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Why should China develop 5g millimeter wave when sub-6ghz network is fully launched?

Release date:2021-12-28Author source:KinghelmViews:483

The global 5g network frequency band is mainly divided into sub-6ghz frequency band and millimeter wave frequency band. 5g millimeter wave network and sub-6ghz network are not the opposite relationship of "only one of the two can choose", but the complementary relationship of "fish and bear's paw can get both". Countries choose which technical route to take first, which is more based on their own national conditions. After the construction of 5g sub-6ghz network is mature in China, the construction of 5g millimeter wave network has also been put on the agenda.

In March 2020, the Ministry of industry and information technology issued the "notice on promoting the accelerated development of 5g", which clearly mentioned that "timely release the frequency use planning of some 5g millimeter wave bands, organize and carry out millimeter wave equipment and performance testing, and reserve for the commercial use of 5g millimeter wave technology". On April 30, 2021, the Ministry of industry and information technology issued the draft for comments on the 5g application "sailing" action plan (2021-2023) (hereinafter referred to as the "draft"), which proposed that by 2023, the penetration rate of 5g individual users in China will exceed 40% and the number of users will exceed 560 million. At the same time, the draft proposed to "timely release the 5g millimeter wave frequency planning, explore the 5g millimeter wave frequency use license, and implement the bidding system". This also means that after the 5g sub-6ghz network is fully launched in China, the construction of 5g millimeter wave in China is about to set sail. In addition, Tian Yulong, chief engineer of the Ministry of industry and information technology, when talking about promoting the high-quality development of the information and communication industry at the press conference of the state information office in March, stressed that "we will orderly promote the construction of 5g network and accelerate the layout of 6G".

5g millimeter wave and sub-6ghz are complementary

Millimeter wave refers to electromagnetic wave with wavelength of 1mm to 10mm and frequency of 30ghz to 300GHZ. In the field of mobile communication, 24ghz-100ghz electromagnetic wave is usually called millimeter wave.

In 2019, the world radiocommunication Conference (wrc-19) of the International Telecommunication Union (ITU) has determined that the millimeter wave band between 24GHz and 86ghz will be used for international mobile communication (IMT), of which 24.25-27.5ghz, 37-43.5ghz and 66-71ghz bands are IMT bands with global integration.

Compared with the 5g system of sub-6ghz (frequency band below 6GHz), 5g millimeter wave communication has a large bandwidth from 24GHz to 100GHz, which makes it have unique advantages such as higher rate, lower delay and flexible elastic air interface configuration, and can effectively meet the requirements of future wireless communication for system capacity, transmission rate and differentiated applications.

For example, in terms of transmission rate, Okla's latest analysis based on a large number of measured data from its Speedtest application shows that the 5g millimeter wave band can reach 16 times that of the sub-6ghz band.

Secondly, 5g uses two dimensions of subcarrier and time slot to transmit data together. Millimeter wave has the characteristics of high bandwidth, large subcarrier interval and small corresponding time slot, which also makes 5g millimeter wave delay only about 25% of sub-6ghz band; Similarly, because millimeter wave has greater available bandwidth and higher transmission rate, it can also provide greater capacity to meet a wider range of terminal access.

In addition, the higher downlink rate of 5g millimeter wave can support intensive spatial reuse while reducing interference, and can better solve the congestion problem of a large number of users accessing the Internet in the same area at the same time. It is especially suitable for applications in densely populated scenes such as stations, airports and stadiums.

In relevant industry application fields, such as ultra-high definition video live broadcast, security monitoring, telemedicine and some industrial applications, which have high requirements for upload rate and low delay, the characteristics of 5g millimeter wave large uplink and lower delay can better meet these requirements.

In particular, 5g millimeter wave network can realize self return without the connection between optical fiber network and core network. The 5g network based on sub-6ghz still depends on the traditional optical fiber return scheme, that is, each 5g base station and the core network need to be connected through optical fiber, which also increases the deployment cost. 5g millimeter wave IAB (integrated access and backhaul) technology can support 5g millimeter wave base stations to use other 5g millimeter wave base stations as relay nodes and finally transmit back to the core network in the form of wireless transmission through multi hop function, which will greatly save the deployment cost. This also enables 5g millimeter wave base stations to support more cost-effective intensive deployment.


In addition, millimeter wave technology can also be applied to 5g Internet of vehicles (v2x) to provide positioning services far exceeding the accuracy of GPS and LTE (the accuracy can reach sub meter level).

Ma Hongbing, general manager of science and technology innovation Department of China Unicom, introduced: "by combining 5g millimeter wave with MEC and AI technology, millimeter wave can provide customized private network services for target customers and can be widely used in smart factory, smart Park, smart wharf and other scenarios."

