Gsm En Los Telefonos Moviles

GSM

Global System for Mobile Communication (GSM)
Definition
Global system for mobile communication (GSM) is a globally accepted standard for digital cellular communication. GSM is the name of a standardization group established in 1982 to create a common European mobile telephone standard that would formulate specifications for a pan-European mobile cellular radio system operating at 900MHz. It is estimated that many countries outside of Europe will join the GSM partnership.

Overview
This tutorial provides an introduction to basic GSM concepts, specifications, networks, and services. A short history of network evolution is provided in order set the context for understanding GSM.

Topics
1. Introduction: The Evolution of Mobile Telephone Systems 2. GSM 3. The GSM Network 4.GSM Network Areas 5. GSM Specifications 6. GSM Subscriber Services Self- Test Correct Answers Glossary

1. Introduction: The Evolution of Mobile Telephone Systems
Cellular is one of the fastest growing and most demanding telecommunications applications. Today, it represents a continuously increasing percentage of all new telephone subscriptions around the world. Currently there are more than 45million cellular subscribers worldwide, and nearly 50 percent of those subscribers are located in the United States. It is forecasted that cellular systems using a digital technology will become the universal method of telecommunications. By the year 2005, forecasters predict that there will be more than 100 million cellular subscribers worldwide. It has even been estimated that some countries mayhave more mobile phones than fixed phones by the year 2000 (see Figure 1).
Figure 1. Cellular Subscriber Growth Worldwide

The concept of cellular service is the use of low-power transmitters where frequencies can be reused within a geographic area. The idea of cell-based mobile radio service was formulated in the United States at Bell Labs in the early 1970s. However, the Nordic countrieswere the first to introduce cellular services for commercial use with the introduction of the Nordic Mobile Telephone (NMT) in 1981. Cellular systems began in the United States with the release of the advanced mobile phone service (AMPS) system in 1983. The AMPS standard was adopted by Asia, Latin America, and Oceanic countries, creating the largest potential market in the world for cellular. In theearly 1980s, most mobile telephone systems were analog rather than digital, like today's newer systems. One challenge facing analog systems was the inability to handle the growing capacity needs in a cost-efficient manner. As a result, digital technology was welcomed. The advantages of digital systems over analog systems include ease of signaling, lower levels of interference, integration oftransmission and switching, and increased ability to meet capacity demands. Table 1 charts the worldwide development of mobile telephone systems.
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Table 1. The Development of Mobile Telephone Systems Year 1981 1983 1985 1986 1991 1991 1992 1994 1995 1996 Mobile System Nordic Mobile Telephone (NMT)450 American Mobile Phone System (AMPS) Total Access Communication System (TACS) Nordic Mobile Telephony (NMT) 900 American Digital Cellular (ADC) Global System for Mobile Communication (GSM) Digital Cellular System (DCS) 1800 Personal Digital Cellular (PDC) PCS 1900—Canada PCS—United States

2. GSM
Throughout the evolution of cellular telecommunications, various systems have been developedwithout the benefit of standardized specifications. This presented many problems directly related to compatibility, especially with the development of digital radio technology. The GSM standard is intended to address these problems. From 1982 to 1985 discussions were held to decide between building an analog or digital system. After multiple field tests, a digital system was adopted for GSM. The next...