How can mobile phones enjoy 5G signals at an altitude of 10,000 meters?
With the squeaking rumbling, a leader shaped like a giant bird, flying across the stadium like clouds and mist, immediately jumped up and skyrocketed for ninety thousand miles. Every day, there are thousands of such outstanding people, transporting "the essence of space, the primates of all things in the universe," spreading their wings and soaring 10,000 meters above the clouds.
But this kind of passenger is always in anxious mood all the time. That's because the dialog box for them to communicate with the world—the mobile phone, is only in the mobile phone flight mode. From the gap-connected Internet, they have turned into unspoken desert islands. Please take a look at their personal monologues: "I had to report to the customer for work, but it was delayed." "Think more about showing your girlfriend the beautiful scenery in front of the window...or take some photos!" It’s so boring for many hours here. If you can play mobile games, it’s so good, but you can’t connect to a web server without a network!” This obvious requirement is calling for the best that everyone has long been unaware of. Friends of: 5G, you hurry up, God, come! In fact, communication satellites covering the whole world have already made surfing the Internet at a height of 10,000 meters a reality, but because of the small network bandwidth and increased costs, of course, they have caused considerable prices. Therefore, with the exception of a few successful men who have experienced it, most people have chosen to endure it. That gives another kind of indoor space for conceived expansion. That is: aren't there many 5G base stations on the road? If the signal can be sent to the sky and the signal can be received on the phone on the plane, will everything be normal online?
Sounds like a good way! But when I think about it, it seems that there are quite a few problems. 1. How far can the base station send the signal? Generally speaking, in a concentrated urban area, the coverage area of the base station is 500 meters. In remote areas, it will hit the head for as many kilometers. At first glance, it does not seem to have the ability to cover up to 10,000 meters. In fact, when building a website in 5G, how many base stations must be, and network planning must be carried out first. The key to network planning is considered from two levels: volume and coverage. To put it bluntly, the capacity is to serve an area of the project. If anyone's online requirements are met, how many base stations must be used.
Because the volume of each base station is constant, a total number of base stations must be calculated from the volume level. For everything to cover a metropolis normally, the number of road base stations required is likely to be tens of thousands. To put it bluntly, it means that the signal sent by the base station has experienced indoor space dissemination loss, blocked by various flowers and trees, and obstructed reflection surface mapping. Finally, it can be received by your mobile phone, and the signal sent on the mobile phone can also be obtained. The larger distance successfully accepted by the base station. Generally speaking, the base station is an outstanding one on the relative mobile phone, and the signal strength of the signal is much stronger than that on the mobile phone, so in theory, it can send far away. For example, the radio and television towers used in many large cities are actually equivalent to a large base station. Because of the large output power and high height, one tower can cover all large cities. If the wireless antenna of the base station is pointed at the sky to send a signal, because there is nothing to block, the propagation loss will be relatively small, and the scope of the signal will be wider. This is simply a straight line of perspective. Moreover, because the planes in the sky are relatively rare, the total number of passengers is also very small, and there are fewer people on the Internet, so when the sky is covered, the main consideration is that the coverage is not the volume.
As shown in the figure below, the line is broken from the height of the base station to the earth, and the line is added until it is the same as the cruise altitude of the aircraft in the sky, and the sky coverage of the base station is obtained: d=d1 d2. If the aircraft's cruise altitude is 12,000 meters, the coverage of a ground-to-air base station can theoretically reach 400 kilometers. Considering some capacity, more than a dozen base stations can cover one channel, and only a few hundred websites are needed to cover all parts of the country. I don’t know that there are also problems to consider here. The base station can send signals so far, but the mobile phone is only a small one hundred grams, and the working ability is weak. Can it receive signals from base stations hundreds of kilometers away? Moreover, communication is twofold, the key to decline, and the upward and downward movements are also very important. The signal strength on a 5G mobile phone is 0.4 watts at most. Can the transmitted signal travel hundreds of kilometers to reach the base station? This leads to the following question. 2. Can the mobile phone receive the signal from the base station on the road at a height of 10,000 meters?
Actually it is not good. Not only can the mobile phone not receive the signal from the base station on the plane, the base station is also unlikely to receive the signal from the base station. What can I do? Let the plane deliver the goods on your behalf. According to the upgrade and transformation of the aircraft, the abdominal cavity of the aircraft is equipped with a technical professional wireless antenna with power amplification, and it can communicate freely with base stations hundreds of kilometers away. After receiving the signal from the base station, the wireless antenna on the plane converts the 5G signal into a wifi signal according to a weapon called CPE (Customer Premises Equipment), so that all passengers can connect to the wifi network. In the 5GL band CPE, the uplink and downlink data information of all customers are finally gathered on the CPE, and then converted into 5G signals, and pushed out according to the L-band wireless antenna, which is resolved by the base station on the road, achieving the closed-loop control of the life of the Pitbull.
3. If the plane can fly so fast, will there be any harm from frequency deviation? Will do. But it can be adjusted according to frequency offset compensation. To put it bluntly, the Doppler effect means that when the aircraft flies towards the base station at high speed, the frequency of the signal will cause a positive deviation and become higher and higher; and when the aircraft leaves the base station, the frequency of the signal will vary. Negative deviation and a sharp decline. According to scientific research, if the 4.9GHz frequency band is used, the frequency deviation has already reached 5CHz when the aircraft speed is 1200km/h. At this time, it must be solved according to the unique correction and optimization algorithm of the base station and CPE before the system software can work normally. middle.
In summary, based on a series of ground-to-air coverage technologies, road base stations can cover the sky, making it a reality to enjoy 5G at a height of 10,000 meters. Many 5G requirements such as remote video conferencing, ultra-clear video, and even cloud gaming platforms mentioned above can be carried out smoothly, making the originally simple and anxious journey more and more convenient, faster and more enjoyable.