Although millimeter wave has more advantages in speed and time delay than sub-6ghz band, it also has its limitations, such as easy signal attenuation, poor penetration and easy to be blocked; Although there are beam forming, beam tracking and other technologies that can solve these problems well. However, sub-6ghz band still has greater advantages in coverage and deployment cost.

In a word, the deployment of 5g millimeter wave network and sub-6ghz network is not a competitive and alternative relationship, but a complementary relationship. Use sub-6ghz to realize 5g wide coverage, and use millimeter wave system to realize indoor venues (sports events, concerts, large conferences), transportation hubs (subway stations, high-speed railway stations) and office area coverage, as well as outdoor hot spot coverage, wireless broadband access, etc. The coordinated deployment of millimeter wave and sub-6ghz can realize the organic combination of large capacity and wide coverage.

The preliminary preparations for China's 5g millimeter wave deployment have already begun and are progressing smoothly

If the sub-6ghz network solves the problem of 5g coverage, the 5g millimeter wave network can give full play to the advantages of 5g to release greater value.

Meng Pu, chairman of Qualcomm China, also said: "To achieve the original design goal of 5g, we need to use all spectrum resources. The low and medium frequency band of sub-6ghz can achieve the balance of coverage, capacity and performance, while the high-frequency millimeter wave above 24GHz can support the ultimate 5g performance and capacity, bring the next-generation wireless connection experience to many scenes and industries, and bring ultra reliable and low delay to vertical fields such as industrial Internet "Mobile communications."

According to the white paper on 5g millimeter wave technology released by GSMA last September, 5g millimeter wave will contribute US $565 billion to global GDP by 2035. Among them, before 2034, the direct economic benefits from the use of 5g millimeter wave band in China will reach about US $104 billion.

At present, 5g millimeter wave deployment has been carried out in the United States, Japan, Europe and Southeast Asia. According to the data released by GSA in March this year, more than 150 operators around the world are investing in 5g millimeter wave technology.


According to the 5g millimeter wave test plan of China imt-2020 (5g) promotion group, millimeter wave testing has been started in 2019 to verify the key technologies and system characteristics of 5g millimeter wave; From 2020, further verify the function, performance and interoperability of millimeter wave base stations and terminals, and carry out high and low frequency collaborative networking verification; At the same time, China imt-2020 (5g) promotion team also carried out typical scenario verification in due time.

In October 2019, under the organization of imt-2020 (5g) promotion group, ZTE and Qualcomm realized China's first 5g millimeter wave interoperability test (iodt) based on smart phones. Two months after the new millimeter wave MIMO OTA test method was defined in the 3GPP rel-16 version released in early July 2020, at the end of September, under the organization of the imt-2020 (5g) promotion group, Qualcomm took the lead in completing the millimeter wave performance test based on the 3GPP rel-16 MIMO OTA test method in the MTNet Laboratory of the Academy of communications and communications. So far, Qualcomm has become the first chip manufacturer in China to participate in and pass all ten 26ghz 5g millimeter wave RF tests.

While millimeter wave testing is advancing in an orderly manner, the characteristics of chip products are also continuously optimized for China's millimeter wave deployment needs. On May 19, 2021, Qualcomm announced the launch of upgrade features and functions specifically for its world's first 10Gbps 5g modem and RF system, Xiaolong X65, released in February: supporting millimeter wave 200MHz bandwidth and millimeter wave SA mode, so as to meet the key requirements for millimeter wave network deployment in China.

In view of the industrial application scenario of millimeter wave, the upstream and downstream manufacturers of China's millimeter wave industry are making efforts. On May 21, 2021, under the technical guidance of imt-2020 (5g) promotion group and China Unicom, ZTE, China Unicom, Qualcomm and TVU networks successfully completed the world's first 5g millimeter wave 8K video return business demonstration based on large uplink frame structure in the 26ghz (n258) band in the laboratory environment.


In this demonstration, ZTE provided a 5g millimeter wave base station, and the 5g multi network aggregation router of TVU networks realized stable return of 8K video content collected in real time through 5g millimeter wave uplink through 5g millimeter wave connection provided by CPE test terminal equipped with Qualcomm snapdragon x55 5g modem, RF system and Qualcomm qtm527 millimeter wave antenna module, Finally, it is successfully received at the receiving end for playback.

According to the 5g millimeter wave test plan of imt-2020 (5g) promotion group, the millimeter wave large uplink frame structure will be promoted in 2021 to support differentiated application scenarios. The real-time transmission of UHD video, especially 8K video, has very high requirements for the uplink bandwidth of mobile network. The dsuuu frame structure used in this demonstration increases the uplink peak rate of the existing millimeter wave technology to three times by allocating more time slots for the uplink. The demonstration verifies the super uplink capability of 5g millimeter wave, which is of great significance to meet the uplink large bandwidth requirements of many 5g industry applications in the future.

