GSM vs. CDMA Defined

Before deciding which technology is superior, let’s talk a little more about these two tecnologies:

  • CDMA: stands for Code Division Multiple Access. Both data and voice are separated from signals using codes and then transmited using a wide frequency range. Because of this, there is more space left for data transfer (this was one of the reasons why CDMA is the preferred technology for the 3G generation, which is broadband access and the use of big multimedia messages). 14% of the worldwide market goes to CDMA. For the 3G generation CDMA uses 1x EV-DO and EV-DV. It has a lot of users in Asia, specially in South Korea.
  • GSM: stands for Global System Mobile. Even though it is sold as “the latest technology” in several countries, this technology is older than CDMA (and also TDMA). But keep in mind that this doesn’t mean that GSM is inferior or worse than CDMA. Roaming readiness and fraud prevention are two major advantages from this technology. GSM is the most used cell phone technology in the world, with 73% of the worldwide market. It has a very strong presence in Europe.

TDMA technology is the less used from the three main digital technologies (GSM, CDMA and TDMA) and we think it will gradually be replaced to CDMA or GSM. That’s why the GSM vs CDMA war. At one corner, GSM operators say it is better “because it uses a SIM chip, it is the most used technology worldwide, it is more secure and it is more advanced”. On the other corner, CDMA followers say it is better “because it is the 3G generation chosen technology and GSM will migrate to CDMA since CDMA is more advanced…”

But which one of these statements are correct? Acording to Nokia, “this discussion is not about technology anymore, but about market”. We think this is the best way to describe the war between these two cell phone technologies.

In the beginning, GSM was in fact superior. It had more services and allowed more data transfer. But CDMA, facing the advantages of the competitor standard, soon delivered the same features found on GSM. Nowadays, it is not possible to say that GSM services are better than CDMA. Multimedia messages, video, high-speed Internet access, digital camera and even PDA function are some of the features we can found on both technologies. The new CDMA 1XRTT technology, which previews what G3 cell phones will bring, is more advanced than EDGE, technology from the beginning of 3G generation, allowing higher transfer rates.

Even the GSM SIM card advantage, that allows you to change your cell phone and keep your phone list, is being surpassed by some CDMA operators with a service that allows you to store your phone book on the operator’s database, allowing you to recover your phone book even if your cell phone is stolen (which is not possible with GSM, since if your cell phone is stolen, your SIM card will be stolen as well). Notice that recently a new accessory called SIM backup was released, which allows you to backup the data stored in your SIM card. Also some GSM operators are offering a similar backup service.

So, nowadays both technologies are equiparated in technology, but this picture won’t be like that in the future. Afterall, CDMA evolution ground is wider and in a few years it will be superior than GSM.  Does this mean that GSM operators will disapear? Not at all. They will migrate over CDMA and the war will continue, because the existing CDMA operators chose to use 1xEV-DO and 1XEV-DV technologies for their 3G network and the existing GSM operators have opted for a different technology, called WCDMA. Also, even though the current GSM operators will migrate to WCDMA, they still can use their existing GSM network. So users won’t feel anything special when the operators shift to the new cell generation (3G), independently from the technology they choose.

GSM vs CDMA Glossary:

  • AMPS: stands for Advanced Mobile Phone Service. Analog cell system.
  • TDMA: stands for Time Division Multiple Access. It works by dividing the spectrum into frequency channels and each user uses each channel for a  specific time, to avoid interference.
  • CDMA 1XRTT: Second generation technology (2.5G, actually) which allows data transfers up to 144 Kbps.
  • EDGE: stands for Enhanced Data Rates for Global Evolution. Technology promoted by GSM operators. Before migrating to WCDMA, EDGE will allow third generation data and voice access with 384 kbps transfer rate.
  • EV-DO: Third generation (3G) from CDMA 1xEV-DO technology. “EV” comes from and “DO” from data-only. It uses a second channel, of 1.25 MHz, exclusively for data transmission. Some countries are already running this standard. In the USA, Verizon and Sprint started this technology in 2004. This tecnology allows hi-speed Internet access (2.4 Mbps) using the cell phone or using a wireless connection from a laptop or PDA.
  • EV-DV: Evolution of EV-DO, but still under development. “DV” comes from data-and-voice. It uses the same channel for trasmiting data and voice. The transfer rate can reach 5.2 Mbps.
  • WCDMA: Wideband CDMA. Third generation technology that will be adopted by GSM operators. Its European version is known as UMTS (Universal Mobile Telecommunications System). It can reach transfer rates up to 2 Mbps.


Brazilian and blog addict, Alessandra Carneiro is a journalist who frequently reports on technology, the Internet, and everything mobile that has a circuit in it. She used to be our news editor and was also former assistant editor at O Dia Newspaper (RJ). She lives in Rio, but loves rainy days.