5G technology has evolved in a different way from previous generations of mobile communication. First, the era of 2G/3G/4G is a leading technology application. Mobile communication technology has been developed continuously. It will be extended to different applications after maturity. Its application focuses on "changing life". 5G is the opposite, and traction technology is applied. First, the application needs and scenarios should be determined, including "life" and "society", and then explore the corresponding specific technologies, such as 5G new radio, NR) design standard is derived from a new application scenario, including: new waveform, new modulation mode, new frame structure, new multiple access technology, new coding technology and large-scale multi antenna technology. In the future, the evolution of mobile communication technology (6G and later) will also appear in the way of "application leading and technology follow".
5G network is a wide-ranging, ubiquitous, intelligent, integrated, green energy-saving network. According to the technical vision in 5G white paper, 5G network will meet the needs of people with ultra-high traffic density, ultra-high connection density and ultra-high mobility, and provide users with high-definition video, virtual reality, augmented reality, cloud desktop, online games and other extreme business experience. 5G will penetrate into the field of Internet of things, and integrate with industrial facilities, medical instruments, transportation tools and other aspects to realize "all things are connected".
2. 5G performance index (5G flower)
In the future and 2020, 5G will solve the challenges brought by differentiated performance indicators in diversified application scenarios. Different application scenarios will face different performance challenges. User experience rate, traffic density, delay, energy efficiency and connection number may become challenging indicators of different scenarios.
5G will open a new era of development for human beings in terms of speed, capacity, coverage, delay, security, user experience and so on. In order to meet the arrival of 5G, China proposes "5G flower", as shown in the following figure, the performance and efficiency requirements define the key capabilities of 5G, just as a blooming flower. Red flowers and green leaves complement each other. Petals represent six performance indicators of 5G, which reflect 5G's ability to meet the needs of diversified business and scenarios in the future, while petal apex represents the maximum value of corresponding indicators; green leaves represent three efficiency indicators, which is the basic guarantee for achieving 5G sustainable development.
The 5G performance indexes included in the above are as follows:
(1) The important performance index of mobile communication system in the past generations of mobility refers to the maximum relative mobile speed of both parties under the premise of satisfying certain system performance. 5G mobile communication system needs to support ultra-high-speed mobile scenes such as aircraft, expressway, urban subway, and at the same time, it also needs to support data acquisition, industrial control low-speed mobile or non mobile scenes. Therefore, the design of 5G mobile communication system needs to support more extensive mobility.
(2) The delay delay is measured by Ott or RTT, the former refers to the interval between the data received from the sender and the receiving end, and the latter refers to the time interval from the sending end to the receiving end data. In the 4G era, the flat design of network architecture greatly improves the performance of system delay. In 5G era, the application scenarios of vehicle communication, industrial control, augmented reality and other business scenarios put forward higher requirements for delay, and the minimum time delay of the air port reaches 1ms. In the design of network architecture, the delay is closely related to network topology, network load, business model, transmission resources and other factors.
(3) In the 5G era, a mobile ecological information system will be built, which takes user-centered as the performance index for the first time. User perception rate refers to the amount of data transmission that users get in MAC layer in a unit time. In the actual network application, the user perception rate is affected by many factors, including network coverage environment, network load, user size and distribution range, user location, business application and other factors. Generally, expected average value and statistical method are used to evaluate and analyze.
(4) Peak rate peak rate refers to the maximum service rate that users can obtain. Compared with 4G network, 5G mobile communication system will further improve the peak rate, which can reach 10Gbps.
(5) In 5G era, there are a lot of Internet of things applications, and the network requires over 100 billion equipment connection capabilities. Connection density refers to the total number of online devices that can be supported in unit area, and is an important indicator to measure the support capacity of 5G mobile network to large-scale terminal equipment, generally not less than 100000 / km2.
(6) Traffic density is the total traffic number in a unit area, which is used to measure the data transmission capacity of mobile network in a certain area. In 5G era, it is necessary to support the ultra-high data transmission in certain local areas. The network architecture should support the traffic of 10tbps per square kilometer. In the actual network, the traffic density is related to many factors, including network topology, user distribution, business model and other factors.
(7) Energy efficiency energy efficiency refers to the amount of data that can be transmitted per unit of energy consumption. In mobile communication system, energy consumption mainly refers to the transmission power of base station and mobile terminal, and the power consumed by the whole mobile communication system equipment. In the design of 5G mobile communication system architecture, a series of new access technologies are adopted to reduce power consumption, such as low power base station, D2D technology, traffic equalization technology, mobile relay, etc.