It is worth mentioning that during the MWC Shanghai Exhibition in 2021, the 5g millimeter wave exhibition area hosted by China Unicom and GSMA and supported by Qualcomm comprehensively displayed 5g millimeter wave applications and terminals supported by 39 leading enterprises in the industry, including multi vendor 5g millimeter wave terminal coverage modules, mobile phones, CPE, PC, AR (augmented reality) and XR (extended reality) devices, live backpacks Robots and other rich categories.

Among them, the diversified application scenarios supported by 5g millimeter wave include: athlete competitive experience, 5g mixed reality intelligent snow field, 8K video transmission, 5g full view event service and free view event live broadcast, 5g millimeter wave panoramic experience, etc. Based on the 5g multi angle live broadcast scheme of millimeter wave, the outfield of Zhangjiakou international cross-country skiing center is directly photographed. The UAV, head mounted camera and professional camera communicate with the base station through wireless network, and multi angle real-time return the athletes' heroic posture on the field of the national cross-country skiing center, so as to realize multi angle live broadcast of the field, Provide diversified viewing experience for actual spectators. At present, China Unicom is the only official communication service partner for the 2022 Beijing Winter Olympic Games. The maturity of 5g millimeter wave related terminals and applications will help to provide better 5g services by using millimeter wave technology in the 2022 Beijing Winter Olympic Games.

5g millimeter wave technology is still evolving, or an important part of 6G

At present, millimeter wave technology is still evolving. For example, the integrated access and return (IAB) technology mentioned earlier; There is also broadband positioning technology that can support accurate terminal positioning; Spread spectrum support: support the frequency band above 52.6ghz and the license free spectrum for license assistance and independent operation; Enhanced beam Management: improve time delay, robustness and performance through full beam optimization and multi antenna panel beam support; Dual connection optimization: reduce the initial access delay of the terminal and improve the coverage when connecting multiple nodes; Power saving characteristics: improve power consumption by maximizing terminal sleep period, and support faster link feedback.

The continuous evolution of 5g millimeter wave related technologies will bring new opportunities in function, efficiency, spectrum and deployment. In addition, 5g millimeter wave technology is also expected to become an important part of the next generation 6G technology.

According to the 6G white paper "next generation hyper connectivity experience" released by Samsung last year, the 6G peak rate will reach 1000gbps and the delay will be as low as 100US. It is possible to complete and commercialize as early as 2028, while large-scale commercialization may be realized around 2030. For these key indicators and time nodes, the views of other communication manufacturers are basically the same.

Samsung also proposed candidate technologies that may be used in 6G standard, such as THz terahertz band, new antenna technology to enhance high-frequency signal coverage, advanced duplex technology, development of network topology and spectrum sharing to improve network utilization and AI application.

The simultaneous interpreting of 6G, the unbounded AI, reveals that the core technology of 6G will be diversified, terahertz communication, visible light communication, advanced modulation decoding, and satellite earth collaborative transmission will become the core technology of 6G.


Qualcomm emphasized the innovation of related technologies, such as AI / ml data-driven design, full duplex, millimeter wave of higher frequency band, enhanced positioning, terahertz frequency band, intelligent interface, green network, RF sensing, new topology, extreme decoupling, cloud neural network structure search, ultra secure communication, new sharing paradigm, etc.


It can be seen that many manufacturers believe that terahertz communication technology will be one of the key technologies of 6G communication. The terahertz frequency band usually refers to the frequency band of 300GHZ ~ 10000ghz, and the electromagnetic wave around 300GHZ can also be regarded as the millimeter wave of higher frequency band. Only by mastering millimeter wave communication technology can we have the opportunity to make a breakthrough in terahertz communication technology.

In mid-2020, Yang Tao, vice president of Huawei's China operator business department, also publicly disclosed that Huawei has been participating in the pre research work related to 6G. The pre researched 6G is mainly in millimeter band and is in the stage of scene mining and technology search.

It is worth mentioning that at the end of 2019, the equipment technology laboratory under NTT group of Japan has developed 6G ultra-high speed chip made of indium phosphide (INP) compound semiconductor, and conducted high-speed wireless transmission experiment in 300GHZ band. When 16QAM modulation is adopted, the wireless transmission rate can reach 100gbps. If the combination of spatial multiplexing technologies such as MIMO and OAM is used, it is expected to achieve high-capacity wireless transmission of more than 400gpbs, which is close to the 6G peak rate requirement.

In addition, in order to realize the integrated high-speed communication network of air, earth and sea, the millimeter wave band will also be the first choice for inter satellite links, user links covered by satellites, and feed links from satellites to ground stations.

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