Why did the 5G millimeter wave supported by the US version of iPhone 12 disappear in the National Bank version?

  In late October, Apple officially released a brand-new smartphone product series for 2020-the iPhone 12 series.

Careful people will notice that only the new iPhone 12 series of the US version supports 5G millimeter waves, while other countries and regions do not have support for millimeter waves, but only support the Sub-6GHz frequency band.

  Why did Apple launch the US "special offer" for the same 5G mobile phone?

In fact, this is due to the different 5G solutions chosen by countries.

  "Choosing different 5G solutions is the choice of each country based on their actual conditions." Professor Chen Jixin, professor of the School of Information of Southeast University, Ph. In the next stage, my country's breakthrough direction in the field of communications.

Communication requirements are increasing, and 5G frequency bands are beginning to fork in

  Looking through the history of human wireless communication, we will find that the frequency of communication is getting higher and higher.

  Taking my country as an example, the working frequency bands of 2G are mainly 900MHz and 1.8GHz, and the working frequency bands of 3G and 4G are mainly 1.9GHz, 2.1GHz and 2.6GHz.

  This is because people are increasingly demanding wireless communications.

In the past, wireless communication was a voice network, but now it is a data network. The higher the frequency, the greater the bandwidth that can be provided. This is like a 4-lane highway that has more cars than a 2-lane, and it can maintain a faster speed. Speed.

  In the past, the choice of wireless communication frequencies between countries was almost the same, but when global wireless communications entered the 5G band, the situation changed.

  "The development trend of 5G technology makes the transmission frequency reach a higher level, and the global 5G solution can be roughly divided into millimeter wave and Sub-6GHz." Chen Jixin said.

  Millimeter waves refer to electromagnetic waves with a wavelength between 1 and 10 mm.

Due to the short wavelength, the corresponding frequency of millimeter wave is 30GHz-300GHz.

Sub-6GHz refers to electromagnetic waves with a frequency lower than 6GHz.

  According to the international standards organization 3GPP standard, the 5G frequency band is divided into two ranges, FR1 and FR2. The frequency range of the FR1 frequency band is 450MHz-6GHz, and the frequency range of the FR2 frequency band is 24.25GHz-52.6GHz.

The frequency of Sub-6GHz and millimeter wave happens to belong to these two frequency ranges.

The two options have their own advantages and disadvantages. The deployment of each country is a realistic choice

  Restricted by the physical characteristics of radio waves, the short wavelength and narrow beam characteristics of millimeter waves have enhanced signal resolution, transmission security, and transmission speed. The storage capacity is also larger, making it easier to solve the problem of user Internet congestion.

However, this technology has a relatively small coverage area and is more suitable for applications in densely populated scenes such as stations, airports, and stadiums.

Although Sub-6GHz is inferior to millimeter waves in terms of propagation speed and bandwidth capacity, its biggest feature is its strong signal penetration, and its propagation distance is farther than millimeter waves, making it easier to solve the problem of signal coverage in a large area.

  Previously, Google conducted a test on millimeter wave and Sub-6GHz coverage in an environment with the same range and the same number of base stations.

  The test results show that at a rate of 100Mbps, the 5G network using the millimeter wave solution can cover 11.6% of the population, while the Sub-6GHz solution can cover 57.4% of the population; at a rate of 1Gbps, the millimeter wave solution is used. The 5G network can cover 3.9% of the population, and the Sub-6GHz solution can cover 21.2% of the population.

In other words, the coverage rate of the 5G network operated by the Sub-6GHz solution is more than 5 times that of the 5G network operated by the millimeter wave solution.

  In addition, the short-wavelength characteristics make the penetration of millimeter waves unsatisfactory.

According to previous studies, 5G mobile phones using millimeter wave technology can be blocked by almost anything, such as phone booths, glass, trees, rain, etc. As long as there is obstruction between the base station and the mobile phone, the 5G network may fall back to 4G.

