The next -generation mobile communication service "5G" will begin in Japan this spring.ENGADGET also reported 5G from various angles, but here's a review of "Why 5G is fast" from a mobile communication mechanism.Thinking about how mobile phones are communicating, the mechanism should be a clue to understand what kind of technology is 5G, what is worthy of expectations, and whether it will spread.Based on the video program "UPSCALED" by ENGADGET's Christopher Scott, we will add a supplement to the current situation in Japan.If you want to grasp the video quickly, you can play it from the end of this article (about 15 minutes, audio is only English).
"5G is here!"......
"5G is here!"However, it often exists when 5G is not here.
In the United States, which has been about a year since the mobile carrier started 5G services, you can use the appropriate smartphone in the right city to experience 5G high -speed communication, which is a measured 1Gbps.This is 20-30 times the speed of 4G LTE.This "in an appropriate city and an appropriate smartphone" is an important point in understanding 5G.yes.The 5G at the beginning does not mean that it can be used in a wide range of places.And it is not something that can be used without replacing the equipment.It is not one technical element that supports 5G, but is a combination of many, such as antenna design, arrangement of radio tower, and frequency bands.Some technical elements are still unclear how they will evolve in the future.
Also, at the moment, just after 5G starts, there is also a variety of experiences in which the world's careers take up as "5G".In fact, what is "5G"?First, let's go back to Omoto and say "What is a mobile phone network?"
Mobile phone network mechanism
Mobile communication with mobile phones is a wireless technology that is also called cellular communication.Celluler is a word derived from cells, that is, cells.It is called cellular communication method, comparable to cells that cover a wide range of areas in many forested radio tower.This technology has a new generation every 10 years."5G" is the 5th generation cellular technology.
Here, let's imagine the scene where one radio tower in the cellular network and the smartphone you have.Your smartphone and radio tower will communicate with a part of a specific radio frequency band assigned for communication.There is an upper limit on the number of smartphones (terminals) that can be connected to one radio tower at the same time.A fine cut end "channel" is assigned for each frequency, and it can only be used at the same time.Therefore, in order for a mobile company to provide many users a communication service, it is necessary to build more radio tower.And if you can handle many frequency bands (that is, many channels) from one radio tower, it will also help many users to communicate.
It is important to note that if the radio tower dealing with the same frequency band is too close, communication may interfere or weaken waves.If the distance between the radio tower is sufficiently separated, the same frequency band is available.Therefore, it is necessary to build as many radio tower as possible, but it should not be too close -The most common person can be connected in the combination of the smallest radio tower, aiming for the overall optimal design.It will be.
By the way, in cellular communication, the radio tower is called a base station.In rural areas, you may see a building with white antennas in three directions around the tower.This is a typical base station, which has a wide range of mobile phones with one tower.In the city center, you may see an antenna lined up on the roof of the building.
The evolution of celluler technology has two directions: "increase the number of people who can connect to each base station" and "increase the amount of data that can be exchanged at once".In the early mobile phone network, an analog voice call could be connected to up to 12 people per base station at the same time.Modern mobile phone networks have become more advanced compared to that, and using advanced technologies such as "time sharing" and "modulation", from Netflix to view Facebook.It supports hundreds and thousands of simultaneous connections for one.
Two frequency bands "sub 6" and "millimeter waves"
Now, let's get into the main subject.What will change in 5G?Actual changes are not necessarily replacing the hardware of the base station.One of the most effective changes is the use of a new frequency band.This can provide more resources.In celluler communication up to the 4G LTE generation, the frequency band of 500 to 2500MHz was mainly used.The frequency band "5G NR (New Redio)" defined in 5G is divided into two main types.One is the 400-6000MHz band, which is called "Sub6".The other is 24-50GHz band.The latter has been greatly appealed as "millimeter waves" (including the exaggeration).
In addition, among the frequency bands of "sub 6", the properties are very different between low frequency bands of 1000MHz or less and relatively high frequency bands with 2500MHz or more.The former is a bandwidth that is often used in mobile phones so far, and the latter is a frequency band called "mid -band".The radio waves of the mobile phone are friends such as light and sound, and have the property of transmitted like waves.The frequency that represents the "low" radio waves is the number of "mountains and valley" in one second, and the unit is Hz (Hertz).1GHz (Gigahertz) ≒ 1000MHz (Megahertz) means that the "mountain and valley" cycle of 1 billion times per second is repeated.
