Having been in the telecommunications industry for some time, the one thing I can say with certainty that has never changed is the ongoing confusion that surrounds the use of industry terms like TDMA, GSM, and LTE. As we live in a word full of acronyms, it’s not surprising that many observers outside the telecommunications field might be confused.
So in an effort to help the cause, I present you with a very brief timeline that will hopefully clear up some misconceptions.
Let’s begin with the communications path/interface between the cell tower and the phone. These are important basics to know when looking at the development of standards for 2G, 3G, and 4G.
- In the early days of analog cellular in the U.S., the only pipe available was AMPS (advanced mobile phone service). This analog channel only allowed one call per radio channel. Analog cellular was also deployed in a lot of different ways across Europe.
- In the move to digital technology, that one-way pipe was divided into slices of time or frames that allowed multiple conversations to have access. This method is called TDMA (time division multiple access).
- While it worked, TDMA was limited to the number of time slices. So they began to use a more efficient way to move information by assigning codes. So we started using CDMA (code division multiple access), which allowed multiple users to share a radio channel. CDMA was not new (it has been used since World War II), but it had never been used in cellular phone systems before.
Here’s where the standards come in. In the early days of analog cellular in Europe, phones would often stop working if you moved from one country to another. So operators got together to define a single standard for mobile telephone service to allow roaming across Europe. This second generation (2G) cellular service became known as GSM (global system for mobile communication). However, the U.S. did not initially adopt the GSM standard. Instead it created its own 2G standard called IS-136. Since IS-136 used time division multiple access, it was often referred to as TDMA IS-136.
With the third generation of mobile telephone networks, a new standard called UMTS (universal mobile telecommunications system) was developed for CDMA, providing a different way for multiple users to share the same pipe.
Things weren’t completely harmonized until LTE (long term evolution) or 4G. So we are finally reaching a point where you can go anywhere in the world and if you say LTE, people know you are referring to 4G (although these two terms are still used interchangeably and sometimes together, depending on the carrier).
This is a very simplified version of how these terms have emerged – and there are lots of nuances within each stage that are worth exploring if you are so inclined.
In the meantime, if you have any questions please leave them in the comments.