Millions of GSM Phones Use … Meaning What, Exactly?

If you’ve ever wondered how the millions of mobile phones around the globe are able to transmit voice, text and other data in an organized and efficient manner, the answer is GSM, which means (or rather, stand for) a global mobile communication system.

The way mobile phones operate around the world is the cornerstone of this modern communication.

What is GSM?

GSM is the international standard for mobile communications. It enables users to transmit data, make phone calls and exchange text messages seamlessly.

GSM operates within a framework of radio channels and cellular technology, allowing multiple users to access the same bandwidth at the same time. In Europe and many other parts of the world, GSM is the only type of cellular service available.

Basics of the GSM System

Developed by the European Telecommunications Standards Institute (ETSI), GSM emerged as a pan-European mobile technology in the 1980s.

Originally, the acronym GSM stood for Groupe Spécial Mobile. The group was established in 1982 by the European Postal and Telegraph Conference (CEPT) to research the benefits of a European standard for mobile telecommunications.

Commercial service using the GSM system did not really begin until 1991. Instead of using an analog service, GSM was developed as a digital system using Time Multiple Access (TDMA) technology.

How Does GSM Work?

At the heart of GSM networks are base transceiver stations (BTS) and base station controllers (BSC), which facilitate communication between mobile devices and the network’s core infrastructure.

Division by Region

GSM systems divide geographical areas into cells, each of which is served by a BTS, ensuring coverage across different regions. These cells vary in size from large shadow cells covering wide areas to small cells serving dense urban environments.

SIM cards

When a mobile device enters a cell, it connects to the nearest BTS, registering its presence with the network’s Home Location Register (HLR). A subscriber identity module (SIM) card, a small electronic chip containing specific information about the user and their mobile services, facilitates this process.

GSM Frequency Bands

Different parts of the world use different GSM frequency bands, according to the International Telecommunication Union (ITU) designation.

The following parts of the world use the GSM-900 and GSM-1800 bands:

Meanwhile, other parts of the world use GSM-850 and GSM-1900:

GSM and TDMA technology

If you’ve ever wondered how it is possible for millions of people to send text messages at the same time with all of those texts finding their way to the right destination, the answer has to be, in part to minimum, with some multiple access time.

Various wireless communication systems, including 2G cellular networks such as GSM, use TDMA as an access method for voice and data transmission. In addition to GSM phones, digital radio systems, satellite communications, certain types of wireless LANs (Local Area Networks), and other applications use TDMA.

Communication Time Slots

TDMA systems divide transmission times into discrete periods or time slots, of which each user is assigned one or more for their communication needs. These time slots are typically very short, often only millions of seconds, and are synchronized across all users within the system.

During each time slot, the user can transmit their data, be it voice, text or multimedia, without interference from other users sharing the same channel.

By ensuring that each user has exclusive access to the channel for a fraction of the total transmission time, it minimizes conflicts and collisions between transmissions.

Advantage of TDMA

A major advantage of TDMA technology is its ability to support multiple users on the same frequency band at the same time. Dividing the available time into slots allows higher capacity and increased data throughput compared to other access methods.

5 Main features of GSM

From its inception as a European standard to its status as a global model, GSM has shaped the landscape of mobile communications, enabling seamless voice calls, text messages and data exchanges across borders and continents. Here are five traits that made him successful:

  1. It has been adopted as a global standard: Widespread adoption of GSM technology facilitates interoperability, enabling users to use the same mobile phones in different regions without compatibility issues.

  2. Multiple access technologies: GSM uses multiple access, including time division multiple access (TDMA) and code division multiple access (CDMA), to serve multiple users on the same radio channel at the same time.

  3. Roaming agreements: GSM network operators often establish roaming agreements with other carriers, allowing users to access cellular services while traveling abroad to ensure continuity of service.

  4. Secure wireless system: With features like encryption and authentication, GSM provides a secure platform for transmitting digital information. This ensures the privacy and integrity of voice calls, text messages and data exchanges over the network.

  5. Short message service (SMS): One of the most popular features of GSM is the short messaging service (SMS), which enables users to exchange texts quickly and efficiently. SMS messages have become part of everyday communication, providing convenience and practicality for many people.

GSM vs. CDMA networks

GSM uses TDM technology rather than code division multiple access (CDMA) technology, which other communication frameworks rely on. Although GSM and CDMA technologies serve similar purposes in mobile communications, they differ in their approach to network architecture and operation.

Unlike TDMA, which divides the transmission time into discrete time slots, CDMA networks assign a unique code to each user and spread the signal across the entire frequency band. But like TDMA, CDMA allows multiple users with CDMA phones to transmit and receive data simultaneously without interfering with each other.

In the United States, the major carriers are divided between TDMA and CDMA. For example, AT&T and Mobile use the GSM system (and therefore TDMA), while T-Mobile, US Cellular and Verizon use CDMA.

We created this article in collaboration with AI technology, then made sure it was fact-checked and edited by a HowStuffWorks editor.

Original article: Millions of Phones Use GSM … Meaning What, Exactly?

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