Radio waves in low frequency bands have properties suitable for long -distance transmission as characteristics.Even if there are obstacles, most of them are wrapped in and passed through, and they do not weaken much.This will be easy to understand when compared to the sound.For example, when a resident of the neighboring house plays music at a loud volume, you can't hear the middle and high notes such as vocals in your home, but the bass base will resonate.The bass of this base and the cellular waves in the low frequency band are similar.
そのため低い周波数帯の電波は、幅広いエリアをカバーするのに使えます。米国のキャリアではT-MobileやAT&Tが600MHzや850MHzを使って、少ない電波塔で広いエリアにサービスを提供しています。日本では「プラチナバンド」として800MHz/900MHz帯が利用されています。一方で、低い周波数帯には大きな弱点があります。帯域幅が少ないため、スピードが出ないのです。携帯電話の通信速度は、1ユーザーあたりに割り当てられた周波数の幅がどれだけあるかに依存しています。低い周波数帯ではそもそも全体で使える量が大きくないので、割り当てる単位となる「チャンネル」では10MHzといったように細切れになりがちです。
Given that the first frequency band that is assigned at 5G is limited, the actual communication speed is often slower than 4G LTE (already assigned a lot of frequency bands).
5G hidden protagonist?"Mid band"
Most of the world's mobile carriers, including Japan, are paying attention to the so -called "mid -band", 2500-4700MHz (2)..5-4.7GHz).This is equivalent to a high frequency range even in sub 6, and it may be extended to 7000MHz in the future.This mid -band is a frequency band higher than most of the currently used mobile phone systems.。On the other hand, the mid -band has many bandwidth, and the channel assigned per user is larger from 50MHz to 100MHz.Appropriate maintenance of this mid -band will make a high -speed communication of several hundred Mbps.
U.S. careers are not focused on mid -band except for Sprint.Instead, the focus is on the "Milli wave band" (24-50GHz), the highest frequency band newly assigned for 5G.There are many bandwidth in the millimeter wave band, and it is possible to assign a large capacity of 800MHz per channel.On the other hand, there are weak points.
Reasons for slow radio waves, mechanism of modulation
Before mentioning the weaknesses of millimeters, let's talk about the "modulation" of celluler communication.Modulation is a process of converting (encoding) the digital data represented by "0" and "1" into a "radio wave shape".In celluler communication modulation, a method called "QAM (right angle phase string width)" is used.This is a technique to replace the form of radio waves, for example, "01" for mountain -shaped, and "00" if it is straight.
QAM modulation is more advanced as the number of patterns to be identified, and there are 16QAM, 64QAM, 128QAM, and 256QAM."4QAM" represents the combination of 4 types, such as "01", in 4 waves patterns, and "16QAM" represents the combination of 4 0 and 1 in 16 types of waves.。
If you make the modulation complex, you can send a lot of information in the same bandwidth. This is because if the radio waves that can be transmitted are strong (if the difference is easy to read), it can be combined. The technical weakness of modulation is exactly what depends on the strength of radio waves. The strength of the radio wave depends on the positional relationship between the mobile phone and the base station. Ideally, when you are next to the base station antenna, the radio wave is the strongest and you can use advanced modulation methods. With LTE, 256QAM is enabled, and you can send a pattern of 256 waveform patterns, that is, 8 0 and 1, such as "00000001". On the other hand, as of February 2020, 5G has rarely used 256QAM. 64QAM is the maximum in actual operation. This is because, especially in high frequency bands, the radio wave intensity tends to weaken. Therefore, it is common to adjust and adjust the control of the modulation. In summary, the speed improvement of 5 g is that (1) the capacity of one channel is large, (2) the number of channels that can be used simultaneously, and (3) can use more complex modulation methods. Improve by combining the three factors: what you can. In the future, the more complex 1024QAM will be implemented. However, ENGADGET's inquiry of Qualcolm states that it will be "a few years ahead."
New antenna technology "MASSIVE MIMO"
Utilizing high -frequency bands such as millimeters, it is indispensable to combine with advanced technology that controls radio waves.One of the new antenna technology "Massive Mimo" is one of them."MIMO" is Multice Input Multiple Output (multiple input and multiple output).This is a technology that uses multiple antennas at the same time on both the base station side and the terminal (smartphone) side, and increases the amount of data that can be sent at the same time by interacting.The conventional 4G LTE base station uses 4 to 32 antennas and uses MIMO technology to send and receive multiple antennas at once.
