The US version of the iPhone has exclusive 5G millimeter waves, and US consumers question whether 5G is fake 5G?

Recently, American consumers complained that the 5G service they enjoy is fake 5G. The reason is that the 5G network coverage is too poor, and the data transmission rate of 5G is too low. Compared with 4G, the improvement is extremely limited. This all stems from the adoption of 5G millimeter wave technology in the United States.

Compared with light waves, millimeter waves use the atmospheric window (when millimeter waves and sub-millimeter waves propagate in the atmosphere, some attenuation due to the resonance absorption of gas molecules is a minimum frequency), the attenuation is small, and it is affected by natural light and The thermal radiation source has little influence.

Advantages: 1) Extremely wide bandwidth. It is generally considered that the frequency range of millimeter wave is 26.5 to 300 GHz, and the bandwidth is as high as 273.5 GHz. More than 10 times the full bandwidth from DC to microwave. Even considering atmospheric absorption, only four main windows can be used when propagating in the atmosphere, but the total bandwidth of these four windows can reach 135 GHz, which is 5 times the sum of the bandwidths of the bands below the microwave. This is undoubtedly very attractive today when frequency resources are tight.

2) The beam is narrow. Millimeter-wave beams are much narrower than microwave beams for the same antenna size. For example, a 12cm antenna has a beamwidth of 18 degrees at 9.4GHz, but only 1.8 degrees at 94GHz. Therefore, it is possible to distinguish small targets that are closer together or to observe the details of the target more clearly.

3) Compared with lasers, the propagation of millimeter waves is much less affected by climate and can be considered to have all-weather characteristics.

4) Compared with microwave, the size of millimeter wave components is much smaller. So mmWave systems are easier to miniaturize.

Although the current global 5G technology is claimed to be a unified 5G technology, the 5G technology used in the United States is still different from the 5G technology in other countries. The 5G millimeter wave technology used by American operators is 5G, while the mainstream 5G is 5G. Centimeter wave technology.

There are two main differences between 5G millimeter wave and 5G centimeter wave. 5G millimeter wave can provide higher data rate and lower latency, but the coverage effect is too poor and easy to be blocked, even raindrops will block the 5G millimeter wave signal; 5G centimeter wave is just the opposite, the coverage effect is good, but The delay is difficult to reach the theoretical delay of the 5G standard, and the data transmission rate is also low.

Previously, all parties liked to emphasize the ultra-low latency and high-speed data transmission rate of 5G when promoting 5G technology. However, in actual operation, operators have found that considering the cost problem, 5G centimeter wave is more practical, and even 5G is more practical. Centimeter wave technology is also unbearable due to the high construction and operating costs of 5G base stations. China Mobile now chooses the low-frequency 700MHz to build 5G networks, which greatly reduces the number of 5G base stations. Obviously, the cost is the priority of operators, and 5G The advantages of technology have been put on the back burner.

As a kind of radio wave, the millimeter wave was inconspicuous in the past. Compared with its lower frequency microwave, the transmission distance is farther, and it has great achievements in the field of communication. The light wave with higher frequency than it is also widely used in digital, communication and other fields. Only in the middle Millimeter waves for locations are left untouched.

At some point, however, mmWave suddenly became the focus of everyone’s attention.

Popular fried chicken on the tuyere

If you want to talk about the tuyere of the current era, I believe that everyone will blurt out terms such as 5G, autonomous driving, artificial intelligence, etc. What is not well-known to the public is that these tuyere uses a technology called “millimeter wave”.

From this, it can be seen that this “wave” called millimeter wave is a tuyere in the tuyere, and it is difficult to think whether it is red or not.

Millimeter waves generally refer to electromagnetic waves with wavelengths of 1-10 mm. Millimeter waves have extremely high bandwidth, and the total available bandwidth is as high as 135GHz, which is five times the bandwidth of the traditional microwave band.

Secondly, the beam of the millimeter wave is very narrow, which can more accurately distinguish the target and restore the details of the target;

Compared with lasers, millimeter waves have lower climate requirements, and compared with microwaves, millimeter wave components are smaller in size, and millimeter wave devices are easier to miniaturize.

However, millimeter waves also have the disadvantages of severe attenuation and high requirements for device precision, and it is these two shortcomings that have restricted the development of millimeter waves in the past. The global 5G network frequency band is divided into Sub-6GHz and millimeter wave, and my country has put the construction of 5G millimeter wave network on the agenda when the construction of 5G Sub-6GHz network is basically mature.

Six days ago, Shanghai held the Mobile World Congress, which Barcelona failed to hold for two years in a row, and a new topic that was most different from the 5G theme in previous years attracted many people’s attention, that is, the millimeter wave that can be seen everywhere.

Many well-known ICT manufacturers have opened 5G millimeter wave demonstration areas, and people lined up to experience how different this new concept is.

So, what exactly does mmWave mean for 5G?

Is it coming in 2021?

Is mmWave just needed for 5G?

With the rapid progress of 5G in the world, China and the United States have been playing an invisible competitive game on 5G in different ways.

But in fact, in terms of network construction and applications, around 5G millimeter waves, both China and the United States have unavoidable headaches.

In China, by the end of 2020, the three major operators have built and opened 710,000 5G base stations by leaps and bounds. Because they are generally built in low and medium frequency bands below 6GHz, although they have the advantage of larger coverage radius than high frequency bands above 6GHz, ideal 5G speed and capacity have not been able to break through.

The high-definition video, VR/AR, V2X autonomous driving, industrial automation, and intelligent Internet of Things that are constantly mentioned in various 5G PPTs represent typical services with high capacity, high speed, and low latency. Do not turn. (After all, mmWave has a very large bandwidth from 24GHz to 100GHz, which is 25 times more bandwidth than the current 3G/4G use, and can really achieve low latency.)

However, in the early stage of 5G construction, the construction and application of millimeter waves are difficult and have many problems. It is said that the largest domestic operator has teamed up with a number of companies and research institutes to invest a lot of money in the research and development of millimeter-wave antennas. After a few years, they are very dissatisfied with the compliance status, and many of the required power devices still rely on imports. .

This year’s iPhone 12 has resumed the grand occasion of increasing the price and picking up goods. Last year, users who waited and watched because the iPhone 11 did not have 5G finally had a reason to change the phone.

At the press conference, Apple also introduced 5G as the most important highlight. The iPhone 12 supports almost all current 5G frequency bands, surpassing mainstream Android models, but only the US version supports millimeter wave frequency bands.

The millimeter wave exclusive to the US version of the iPhone 12 and the sub-6GHz supported by the National Bank version are actually the two major branches of the current global 5G network frequency band.

As the name implies, millimeter waves have frequency wavelengths less than 10 mm, and generally refer to the frequency band above 24 GHz. Sub-6 GHz is a network frequency band below 6 GHz, and is also called ‘centimeter wave’ because the wavelength is in the centimeter level.

Millimeter wave and centimeter wave, the name seems to be that millimeter wave has won, just like millimeter-level positioning in navigation satellites is obviously more accurate than centimeter-level positioning, so is 5G millimeter wave more powerful than sub-6GH?

Indeed, millimeter wave has the advantage that sub-6GHz is difficult to match, which can be reflected from the most intuitive network speed.

According to the actual measurement data of the network speed measurement platform Ookla, the download speed of 5G millimeter wave terminals is 4 times that of the frequency band below 6GHz, the average rate reaches 900 Mbps, and the peak rate exceeds 2Gbps.

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