3. Three application scenarios of ITU
The ITU-RWP5D held by ITU determines that 5G in the future has three main application scenarios as follows:
1) Enhanced mobile broadband (eMBB)
2) Mass machine type communications (mMTC)
3) Ultra reliable and low latency communications (URLLC)
It includes: Gbps mobile broadband data access, smart home, intelligent building, voice calling, smart city, 3D video, super high definition video, cloud work, cloud entertainment, augmented reality, industry automation, emergency mission application, automatic driving vehicle and so on.
3.1 enhanced mobile broadband eMBB
Enhanced mobile broadband refers to the further improvement of user experience and other performance based on the existing mobile broadband business scenarios. The application scenario with human centered focus on ultra-high transmission data rate and wide coverage of mobility assurance. It mainly includes the hot spot high capacity scenario of huge data flow in super dense areas such as stations and stadiums. The performance requirements in this scenario include 1 Gbit/s user experience rate, 10gbit/s peak rate and 10tbit/ (s · km2) traffic density. In addition, the eMBB also includes continuous wide area coverage scenarios that need to ensure the business continuity of users in high mobility. The challenge is to provide users with a user experience rate of more than 100 Mbit/s at any time and anywhere, and ensure the continuity of business and the basic service capability of the network. The most intuitive feeling of 5G in this regard is the rapid increase of network speed. Even if you watch 4K high-definition video, the peak speed can reach 10Gbps. The enhanced mobile broadband eMBB scene applications include augmented reality (AR), virtual reality (VR), and 4K, 8K Ultra HD video and other high-speed applications.
3.2 mass machine type communication mMTC
The massive terminal connection scenario mainly aims at the scene of large number of connections and business characteristics difference of devices such as MTC (machine type communication) equipment and sensors. 5G low power consumption, large connection and low delay high reliability scenarios are mainly for Internet of things services. As a newly developed 5G scenario, the focus is on solving the problems that traditional mobile communication can not support the application of the Internet of things and vertical industries. It is mainly used in inter machine communication, mainly based on sensors, including smart city, logistics management, intelligent agriculture, remote monitoring, tourism management, smart family, smart community, sharing equipment, wearable equipment, environmental monitoring, forest fire prevention and other application scenarios with sensing and data acquisition as the target, which meet the needs of huge number of access equipment and extremely low power consumption, and it is expected to reach 100 The performance index of the connection density of 10000 / km2 has the characteristics of small packet, low power consumption and mass connection.
3.3 Ultra reliable and low delay communication URLLC
URLLC is characterized by high reliability, low delay and high availability. In this scenario, the connection delay should reach 1ms level, and the high reliability (99.999%) connection under the condition of high-speed mobile (500km/h) should be supported. URLLC has a great potential in the driverless business. It is mainly for applications with high requirements for delay and reliability, such as low time delay and high reliability scenarios such as vehicle network and industrial control. The network needs to provide users with MS level end-to-end delay and nearly 100% service reliability guarantee. This is far from the end-to-end delay and service interruption time of 4G network, which requires 5G network to provide users with end-to-end delay and service interruption time for higher reliability and higher reliability Low delay requires that key enabling techniques be proposed. In addition, this is also important for the safety protection industry.
There are three main types of high reliability and low delay communication scenarios: the first is to save time, improve efficiency and save resources; the second is to keep people away from danger and operate safely; the third is to make life more colorful. It includes the following scenarios and applications: artificial intelligence, automatic driving, traffic control, remote construction, remote training, telemedicine, simultaneous interpretation, industrial automation, etc., which have low delay requirements.
4. IMT-2020 four main technical scenarios
4.1 Introduction to four technical scenarios
Later, imt-2020 (5G) introduced 5G main application scenarios as follows: continuous wide area coverage, hot spot high capacity, low power consumption and high reliability, which is basically consistent with the three application scenarios of ITU, based on the main application scenarios, business requirements and challenges of mobile Internet and Internet of things.
(1) Continuous wide area coverage scenario is the most basic coverage mode of mobile communication. It aims to ensure the mobility and business continuity of users, and provides seamless high-speed business experience for users. The main challenge of this scenario is to provide users with more than 100Mbps user experience rate anytime and anywhere (including the harsh environment such as cell edge and high-speed mobile).
(2) Hot spot high capacity scenario, mainly for local hot spot areas, provides users with high data transmission rate, and meets the high traffic density demand of the network. The main challenges of this scenario are 1Gbps user experience rate, 10Gbps peak rate and traffic density demand of 10tbps/km2.
