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Features of lifting mobile communication

Time:2021-01-12 View:

Mobile communications communicates communication between mobile users and fixed point users or between mobile users.
Communication: one or two parties are in motion. Including land, sea and air mobile communication. The frequency band used covers low frequency, intermediate frequency, high frequency, very high frequency and ultra high frequency. The mobile communication system consists of mobile station, base station and mobile exchange office. To communicate with a mobile station, the mobile exchange office sends a call to the whole network through each base station, and the called station sends a response signal after receiving it, after receiving the response, the mobile switching office assigns a channel to the mobile station and transmits a signal to ring the mobile station from this channel.

Introduction
Mobile communication (Mobile communication) is the communication between moving bodies or between moving bodies and fixed bodies. The moving body can be a person or an object in the moving state such as a car, train, ship, radio, etc.
Mobile communication is a modern technology for wireless communication, which is one of the important achievements in the development of electronic computers and mobile Internet. With the development of the first, second, third and fourth generation technologies, mobile communication technology has entered the era of the fifth generation (5G mobile communication technology), this is also one of the main technologies that change the world at present.
Modern mobile communication technology can be divided into low frequency, intermediate frequency, high frequency, very high frequency and ultra high frequency. In these frequency bands, technicians can use mobile station technology, base station technology and mobile switching technology, connect terminal devices in the mobile communication network to meet people's mobile communication needs. From analog mobile communication system, digital cellular communication system and mobile multimedia communication system to the current high-speed mobile communication system, the speed of mobile communication technology is continuously improving, and the delay and error code phenomena are reduced, the stability and reliability of the technology are constantly improving, providing a variety of flexible communication methods for people's production and life.
In the past half century, the development of mobile communication has had a profound impact on people's life, production, work, entertainment, politics, economy and culture. 30 years ago, the imaginary UAV, smart home, online video, online shopping, etc. have been implemented. Mobile communication technology has gone through five development stages: simulation transmission, digital voice transmission, Internet communication, personal communication and new generation wireless mobile communication.

Features
(1) mobility
It is to maintain the communication of the object in the moving state, so it must be wireless communication, or the combination of wireless communication and wired communication.
(2) complex radio wave propagation conditions
Because the moving body may move in various environments, electromagnetic wave will produce reflection, refraction, diffraction, Doppler effect and other phenomena during propagation, resulting in effects such as multipath interference, signal propagation delay and broadening.
(3) serious noise and interference
Automobile spark noise, various industrial noise, intermodulation interference between mobile users, adjacent channel interference, co-frequency interference, etc. in urban environment.
(4) complex system and network structure.
It is a multi-user communication system and network, which must enable users to work in a coordinated manner without interference. In addition, the mobile communication system should also be interconnected with the local telephone network, satellite communication network, data network, etc. The whole network structure is very complex.
(5) high frequency band utilization and good equipment performance are required.