Author | Ma Chao
Zebian | Hu Weiwei
Exhibition | CSDN (ID: CSDNnews)
The three major US stock indexes recently ushered in two epic slump, first on March 9, the Dow fell nearly 19 points, the S & P 500 plunged 7 percent, both fuse; after March 12 is the S & P 500 in the opening 5 minutes then slid 7 percent, triggering fuse again, and with the multi-national political figures confirmed infected with the new virus crown, the United States declared a state of emergency.
In US stocks fuse "living longer see" Background two-week, the US Federal Communications Commission auction millimeter wave spectrum, accelerate the construction of 5G initiatives, there is the taste and feel of Chinese copy "new infrastructure" of the job. However, "the world is a big copy paper," We know that the financial crisis in the beginning of the last century, the United States is relying on the construction of highways and other infrastructure out of the woods, the face of the crisis, the United States hopes to 5G, etc. the emerging field of information technology construction, it would be a sensible approach.
According to the US Federal Communications Commission, they, auction 39GHz and 47GHz spectrum obtained from 37GHz to 5G of $ 4.5 billion in revenue, but also received nearly $ 3.1 million in incentive bonuses to speed up the clearance from these bands now some licensees.
These two combined revenue of $ 7.558 billion. The auction giant called the event, which Verizon come out on top in the latest bid to win the 4940 license, followed by AT & T won the 3267 license, 2651 Dish Network license and T-Mobile the 2384 license.
Prior to recording the highest turnover of the largest US spectrum auctions is 24GHz and 28GHz bands two waves of $ 2.7 billion, so from this high price of nearly $ 7.6 billion deal, the United States can be seen in other high-tech to bring 5G the new economic growth point is in dire need of. Here the author do some technical interpretation auction behind 5G millimeter wave.
Why millimeter wave 5G become the darling of the times
It refers to a millimeter-wave band 30GHz ~ 300GHz, corresponding to a wavelength of 1mm ~ 10mm. It refers to millimeter-wave communication as a carrier wave communication for transmitting information carried out. Millimeter wave spectrum auction, in fact, the right to use the millimeter wave spectrum auction. It belongs to the millimeter-wave high frequency band, as to the direct wave which propagates in space, a very narrow beam having good directivity. The main advantage of millimeter waves is as follows:
Extremely wide bandwidth: millimeter wave bandwidth of up to 270GHz. Over the full bandwidth from DC to the microwave 10 times. Even considering atmospheric absorption, use of only four main windows propagates in the air, but also the total bandwidth of up to four windows 135GHz, microwave or less 5 times and bandwidth of each band. With a variety of multiple access multiplexing technique can greatly enhance the use of channel capacity for high-speed multimedia transmission services, which undoubtedly attractive in a tight frequency resources today.
Narrow beam: narrow beam of millimeter-wave beam at the same size than the microwave antenna much. For example a 12cm antenna, when the beam width of 18 degrees 9.4GHz, 94GHz and a beam width of only 1.8 degrees. It can be resolved spaced closer or smaller target more clearly observe details of the object.
High reliability: higher frequency interference so small, to provide a stable transmission channel; compared with a laser, the millimeter wave propagation is much less affected by climate.
Strong directional: Because the beam is narrow, increasing the difficulty of eavesdropping, for short-range ad-hoc communication;
Very short wavelength: desired antenna size small, compared to microwave, millimeter wave components of much smaller size. Therefore millimeter-wave systems more easily miniaturized.
There is a problem of millimeter wave
In the 30 years between the development of mobile communications, millimeter wave has always been a wild land, due to the past, people are not high bandwidth requirements for mobile communications, optical fiber transmission have only 512K or less of the era, millimeter wave technology offers In fact, high bandwidth and do not have much significance.
At the same time, also because of problems millimeter wave transmission distance, so operators need to set up more base stations in order to ensure network coverage, so the low speed of the Internet era, people's attention from the natural millimeter wave. Millimeter wave short summary of the principal should have the following aspects:
Shorter distance: high-frequency characteristics of the millimeter wave technology, millimeter wave propagation distance as compared to low frequency itself is shorter, so operators need to implement a large-scale coverage often requires a more base stations and operating costs.
Attenuation caused by rain and suspended particulate matter more: millimeter wave is mainly affected by air to absorb all kinds of suspended particulate matter larger than the microwave, millimeter-wave signal in bad weather conditions, especially during rain attenuation serious, to spread the effect of great impact. Typically, the larger instantaneous rainfall intensity, the greater the distance, the larger the raindrop, the attenuation due to the stronger. Therefore, to deal with rain attenuation is the most effective way to design, leaving enough margin level attenuation during the millimeter-wave communication system or communication lines.
Millimeter wave antenna technology too difficult: because the current power integrated circuit (IC) emission is not high, and millimeter wave easily absorbed by air, so to signal long range, they need to use high-gain antenna, but only high-gain antenna can focus on a direction towards a launch, because the mobile phone users are not only in a fixed position, but multi-faceted mobile, mobile phone antenna will therefore be as phased array radar-like non-stop scanning, in order to contact with the transmitter, and how to make phone scanning angle phased array antenna broad enough, millimeter-wave applications is a major technical problems to face promotion.
5G age, technology is king
5G era, bandwidth and user experience has become the first mobile network to meet demand, so the millimeter wave will be so interesting. Since the above mentioned also the biggest drawback is the attenuation of the millimeter wave propagation in the atmosphere near the transmission distance and large. In case of suspension and precipitation attenuation serious, so that it corresponds to several key technologies related to the 5G:
Massive MIMO: large-scale multi-input, multiple output antenna technology, MIMO antenna is the meaning of "multiple input, multiple output" (Multiple-Input Multiple-Output ). In the era of 4G MIMO technology has been applied, but that is up to 8 base station antenna, phone antenna 4, but in the millimeter-wave band applications, the antenna is transmitting power can not be increased, the gain of the transmit and receive antennas can not increase too much, Therefore, only solution - increasing the number of transmit and receive antennas, and the mm wave length, mutual interference between the small distance between the antennas can be closer together, the 5G antenna number is not counted, but the array The antenna, which is Massive MIMO.
Beamforming: beam forming, 5G era of large-scale antenna beam-forming technology is the basic condition. In the absence of jamming, the electromagnetic wave is a 360 degree spread, much of it is not received, wasted, so that the antenna array may be artificially predetermined direction toward the electromagnetic wave propagation, and the more the number of antennas, electromagnetic wave propagation the more centralized direction. Beamforming allows wireless transmission of a signal directed to the desired direction for use, but also the need to constantly adjust beam steering technology according to the position change in the signal reception point, which is the key to the beam-forming technique.
5G era in the world, Huawei is rated one of the best. 2019, Ren said in an interview once said: "The world rarely do 5G manufacturers, Huawei is doing the best; the world can do little microwave manufacturers, Huawei has done the most advanced able to 5G. the base station and the most advanced microwave technology to combine into a base station, the world's only one company can do is Huawei. "
Microwave here actually refers to the millimeter-wave, opportunities always favor those who are prepared, in the present case, the whole world will look forward brought about by growth 5G, I believe we will be able through the clutter and reach the peak.
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