The 700Mhz frequency band has the characteristics of wide coverage, strong penetration, and low networking cost, so it is also called the golden frequency band. A few days ago, China Mobile and China Radio and Television officially released the results of centralized procurement of 5G 700M base station and antenna products, and the curtain of my country’s 5G 700M large-scale construction has also officially opened.
In China, no frequency band has attracted as much attention as 700Mhz. According to the plan of China Mobile and China Radio and Television to jointly build and share 5G network, China Radio and Television and China Mobile will complete the deployment of 400,000 stations with 700MHz within the year in 2021; in the first half of 2022, it plans to open 480,000 stations and fully support 5G broadcasting services; within two years To achieve full network coverage, however, in addition to frequency clearing work, 5G 700MHz also faces many challenges in terms of technology and coverage.
Clear frequency needs to be accelerated
The 700MHz frequency band specified by the 3GPP standard was originally a radio and television frequency band. Therefore, 700MHz migration is an important basic condition for 5G network construction and operation.
For the construction of 5G 700MHz network, China Radio and Television has also officially launched frequency clearing work. On July 5th, following the failure of the first tender, China Radio and Television launched the general contracting (EPC) (second) tender for the national terrestrial digital TV 700MHz frequency migration project. The tender project involved a total of 6,026 stations and 12,350 channels. The budget amount is still 1.8 billion yuan. The second frequency-clearing bidding is planned to announce the bidding results on July 26.
The work of frequency clearing is heavy and difficult. Some high-power broadcasting towers still occupy important frequency resources. The clearing work will inevitably bring about great changes in ground analog and ground digital transmitters. Undoubtedly, the previous 700MHz frequency migration project failed to bid because the number of valid bidders was less than 3, which to some extent explained the complexity of the 700MHz frequency clearing work.
In May of this year, during the 2021 China International Radio and Television Information Network Exhibition, Song Qizhu, chairman of China Radio and Television, pointed out that China Radio and Television has signed a co-construction and sharing agreement with China Mobile, formulated a construction plan to achieve full network coverage within two years, and completed the equipment. model selection and technical testing, the construction of the 5G 700MHz network of radio and television is being promoted as planned, and the “construction and operation” plan is being refined and improved, and the No. 192 section will be implemented in an orderly manner for commercial use nationwide.
Relevant persons in the radio and television industry have pointed out that with the help of China Mobile’s rich network construction experience, once the network construction starts, the two parties only need to proceed according to the plan and will not encounter too many difficulties. What affects the final commercial time point of the 700MHz network is the frequency migration work of the radio and television itself. 700M frequency clearing is to realize the business migration of terrestrial analog TV and terrestrial digital TV broadcast in the 700M frequency band.
It is worth noting that a few days ago, the “5G Application “Sailing” Action Plan (2021-2023)” clearly pointed out that the 5G frequency resource guarantee should be strengthened. Continue to do a good job in the interference coordination of radio stations such as 5G base stations and satellite earth stations. Promote the frequency migration of radio and television services in the 700MHz band, and accelerate the deployment of 5G networks in the 700MHz band.
Therefore, for radio, television and mobile, there are still digital broadcasts in some frequency bands of 700MHz, and frequency cannot be cleared in a short time. Therefore, for the deployment of 700MHz NR, it is still necessary to consider the inter-system interference with broadcasting towers. .
Capacity issues come to the fore
As we all know, the higher the frequency of 5G, the higher the peak rate it can provide, but the opposite is the worse the coverage effect. Therefore, the coverage of 700MHz is excellent, and its coverage radius is about 3- of the 2.6GHz band. 4 times, and the coverage area is 10 times that of the 2.6GHz frequency band. According to reports, using the 700M frequency band, it only needs to build 450,000 to 500,000 base stations to achieve 5G network coverage across the country.
However, due to the low frequency of 700M, the wavelength is relatively large, so that the size of the required antenna element must be correspondingly larger when the signal is sent or received, and in terms of available bandwidth, the available bandwidth of 700M is compared to 2.6GHz. , 3.5GHz is much smaller, which makes the problem of insufficient capacity even more serious.
