What is a “generation” of cellular networks?
The generation of cellular communication is a set of functional capabilities of the network, namely: registration of a subscriber, establishment of a call, transfer of information between a mobile phone and a base station over a radio channel, a procedure for establishing a call between subscribers, encryption, roaming in other networks, as well as a set of services provided subscriber.
The evolution of cellular systems includes several generations of 1G, 2G, 3G and 4G. Standards of various generations, in turn, are subdivided into analog (1G) and digital communication systems (the rest).
Let’s consider them in more detail.
Communication has always been of great importance to humanity. When two people meet, a voice is enough for them to communicate, but as the distance between them increases, the need for special tools arises. When Alexander Graham Bell invented the telephone in 1876, a significant step was taken to allow two people to communicate, but to do this, they needed to be near a fixed telephone set! For more than a hundred years, wire lines have been the only way for most people to organize telephone communications. Radio communication systems that do not rely on wires for network access were developed for special purposes (for example, the army, police, navy, and closed car radio networks), and, eventually, systems appeared that allowed people to communicate on the phone using radio communication. These systems were primarily intended for people who traveled in cars and became known as mobile telephone systems.
First generation of mobile communications (1G)
The official birthday of cellular communications is April 3, 1973, when Motorola’s head of mobile communications, Martin Cooper, called Joel Engel, AT&T Bell Labs’ head of research, while on a busy New York street. This technology was commercialized 11 years later, in 1984, in the form of first generation (1G) mobile networks, which were based on an analog method of information transmission.
The main standards for analog mobile communications are AMPS (Advanced Mobile Phone Service) (USA, Canada, Central and South America, Australia), TACS (Total Access Communications System) (England, Italy, Spain , Austria, Ireland, Japan) and NMT (Nordic Mobile Telephone – northern mobile phone) (Scandinavian countries and several other countries). There were other standards for analog mobile communications – C-450 in Germany and Portugal, RTMS (Radio Telephone Mobile System) in Italy, Radiowoman 2000 in France. In general, mobile communications of the first generation were a patchwork quilt of incompatible standards.
All analog standards use frequency (FM) or phase (PM) modulation for voice transmission and frequency shift keying for transmission of control information. This method has a number of significant disadvantages: the ability to listen to conversations by other subscribers, the lack of effective methods to combat signal fading under the influence of the surrounding landscape and buildings or due to the movement of subscribers. To transmit information from different channels, different parts of the frequency spectrum are used – the Frequency Division Multiple Access (FDMA) method is used. This is directly related to the main disadvantage of analog systems – relatively low capacity, which is a consequence of insufficient rational use of the allocated frequency band in frequency division of channels.
This led to the need for a common European mobile communication system with high capacity and coverage of the entire European territory. The latter meant that the same mobile phones could be used in all European countries and that incoming calls had to be automatically routed to the mobile phone regardless of the user’s location (automatic roaming). In addition, a single European market with common standards was expected to result in cheaper user equipment and network elements, regardless of manufacturer.
Second generation mobile communications (2G)
In 1982, the CEPT (French Conference euro penne des administrations des posts et telecommunications) formed a working group called the Groupe Specials Mobile (GSM) to study and develop a pan-European terrestrial system general purpose mobile communications – the second generation of cellular telephony (2G) systems. The name of the GSM working group also came to be used as the name of the mobile communication system. GSM was originally intended only for ETSI member countries. However, many other countries also have a GSM system implemented, such as Eastern Europe, Middle East, Asia, Africa, Pacific and North America (with a GSM derivative called PCS1900). The name GSM has come to mean “Global System for Mobile Communications”, which is in keeping with its essence.
The first mobile networks of the second generation (2G) appeared in 1991. Their main difference from the first generation networks was the digital way of transmitting information, thanks to which the beloved by many, the service of exchanging short text messages SMS (Short Messaging Service) appeared. When building second-generation networks, Europe went by creating a single standard – GSM; in the United States, most 2G networks were built on the basis of the D-AMPS (Digital AMPS – digital AMPS) standard, which is a modification of analog AMPS. By the way, it was this circumstance that caused the appearance of the American version of the GSM standard – GSM1900. With the development and spread of the Internet, for mobile devices of 2G networks, WAP (Wireless Application Protocol) was developed – a protocol for wireless access to the resources of the global Internet directly from mobile phones.
The main advantages of 2G networks over their predecessors were that telephone conversations were encrypted using digital encryption; 2G system introduced data transmission services, starting with SMS text messages.