1. INTRODUCTION TO THE STANDARD GSМ 1.1. Brief history of development.

In the early 1980s, the rapid development of analog cellular mobile communication systems began in Europe, especially in the countries of Scandinavia, Germany, France and the UK. Each country has developed its own system, incompatible with others, both in terms of equipment and services provided. As a result, the equipment of the mobile communication systems of each state was used only within its national borders and had a very limited sales market. Thus, it became necessary to create a single European standard for mobile communications.

In 1982, the Conference of European Postal and Telecommunications Offices - CEP (ConferenceofEuropeanPostsandTelegraphs), in order to study and develop a pan-European public mobile cellular communication system, created a group called Group Special Mobile (GSM). Developed mobile communication system, which was named

The Global System for Mobile communication (Global System for Mobile communication, abbreviated to GSM), had to meet the following criteria [1.1], such as:
- high quality voice transmission;
- low cost of equipment and services provided;
- to be a pan-European cellular communication system;
- the most efficient use of radio frequencies and to have spectral efficiency;
- have a high capacity that meets growing requirements;
- be compatible with the digital network of integrated services - ISDN (Integrated Services Digital Network) and with other data transmission systems;
- maintain good security of information transfer;
- support international roaming;
- support portable user equipment, etc.

One of the key factors necessary for the success of GSM in the late 80s was the factor of incompleteness of standardization. In 1989, the business of creating and improving the GSM standard was transferred to the European Telecommunications Standards Institute - ETSI (European Telecommunications Standards Institute), and already in 1990, the specifications of the first phase of the GSM standard (GSM1-G1) were published.

We use the short list of the most important milestones in the development of the GSM system proposed by Nokia [1.2].

1982 - CEP initiates any cellular mobile communications system.

The European Commission - EU (European Commission) issued a directive that required members of EU member states to reserve frequencies in the 900 MHz frequency band for GSM, which allows roaming.

1985 - CEP decides on a GSM work program.

1986 CEP conducts testing of 8 GSM experimental systems in Paris.

1987 - Memorandum of Agreement (Memorandum of Understanding - MoU).

The distribution of operating frequencies: 890 ... 915 MHz (from the terminal (mobile phone) to the base station); 935 ... 960 MHz (from the base station to the terminal).

1988 - ETSI is created. ETSI has included administration members, industry representatives and a user group as members.

1989 - The final recommendations and specifications for GSM Phase1 [1.1] are developed and introduced.

1990 - The ratification of GSM systems is implemented and the 1st GSM GSM Congress in Rome is held with 650 participants.

1991 - The first official telephone conversation in the world in the GSM system (July 1, 1991).

By mid-1991, commercial GSM services were maintained.

In connection with the improvement of computer technology and advances in the technology of GSM radio systems, it began to rapidly develop, improve and expand its services.

1992 - The world's first GSM network is organized in Finland. In December 1992, 13 GSM networks were already organized in 7 regions. The first outside of Europe.
Australian operators have signed a contract with GSM MoU.

The new frequency band is allocated for GSM: GSM1800 (DCS1800 - Digital Cellular System 1800): (1710 ... 1785) MHz (from MS and BTS); (1805 ... 1880) MHz (from BTS to MS).

1993 - The first demonstration of the GSM system in Africa: Telecom-93 in Cape Town. An agreement has been established between several operators about roaming.

In December 1993, 32 GSM networks were established in 18 regions in Africa.
In 1993, 36 GSM networks were already operating in 22 countries and another 25 countries chose the GSM standard or raised the question of its adoption [1.3, 1.4]. Despite the fact that the GSM system was standardized in Europe, it is in fact not a European standard [1.3].

1994 - The first GSM network is opened in South Africa. The GSM Phase 2 network offered data and fax services and received implementation.

In December 1994, 69 GSM networks were already operational.
GSMMoU has formally registered as an association with 156 members from 86 regions in Switzerland. The GSM World Congress was held in Madrid (1,400 participants). GSM networks are implemented in the countries of the Middle and Far East, Australia, South America and Africa.
In early 1994, the number of GSM subscribers worldwide reached 1.3 million. There are already 117 GSM networks in the world.

Facsimile communication, data transmission and SMS (ShortMessageService — short message service) and roaming were introduced everywhere. GSMPhase2 has been standardized, including adaptation for GSM1900 (PCS1900 - PersonalCommunicationSystem1900) [for adaptation in the US standard network - D-AMPS]. The first GSM1900 network was implemented in the USA. Telecom-95 organized in Geneva a demonstration of 33.6 kbps multimedia data transmission in GSM (developed by Nokia).

1995 - By the beginning of 1995, there were already over 5 million GSM subscribers. In 1995, in the second phase, GSM (GSMPhase2 - GSM900 / 1800) was recommended to fix and install additional services (the “short message” service was improved, the radio access was improved and the SIM card was introduced).

1996 - By December 1996, there were 120 GSM networks in the world.
In addition to prepaid SIM cards of the SIM-8K type have been issued.

1998 - We passed the test of the GSM network in Singapore, high-speed data switching circuits (HSCSD - SpeedCircuitSwitchedData).
By the end of 1998, there were 120 million GSM900 / 1800/1900 users in the world, and 2 million GSM1900 users in the United States.

1999 - The first mobile data transmission used basic packet radio service (GPRS — GeneralPacketRadioService) on a functioning GSM network. At the end of 1999, the number of GSM networks exceeded 344 in 127 countries, and the number of GSM users in the world was 250 million.

After 2000. After the development of recommendations for GSM Phase 2, the GSM standard continued to evolve and improve. This led to the fact that the so-called GSM Phase 2 + system was introduced, which differs from the previous ones - mainly marketing with modern technical support: a wider frequency band in combination with smaller cell sizes, which allows building much larger cellular networks, calculated to a mass mobile communication system with relatively compact, lightweight, convenient and relatively inexpensive mobile phones (terminals).

The GSM mobile cellular communication system was developed and implemented as an open public information system.

However, as it turned out in practice, GSM capabilities were not limited to the functions incorporated in this system.
Already in 1990, under the auspices of the European Commission (EU) for high-speed networks, the development of a unified standard unifying train control systems began. By 1993, thanks to funding from the International Union of Railways (IUR — the International Union of Railways), the ETCS (EuropeanTrainControlSystem) standard was developed

The European train control system, as a new unified standard of train control systems on all European railways [1.5]. The standard was based on the GSM standard, called GSM-Railway (GSM-R), while the GSM system is used for receiving, processing and transmitting all types of information signals via radio channels: voice, signals from automation systems and telemechanics.