Ubiquitous Network - Ubiquitous Internet

There are thousands of fans of Doc.com, and the mobile phones used by fans are also various. I believe some fans will find that when some users want to turn on data traffic, they find that the settings interface has changed to "Cellular Network". You must be curious. What is a "cellular network"?

In fact, the concept of cellular network has already appeared in the late 1940s. After the continuous development of technology, we are now in the fifth generation of cellular mobile communication system. Then do you know why it is called a cellular network? Let Doc take you through it!

Why is it called cellular network?

Everyone knows that there are many types of mobile communication application systems, such as satellite communication systems, radio paging systems, trunking systems, etc. In order to pursue maximum coverage and maximize resource utilization, the mobile communication system uses a conclusion in mathematical calculations to establish a cellular communication system: a circle with the same radius covers the plane. When the center of the circle is at the center of the surrounding hexagons, At the exact center, the smallest number of circles is used. So the base station coverage is distributed in a hexagonal shape, with a base station in the center of each hexagon, making the entire network like a honeycomb, so it is called a cellular network.

How do cellular networks work?

The cellular network is mainly composed of three parts: mobile station, base station subsystem and network subsystem. ##Mobile stationNetwork terminal equipment, For example, mobile phones and cellular industrial control equipment. Base Station SubsystemConverter between wireless network and wired network, mobile base station, wireless transceiver equipment, dedicated network and digital equipment. Network subsystem Places computer system equipment, switches, closed-circuit television control equipment, etc. In a cellular network, each base station is responsible for providing radio signal coverage within a certain range. These base stations are connected to each other through the control system and transmission system to form a complete communication network. Since the coverage of each base station is limited, multiple base stations need to cooperate with each other to ensure that communication can be achieved throughout the network coverage. So how does the cellular network achieve communication? In the cellular network, each base station is connected to a switch. When a mobile phone user enters an area, the mobile phone will automatically connect to the base station in the area. The switch is responsible for forwarding the mobile phone user's communication request to the target user or other networks. , the base station will transmit your signal to the signal tower through radio waves, and then the signal tower will transmit the signal to other base stations, and finally reach the destination. This process is like bees transmitting information in the hive. If a mobile phone user is within the coverage area of ​​multiple base stations, the mobile phone will give priority to connecting to the base station with a better signal. If many mobile phones are connected to an area, will the signal become worse? This has to mention the frequency reuse of cellular networks! When using a mobile phone to communicate, each person has to occupy a channel. If there are too many people talking, the limited channel will not be enough, which will lead to communication congestion. The emergence of cellular networks has solved this problem. The use of cellular structure allows different base stations to use the same frequency for communication, thus achieving the purpose of saving frequency resources. For example, we divide a city into 12 regions, and every 3 regions form a district group. Let them all use 100 channels together. Then, we can divide the 100 channels into 10 groups, each group has 10 channels. Area No. 1 of the first block group uses the channel group 1, and area No. 2 of the first block group uses the channel group 2. And so on. After arrangement, the same numbered area in different area groups can reuse the same channel group. Although the radio frequencies used by base stations in these areas are the same, because they are far apart from each other, the range of radio waves is limited and will not cause interference to each other. In this way, a set of frequencies can be reused 6 times. Originally, 100 channels can only be used by 100 users to talk at the same time. After frequency reuse, 600 users can talk at the same time, which greatly improves the efficiency of channel use.

Conclusion

In fact, cellular networks are not only widely used in mobile communications, but also indispensable in the Internet of Things. Compared with traditional wireless network technology, the cellular Internet of Things has higher reliability and stability, and currently covers many fields such as industry, agriculture, medical care, and smart homes. Although cellular networks can support a large number of devices connected at the same time, they still face some challenges. First of all, radio waves may be affected by factors such as buildings and terrain during transmission, causing signal attenuation or interruption. Secondly, as more and more people use mobile phones and other devices, network congestion problems are becoming increasingly serious. Okay, Document Master and everyone have learned the following knowledge: Cellular network is exquisite mathematics, and it is also a natural aesthetics borrowed from the natural evolution of bees. To operate perfectly, cellular networks require the cooperation of more communication equipment, such as mobile base stations, switches, etc. Everything is developing and changing, and cellular networks also face different challenges, and they continue to face challenges and continue to make progress. This article comes from the WeChat public account: ZTE Documents (ID: ztedoc)

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