5G without "it" is like building a house without land

As a city's population continues to grow, it needs to build more houses. The biggest problem it faces is the limited land available for building houses. The solution to this problem is nothing more than opening up new construction land and optimizing existing construction land. The development of mobile communications is similar. Radio frequencies, like land, carry the construction of mobile communication buildings. The first problem faced by each new generation of communication technology in commercial use is the scarcity of available radio frequencies. Therefore, the development of the industry is also accompanied by the process of constantly opening up new spectrum and optimizing existing spectrum. The current development of 5G is more prominent.

This week, the biggest event in the industry is the Mobile World Congress (MWC) held in Shanghai. Due to the epidemic, this event with the greatest influence on the global ICT industry was cancelled in 2020. This re-launch also gave the global 5G industry a stage to showcase the achievements that have been kept in the box for more than a year, including the achievements in the use of radio frequencies for 5G construction. Of course, the focus of the achievements is still on opening up new "land" and optimizing existing "land".

Millimeter wave is the only choice to open up new "land"

A highlight of this MWC is the 5G millimeter wave exhibition area, which is hosted by China Unicom and GSMA, supported by Qualcomm, and jointly participated by 39 companies including ZTE, Huawei, OPPO, and Purple Mountain Laboratory.

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As we all know, the current main force of my country's 5G network construction is in the mid-frequency band, namely China Mobile's 2.6G+4.9Ghz, China Telecom and China Unicom's 3.5Ghz. This year, China Radio and Television will start 5G network construction on the 700MHz frequency band, and the mid- and low-frequency networking pattern has been formed. However, even if the radio management department has more sophisticated means of maneuvering, it cannot change the current situation of limited number of mid- and low-frequency bands, so it is a must to move towards the undeveloped and resource-rich millimeter wave band. Just as an old city has only limited housing construction area, to build new houses, city managers need to develop land in the new city.

Although the spectrum efficiency of 5G has been improved several times compared with 4G, more frequency resources are still needed to achieve the KPI set by 5G, especially the goals of high speed, large bandwidth and low latency of 5G. Operators have limited frequency bandwidth in the mid-frequency band. For example, China Telecom and China Unicom have 100MHz in the 3400-3500Mhz and 3500-3600Mhz bands respectively. After the two parties jointly build and share, they only have 200M bandwidth through frequency sharing; China Mobile has 160M bandwidth in the 2515-2675Mhz band and 100M bandwidth in the 4800-4900Mhz band, and it is not continuous bandwidth; although China Radio and Television has the 700MHz golden band, it only has 60M bandwidth resources in this band.

Obviously, the current status of low- and medium-frequency bandwidth resources cannot meet the requirements of 5G key performance indicators. 5G needs to achieve a peak rate of tens of Gbps, an experience rate of 100Mbps-1Gbps, a traffic density of tens of Tbps per square kilometer, and a minimum air interface latency of 1 millisecond. These KPIs cannot be achieved by technology alone, and more frequency bandwidth resources are needed. Just as a city's population is in a period of rapid growth, simply increasing the number of floors per unit area on the existing building land is far from meeting the population's housing needs, and more land supply is still needed.

As early as March 2020, the Ministry of Industry and Information Technology issued the "Notice on Promoting the Accelerated Development of 5G", proposing to release the frequency use plan of some 5G millimeter wave bands in a timely manner, organize millimeter wave equipment and performance testing in combination with the national frequency planning schedule, and prepare for the commercial use of 5G millimeter wave technology. In its research report "5G Millimeter Wave Opportunities in China", GSMA proposed that for millimeter wave spectrum, Chinese regulators should consider allocating continuous spectrum of about 1 GHz bandwidth to each operator to support the additional needs of data-intensive applications.

In terms of the economic contribution of millimeter wave, GSMA predicts that by 2034, the economic benefits brought by the use of millimeter wave bands in China will have an effect of approximately US$104 billion, which is about half of the estimated contribution of millimeter wave bands in the Asia-Pacific region.

Economic contribution of 5G millimeter wave in Asia-Pacific countries in 2034 (Unit: billion US dollars, source: GSMA)

Considering the expected contribution of 5G mmWave to China's GDP, the vertical industry sectors of manufacturing and utilities such as water and electricity are the industries with the largest visible contributions, accounting for 62% of the total contribution; followed by professional services and financial services, accounting for 12%; and information communication and trade accounted for 10%. Given China's importance in the global manufacturing industry, the dominance of manufacturing in China's GDP is expected. As the use of 5G mmWave continues to grow, this economic advantage, coupled with the numerous potential industrial applications of 5G mmWave, will contribute to the significant impact of vertical industries on GDP.

China's 5G millimeter wave economic contribution to vertical industries (Source: GSMA)

Millimeter waves have made significant economic contributions, and with 5G officially commercialized for more than a year, infrastructure construction and application implementation accelerating, the industry is increasingly calling for the commercialization of 5G millimeter waves. All parties at this MWC once again expressed this view, including millimeter wave efficiency improvements and a mature industry chain.

Large-scale sports events are not only a showcase for new technologies, but also a parade ground. The 2022 Winter Olympics may be a good opportunity for the commercial use of 5G millimeter waves. During the Winter Olympics, spectators, media broadcasters, event organizers and participants will experience the "Technology Winter Olympics" through 5G. According to information disclosed by China Unicom, 5G+8K broadcast-level video uplink and downlink transmission, 5G mixed reality smart ski resorts, and 5G free-viewpoint event live broadcasts have been planned. By then, high-definition video broadcasting and photography, 360-degree panoramic views, AR/VR, and venue AI video surveillance will be implemented. These scenarios cannot be supported by medium and low frequencies alone, and millimeter waves must play a role.

