidth. In order to support a richer spectrum type/band (in order to connect as many devices as possible, 5G will utilize all available spectrum, such as millimeter microwaves, unlicensed bands) and deployment methods. The 5G NR will introduce a scalable OFDM interval parameter configuration. This is crucial because when the FFT (Fast Fourier Transform) is a larger bandwidth extension size, it must be guaranteed that the complexity of the processing is not increased. In order to support different channel widths of multiple deployment modes, 5G NR must adapt to different parameter configurations in the same deployment, and improve multiplexing efficiency under a unified framework. In addition, 5G NR can also implement carrier aggregation across parameters, such as aggregation of millimeter waves and carriers below 6 GHz.
OFDM windowing improves multiplex transmission efficiency
5G will be used in large-scale Internet of Things, which means that billions of devices will be connected to each other, and 5G will need to improve the efficiency of multiplex transmission to cope with the challenges of large-scale Internet of Things. In order to prevent adjacent bands from interfering with each other, in-band and out-of-band signal radiation must be as small as possible. OFDM can implement post-processing, such as time domain windowing or frequency domain filtering, to improve frequency localization.
Flexible frame design
At the same time of designing 5G NR, the flexible 5G network architecture is adopted to further improve the efficiency of 5G service multiplex transmission. This flexibility is reflected in the frequency domain and in the time domain. The 5G NR framework can fully satisfy the different services and application scenarios of 5G. This includes a Scalable Transmission Time Interval (STTI) and a Self-contained integrated subframe.
Advanced new wireless technology
At the same time of 5G evolution, LTE itself is still evolving (such as the recently implemented Gigabit 4G+). 5G will inevitably use advanced technologies currently used in 4G LTE, such as carrier aggregation, MIMO, and non-shared spectrum. This includes many mature communication technologies:
Massive MIMO: from 2x2 to the current 4x4 MIMO. More antennas also mean more space. It is obviously unrealistic to accommodate more antennas in a space-limited device, and only more MIMO can be superimposed on the base station side. From the current theory, 5G NR can use up to 256 antennas at the base station side, and through the two-dimensional arrangement of the antenna, 3D beamforming can be realized, thereby improving channel capacity and coverage.
Millimeter Wave: The new 5G technology is for the first time to apply frequencies above 24 GHz (commonly known as millimeter waves) for mobile broadband communications. A large number of available high-band spectrums provide the ultimate in data transfer speed and capacity, which will reshape the mobile experience. However, the use of millimeter waves is not an easy task, and transmission in the millimeter wave band is more likely to cause path obstruction and loss (limited signal diffraction capability). In general, signals transmitted in the millimeter wave band cannot even penetrate the wall. In addition, it faces problems such as waveform and energy consumption.
Spectrum sharing: with shared spectrum and unlicensed spectrum,