In this regard, in April last year, the Ministry of Industry and Information Technology officially issued the “Notice on Adjusting the Frequency Use Planning of the 700MHz Band” to use the 703-743MHz and 758-798MHz frequency bands for FDD (Frequency Division Multiplexing) duplex communication in the 5G system, the uplink , each has a bandwidth of 40MHz in the downlink, and two-way simultaneous communication without mutual interference improves the system capacity of the 5G network and the coverage of a single base station. Therefore, in actual use, operators combine the advantages of the 5G TDD system. Among them, 2.6G or 3.5G carriers mainly focus on downlink capacity, while 700M supplements downlink capacity, it mainly focuses on uplink coverage, and optimizes the shortcomings of insufficient 700M bandwidth.
In terms of the number of base stations, 700MHz NR has the characteristics of short construction period and large number of constructions in China. It needs to complete the construction of 480,000 stations in a short time, and has high requirements for construction rhythm and supply speed.
In this regard, some experts suggested that in the initial stage of network construction of 700MHz NR network, a different network roaming scheme should be adopted, and only the core networks of China Mobile and China Radio and Television should be connected. In the second stage, after the 700MHz NR scale network is formed, the access network sharing scheme is adopted, and China Mobile independently builds the transmission network, which is connected to the core network nodes of China Mobile and China Radio and Television respectively.
In terms of equipment, although 700MHz has been accumulated in the industry chain in the 4G era, the 700MHz NR networks that have been commercialized abroad are mostly 2*10M and 2*20M bandwidth, mainly 2T2R and 2T4R equipment, while domestic 5G 700MHz is 2*10M and 2*20M. *30MHz large bandwidth is used as the deployment standard, and 4T4R is used as the product standard. The innovation of product technology also brings new challenges to equipment manufacturers.
Taking CITIC Mobile as an example, CITIC Mobile uses service channel wireless detection technology combined with flexible configuration of control channel resources to ensure site performance, speed up the pace of 700M construction, reduce the number of stations, and ensure that 700M construction sites should be fully opened. The frequency domain position of the common control channel can be flexibly configured to ensure that users can access the 700M network normally.
Industry experts also pointed out that if 700MHz can obtain more bandwidth for the deployment of 5G, it will better achieve low-cost and wide coverage of 700MHz NR.
Give full play to the “golden frequency band” to accelerate application empowerment
As a leading technology in the new generation of information and communication technology, 5G is a key new infrastructure that enables the digital economy. In the two years since the commercial use, the number of 5G base stations in my country has exceeded 900,000, and the number of 5G terminal connections has exceeded 330 million. It has accelerated from network construction to a new stage of application innovation.
Coverage is not the purpose, the application is the core. Obviously, the iterative development of technology is to better support the industry. It is necessary to focus on the actual needs of the industry, implement reality, and base on the needs of the industry and the public to iteratively develop 5G technology to realize the interconnection of everything. 700MHz will play a great role in network traffic migration, 5G user experience improvement, and empowerment of thousands of industries.
“The deployment of 700MHz will quickly cooperate with 2.6GHz to form a large-scale continuous coverage this year, and the expansion of the coverage area will help 5G empower thousands of industries.” Regarding the co-construction and sharing of China Mobile and China Radio and Television, CITIC Mobile operator Deng Hongwei, president of the network product line, pointed out that the co-construction and sharing of the 700MHz high-quality frequency band will help the golden frequency band to play the greatest role, and it will help the two operators, China Mobile and China Radio and Television, to launch high-quality 5G services, which can effectively help the construction of the 5G industry and promote 5G. The business is developing rapidly and blooming everywhere. The implementation of the joint construction and sharing between China Mobile and China Radio and Television can achieve a win-win situation.
At present, my country’s 5G development has entered a “no man’s land”, and there is no mature international experience in technology, industry, and application to learn from. Demand continues to rise. Under the effect of cost effects, equipment manufacturers’ base station manufacturing costs continue to decrease, achieving a win-win situation for operators and equipment manufacturers. At that time, as a channel connecting all things in society, how to make the “channel” of 5G maximized Its value capability will also attract continuous exploration by all parties in the industry chain, forming a favorable situation for the accelerated development of digital transformation and upgrading in various industries.
Source: Communication Industry Network
Author: Dang Bowen