At the 2019 World Radiocommunication Conference (WRC-19) held in Sharm el-Sheikh, Egypt, approximately 3,400 representatives from 165 member states reached multiple agreements. Among them, the 5G millimeter wave issue that determines the future development of global communications is the top priority of all countries and international organizations.
After a month of debate and coordination, the International Telecommunication Union (ITU) finally determined the 5G millimeter wave frequency band to “expand”, and representatives of various countries reached a consensus on the use of 5G millimeter wave spectrum: 24.25 GHz-27.5 GHz (26 GHz), 37 GHz-43.5 GHz (40GHz), 66 GHz-71 GHz, a total of 14.75GHz bandwidth spectrum resources, marking for the future development of 5G and the International Mobile Telecommunications System (IMT); in the 45.5GHz-47GHz frequency band, some countries use the mark in the footnote In the IMT; in the 47.2GHz-48.2GHz frequency band, countries in Region 2 (the Americas) and some countries in some regions are marked for IMT in the footnote. Among them, the 24.75-27.5GHz and some 40GHz millimeter wave frequency bands promoted by China have been adopted globally.
On the 5G millimeter wave issue (1.13 issue), the Chinese delegation actively strives for my country’s position, and has given full play to the leading role. The main person in charge of the issue is Dr. Wang Tan, a senior engineer from the National Radio Monitoring Center/National Radio Spectrum Management Center.
The past and present of 5G millimeter wave
Millimeter waves, that is, electromagnetic waves with a wavelength between 1 and 10 millimeters, usually correspond to the radio frequency spectrum between 30 GHz and 300 GHz. For a long time, millimeter wave has been regarded as the “wild area” of mobile communication due to its short propagation distance and poor penetration. However, with the advancement of technology and the advent of 5G, millimeter wave spectrum has advantages such as continuously available ultra-large bandwidth. , Which can meet the 5G system’s transmission requirements for ultra-large capacity and extremely high speed, and is an important part of the future construction of 5G networks. In the case that it is difficult to release the useful spectrum resources in the mid-to-low frequency band (below 6GHz) in some areas, the millimeter wave frequency band has become a “new continent” that supports and guarantees the long-term development of 5G hotspot applications.
Compared with the previous mobile communication system, which is mainly for free communication between people, 5G opens a new era of “Internet of Everything”. In the fields of smart home, smart city, smart cloud, 3D video, telemedicine, virtual and augmented reality, and large-scale machine-to-machine communication for industrial automation, 5G technology will be deeply integrated with other information technologies and be widely used. According to the International Telecommunications Union (ITU), between 2020 and 2030, mobile broadband data traffic will increase by 10 to 100 times, and the number of devices connected to the Internet will reach 50 billion by 2025.
Finding additional spectrum resources in the millimeter wave band for 5G is one of the important topics of the WRC-19 conference. The topic of 1.13 specially set by the conference is to fully explore this new continent and find new frequency bands for 5G in several candidate frequency bands in the frequency range of 24.25GHz-86GHz. However, in the frequency range of 24.25GHz-86GHz, there are also multiple radio services such as satellite communications, earth resources and climate change monitoring, and radio astronomy. To this end, the task of this topic also includes, on the basis of carrying out compatibility studies, amending relevant international rules or formulating protective measures to avoid interference between 5G services and the above-mentioned radio services, and to create a harmonious coexistence and common development of wireless service ecosystems. .
Whether it is the determination of the 5G millimeter wave frequency band, the modification of international regulations, or the formulation of protection measures, the results will have a profound impact on the trillion-dollar information and communication technology industry. “Therefore, at the WRC-19 conference, the 5G millimeter wave issue is the top priority of the world and international organizations, and it has also become the main battlefield for their debate.” Wang Tan said.
The battle of three focal points decides where to go in the future
After the exchanges, discussions and consultations of several special meetings in the first week of the conference, the participants basically reached a consensus on the identification of all or part of the 26GHz, 40GHz and 66GHz-71GHz frequency bands, but the focus of the debate was mainly on these three frequency bands. On the conditions of use.
