Mobile communications - generations

Mobile communications - generations Since mid 80's of the last century people have started to use mobile phones, cell phones. Technologies, that such radio communications are based on, improve constantly. Consequently, the quality and quantity of services provided are also improved. At the moment there are already 4 generations of mobile telephony - 4 steps, which are characterized by some significant technological breakthroughs. Let's briefly take a look, what new was introduced with each generation. As far as in English generation starts with "g", each of the generations is called by a serial number with the letter G in the end. Thus, the first generation, of 1G standard, was being developed since the early 70s, and was implemented in the mid-eighties. It was an analog connection. For data transfer, the frequency modulation and frequency division of channels -- FDMA -- were used. Due to such method the network capacity was low, just like the data transfer rate - only 1.9 kilobits per sec. There were no additional features. Common standard of networks of the first generation was a standard Advanced Mobile Phone Service, AMPS, frequency of 800MHz. It became widespread in the USA. With the growing number of subscribers and the development of digital circuits the transition to digital systems was inevitable. So the second generation networks 2G appeared. At the moment, despite the gradual transition to more modern standards, the 2nd generation remains the most common. The 2G standard is a well-known GSM; the range is 1800MHz most often. It uses time-division multiple access. Multiple users separated by the time intervals of transmission can operate in the same frequency band. The size and weight of phones themselves diminished at once. The number of subscribers increased. The transfer rate increased immediately to 14.4 kilobits per sec. Many new features appeared, such as call forwarding and call hold, caller ID, rater, voice mail and, of course, short messages sending, SMS. The only disadvantage with respect to analog systems can be possibly only the greater number of base stations to cover the territory. Later, by the end of the 90s, within the 2 generation there was a noticeable superstructure - an improvement. GPRS. And it gave the opportunity to transfer data between devices and external networks. That is, access to the Internet from a mobile phone became available. The 2nd generation ...