[Invitation] 2018 NI RF Test Seminar Shanghai Station, facing the 5G wave, are you ready?
Simply put, 5G is the fifth generation communication technology, mainly in the wavelength of millimeter, ultra-wideband, ultra-high speed, ultra-low delay. 1G realized analog voice communication, Big Brother did not have a screen; 2G realized voice communication digitization, the function machine has a small screen to send text messages; 3G realize multimedia communication such as pictures outside the voice, the screen is bigger The picture is, 4G realizes the local high-speed Internet access, and the large-screen smart machine can see short video, but in the city's signal, the old family signal is poor. 1g ~ 4g is a more convenient and fast communication between people and people, while 5G will be implemented at any time, anywhere, letting human beings dare to look forward to the way with live broadcasts through live broadcasts.
Communication technology, in the end, it is divided into two - wired communication and wireless communication.
Information data is either in air (see can't see, touch), or spread in real things (see, touch).
Communicate data on wired media, the rate can reach a high value. This part is the bottleneck of mobile communications.
At present, the mainstream 4G LTE, the theoretical rate is only 150Mbps. This and wired is completely no way.
Therefore, 5G If you want to achieve the high rate of end-to-end, the focus is the bottleneck that breaks through the wireless parts.
Wireless communication is to communicate with electromagnetic waves. Electric waves and optical waves belong to electromagnetic waves.
The functional characteristics of electromagnetic waves are determined by its frequency. Electromagnetic waves of different frequencies have different attributes, there is different purposes.
For example, high frequency gamma rays have a large killing force, which can be used to treat tumors.
We currently use radio waves to communicate. Of course, optical wave communications are also rising, such as LIFI.
The radio wave belongs to an electromagnetic wave, and its frequency resources are limited.
In order to avoid interference and conflict, we further divide the lanes on the highway of electric waves, assign different objects and uses.
All along, we mainly use the intermediate frequency ~ ultra-high frequency to communicate with mobile phone.
For example, "GSM900", "CDMA800", which means that it means that the operating frequency segment is at 900 MHz GSM, and the operating frequency segment is at 800MHz CDMA.
At present, the world's mainstream 4G LTE technical standards belong to special high frequency and ultra-high frequency.
Our country mainly uses ultra-high frequency:
Everyone can see that with the development of 1G, 2G, 3G, 4G, the radio wave used is getting higher and higher.
This is mainly because the higher the frequency, the more frequent resources can be used. The richer frequency resources, the higher the transmission rate that can be realized.
Higher frequency → More resources → faster speed
Frequency resources are like compartments, the higher the frequency, the more traffic, the more information that can be loaded in the same time.
So, how much is the frequency used in 5G? As shown below:
The frequency range of 5G is divided into two: one is 6 gHz or less, this and the current difference between our 2/3 / 4G is not too big. There is also one, it is very high, at 24GHz, currently, 28GHz is mainly used for testing.
If you press 28GHz, according to the formula we mentioned above:
This is the first technical feature of 5G -
The bottom line is "mm wave"
Since the frequency is so good, you will be asked: "Why don't we use high frequencies?"
It is not necessary to use it.
Significant features of electromagnetic waves: The higher the frequency, the shorter the wavelength, the closer to the linear propagation (worse the wreath of the wall). The higher the frequency, the greater the attenuation in the propagation medium.
You look at the laser pen (about 635nm wavelength), the light shot is straight, it will not go.
Look at the satellite communication and GPS navigation (about 1cm wavelength), if there is a shield, there is no signal.
Satellite mouth, must calm down the direction of the satellite, otherwise, even if it is slight, it will affect the signal quality.
Mobile communication If used in a high frequency, then its biggest problem is that the transmission distance is significantly shortened, and the overlay capacity is greatly reduced.
Cover the same area, the number of 5G base stations required will be larger than 4g.
What is the number of base stations mean? Cost!
The lower the frequency, the more money is saved, the more favorable competition. That is why, these years, telecommunications, mobile, and Unicom compete for the head of the head.
Some bands are even called - Gold Frequency Section.
This is why, 5G era, operators desperately demonstrate the equipment, and hope that the base station will cut prices. (If you really go to 5G, according to the previous model, the equipment manufacturer will send a big wealth.)
Therefore, based on the above reasons, under the premise of high frequency, in order to mitigate the cost of network construction, 5G must find new ways.
First, it is a micro base station.
There are two kinds of micro base stations and a macro base station. Look at the name, I know that the micro base station is very small, the Hongji station is very big!
Acer Station:
In fact, there are many micro base stations, especially in urban and indoors, often can be seen.
Later, to the 5G era, the micro base station will be more, and it will be installed everywhere, almost everywhere.
So many base stations are around, will it affect the human body? Not.
In fact, and traditional cognition is just the opposite, in fact, the more the number of base stations, the smaller the radiation!
You want to, in winter, a group of people's houses, a big power heater is good, or a few small power heaters?
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The base station is small, the power is low, and everyone is good. If only one large base station is used, close, radiation is large, far away, no signal, but not good.
In the past, the big brother had a long antenna, and the early mobile phones also had a high-tech small antenna. Why don't our mobile phone don't have an antenna?
In fact, we don't need an antenna, but our antenna becomes smaller.
According to the antenna characteristics, the antenna length should be proportional to the wavelength, approximately 1/10 ~ 1/4.
As time changes, our mobile phone's communication frequency is getting higher and higher, and the wavelength is getting shorter, the antenna will be shortened!
Millimeter wave communication, the antenna also turns millimeter. . .
This means that the antenna can make it inside the phone, and even a lot of roots. . .
This is the third big killer of 5G -
MIMO is "Multiple-Input Multiple-Output), multiple antennas, and multiple antennas are received.
In the LTE era, we already have MIMO, but the number of antennas is not much, can only be said to be a primary version of MIMO.
In the 5G era, continue to carry MIMO technology, and now turn into a enhanced version of Massive Mimo (Massive: large-scale, large number).
There are many antennas in the mobile phone, and the base station is not more useful.
The previous base station, the antenna is then a few:
5G era, the number of antennas is not based on roots, and it is "array". . . Antenna array. . . At glasses, you have to dense phobia's rhythm. . .
However, the distance between the antenna is not too close. Because of antenna characteristic requirement, the distance between the multi-antenna array requires the distance between the antenna or more than half a wavelength. If the distance is near, it will interfere with each other and affect the transmission and reception of the signal.
Everyone has seen the light bulb glow? In fact, when the base station transmits the signal, it is a bit like a light bulb. The signal is launched around, for light, of course, it is illuminated throughout the room, if it just wants to illuminate a region or object, most of the light is wasted. . .
The base station is also the same, and a lot of energy and resources are wasteful. Can we find an invisible hand, take the scattered light beam? This saves energy and ensures that there is enough light to illuminate. The answer is: Yes. This is -
In the current mobile communication network, even two people face each other's mobile phones (or mobile photos), the signals are transferred through the base station, including control signaling and packets. . .
In the 5G era, this situation is not necessarily.
5G fifth largest features - D2D, that is, Device to Device.
D2D
The 5G era, two users under the same base station, if they communicate with each other, their data will no longer be forwarded through the base station, but directly to the mobile phone. . .
In this way, a large number of aerial resources are saved, and the pressure of the base station is also reduced.
Original address: https://www.eeboard.com/news/5g-152/
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