Millions of phones use GSM… What exactly does that mean?

If you’ve ever wondered how millions of cell phones around the world transmit voice, text, and other data in an organized and efficient manner, the answer has to do with Cell phone, meaning (or rather: stands for) global system for mobile communications.

This cornerstone of modern communications underlies the way mobile phones work around the world.

What is GSM?

GSM is the international standard for mobile communications. It allows users to send data, make 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 simultaneously. In Europe and many other parts of the world, GSM is the only type of mobile service available.

Origin of the GSM system

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

The abbreviation GSM originally stood for Groupe Spécial Mobile. The Conference of European Post and Telegraphs (CEPT) established the group in 1982 to explore the benefits of a European standard for mobile telecommunications.

Commercial service using the GSM system did not begin until 1991. Instead of using analog services, GSM was developed as a digital system using Time Division 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 communications between mobile devices and the network’s core infrastructure.

Distribution by region

GSM systems divide geographic areas into cells, each served by a BTS, ensuring coverage in different regions. These cells vary in size, from large umbrella cells that cover large areas to smaller cells that focus on dense urban environments.

SIM cards

When a mobile device enters a cell, it connects to the nearest BTS and registers its presence in 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) designations.

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 millions of people can send text messages at the same time while all those text messages find their way to the right destination, the answer, at least in part, has to do with time-division multiple access.

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

Communication time slots

TDMA systems divide transmission times into discrete intervals or time slots, with each user allocated one or more for his or her communication needs. These time intervals are typically very short, often only milliseconds, and are synchronized across all users within the system.

During any time slot, the user can transmit their data, whether 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, conflicts and collisions between transmissions are minimized.

The TDMA advantage

A big plus of TDMA technology is the ability to support multiple users simultaneously on the same frequency band. Dividing the available time into slots provides higher capacity and greater 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 mobile communications landscape, enabling seamless voice calling, text messaging and data exchange across borders and continents. Here are five features that made it a success:

  1. Acceptance as a global standard: The widespread adoption of GSM technology facilitates interoperability, allowing users to use the same mobile phones in different regions without compatibility issues.

  2. Multiple access technologies: GSM uses multiple access technologies, including Time Division Multiple Access (TDMA) and Code Division Multiple Access (CDMA), to accommodate multiple users simultaneously on the same radio channel.

  3. Roaming agreements: GSM network operators often enter into roaming agreements with other providers, allowing users to access mobile services while traveling abroad to ensure continuity of service.

  4. Secure wireless system: With features such as encryption and authentication, GSM provides a secure platform for transmitting digital information. This guarantees 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 Message Service (SMS), which allows users to exchange texts quickly and efficiently. Text messages have become part of everyday communication and provide both convenience and functionality for many people.

GSM vs CDMA networks

GSM uses TDM technology instead of CDMA (Code Division Multiple Access) technology, which other communications 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 transmission time into separate time slots, CDMA networks assign a unique code to each user and distribute the signal over the entire frequency band. But similar to TDMA, CDMA allows multiple users with CDMA phones to send and receive data simultaneously without disturbing each other.

In the United States, the major airlines 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 using 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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