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CDMA (Code Division Multiple Access)

CDMA (Code Division Multiple Access) - Man on Cell Phone

What is CDMA?

CDMA stands for Code Division Multiple Access and is one of the two primary cellular network systems implemented in the United States and Canada. The other main system is GSM, which is used by such providers as Rogers Wireless. CDMA can be differentiated from TDMA-based technologies (such as GSM) in the way that it is used to distribute bandwidth (or the amount of network transmission dedicated to sending your voice calls, text messages, and the like).

How CDMA Works Compared to GSM

CDMA divides the bandwidth by cutting up the transmission pie based on "code". In a nutshell, phones get a piece of bandwidth only when they need it, and these "access codes" (I guess you could call them) are recycled. CDMA can be thought of as being more efficient that TDMA/GSM, because CDMA only transmits data when it needs to (it never transmits silence). By contrast, TDMA distributes bandwidth based on time (TDMA stands for Time Division Multiple Access). Each bandwidth cycle is divided by the number of users, and you -- with a single handset -- are given a proportion of the cycle, every cycle, whether it is silence being sent or actual voice data.

Take-Home Message

The important thing to remember is that CDMA is distinctly different than GSM, and as a general rule of thumb, any cellular service provider will subscribe either to CDMA-based standards or GSM-based standards. There are a few exceptions (like Alltel Wireless), but these are more commonly as a result of mergers than as planned infrastructure.

CDMA-based Cell Phone Technologies

The current (basic) CDMA technology being used by such companies as Telus Mobility, Sprint, and Verizon Wireless can either simply be referred to as CDMA, as CDMAone, or the official name, IS-95. As we move toward higher bandwidth needs (for transferring ringtones, XM Satellite Radio, games, and even Mobile TV), the need for faster data transmission becomes paramount. Here a couple of developments that are either already implemented or not far off on the horizon:

  • CDMA2000/1xRTT: 1xRTT (one time radio transmission technology), otherwise known as CDMA2000, isn't quite 3G technology and is usually considered as being part of the 2.75 generation of mobile data. It is perfectly capable of handling WAP mobile web and sending simple text and picture messages, but if you have heavier bandwidth needs, you should probably consider full-on 3G technology like…
  • 1xEV-DO/IS-856: EV-DO stands for Evolution-Data Optimized, and is a 3G standard implemented in a number of countries, including Canada, Japan, Russia, New Zealand, and Brazil. With much faster data transfer rates, customers can enjoy Mobile TV, streaming mobile radio, and much more.

North American CDMA Service Providers

In Canada, there are two main CDMA cellular service providers:

  • Telus Mobility: Telus is perhaps best known for their unique marketing campaign (which they inherited when they purchased Clearnet Communications in 2000), featuring a number of colorful, tropical animals in whimsical situations. For more on Telus Mobility, check out our article here.
  • Bell Mobility: When the 2006 Winter Olympics rolled into Italy, Bell Mobility rolled out its new advertising campaign with Frank and Gordon, a couple of inseparable male beavers "in an ambiguous relationship." For more on Bell Mobility, have a look at our LoveToKnow article here.

In the United States, there are also two main CDMA mobile operators, though there are several regional service providers that operate on CDMA-based technology as well.

  • Verizon Wireless: Verizon is really pushing their V CAST Music service, showcasing their latest acquisition, the lovely LG Chocolate Phone. It's sweet, it's powerful, and it's available only through Verizon. Read more on their handsets and cell plans.
  • Sprint PCS: Sprint has merged with Nextel, and while the latter is heavily promoting its Push-to-Talk walkie-talkie service (based on Motorola's iDEN standard), Sprint is a CDMA provider through and through. Be sure to check out our article on their phones and plans.
CDMA (Code Division Multiple Access)