What is a cellular system
Cellular means that the mobile network is shaped like cellular coal. The cellular communication system has experienced the first generation (1G), the second generation (2G), and is developing towards the third generation (3G), and the fourth generation (4G) March forward. The first generation of mobile communication systems simulates cellular phones. There are mainly NMT in Northern Europe (450MHE and 900MHE) and 900MHE, which have been used in China. The second generation mobile communication system is a digital cellular phone. China has adopted the European GSM system, China Unicom's public CDMA system (Code Division Multiple Access, 800MHE), etc. Because CDMA adopts coding technology of code division multiple access, its frequency utilization rate is high. The same frequency can provide more call channels, and its quality and confidentiality are also better. The goal of the third-generation mobile communication is for high-speed data and multimedia applications. When the terminal is used, it can reach 2Mb / s indoors, the rate of walking is 384kb / s, and the speed of high-speed vehicles is 144kb / s. The third-generation mobile communications has passed several major 3G standards under the requirements of the International Telecommunication Union IMT-2000 technical standards. While developing 3G, the world has begun to research and develop the fourth generation mobile communication (4G) and the fifth generation mobile communication (5G). The transmission rate of 4G can reach 10mb / s. 4G will be able to combine the LAN (similar to infrared, which can replace the wiring of the electrical equipment of indoor computers) wireless LAN and 3G technology to form a seamless communication solution and corresponding The product. In addition to calling and receiving rich multimedia information, 5G mobile phones can also demonstrate 3D stereo games and participate in 3D stereo video conferences.
Glass exit signs and emergency lights help to safely evacuate even the most complex buildings. When a fire or natural disaster causes a building to lose power, these signs are intact and illuminated, guiding those inside to safely evacuate and escape. The glass exit signs are highly permeable, giving you clear directions even in the dark, and the letter words "EXIT" can be custom printed on the glass. Suitable for use in shopping malls, cinemas, parking lots, office buildings, hotels, and other public places. Glass emergency signs are easy to install, can be mounted on the wall or hung from the ceiling, and can be rechargeable for continuous operation.
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