Millimeter wave generally refers to electromagnetic wave with wavelength of 1 ~ 10mm and frequency of 30 ~ 300 GHz. In the millimeter wave band, a super wide bandwidth communication system up to 800 MHz can be built, and the communication rate is up to 10 Gbit / s, which can meet the requirements of ITU for 5g communication system. Millimeter wave has become a necessary part of 3GPP 5g mobile communication system [1-4]
Domestic 5g systems below 6 GHz have been fully commercial on November 1, 2019, and the industry's attention has turned to 5g subsequent evolution and 5g millimeter wave system. Millimeter wave industry chain has carried out a lot of research in high-frequency device performance , beamforming and beam management algorithm , link characteristics . Operators have also begun to consider 5g millimeter wave deployment and application from the perspective of system application [8-10]. Reference  analyzes the key technologies of millimeter wave system, and puts forward work suggestions to promote the development of millimeter wave industry. Reference  puts forward several main deployment scenarios of millimeter wave, and further puts forward the development requirements of equipment and terminals and network deployment planning.
However, from the feedback of many industry meetings, all parties in the communication industry are not clear about the millimeter wave industry route and lack confidence in the millimeter wave industry. The reasons are as follows: first, the current 5g has just been deployed, and there are no killer applications. Millimeter wave deployment lacks the promotion of business requirements. Second, there is a lack of systematic analysis on the positioning of millimeter wave communication system in communication system and the development of millimeter wave system industry, resulting in differences in the industry's expectations of the scale of millimeter wave industry. Third, at present, the domestic millimeter wave industrial chain is relatively weak, the equipment and terminals can not meet the deployment needs in the short term, and the industrial chain still needs some development time.
Firstly, this paper introduces the progress of millimeter wave standardization and the development status of millimeter wave industry, analyzes the necessity of millimeter wave system from the perspective of industrial development and 5g system design, and finally puts forward the typical application scenarios of millimeter wave based on the analysis of millimeter wave key technologies and industrial chain.
5g millimeter wave standardization and spectrum usage
1.1} 5g millimeter wave standardization
Spectrum is the most valuable resource in the mobile communication industry. The formal commercial use of any generation of mobile communication technology must obtain certain spectrum resources. The main goal of ITU for the topic 1.13 of the 2019 world radiocommunication Conference (wrc-19) is to seek a globally or regionally coordinated millimeter wave band for 5g, which is an important support for 5g millimeter wave research in the world. The recently concluded ITU wrc-19 conference put forward clear frequency band suggestions for millimeter wave band. A total of 11 frequency bands in the range of 24 ~ 86 GHz were discussed this time. The main conclusions of the conference are shown in Table 1.
Table 1 # 1.13 main conclusions of the topic
1.1.1} 24.25-27.5ghz frequency band
The logo 24.25-27.5 GHz can be used for IMT systems worldwide. Meanwhile, in order to protect the existing satellite in use system, 5g system shall meet the following technical requirements.
a) Out of band technical indicators.
(a) For the EESS (passive) service band range of 23.6 ~ 24 GHz, the unexpected transmission limit of IMT base station to any out of band per 200 MHz is - 33 DBW. After September 2027, the above limit will be adjusted to - 39 DBW, but the previously deployed base stations will not be affected.
(b) For the EESS (passive) service band range of 23.6 to 24GHz, the limit of unexpected transmission of IMT mobile terminal to any out of band per 200MHz is - 29 DBW. After September 2027, the above limit will be adjusted to - 35 DBW, but the previously used terminals will not be affected.
b) In band technical indicators.
(a) The transmitting antenna of the outdoor base station usually points below the horizontal line, and the mechanical direction needs to be at or below the horizontal line.
(b) For the IMT base station whose EIRP value of each beam exceeds 30dB (w / 200 MHz), the maximum radiation direction of its antenna shall deviate from the geostationary satellite orbit within the sight distance of the IMT base station & plusmn; 7.5 degrees.
(c) All competent departments are encouraged to keep the antenna pattern of IMT base station within the approximate envelope specified in ITU R m.2101 proposal.