For 5G, opening up new "land" currently focuses on developing millimeter waves and giving full play to their performance.

Optimizing existing “land use”, spectrum pooling sees new progress

In the previous development of mobile communications, the industry has long been aware of the drawbacks of discontinuous and fragmented spectrum resources. Therefore, it will promote the optimization of existing spectrum resources through various technical and market means, so that the spectrum resources between different operators and different networks within the same operator can form a "pooled" resource, forming a 1+1>2 effect.

In the past few years, global operators have been gradually promoting 2G/3G frequency reduction and network withdrawal, freeing up spectrum resources for 4G and IoT, or re-cultivating some 4G frequency bands for 5G. This is a typical practice of optimizing the existing "land use". For example, China Telecom launched the 800MHz frequency re-cultivation in 2016, and the CDMA network that originally occupied 800MHz was withdrawn. In 2017, a 4G network was built in this frequency band, and on this basis, it was quickly upgraded to build the world's largest NB-IoT network; for another example, China Mobile currently has 5G resources in the 2.6GHz frequency band, of which the 2575-2635MHz frequency band is the re-cultivation of China Mobile's existing 4G frequency band.

In addition, technological progress is also the main means of optimizing the existing "land use". For example, as early as the 4G era, spectrum sharing technology was put on the agenda, such as the sharing of static spectrum of 3G/4G networks in some ranges. In the 5G era, dynamic spectrum sharing (DSS) is given an important position. 5G networks can expand their spectrum usage range to some 4G low-frequency bands, achieve wide coverage, and facilitate the smooth evolution of 4G to 5G. At present, operators around the world have started commercial use of 4G/5G dynamic spectrum sharing. For example, Vodafone and Swisscom use dynamic spectrum sharing technology to build 5G networks.

During this MWC conference, another highlight was the joint release of Super Frequency Fusion Technology by China Telecom and Huawei. This technology uses spectrum pooling to achieve a new spectrum fusion technology that transforms discrete spectrum from simple aggregation to fusion and flexible scheduling between spectrums, thus improving resource efficiency. If millimeter wave is the core direction of opening up new "land use", Super Frequency Fusion Technology is the latest achievement in optimizing existing "land use", especially the optimization of existing medium and low frequency resources.

Source: China Telecom

When introducing the super frequency fusion technology, Peng Honghua, president of Huawei's 5G product line, pointed out that the use of discrete spectrum requires innovation in hardware and software solutions on the network side. In terms of hardware, base station equipment needs to have multi-band and large bandwidth capabilities. In terms of software functions, it is necessary to innovate minimalist control channels and uplink/downlink spectrum pooling and unified scheduling functions to provide a more extreme 5G network experience and support the long-term development of 5G.

Super frequency fusion technology solves the problem of frequency fragmentation and discretization. Zhang Xin, general manager of China Telecom's 5G co-construction and sharing working group, mentioned that in addition to the mainstream 5G frequency bands of operators, commercial terminals will support 5G in the 1.8GHz and 2.1GHz frequency bands with a cell bandwidth greater than 20M in 2021. In addition, in the Sub 1GHz spectrum, China Telecom only has 11M bandwidth in the 800MHz and 900MHz bands. It can be seen that these resources are scattered in different frequency bands, and the bandwidth of the spectrum resources in each frequency band is not large. If there is no corresponding technology, it will form a situation of "tasteless to eat and a pity to abandon". Super frequency fusion technology aggregates discrete and fragmented frequencies to form a frequency band similar to a continuous large bandwidth, which can indeed provide substantial support for 5G networking.

In my opinion, spectrum refarming, spectrum sharing, and super frequency fusion are all means to optimize existing spectrum resources, but compared with previous means, super frequency fusion is obviously a revolutionary improvement. The example of building a house may not be very appropriate, but it is quite vivid:

• Spectrum refarming is similar to demolishing a house on a piece of land and then replanning and building a new one. To a certain extent, it releases a relatively large area of ​​land and has more room for operation.
• Spectrum sharing can perhaps be compared to the re-allocation of existing housing stock, just as some real estate agents are promoting the matching of housing supply and demand, or optimizing the allocation of public housing through overall planning;
• Super frequency fusion is similar to facing unused land on stock building land. These unused parts are very scattered and fragmented, and each area is very small, such as public areas in some communities, idle passages, corners left when building houses, etc. These places are often only a few square meters each, and it is almost impossible to fully utilize them to build habitable residences. In some cases, super frequency fusion is similar to these fragmented "land". Of course, housing is a physical entity and cannot be integrated by physical means. Super frequency fusion can use virtualization technology to integrate these scattered physical radio frequency resources into continuous frequency bands. From this perspective, it is indeed a revolutionary improvement.

Just like land resources, radio frequencies are also non-renewable resources. With the intergenerational advancement of mobile communication technology, more radio frequency resources are constantly being occupied, while frequency utilization efficiency is also being continuously improved to optimize the existing frequency space. No matter how fast 5G develops, radio frequencies will always be the basic resources for carrying 5G communications. We look forward to more frequency development and optimization technologies, business models, and mature applications of industrial ecology.