  "If millimeter waves are used to deploy 5G networks, more base stations must be built in the same area to complete coverage, and the network cost is relatively high." said Xu Xin, chairman of Zhongke Zhida Internet of Things System Co., Ltd.

  In 5G construction, capital investment is an important factor that has to be considered.

  Compared with millimeter waves, Sub-6GHz radio frequency devices can continue to use the original 4G industry chain, and the technology is more mature, while the base stations in the Sub-6GHz frequency band can also be transformed on the basis of the original 4G base stations, which greatly saves costs.

  However, the design and production of sub-micron integrated circuit components working in the millimeter wave frequency band have a high threshold for design and production, and require higher capital investment, which to a certain extent also hinders the commercial development of millimeter wave solutions.

  At present, my country mainly adopts the Sub-6GHz scheme.

South Korea, Japan, Europe and other countries or regions are developing both frequency bands.

Network construction depends on the specific needs of operators and use environments.

  Due to historical reasons, most of the spectrum that can be allocated in the US communications field is occupied by the military, leaving only frequencies higher than 27.5 GHz. Therefore, the 5G deployment of US operators has to start with millimeter waves.

Millimeter wave will release greater potential, my country is actively deploying research and development applications in this field

  In fact, for the construction of 5G networks, whether it is Sub-6GHz or millimeter wave, there is no distinction between advantages and disadvantages, but actual factors lead to different development sequences.

It is understood that it is difficult to obtain a wider continuous spectrum in the current golden communication frequency band below 6 GHz. In contrast, the millimeter wave frequency band still has a large amount of potentially underutilized spectrum resources.

  Relevant experts believe that from a long-term perspective, millimeter waves may promote 5G to release greater potential in the future.

  For example, millimeter waves have higher resolution in radar, imaging, etc. With the rapid development of technologies such as autonomous driving, millimeter waves will be widely used in all aspects of people's daily lives.

In addition, because of the low-latency characteristics of millimeter waves, it also has broad application prospects in cutting-edge technologies such as remote robot control and telemedicine.

  As for the construction of millimeter waves, our country has also not stopped.

  In March of this year, the Ministry of Industry and Information Technology issued the "Notice on Promoting the Accelerated Development of 5G", which mentioned that "the plan for the use of some 5G millimeter wave bands will be released in due course, and millimeter wave equipment and performance tests will be organized to prepare for the commercial use of 5G millimeter wave technology. "Institutions including China Telecom have actively participated in the millimeter wave experiment organized by the Ministry of Industry and Information Technology.

  In view of the characteristics of millimeter wave, operators no longer directly cover the wide area of ​​the network signal, but only deploy in areas where "blindness" needs to be supplemented, mainly to solve the problem of capacity requirements in indoor and hot spots.

  Chen Jixin believes that millimeter waves are more sensitive to the propagation conditions of the natural environment. How to use millimeter waves to provide stable communications in unstable natural environments is a challenge that major operators need to face when building base stations.

In addition, millimeter wave services and networking capabilities also need further verification.

  It is understood that the current mainstream mobile communication equipment providers have launched base station equipment supporting 5G millimeter waves.

China Unicom has reached a cooperation with the 2022 Beijing Winter Olympics and will promote the use of millimeter waves during the Beijing Winter Olympics.

Once the usage is good, it will greatly promote the development of millimeter wave technology.

  In terms of chips, in June this year, Nanjing Network Communications and Security Purple Mountain Lab has developed a CMOS millimeter wave fully integrated 4-channel phased array chip, and completed the chip packaging and testing. Samsung and Huawei have already supported millimeter wave engineering prototypes, and others Chip manufacturers are also launching millimeter wave products one after another.

  In the opinion of relevant experts, the maturity of the millimeter wave industry chain will affect the deployment scenarios and deployment scale of millimeter waves. To truly promote the wide application of millimeter waves, key technologies, core components, and chips need to be further improved and improved.

This requires operators and the industry to jointly carry out technical research to create cost-effective hardware facilities and commercial systems.

  Intern Lei Haoran, reporter Zhang Ye