1.1.2} 37 ~ 43.5ghz frequency band
Identify 37 ~ 43.5ghz frequency band or part of it can be used in IMT system all over the world. Meanwhile, in order to protect the existing satellite in use system, 5g system shall meet the following technical requirements.
a) In order to protect EESS (passive) in 36 ~ 37 GHz band, the mandatory useless emission limits applicable to IMT stations operating in 37 ~ 40.5 GHz band are - 43 dB (w / MHz) and - 23 dB (w / GHz). In order to achieve better protection, it is recommended that all competent departments consider - 30 dB (w / GHz).
b) When deploying an IMT base station in the 42.5 ~ 43.5 GHz band, practical measures shall be taken to ensure that the transmitting antenna of the outdoor base station usually points below the horizontal line. The mechanical direction needs to be at or below the horizontal line.
c) When deploying an IMT base station in the 42.5 ~ 43.5 GHz band, for an IMT base station with an equivalent isotropic radiated power (EIRP) value of more than 30 dB (w / 200 MHz) per beam, the maximum radiation direction of its antenna shall deviate from the geostationary satellite orbit within the sight distance of the IMT base station & plusmn; 7.5 degrees.
d) All competent departments are encouraged to keep the antenna pattern of IMT base station within the approximate envelope specified in ITU R m.2101 proposal.
1.1.3} 66 ~ 71 GHz band
Identify that 66 ~ 71 GHz band can be used for IMT system in some countries in zone 1, zone 3 and zone 2. Meanwhile, in order to protect the existing satellite system in use, 5g system needs to meet certain compatible coexistence technical requirements.
1.1.4} 45.5 ~ 47 GHz band
Identify that 45.5 ~ 47 GHz band can be used in IMT system in some countries. Meanwhile, in order to protect the existing satellite system in use, 5g system needs to meet certain compatible coexistence technical requirements.
1.1.5} 47.2 ~ 48.2 GHz band
Identify that 47.2 ~ 48.2 GHz band can be used in IMT system in some countries.
a) When deploying an IMT base station in the 47.2 ~ 48.2 GHz band, practical measures shall be taken to ensure that the transmitting antenna of the outdoor base station usually points below the horizontal line. The mechanical direction needs to be at or below the horizontal line.
b）When the IMT base station is deployed in the 47.2 ~ 48.2 GHz band, for the IMT base station with the equivalent isotropic radiation power (EIRP) value of each beam exceeding 30 dB (w / 200 MHz), the maximum radiation direction of its antenna shall deviate from the geostationary satellite orbit within the sight distance of the IMT base station ± 7.5 degrees.
c）All competent departments are encouraged to keep the antenna pattern of IMT base station within the approximate envelope specified in ITU R m.2101 proposal.
In 3GPP, the discussion and formulation of RF standards for millimeter wave band are led by 3GPP RAN4. The research is divided into two stages: the first stage is to study frequencies below 40 GHz to meet urgent commercial needs, which was completed in December 2018. Phase 2 is planned to start in 2018 and complete in December 2019. This phase focuses on frequencies up to 100 GHz to fully realize the vision of imt-2020. 5g frequency band has diversity, generally including below 6 GHz and 24.25 ~ 52.6 GHz. The millimeter wave spectrum below 52.6 GHz is defined in phase 1 spectrum allocation, as shown in Table 2.
Table 2 # 3GPP millimeter wave band
In 3GPP, the above millimeter wave band and 3.5 GHz NR system are synchronized and standardized, and the curing of R16 version will be completed in early 2020.1.2} 5g millimeter wave spectrum allocation and use
At the initial stage of millimeter wave deployment, most countries focused on the two frequency bands of 26 GHz and 28 GHz, and invested the most resources in these two frequency bands. The United States, South Korea, Japan and other countries have successively completed the division and auction of 5g millimeter wave spectrum, and the prospect of 5g commercial deployment is clear. Britain, Germany and other countries have confirmed 5g medium and high frequency bands to be allocated or tendered 
At present, the specific plan of millimeter wave spectrum in China has not been officially released. In July 2017, the Ministry of industry and information technology approved that 24.75 ~ 27.5 GHz and 37 ~ 42.5 GHz frequency bands are used for millimeter wave experimental frequency bands for 5g technology research and development in China. The test sites are the laboratory of China information and Communication Research Institute and the 5g technology test field in Huairou and Shunyi, Beijing. The domestic imt-2020 (5g) promotion group has established a high-frequency discussion group to formulate industry standards such as millimeter wave key technical requirements and millimeter wave field performance test methods. At present, RF test specifications have been defined and field and field tests have been started. Key technologies and system characteristics of 5g millimeter wave will be verified in 2019; Focus on verifying the function, performance and interoperability of millimeter wave base station and terminal in 2020; Typical scenario verification will be carried out from 2020 to 2021.
