The mobile Internet is becoming more and more involved in our daily lives, so the presence or absence of mobile phone signals will have a very real impact on its users. Why do mobile phones sometimes have no signal? Xiaobian takes everyone to see.
The product form of the smartphone (the influence of materials, the design of the antenna), and the pattern of the telecom operators (bands) have also been visible in the past few years, and they are also tangible changes, which directly or indirectly Affects the signal reception of the mobile phone.
Some people have a fear when the mobile phone has no signal.
In the actual situation, we know that the mobile phone is in the subway, in the elevator, in the mall, or in the suburbs, there may be no signal. So in order to answer the question of why the mobile phone has no signal, we might as well change the angle from how the mobile phone performs normal communication as the starting point.
So what are the conditions for the mobile phone to receive the signal (communicate with the base station)? The simple summary comes down to the following three points. If these three points are well met, the mobile phone we hold in our hands can also be called a mobile phone and can be used as a communication tool.
1. The mobile phone is within the signal range of the base station
2, the phone can send out and receive the signal
3. The standard frequency bands of the two can match
Whether the mobile phone is within the signal range of the base station
A large tower (base station) is used to establish and maintain contact between mobile phones and mobile phones, mobile phones and content sources. Smartphones have been popular for so many years, and it is estimated that most consumers should have a similar understanding of this.
"The big tower (base station) brings a signal to the mobile phone." This statement is true, but for friends living in the city, the iron used to transmit signals (high-frequency radio waves) is not imagined. It's so big, and its radiation is not that high.
A beautified tree-like cellular data network base station in the city
1. Limited base station processing capacity in cities
In a city, the base station exists in a "small but many" way. If the range of different base stations and their signal coverage can be graphically represented, it should be a honeycomb-like shape, so there will be a setting option in the mobile phone. An option for cellular data networks.
The advantage of cellular data networks is to address high-density access requirements. If a city only has a large tower in the middle of the city, it cannot solve the problem of frequency reuse (a frequency can only correspond to one piece of information), and the attenuation of signal strength. .
The signal range covered by the base station in the city is graphically similar to the hive style
2. Limited coverage of small base stations
The signal coverage of a small base station is almost within one kilometer of its radius, so there are many such base stations in the main city of Beijing. However, the rapid expansion of the city's base station construction is not timely, and naturally there are some blind spots.
The base station is small in scale, and the penetrating power of the signal is relatively weak. Therefore, mini base stations are set up in the office buildings and subway stations to enhance their signal coverage. But the "iron scorpion" like the elevator is basically unsolvable, so if you want to call, don't go to the elevator.
The "iron scorpion" shape of the van elevator has a great influence on the signal of the mobile phone.
3. There is a physical signal dead zone between each base station
In addition to the complete lack of coverage (mainly 3G\4G network) and the weak signal penetration, when we are at the node location of each small base station, the choice of mobile phone edge signals for different frequency bands will also cause network quality. This is also inevitable.
Can the phone send out and receive a signal?
It took a decade to push forward. It was not uncommon for the mobile phone to have an antenna and a bump. After all, the development of the semiconductor and communications industries was not as developed as it is today. Of course, the scale of the construction of base stations is not as large and so systematic.
Although the design of the external antenna has been completely eliminated in the evolution of the mobile phone in the past ten years, the mobile phone itself still needs to have the design of the physical antenna, and the baseband chip and radio frequency chip matched with it. Then this system will also determine the signal transmission and reception.
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