Focus 1: 26GHz frequency band: Is the out-of-band radio frequency limit wide or strict? “Among the more than ten candidate frequency bands, the 26GHz frequency band (24.25GHz-27.5GHz) has the advantages of low frequency, large bandwidth, and relatively little difficulty in equipment implementation. It is the’sweet pastry’ that the global 5G industry is striving for. Although the world A consensus has been reached on this frequency band, but since this frequency band is adjacent to the satellite earth exploration service (passive service), it may cause interference to him, so the industry hopes to reduce the possibility of interference through technical means.” Wang Tan said. “This is a lumped interference scenario. The satellite system is deployed in the sky. That is to say, only after the large-scale deployment of 5G base stations around the world can we verify its substantial impact on the satellite system.” Wang Tan further introduced that it is currently difficult to resemble ground stations. Similarly, a small number of interference tests between stations can only be used to calculate the out-of-band useless radio frequency limit of 5G base stations through theoretical simulation. Due to different calculation methods and different research results, coupled with differences in the development strategies of related industries in various countries, there are big differences in the limits of the out-of-band useless radio frequency of 5G base stations.
“The larger the limit, the more lenient. The smaller the limit, the stricter the technical indicators.” Wang Tan explained. Through a large number of meticulous research conclusions, my country shows that based on the basic assumptions and simulation conditions recommended by ITU-R, it is necessary to appropriately tighten the out-of-band indicators of existing IMT base stations and terminals; The beamforming effect of the final adjacent frequency band can be reduced appropriately. In addition, there is another important difference in the 26GHz frequency band, that is, in order to protect the in-band fixed-satellite services and inter-satellite services, it may be necessary to limit the deployment of 5G base stations and the in-band radio frequency indicators.
Focus 2: 40GHz frequency band: Is the identification of all frequency bands or some frequency bands clear? The 40GHz frequency band (37 GHz-43.5GHz) is also the potential frequency band of IMT that countries all over the world pay attention to. This part of the spectrum is subdivided into three continuous frequency bands, 37 GHz-40.5 GHz, 40.5 GHz-42.5 GHz, and 42.5 GHz-43.5 GHz. Unlike the technical differences in the 26GHz frequency band, the focus of the debate around the 40GHz frequency band is whether to identify all three frequency bands for IMT, or to clarify only one of them? Our country’s view is to mark part of it for IMT. “Wang Tan said, “China hopes that the space and terrestrial industries will develop in a balanced manner. While promoting the development of 5G, it is equally important to give space to the satellite industry and to protect the normal operation of other radio services. “
Focus 3: 66GHz-71GHz: for IMT or for wireless LAN? Prior to the 66GHz-71GHz frequency band, mobile services have been the main division, and whether it is used for 5G is still under debate. “Actually, 5G and wireless LAN are two different technologies. Experience shows that the usage scenarios of the two are relatively close, and it may be difficult to share the same frequency.” Wang Tan explained, “In order to further accelerate the development of the 5G industry, my country believes that 66GHz should be used. The -71GHz frequency band is used for 5G, and the issue of sharing 5G and wireless LAN technologies is not emphasized at this stage, so as to release enough signals for the global 5G industry.”
5G millimeter wave frequency band logo forms a global solution
At WRC-19, after several weeks of intense exchanges, discussions, consultations, and compromises, until the night before the closing ceremony, representatives of various countries finally reached a consensus on the use of 5G millimeter wave spectrum and determined 24.25 GHz-27.5 GHz, 37 GHz-43.5 GHz or part of it, 66 GHz-71 GHz is the 5G global unified working frequency band. Wang Tan said, “A large number of millimeter-wave spectrum resources with continuous bandwidth will provide effective support for the large-scale application of 5G technology in corresponding scenarios, and lay the foundation for the mature development of 5G-related industry chains, thereby accelerating the pace of global 5G system deployment and commercialization. “
Wang Tan further explained that in the 24.25 GHz-27.5 GHz frequency band, in order to promote the coordinated development of 5G technology applications and existing radio services, the conference adopted a “two-step” plan: by September 1, 2027 at the latest, considering 5G millimeters For the realization of the wave industry, the 5G system out-of-band radiation limit can be relatively loose; but after September 1, 2027, the 5G system out-of-band limit must adopt a strict limit to protect the satellite earth exploration in adjacent frequency bands as much as possible (no Source), radio astronomy and other existing radio services. At the same time, the conference also requested the relevant study groups of the ITU Radiocommunication Sector (ITU-R) to follow up on changes in IMT technical characteristics in a timely manner, and continue to evaluate the possible impact of these changes on space stations, so as to take action when necessary.