025g millimeter wave industry chain
Millimeter wave baseband has the same maturity as 5g low-frequency equipment, but the RF related functions and performance are far behind 5g low-frequency equipment. At present, the millimeter wave spectrum planning has not been clarified in China, so the equipment frequency band of the manufacturer is mainly North America, Japan and South Korea. The equipment can support basic functions, but some functions such as beam management and mobility need to be further improved. Qualcomm has been able to provide a commercial millimeter wave terminal chip x55, which has a single carrier bandwidth of 100 MHz and does not support a single carrier of 400 MHz or even 800 MHz. In terms of commercial terminals, oppo / vivo / ZTE expects to launch its flagship terminal based on x55 chip in the first quarter of 2020.
High frequency devices and chips are the basis of millimeter wave communication equipment. In order to meet the needs of higher-order modulation and multi-user communication, high-frequency power amplifiers and low-noise amplifiers need to further improve the performance of output power, power efficiency and linearity; PLL system needs to further improve its phase noise and tuning range; The filter needs to improve its bandwidth, insertion loss and other performance; Digital to analog and analog-to-digital converter devices need to meet the sampling requirements of at least 1 GHz channel bandwidth, improve accuracy and reduce power consumption; The new high frequency array antenna needs to meet the needs of high gain beam and wide range spatial scanning. In terms of high-speed and high-precision digital to analog and analog-to-digital conversion chips, high-frequency power amplifiers, low-noise amplifiers, filters, integrated packaging antennas, etc., at present, there is not much technical accumulation in domestic R & D achievements and technical prototypes, but the application of achievements is biased towards military industry, and there is a disconnection between prototype system and industrialization in the industrial chain of communication industry, There is a big gap between the process maturity of device materials suitable for civil communication and global leading enterprises.
As the key step of 5g high-frequency communication system towards practicality, low-cost and high reliability packaging and testing technologies are also very important. At present, there are few models of 5g millimeter wave chips and terminals in China, the types and forms of coverage are not rich enough, and the maturity of the industrial chain lags behind 5g low frequency, as well as the international advanced level such as the United States and Europe, which are the obstacles to the development and application of 5g millimeter wave in China.
03Clear demand for 5g millimeter wave system3.1. The extension of mobile communication system to millimeter wave is an inevitable choice in the face of business needs
In order to meet the communication rate requirements of services, on the one hand, mobile communication systems need to further improve the spectrum efficiency and improve the service carrying capacity of the system by means of high-order modulation and large-scale MIMO. On the other hand, it is necessary to increase the system bandwidth and continuously enhance the data service capacity through carrier aggregation, dual connection and other technologies. However, at present, the spectrum resources below 6 GHz have been allocated completely, and it is difficult to find a continuous large bandwidth spectrum to support the ultra-high data transmission rate of mobile communication.
Compared with the low-frequency band, the millimeter wave band has rich bandwidth resources and can realize 800 MHz large bandwidth transmission, which makes it possible for ultra-high-speed communication services. At the same time, the length of millimeter wave and the size of components are small, which is convenient for equipment integration and miniaturization.
With the development of high-capacity, high-speed and low delay services, the communication frequency band is bound to extend to millimeter wave. At present, it has been determined that the basic architecture of 5g mobile communication will adopt the communication mode of combining medium and low frequency band and millimeter wave band.3.2 accelerating the development of millimeter wave industry chain is an inevitable requirement for participating in international competition
Mobile communication plays a great role in promoting the economy. 5g and even 6G mobile communication technology and industry are important fields of international competition. Millimeter wave system is not only an important part of 5g communication system, but also the technical preparation of 6G higher frequency mobile communication system. It can be seen from the fact that millimeter wave band allocation has attracted extensive attention from the industrial and economic circles at the ITU WRC conference at the end of 2019 that millimeter wave is one of the focuses of competition in the communication field. According to the analysis of the social and economic benefits of providing 5g services in the millimeter wave band released by GSMA, the early leading advantages of millimeter wave in the Asia Pacific and the Americas are expected to create the largest share of GDP, reaching US $212 billion and US $190 billion respectively; The GDP growth rate generated by millimeter wave in Europe will be higher than that in any other region, reaching 2.9%.