Most of the current high -end smartphones now support 4x4 mimo, that is, to communicate with four antennas. Many smartphones in the popular price range are less than that, 2 × 2 mimo, or many things that can only be communicated with one antenna. However, even if the smartphone side supports 4x4 mimo, the number of channels assigned by one base station is limited, so it does not always interact with the four antennas of the base station. The Massive Mimo base station is further increased the number of this antenna and has a large number of antennas that are 64 to 256 in one base station. Since the millimeter wave band has a sufficient number of channels, if you prepare a large number of antennas of MASSIVE MIMO, you can afford to use 4x4 mimo for many users. Future 5G smartphones are expected to be realized as 8x8 mimo, and it is likely to help 5G faster. However, it is necessary to wait for a smartphone maker to put a 5G smartphone with many antennas. If you attach dozens of antennas to modern smartphones, costs are high and battery life is consumed. And in the first place, there is still an issue to prepare a space to store many antennas. However, manufacturing technology is mature over time, so smartphones with many antennas will be a realistic price.
"Beam forming" that hit radio waves in the target direction
The advantage of the design of Massive Mimo is that you can use "beam forming".This is a technology that controls the antenna signal for a smartphone so that it hits.The mobile phone antenna generally transmits radio waves in a horizontal 180 degree direction.The Massive Mimo base station, which has many antennas, is the same.
Beam forming uses the physical properties of radio waves to apply a strong signal (beam) in the target direction.For example, if you send a signal with the same content from two antennas at the same time, the signal becomes stronger in the overlapping parts.If you add this to four, it will be a stronger signal.And by adjusting the output of each antenna, you can control strong radio waves in the target direction.It is not only one direction such as a flashlight or searchlight, but a broadcast (broadcast) mechanism that spreads throughout the whole, but the beamforming allows you to send a strong signal to the target position.
And the base station receives all the signals sent by mobile phones.Based on its strength, a technology that calculates the position with a mobile phone is incorporated based on the signals reflected on walls.You can use this to determine the direction to hit the beam forming.Beam forming is not a technology used only for millimeter waves.According to Qualcom, even in the mid -band frequency band as well as the mid -band, 5G can accommodate more users (speeding up per user) as long as the position position of 4G LTE works.increase.
The millimeter wave band is large, but the task is to expand the area
Milling waves still have the troublesome nature to overcome.Radio waves with high frequencies have the property of being easily absorbed when hitting an object.In the case of millimeters, it is absorbed by almost all the hits.Trees, walls, and even more energy -efficient glass do not reflect, and they are absorbed.
There are some concerns that the nature of the millimeter waves may increase the risk of getting cancer if it hits the skin, but there is no concern.If 5g millimeters cause cancer, you will not be able to have a more powerful 4G LTE mobile phone.Rather, millimeters are "too weak".Even air is a factor that attenuates the water.There have been reports that just raining or fogging will reduce the traffic light strength of millimeters.The use of millimeters has the potential to dramatically increase the speed of 5g.However, due to its physical characteristics, even if the cover area will spread in the future, it will be as hard as possible to expand to 1 km around the base station.
Due to these physical properties, the use of the millimeter wave band is limited to places where you can't afford to build a number of base stations, such as dense and indoor commercial facilities where many people gather.I understand.Especially in indoor facilities, a very small base station will be built and covered every 50m.However, 5G can dramatically improve the indoor communication environment.In the future, in shopping malls, airports, office buildings, stadiums, etc., Wi-Fi and 5G will automatically switch to those who can communicate at higher speeds.There is a possibility.
Is the US carrier neglecting the mid -band?
Looking at the 5G introduction of US carriers, T-Mobile and Sprint are being introduced from the low frequency band of sub 6.On the other hand, Verizon, on the other hand, is unusual in the world, and has a policy of focusing on millimeters and developing 5G.The result of Verizon's focus on millimeter waves is a mixture of good or bad.If it leads to millimeters, the communication speed exceeds 1Gbps and is very fast.On the other hand, those who have tried it at the beginning of the development also described many complaints about the area.The strange thing about US mobile carriers is that they almost ignore the high frequency band "mid -band" even in sub 6.
A mid -band is a bandwidth used by most countries in the world to introduce 5G.In order to communicate several hundred Mbps in sub 6, a low frequency band alone is not enough, and the use of a mid -band is essential.Moreover, in the mid -band, this speed can be realized without a penalty like millimeter (the narrow cover area).
