Medium and low frequencies may become the main force in 5G signal deployment. Will 4G become slower?

It has been nearly a year and a half since the first 5G mobile phone was launched in China, and the development speed of 5G in China can be said to be rapid. On December 24, at the State Council Information Office meeting, the Ministry of Industry and Information Technology stated that 580,000 new 5G base stations were added in China in 2020, achieving coverage of all cities and prefectures across the country. This year, the shipment volume of 5G mobile phones in the domestic market reached 144 million units. We can also clearly perceive that the vast majority of new phones on sale in the market are 5G products.

Recently, the Ministry of Industry and Information Technology announced another major move - issuing 5G medium and low frequency band use licenses with a validity period of 10 years to the three major domestic operators. The Ministry of Industry and Information Technology also specifically pointed out in the document released that some existing 4G frequency resources are allowed to be re-cultivated for 5G.

Medium and low frequencies may become the new force in 5G signal deployment

In fact, as early as the end of 2017, the Ministry of Industry and Information Technology announced the frequency use plan within the 3000-5000MHz frequency band, making my country the first country in the world to divide the 5G mid-frequency band. The specific division is: 3300-3400MHz (limited to indoor use), 3400-3600MHz and 4800-5000MHz. At the end of 2018, the 5G frequency bands obtained by the three major operators were settled. Specifically, China Mobile obtained the frequency bands of 2515-2675MHz (n41) and 4800-4900MHz (n79), China Telecom obtained the frequency bands of 3400-3500MHz (n78), and China Unicom obtained the frequency bands of 3500MHz-3600MHz (n78).

It is not difficult to see that in 5G construction, my country is taking the Sub-6GHz technology route and quickly completing the laying of 5G signals in the mid-frequency band. Compared with millimeter waves, the mid-frequency band has a lower absolute rate and a slower theoretical network speed, but it is better than millimeter waves in terms of signal coverage and signal penetration. The United States, which tried to use millimeter waves as the main force of 5G, now seems to have been slapped in the face. Foreign media once pointed out in the actual measurement of 5G signals that the anti-interference ability of 5G millimeter waves is extremely poor. Even a person standing between the test mobile phone and the signal tower can cause the 5G network speed received by the mobile phone to drop sharply.

However, even so, the coverage of 5G base stations is still much smaller than that of 4G, 3G and even 2G. After searching the information and obtaining more specific data, this comparison is particularly obvious:

• The coverage radius of 2G base stations is about 5-10 kilometers
• The coverage radius of 3G base stations is about 2-5 kilometers
• The coverage radius of 4G base stations is about 1-3 kilometers
• The coverage radius of 5G base stations is about 100-300 meters

In addition, the operation of re-cultivating the 4G frequency band for 5G has been quietly tried before the official permission of the Ministry of Industry and Information Technology. In fact, the n41 obtained by China Mobile comes from the 4G frequency band of China Telecom and China Unicom on 2600MHz. According to the previously announced schedule, China Telecom completed the vacating of the frequency of 2635~2655MHz in September 2019, and China Unicom completed the vacating of the frequency of 2555~2575MHz band. Similarly, China Mobile also vacated part of the 900MHz and 1800MHz spectrum to China Unicom and China Telecom.

What is interesting in this process is that the 4G spectrum vacated by China Telecom and China Unicom is basically TDD. Although in the 4G era, the slogans of the three major operators were to build TDD and FDD together, in actual implementation, China Mobile mainly uses TDD, while China Unicom and China Telecom focus on FDD. Therefore, the withdrawal of the 2600Hz spectrum has little impact on the two major operators, and at the same time provides great convenience for China Mobile's 5G construction.

Similarly, the 900MHz and 1800MHz spectrum vacated by China Mobile has given the other two operators more room for 4G construction.

2G, 3G, who will go and who will stay?

As more advanced communication technology standards are implemented, the gradually outdated network standards will have to "step down and let the wise take over" to release valuable spectrum resources. Globally, many countries or regions have completed the withdrawal of 2G and 3G spectrum. Take Taiwan, my country as an example. As early as July 2017, all 2G base stations were officially shut down, and all 3G base stations were shut down a year later. If nothing unexpected happens, many regions in the future will be in the 4G+5G networking state.

But in mainland China, the situation is obviously much more complicated, and the specific solutions given by the three major operators are also different. According to the data released by the Ministry of Industry and Information Technology in July this year, the number of 2G users in mainland China is still as high as more than 200 million, accounting for 17% of all mobile users. In addition to a large number of individual 2G users, there are also many 2G networks used by IoT devices.

