How to resolve the conflict between 5G intermediate frequency and satellite C band?

At present, various regions continue to accelerate the construction of 5G networks. Since the 5G mid-band is similar to or the same as the satellite communication C-band frequency, relevant departments have also actively promoted the improvement of the coordination mechanism of relevant operators in the long run to meet the actual needs of all parties. Anhui recently announced some coordination measures since the start of 5G deployment.

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In order to properly solve the interference problem of 5G mid-frequency band base stations on satellite earth stations, in May 2019, the Ministry of Industry and Information Technology issued the 5G Interference Coordination Management Regulations, the 5G Interference Coordination Work Guidelines and other documents, requiring radio management agencies to strengthen overall coordination and adopt various equipment technical modifications such as adding filters to satellite earth stations to eliminate or reduce the impact of interference.

Among the 5G frequency licenses issued by the Ministry of Industry and Information Technology to the three major basic telecommunications operators, China Telecom and China Unicom can use the 3400-3600MHz (i.e. 5G mid-band) frequency band to jointly build and share 5G networks, but the 5G mid-band is adjacent to or co-frequency with the satellite communication C-band (generally 3700-4200 MHz, and the extended band uses 3400-4200MHz). The C-band has long been widely used for data transmission by satellite earth stations in radio, television, meteorology, banking, securities, and news publishing. For example, the C-band satellite earth station is one of the main signal sources for radio and television programs.

With the full deployment of 5G construction, the co-frequency or adjacent frequency interference caused by mid-frequency 5G base stations to C-band satellite earth stations is inevitable. If the 5G mid-frequency interference problem cannot be solved in a timely, proper and effective manner, it will not only seriously affect radio and television broadcasting, as well as the business work of important departments such as news publishing and finance, but will also greatly delay the progress of 5G construction and delay the strategic layout of "new infrastructure".

Since 2019, the Anhui Provincial Department of Economics and Information Technology has guided radio management agencies to formulate the following measures:

First, a list was drawn up. In 2019, the Anhui Provincial Department of Economics and Information Technology took the lead in organizing a cleanup and inspection of the province's C-band satellite earth stations, and took the lead in establishing a provincial 5G mid-band satellite earth station protection list in the country. A total of 585 earth stations from departments such as radio and television, meteorology, securities, banks, and the Anhui branch of Xinhua News Agency were included in the protection list. Satellite earth stations included in the list are "protected by listing", and the establishment of the list also provides a reliable basis for interference coordination.

The second is to establish a mechanism. Anhui has convened two special coordination meetings with telecommunications operators and satellite earth station installation and use departments to identify coordinators and contacts and establish a regular 5G interference rapid coordination and disposal mechanism. The radio management offices of various cities have also taken the lead in establishing local interference coordination mechanisms.

The third is monthly scheduling. Since September 2019, the "two tables and one list" for 5G interference coordination have been established: the "5G base station construction schedule", the "5G interference coordination schedule", and the "satellite earth station protection list". The province's 5G interference coordination work is scheduled on a monthly basis and supervised by a chart.

Fourth, focus on key areas. Radio management agencies across the province are required to strengthen spectrum monitoring, formulate emergency response plans, focus on important areas and important time nodes, and quickly check the interference of 5G base stations on satellite earth stations for Anhui Radio and Television Station, the Provincial Department of Civil Affairs, Anhui Branch of Xinhua News Agency and other departments during the 70th anniversary of the founding of the People's Republic of China and the 2020 "Two Sessions", effectively guaranteeing the use of satellite earth stations by key departments and ensuring the safety of important radio services such as radio and television.

Fifth, focus on technical transformation. Starting from December 2019, the Anhui Provincial Department of Economics and Information Technology took the lead in coordinating Anhui Telecom to implement technical transformation of satellite earth stations included in the protection list, and adopted technical means such as installing filters to eliminate 5G interference. As of the end of June 2020, 330 satellite earth stations in the province had completed technical transformation, and the coordinated transformation completion rate reached 70.8%. The coordinated transformation completion rate in key 5G construction areas such as Hefei reached more than 90%.

From the comparison of the situation before and after the technical transformation of satellite earth stations across Anhui Province, the interference caused by 5G base stations has been basically eliminated, the construction and operation of 5G base stations have been smoothly promoted, and the interference coordination effect is significant.

As the pace of 5G construction accelerates, the number of 5G base stations grows rapidly, and the site density continues to increase. Various types of interference related to 5G will occur frequently, and the difficulty of interference coordination and resolution will increase. Therefore, Anhui Province has formulated two routes:

On the one hand, we will earnestly implement the technical transformation of equipment to ensure that the coordination completion rate meets the standard. In the reverse order, we will actively coordinate and urge Anhui Telecom and the satellite earth station installation and use units to support and cooperate with each other to speed up the progress of satellite earth station equipment technical transformation, and ensure that the coordination completion rate of satellite earth stations included in the protection list by the end of the year reaches more than 95%, and that key areas such as Hefei are fully transformed and the coordination completion rate reaches 100%.

On the other hand, we will investigate and punish illegal frequency usage and station installation to ensure 5G radio safety. We will further strengthen the research on 5G interference mechanism technology, carry out 5G spectrum protective monitoring, strengthen the source control of radio transmission equipment production and sales, continue to make efforts, and focus on rectifying illegal frequency usage and station installation that interfere with 5G services, so as to create a good electromagnetic environment for the province's 5G construction and add strength and empowerment.