(3) Low power and large connection scenarios are mainly for smart cities, environmental monitoring, intelligent agriculture, forest fire protection and other application scenarios aiming at sensing and data acquisition, which have the characteristics of small data package, low power consumption and mass connection. This kind of terminal is widely distributed and numerous. It requires not only the network to have the support capacity of over 100 billion connections, meet the requirements of the density index of 1 million / km2 connections, but also ensure the ultra-low power consumption and ultra-low cost of the terminal.
(4) Low delay and high reliability scenarios are mainly for special applications in vertical industries such as the Internet of vehicles and industrial control. Such applications have high index requirements for delay and reliability, and provide users with MS level end-to-end delay and nearly 100% service reliability guarantee.
Continuous wide area coverage and hot spot high capacity scenarios mainly meet the needs of mobile Internet services in 2020 and the future, and are also the main technology scenarios of traditional 4G. Low power, large connection and low delay high reliability scenarios are mainly for Internet of things services, which are new 5G expansion scenarios, focusing on solving the traditional mobile communication can not support the application of the Internet of things and vertical industries.
|Continuous wide area coverage
||100Mbps user experience rate
|Hot spot high capacity
||User experience rate: 1Gbps
Peak rate: 10Gbps
Flow density: 10tbps/km2
|Low power and large connection
||Connection density: 106/km2
Ultra low power consumption, ultra low cost
|Low delay, high reliability
||Opening delay: 1ms
End to end delay: ms
Reliability: close to 100%
5G scenarios and key performance challenges
4.2 Relationship between 5G technology scenario and key technologies
Four 5G typical technology scenarios, such as continuous wide area coverage, high capacity of hot spots, high reliability with low delay and low power consumption and large connection, have different challenging index requirements. Under the premise of considering the possibility of coexistence of different technologies, the combination of key technologies should be reasonably selected to meet these requirements.
In the continuous wide area coverage scenario, it is limited by the station address and spectrum resources. In order to meet the demand of 100Mbps user experience rate, besides the need for as many low frequency resources as possible, the spectrum efficiency of the system will be greatly improved. Large-scale antenna array is one of the most important technologies. The new multi access technology can be combined with large-scale antenna array to further improve the spectrum efficiency and multi-user access capability of the system. In the aspect of network architecture, the paper integrates a variety of wireless access capabilities and centralized network resource coordination and QoS control technology to provide users with stable experience rate assurance.
In hot spot high capacity scenarios, high user experience rate and high traffic density are the main challenges facing the scene. Ultra dense network can reuse frequency resources more effectively, greatly improve the frequency reuse efficiency in unit area; full spectrum access can make full use of low frequency and high frequency resources to achieve higher transmission rate; large-scale antenna, new multiple access, etc. The combination of technology and the first two technologies can further improve the spectrum efficiency.
In the low power and large connection scenario, the major challenges facing the scenario are massive device connection, ultra-low terminal power consumption and cost. The new multi access technology can improve the equipment connection ability of the system by the superposition transmission of multi-user information, and can effectively reduce signaling overhead and terminal power consumption through dispatching free transmission; new multicarrier technologies such as F-OFDM and FBMC have significant advantages in flexible use of fragment spectrum, support narrow band and small packet, reduce power consumption and cost; in addition, terminal * direct communication (D2D) can be used ）*It can avoid long distance transmission between base station and terminal, and can effectively reduce power consumption.
In low delay and high reliability scenarios, the transmission delay, network forwarding delay and retransmission probability should be reduced as much as possible to meet the high delay and reliability requirements. Therefore, shorter frame structure and better signaling process are needed to reduce signaling interaction and data transfer by introducing new multi access and D2D technologies supporting non scheduling, and more advanced modulation coding and retransmission mechanism are used to improve transmission reliability. In addition, in the network architecture, the control cloud can reduce the network transmission delay by optimizing the data transmission path, controlling the business data close to the forwarding cloud and accessing the edge of the cloud.
5. Top ten application scenarios in 5G Era
Combined with the most possible and relevant application scenarios in 5G era, it mainly includes:
Cloud VR / AR (real-time computer image rendering and modeling), Internet of vehicles (remote control driving, formation driving, automatic driving), intelligent manufacturing (wireless robot cloud control), intelligent energy (feeder automation), wireless medical (remote diagnosis with force feedback), wireless home entertainment (Ultra HD 8K video and cloud games), networked UAV (professional inspection and security), social security Traffic network (Ultra HD, panoramic live), personal AI assistance (AI assisted intelligent helmet), smart city (AI enabled video surveillance).