The first steps
Wireless radio communications are the sources of mobile calls. In fact, we are talking about the same type of communication used by organizations such as police, firefighting department or ambulances. The system later became more commercially available and used in cars or as briefcases. The increased demand for using these services soon revealed their capacity limitations. Thus, cellular networks began to work as a way to provide widespread telephony services.
First generation (1G)
The first analog automated cellular networks were launched in Japan in the late 1970s and spread throughout the country until 1981. In the same years, Nordic countries (Finland, Sweden, Norway and Denmark) also launched similar networks. The first American cellular network was launched in 1983.
The reason for the use of the cellular name, which was later shortened to Cell, was the way antennas were arranged and used to transmit signals. As long as the user was in the area (cell) of a particular antenna, all communications were made through the same antenna, but when it arrived at another antenna's cell, communications were transmitted to the second antenna's signal channel. The configuration of the antennas was performed in such a way that no similar frequencies be used in the two adjacent cells to eliminate the possibility of interference. However, reuse of a frequency in non-adjacent cells was predicted.
The first generation of mobile networks, while being very advanced at the time, had a simple structure. These networks were used only for voice calls and did not have much security. In fact, the conversations that were made on these networks could easily be eavesdropped using a simple scanner.
With all these issues, mobile networks could quickly establish their position among users. The statistics show that the market has grown from 30 to 50 percent per year and to 20 million subscribers by 1990.
Second generation (2G)
With the expansion of mobile networks and increased consumer demand, it was time to optimize services essentially in several aspects. Thus, the second generation of mobile networks launched in the early years of the 1990s. The main difference of this generation was the use of digital modulation instead of the previous generation's analog method. In this way, the quality of voice conversations has improved considerably.
Another important event in this generation was the division of the global market between the two standards. The European countries developed the GSM system (Global System for Mobile Communications). On the other hand, the US went through the CDMA (Code-Division Multiple Access) standard, which was later used in South Korea. These two standards have multiple technical differences, but the GSM standard is the focus of our discussion due to its wider use and reliance on the SIM card.
The digital nature of 2G also has other capabilities than just better conversations quality for users. One of these capabilities was the ability to exchange SMS (Short Message Service), which later evolved with MMS (Multimedia Messaging Service).
The second generation of mobile networks initially provided very limited facilities for data exchange and Internet access. This situation continued until the introduction of GPRS (General Packet Radio Service) in the late 1990's. The technology provided a method for always-on data communication to the network for the transmission of information. The second-generation networks that are equipped with this technology are known as 2.5G networks. The maximum transmission speed of the GPRS data is from 56 to 114 kbps, which of course can't be considered as a significant speed. So, due to the gradual growth of user dependency on Internet services, an upgraded version of GPRS, called EDGE (Enhanced Data Rates for GSM Evolution), was introduced. During its evolution, the technology was able to deliver data rates up to 400 kbps. Networks that use this technology are sometimes known as 2.75G.
Third-generation networks (3G)
The third generation of mobile networks delivers extreme call quality and capabilities. At the same time, this generation introduced the possibility of making video calls. But in the meanwhile, it's possible to say the third-generation achievements in data transfer are most important to users.
The third generation of mobile networks was designed to provide a minimum data transfer rate of 145 kilobits per second. However, the process of evolution and improvement of various technologies and standards in this generation has continued steadily. These technologies maximized the nominal data transfer rate to 10 megabits per second. In fact, there are still many discussions about considering some technologies as the third or fourth generation. However, the third generation of mobile networks, which has been evolving around the next generation of 3.5G, has been able to create a good user experience from high-speed Internet connections for users and their dependence on Internet services. High speed and easy access have led users to take advantage of online applications that provide a variety of features. In this way, the third generation paved the way for fourth-generation networks, focusing solely on providing services and solutions for faster and more convenient Internet access.