Monday, September 17, 2012


Global system of Mobile (GSM) and Code division Multiple Access (CDMA) are two very well known terms in telecommunication. GSM is more dominant technology used around the world, In U.S CDMA is more dominant standard. Although Both GSM and CDMA technologies are used for mobile communication yet these two differs in technology used , Call quality, Coverage , Data transfer speed etc.

Here is brief discussion on GSM and CDMA technology , which let you to understand difference between GSM and CDMA technology.

In CDMA , entire frequency band is available to user, in order to differnciate a special code , known as pseudo code is generated for every device or user , signals are spread using this unique code given to individual user, and at the receiving end signals are decoded.
In GSM , frequency band is divided into channels and each channel is divided into time slots, each channel has 8 time slots. GSM  works on Time division multiple access (TDMA) technology. Time slots are made available to user for making or receiving calls.

To use GSM and CDMA services you need to use different hardware or mobile phone. Same mobile phone can not be used for both. You can swap GSM SIM between mobile phones but CDMA mobile phones are generally locked, your phones directly connected to your service provider, your operators allows you to store data including phone book on the Operator's Data Base.

CDMA's EVDO technology is more faster than GSM's GPRS (General packet Radio service) and EDGE. But CDMA service requires dedicated connection to provide high speed ,means if you are using Data your voice calls may block, but GPRS sends in Packet, it means you GSM handsets don't block your voice calls.
Both Technologies can be used in 3G mobile phones, but GSM 3G speeds can be faster than CDMA 3G speeds.CDMA 3G service CDMA-2000 or EVDO has downstream data rate of 15.67 Mbps and GSM 3G standard with UMTS is HSPA+ , which provides you downstream speed of 28 Mbps.

CDMA call quality is far better than GSM. various factors such as echoes, call drop, voice distortion are almost non-existent in CDMA. In GSM , there is high probability of errors.

Check GSM towers photos - click here  

Overall GSM has 75% market share and CDMA has 25% global market share.In most of the contries both technologies are available for mobile communication, but GSM is most preferred service due to ease and advancement of technology.


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