In the 37 GHz-43.5 GHz frequency band, the conference has added a footnote to the allocation table of this frequency band: Each region and country can use the entire frequency band or part of it for IMT, but the fixed-satellite service (FSS) application of this frequency band should be taken into consideration. possible.
In the 66GHz-71GHz frequency band, which is also stalemate in the debate, Region 1 (Arab countries, Africa, Europe, CIS countries) and Region 3 (countries in Asia and the Pacific) are the first to reach unification and support the identification of this frequency band for 5G. After intense internal discussions in Region 2 (the Americas), it finally reached an agreement to add a footnote. So far, 5G has achieved a unified global identification in this frequency band.
While the frequency is being determined, standard work is advancing simultaneously. It is reported that the ITU-R working group responsible for IMT-2020 or 5G (WP5D) is carrying out 5G candidate technology evaluation work to ensure that existing candidate technologies can meet the performance requirements of 5G networks. The evaluation work will be completed in early February 2020, after which the global 5G technology standardization work will also be completed. At that time, 5G technical standards will support all 5G application scenarios.
Committed to 5G frequency research to promote the leapfrog development of global communications
Wang Tan joined the center after graduating from Beijing University of Posts and Telecommunications in 2012 with a doctorate degree. From the beginning, he was actively involved in the frequency research of China’s fourth-generation mobile communication system (4G). In the past few years, from software simulation to hardware testing, from frequency planning to licensing, and research support for re-cultivation, he has always contributed to my country’s 4G commercial use.
Since the world entered the 5G era in early 2013, Wang Tan has been actively engaged in 5G research. Under the guidance of the Ministry of Radio Administration and Information and Communication Development Department and other related departments, with the strong support and participation of the industry and related institutions, relying on China IMT-2020 (5G) Promotion Group Spectrum Working Group, WRC-19 Conference 5G Millimeter Wave Issue (1.13 Issue), National Science and Technology Major Project “IMT-2020 Candidate Frequency Band Analysis and Evaluation” and other channels have established bridges and bonds with relevant parties , Carried out the frequency research work of 5G millimeter wave in all directions. He has also successfully served as the chairman of the report group of the ITU 1.13 topic ad hoc group TG5/1 working group on the 26GHz frequency band. He led the completion of the compatibility analysis of the 5G system and other radio services in the 26GHz and other frequency bands, and achieved the results of synchronization with the world and leading the world. In recent years, Wang Tan has participated in coordinating my country’s cumulative output of more than 50 5G frequency-related manuscripts to ITU and the Asia-Pacific Telecommunications Organization, making unremitting efforts for the harmonization of 5G millimeter wave global frequencies and the proper protection of existing services.
“Frequency planning research work is like running a marathon, four years of research cycle, four weeks of meetings, close to the door for nearly 40 hours, finally got results that satisfy all parties,” Wang Tan said. Now that the conference has ended smoothly, looking back at this one-month conference, topic 1.13 can be said to be the topic with the most meetings, the most controversy, and the longest time span. Before and during the conference, the views of major regional organizations and major powers frequently collided, refused to give up and did not compromise. In the middle and late stages of the conference, as the main representative of China, he single-handedly participated in the close meeting of the six major telecommunications regional organizations on 1.13 for nearly a week and argued for reasons. The conference has only 3 seats for each regional organization. The final “global combination plan” for each frequency band of 1.13 was closed and the discussion was extremely intense. At the final stage of the conference, he also participated as a representative of China in the final rounds of large-scale coordination meetings personally chaired by the chairman of the conference. He actively voiced coordination for the realization of my country’s rights and interests, and achieved results that were recognized by all parties. At the last moment of the conference, in order to escort the result to be passed, he persisted until the last moment of the plenary session…
Behind the role of the great power of the Chinese delegation returning from WRC-19 are the heroes behind the scenes who are as deeply rooted in the soul, hidden in the blood, and cast in the bone marrow like him.