Despite the fact that 3G is already actively used in almost every cell phone, the average person still does not understand: where did such a sharp improvement in the quality of communication come from and why so much talked about the new technology? Alas, it is impossible to understand this when speaking exclusively about 3G, because everything is learned in comparison - and it is in comparison with previous generations that the "troika" made a revolution.
The cell phone in your pocket works like a small radio: it transmits your speech to the base station using certain frequencies. Everything seems to be simple: the device of any user tunes to a specific frequency and uses it throughout the conversation. Accordingly, the number of subscribers in the network depends only on the available frequency band. In scientific parlance, this is called FDMA - Frequency Division Multiple Access, and this is the first generation of cellular communications. However, practice shows that the number of subscribers in this case turns out to be unjustifiably small, and the available bandwidth is used irrationally. Therefore, having carried out the appropriate calculations, the engineers found out that it is not necessary to transmit the signal all the time. A segment of 1/8 of a second is enough so that a person does not notice communication breaks: therefore, several times more subscribers were placed on each frequency, who shared not only the frequencies, but also the transmission time, communicating with the base station for only a small fraction of a second. Second generation systems were built on TDMA - Time Division Multiple Access. The third generation of networks uses a fundamentally different communication scheme, and that is why it is considered revolutionary. Now there is no need to divide space by time or frequencies, because all subscribers simultaneously use the entire spectrum throughout the entire conversation. This is achieved through a fundamentally new technology: CDMA. Now the signals are differentiated among themselves not in time or frequency, but thanks to special codes embedded in the transmitted information. Thus, referring to the entire space with a specific code, the base station will allocate for itself only one necessary conversation. Mnemonically, it is convenient to think of it as a room full of people. In the first and second generations, people spoke in turns or in different corners of the room so as not to interfere with each other. Now people speak different languages. And if you enter such a room, then from the general cacophony of sounds you can easily distinguish conversations in your native language. Obviously, this approach has opened up much greater opportunities for the transfer of information, available speeds and the number of subscribers, because now there are practically no restrictions on the use of network resources.
