What is 700MHz?
700MHz band is the golden band of wireless frequency, which has been used for broadcasting signals in China before.
On March 25 this year, the Ministry of industry and information technology issued the notice on adjusting the frequency use planning of 700MHz frequency band, re planned part of the spectrum resources originally used for radio and television services for mobile communication systems, and defined the duplex mode of mobile communication systems, radio frequency use licenses, and radio stations (stations) setting use licenses Relevant requirements for the completion of coordination between mobile communication system and existing radio services, etc.
The notice specifies:
take702-798MHzThe frequency band frequency use planning is adjusted for the mobile communication system, and703-743/758-798MHzBand planning is used for mobile communication system with frequency division duplex (FDD) working mode.
Also in March, 3GPP passed the proposal of n28 band spread spectrum, extending 2x20mhz in R15 to that in R162x30MHz/40MHzSo far, 700MHz has become a very important frequency band of 5g.
two 5g has the advantage of 700m
High frequency and low frequency of radio waves are relative concepts. They have different application scenarios due to different transmission characteristics. Generally speaking, the low-frequency signal has long wave length, small radio wave attenuation, easy scattering and diffraction in transmission, which is suitable for network coverage. High frequency signal has many frequency points, high information transmission rate, smaller antenna size, and easy to achieve high-power transmission. According to ITU research, the best spectrum for mobile communication is in the range of 400mhz-6ghz.
Radio high and low frequency signal characteristics
700MHz is the golden band for the development of mobile communication. 700MHz network advantages include:
1、 The coverage is wide, the number of base stations required is small, and the network construction cost is reduced;
2、 Strong diffraction ability, low loss, improve indoor dead angle problem;
3、 High transmission efficiency; It has lower Doppler frequency offset and more reliable signal demodulation.
This is a comparison of the coverage radius of macro stations and the number of base stations required in the same area
To put it simply, 5g base stations are built in the global 3.5GHz frequency band, which requires 15 base stations to fully cover the area, and only two 700MHz 5g base stations.
Radio propagation modes mainly include direct, diffraction (ground wave), refraction and reflection (sky wave) and scattering propagation. In an ideal state (without obstacles), the frequency has no effect on the transmission distance. In practice, signal penetration will lose a lot of energy, resulting in shortened transmission distance and less coverage.
This leads to the key factor determining the propagation characteristics is the frequency and antenna gain. The antenna gain cannot increase infinitely, and the frequency becomes particularly important, which is the treasure of 700m.
Of course, 700MHz is not without disadvantages. For example, in terms of capacity and rate, it is much worse than high frequency, but it can also exceed 180MB, which can actually meet most requirements. In addition, the antenna requirements are relatively large, which is not suitable for small base stations. Finally, there is the problem of interference with broadcast channels in many places.
Using 700MHz combined with high-frequency dual band network is an ideal network layout scheme. The high-frequency band focuses on solving the capacity demand, and 700MHz meets the needs of wide coverage and indoor coverage.
three Current usage of 700MHz
700m frequency band is mainly used for analog television in radio and television, but with the promotion of wired digital, 700m is rarely used. This time, the Ministry of industry and information technology has issued a document requiring frequency clearing for 5g.
From the database information of existing radio and television stations, monitoring results and analog TV coverage published by radio and television, in the 700MHz spectrum of major large and medium-sized cities, the 700MHz frequency band is rarely used, and there are fewer high-power transmitters. Therefore, the difficulty of radio and television frequency clearing is still relatively small.
China Radio and television also has 5g license and led 700m to adopt 2x30m / 40m scheme in 3GPP, so that 700m has greater imagination in spectrum width.
The Federal Communication Commission (FCC) has been trying to replace radio analog television broadcasting with more effective digital services. In 2005, the United States passed the digital television conversion and Public Security Act, which stipulates the distribution of spectrum released after analog-to-digital conversion of television broadcasting system in the United States. 700MHz (698-806mhz) was used for 52-69 channels of UHF TV, and then released for other purposes. Among the 108MHz spectrum resources released, 24MHz is planned for public security services and 84mhz is planned for commercial services.
In 2008, the United States sold the 84mhz frequency band to seven American communication operators at a price of US $19.59 billion, many of which were used for 4G. Now the United States wants to use the 700m frequency band with large bandwidth, and the integration will be very difficult.
In June 2015, Germany became the first country in Europe to auction 700MHz spectrum for mobile broadband communication. Deutsche Telekom, the operator with 700MHz spectrum license, needs to provide high-speed mobile broadband services for 98% of the German population, with a total auction amount of 1 billion euros.