At present, the domestic millimeter wave industry chain lags behind the United States as a whole, especially the industrialization level of high-frequency devices. After extensive research, the domestic millimeter wave industry chain mainly focuses on the disconnection between prototype system and prototype chip and large-scale production. The trial production and testing of prototype system and prototype chip requires a long cycle and large investment, and needs the support of industrial policy. At present, the Ministry of industry and information technology, the Ministry of science and technology and other ministries and commissions are inclined in major projects and industrial policies. Some economically developed provinces also regard millimeter wave and other high-frequency industrial chains as key development directions for support. Domestic production, learning and research institutions have also made efforts in this regard to improve the technical capacity and industrial level of domestic millimeter wave devices and chips.3.3 the application scenario of millimeter wave system is gradually clarified
Considering the millimeter wave propagation characteristics and coverage capacity, 5g millimeter wave is suitable for deployment in relatively open, unobstructed or less sheltered park environment. After many industry conferences and seminars, the industry has identified the typical deployment scenarios of millimeter wave.
a）Industry private network scenario. Combined with MEC and AI technologies, 5g millimeter wave system can provide an intelligent solution of "large capacity and high rate localization" for the coverage area, and meet the needs of industry customers for low delay, large bandwidth and safe isolation.
b）Brand value area. At the initial stage of deployment, millimeter wave will be combined with 5g systems in the frequency band below 6 GHz to form a 5g system high-frequency and low-frequency hybrid networking mode, which is used to cover important brand value areas, improve brand value, or for heat absorption in crowded places and hot spots, so as to provide further large-capacity upload capability.
c）Large bandwidth backhaul scenario. Millimeter wave can be used as a wireless backhaul link to solve some fixed wireless broadband scenarios in which optical fiber cannot be deployed or the cost of optical fiber is too high, or millimeter wave self backhaul networking scenarios by using the system peak rate of up to 800 MHz bandwidth and 10 Gbit / s.
3.4 millimeter wave system is the competitive highland of service capability of operators
Compared with 5g low-frequency, millimeter wave technology has unique advantages such as bandwidth, delay and flexible air interface configuration. It can effectively meet the requirements of future wireless communication system capacity, transmission rate and differentiated applications. It is a necessary means for operators to meet large bandwidth uplink services. Carrying out millimeter wave research and pilot application as soon as possible is conducive to operators to guide the formulation of millimeter wave standards and equipment R & D direction, make preparations for millimeter wave networks and equipment as soon as possible, and then seize the highland of network capacity of 10 Gigabit bandwidth.
04Analysis of typical application scenarios of 5g millimeter wave
Smart Winter Olympic venues are typical scenarios for millimeter wave applications. Carry out indoor high and low frequency hybrid networking in large venues to create pure wireless venues, meet 4K and 8K camera broadcasting of TV media in venues, meet multi angle real-time experience such as real-time VR images and athletes' perspective images, and meet business services such as public self shooting, live broadcasting and venue security. The millimeter wave self transmission system is deployed along the track in the outdoor venues of the Winter Olympic Games. With the help of millimeter wave video information with high bandwidth and high rate, the camera set up beside the track can avoid complex wiring work and hidden dangers of cable safety in harsh environment.
a) Broadcast and video. There are many venues for the Winter Olympic Games,The competition venue is frequently changed, and the positions of athletes and spectators are also moved and changed at any time. With the help of millimeter wave with high bandwidth and high rate, the camera can avoid repeated wiring and be more flexible and fast.
b) 360 degree panoramic camera. The Winter Olympic venues are equipped with 360 degree cameras and 5g millimeter wave network for live broadcast of the competition. TV viewers can no longer only enjoy the pictures taken on the platform, but can choose the lens and angle at will to change the viewing angle.
c) Athlete's head mounted AR / VR. Wearing convenient and compact wearable devices for athletes, such as head mounted AR / VR, can make use of augmented reality and virtual reality technology to display and disassemble the wonderful process of the competition from an athlete's perspective, and assist in superposition with corresponding images, explanations and 3D models, so that competitive sports are no longer single and boring, but more vivid, vivid and rich, Meet the audience's multi angle, multi visual and immersive viewing experience.
d) Selfie and live broadcast of wanghong. There may also be many online self shooting and live broadcasting services in the Winter Olympic venue. The self timer return puts forward high requirements for the network uplink. Millimeter wave can effectively provide the large bandwidth uplink requirements that the current sub6 GHz system cannot meet.
e) Venue AI video surveillance and face recognition. The combination of innovative monitoring technologies such as mobile robots, patrol UAVs and mobile face recognition with traditional methods can improve the security level of the Winter Olympic Games. The special network of 5g millimeter wave MEC AI can quickly upload the video images collected by the mobile terminal and carry out edge intelligent recognition, so as to realize real-time analysis of venue situation and rapid intelligent recognition of faces, so as to ensure the safety of venues.
This paper introduces the progress of millimeter wave standardization and the development status of millimeter wave industry, analyzes the necessity of millimeter wave system from the perspective of industrial development, competitive demand and application scenarios, finally puts forward the millimeter wave application scenario represented by smart Winter Olympic venues, and introduces the possible typical businesses.
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