Specifically speaking of the three major operators, China Mobile is currently more inclined to retain 2G, withdraw 3G, and develop 4G and 5G. It is not difficult to understand why China Mobile gave up 3G. The license it obtained was TD-SCDMA, which had many problems in both technology and actual experience, which made China Mobile very anxious. After the 4G network became popular, China Mobile was naturally eager to get rid of the negative assets of 3G. Moreover, China Mobile was the first among domestic operators to popularize VoLTE, so there was no need to downgrade to 3G to make calls, not to mention the protection of 2G.

China Telecom is also quite special. It originally obtained a CDMA license, which carried 2G and 3G networks. Today, Telecom is also trying to reduce the maintenance costs of the CDMA format and focus on 4G and 5G. If you have observed carefully, you can find that many new phones on sale lack support for CDMA networks in the network parameter column. In fact, the baseband chips of most mobile phones are compatible with CDMA, and the practice of shielding this format is required by Telecom. Correspondingly, Telecom has also completed the large-scale promotion of VoLTE, and most mobile phones have the VoLTE switch turned on by default.

On the China Unicom side, the situation is different. China Unicom, the weakest in the 3G era, got the best WCDMA license, and the theoretical network speed was the fastest. Xiao Lei still remembers that in places with good signals and few people, the actual download speed of China Unicom 3G cards could reach more than 1MB/s, almost reaching the threshold of 4G network. Through large-scale construction, 3G is still China Unicom's most widely covered network, and often fills the gaps that 4G cannot cover. Therefore, China Unicom is also the least active of the three major operators in promoting VoLTE. It took about five or six years from the initial trial to the nationwide implementation.

Therefore, China Unicom chose to start with 2G in terms of network withdrawal. As early as 2018, China Unicom announced the withdrawal of 2G networks in areas with good 3G and 4G network coverage. In November this year, it announced the full withdrawal of 2G networks.

At present, the main force of 5G signal coverage still relies on medium-frequency networks. Although their coverage is wider than that of millimeter waves, a coverage of several hundred meters is still not enough, which also makes the cost of 5G construction still extremely high. The number of hundreds of thousands of 5G base stations seems to be a lot, but it is only one-tenth of the number of 4G. This means that if 5G coverage is to catch up with 4G, the investment amount must continue to increase.

From this perspective, the spectrum after the 2G and 3G networks are cleared will be owned by 5G in the future to achieve low cost and wide coverage. Of course, the theoretical speed of low-frequency 5G is definitely not as good as that of medium- and high-frequency 5G, but the actual experience will still be better than that of 4G networks. Moreover, in terms of 5G coverage, it is more urgent to achieve "having" than to achieve "good". Now the Ministry of Industry and Information Technology directly allows operators to use the re-released frequency resources for 5G construction, which has a very positive effect on the acceleration of 5G in China. It is believed that 5G coverage will soon be expanded from the prefecture-level city to the district, county and even township level, which will also promote the further development of 5G-related industries.

Will 4G become slower?

In fact, many people asked this question last year. For this reason, Sina launched a survey on Weibo, with more than 200,000 participants. As a result, more than 70% of netizens said that they felt the network speed was slowing down. After the claim of 4G speed reduction sparked heated discussions on the Internet, operators also responded, with the same wording that there was no artificial speed reduction. At the same time, relevant reports also stated that the mobile network speed was not only not decreasing, but was increasing.

These two completely different statements may both be true. On the one hand, the operators did not deliberately slow down 4G. But on the other hand, with the rapid development of mobile Internet, the large-scale popularization of high-load applications such as short videos and the continuous expansion of App size have put forward more severe tests on network carrying capacity. Although 4G will still be the backbone of mobile networks for a long time in the future, its priority in base station construction is definitely not as high as 5G. In this case, 4G users may find it difficult to avoid the problem of reduced network experience.

Of course, from a longer-term perspective, the rapid advancement and construction of 5G networks will obviously be more beneficial to users and all walks of life. In the future, the use scenarios of 5G mobile phones will be further broadened, and even new killer applications will be spawned. At the same time, 5G can also provide more support for commercial scenarios. Nowadays, most of the mobile phones on the market have the ability to support 5G. The price of 5G packages is constantly decreasing, and the signal coverage is constantly expanding. Domestic users will get a better network experience, which is still worth looking forward to.

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