France auctioned six frequency bands of 700MHz spectrum, orange and freemobile auctioned two frequency bands respectively, Bouygues Telecom and SFR auctioned one frequency band respectively, with a total auction amount of 2.8 billion euros.
France assigns 698-703 / 753-758mhz and 733-736 / 788-791mhz to PPDR（Public protection & disaster relief, broadband wireless communication for public protection and disaster relief）
In 2019, France announced the gradual release of 700MHz spectrum nationwide.
Ofcom, the British telecommunications regulator, announced that 700MHz frequency band will be released for mobile broadband communication in 2020.
Japanese operators NTTDoCoMo and KDDI began to use 700MHz spectrum to provide LTE services in 2015 and put into commercial operation. There is no timetable when they will be used for 5g.
On the whole, countries all over the world attach great importance to the application of 700MHz in 5g, but China obviously has such an advantage. Radio and television hold 700m full spectrum, which is very conducive to unified network construction.
four How is the current 5g progress at 700MHz?
China Radio and television obtained 5g license on June 6, 2019, and 700m was clearly adjusted for mobile communication system, which was won by China Radio and television703-733/758-788MHzBand, and promoted 3GPP to expand the original n28 from 2x20mhz to 2x30m / 40m. Later, it reached a co construction and sharing agreement with China Mobile and introduced state grid, Alibaba, etc.
On the morning of October 12, 2020，China Radio and television networkThe inaugural meeting of the company was held in the building of the State Administration of radio and television。Initiated and jointly organized by 46 companies，China Radio and television network Co., Ltd., with a total registered capital of 101.2 billion yuan, was officially unveiled and signed strategic cooperation agreements with State Grid and Alibaba.
However, radio and television obviously wants to follow the differentiated 5g development direction. Zeng Qingjun, deputy general manager of China Radio and television network Co., Ltd., once introduced“As a state grid company, how to avoid homogeneous competition with the three "big brothers" of mobile communication, form differentiated development and realize the overall layout of the four central operators is a very important topic. It is not easy to solve this problem.”
Radio and television tries to use 5g NR for differentiated development in the broadcasting field. HD TV viewing on mobile phones is similar to the previous CMMB, which is free of downlink traffic and interactive with uplink traffic. This application should be the futureDifferentiated market space for radio and television development 5g。
According to the implementation plan for the construction of China Radio and television 5g pilot network, China Radio and television will start large-scale network construction in 2020: from January to June 2020, it will build networks in 40 large and medium-sized cities and start commercial preparations; From July to December 2020, it will be expanded to 334 prefectures and cities and key tourist cities. At present, it is far from being realized.
Of course, in 700m, radio and television and the three operators should cooperate more than compete. 5g using 700m high-frequency hotspot is the best network scheme.
five Problems encountered in the joint construction of radio and television and mobile 700m?
In May, China Radio and television and China Mobile officially announced that 700m was jointly built and shared, but how to promote it is still a fog.
China Mobile issued China Mobile 5g communication index report (phase II), which proposed5g mobile phones should support 700m band with high quality。
Subsequently, China Mobile Zhejiang started the bidding for the procurement project of 700m multi frequency antenna in 2020.
But then the tender was cancelled..
Are there any problems in the cooperation between radio, television and mobile on 700m?
From the perspective of technology and operation, the cooperation between radio, television and mobile is almost perfect:Radio and television can directly use the mature network and operation of mobile, and mobile can use 700m to achieve 5g full coverage and greatly reduce the cost.
If there is a problem, it is mostly a problem of interest and business.
six Which 5g phones support 700m?
5g mobile phones support 700m, which can be said to be very important. 5g frequency is higher than before, and coverage is always a problem. If 700m is supported, it will definitely be a great advantage in 5g signal in the future.
According to our incomplete list, the following models currently support 700m:（Welcome to add）
Many models of modems still only support 2x20mhz bandwidth. The current standard requires that they support 2x30mhz at most (2x40mhz on the base station side). Whether they can be extended to 2x40mhz in the future depends on the 3GPP standard expansion.
700m is definitely a 5g frequency dividend. It can play a great role in increasing coverage, saving investment, or reducing the energy consumption of 5g base stations.
The decision of the Ministry of industry and information technology to allocate 700m to mobile communication is a great support for 5g construction, which shows the state's support and expectation for 5g construction. You know, in Europe and America, the auction of 700m band is often tens of billions of dollars.
The difficulty lies in the competition and cooperation between radio and television and the three traditional operators. How to win-win cooperation and jointly promote the most reasonable scheme of 700m needs wisdom to solve.
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