Things that are likely to be realized with 5G
What can I do with high -speed mobile communication from hundreds of mbps to 1Gbps?First, media streaming is a promising application.5G can stream everything.And this high speed is further deepened in cooperation with the cloud.For example, if you immediately upload the video you shot to the cloud, you will not need storage on your smartphone.You can download it from the cloud when playing.Or, if you imagine a camera without a memory card that updates the video taken in 4K to the cloud as it is, it will be easier to understand.
The most ideal scenario may no longer need a wired Internet at home, and all communications may be integrated into 5G.The price may be integrated for all devices, and you may be able to pay from your home Wi-Fi to your smartphone or other things in one charge system.5G can cause significant changes in the "plain" field, such as manufacturing, infrastructure, and research.For example, a high -resolution image sensor will be available in such a field.In addition, the data collected from a huge number of machines can be transmitted to the analysis server, and a network in which the machines work together will be shaped.
In these fields, characteristics other than 5G capacity are also important.For example, the characteristic of low latency (low delay).This is a very short time that communication to the base station is 1 milliseconds one way.In the case of 4G LTE, it costs 20 to 70 milliseconds, so it has been greatly reduced.However, it will still take several years to be able to actually enjoy 5G low delay performance.Low delay may change the field of mobile gaming.In particular, cloud gaming services, such as Google's "STADIA" and Microsoft's "XCLOUD", need to quickly react to players to the game.Here is the value of low delay.
In addition, 5G is a powerful tool for realizing "true autonomous driving".For example, research is underway to communicate between cars and use mobile communication to communicate information such as the current location and lane change.The information obtained from each car is aggregated and analyzed in the city's transportation center, which will help reduce traffic and efficiently deploy emergency vehicles.
5G issues are cost and feasibility
The use of these 5G is really wonderful if it is realized.But some skepticism will need to be raised here.A mobile carrier can be described based on the features of 5G, which will be realized in an ideal environment.For example, the high speed performance is to appeal to "More than a few Gbps!"In a limited area, the speed exceeds 1Gbps is also available, and this is certainly not a complete decoration.
This was the same when the 4G LTE was introduced.In the early 4G LTE industry standard (3GPP Release 8 formulated in 2008), the standard maximum speed was 300Mbps.However, the actual 4G LTE speed in the United States is only 15 to 30 Mbps as of 2020."5G", which is now advertised and introduced in the media, is basically a concept stage technology.Smartphones and communication equipment manufacturers continue to increase their manufacturing capacity, but only dozens of smartphones that can be used for 5G have appeared.And there is no way to know the situation how much of them actually performs high -speed communication at 5g.
Of course, many 5G smartphones will appear in the future, and the number of low -priced smartphones will increase.On the other hand, as of the early 2020, the price of 5G smartphones has stopped.However, in countries other than the United States, which are developing mainly 5g of mid -band, the number of cheaper 5G smartphones is increasing.If you give up the millimeter waves, it seems that you may get a cheaper 5G smartphone.The speed of mobile communication has exceeded the speed of home broadband communication in many countries.There is no doubt that high -speed wireless communication is convenient for people's lives.
一方で、このように主張する必要もあるでしょう。高額な通信プランと通信容量の上限設定は、特にモバイル通信に依存している人には大きな問題となります。3秒でBlu-rayディスク1本分の高画質な映像をダウンロードできるほど高速な5Gが、この問題を加速させてしまう懸念があります。また5Gで積極的に投資が進んでいる都市部では、すでに適切なインターネットに接続できる環境が整っている場合も多くあります。それにもかかわらず世界で5Gを展開するキャリアの多くは、もっとも高額な料金プランでもデータ利用時の上限を設定しています。そして米国では、AT&Tが段階制の5Gプランを設定する可能性さえ示唆しています。みなさんどう思いますか？5Gに興奮していますか？
[Recommended articles for those who want to know more about 5G] -What are two types of 5G── "millimeters" and "sub6"?Xperia 1 II is only the latter, au, and the "true 5G" is a new technology "DSS" 4G and a frequency band that instantly becomes a transe to remote medicine in the mid -21 years with a very low delay and a 5G area.Softbank, 5G, jointly maintain local base stations in the regional regions ・ Move unmanned construction aircraft with “5G”.Possibility of "Local 5G" ・ Docomo, the technical concept for the next “6G” of 5G is released
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