What is CDMA and GSM?-- Mobile phones

Hi , this is ravi, for many days i used to have a doubt in my mind about the difference between CDMA and GSM mobiles. The only difference i know was CDMA mobiles dont have sim card and GMS do.

 

*In this post i would like to share the differences , advantages between CDMA and GSM.

*First thing first , CDMA  and GSM are not mobile models  and not the names of the moblie network providers.They are network techonologies that carry voice signal across network.

In our world celluar service there are two main competing network technologies:

 

1) GSM   - Global System for Moble communications. or (TDMA).

 

2) CDMA - Code Divison Multiple Access.

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GSM : GSM is a "branded" term referring to a particular use of TDMA(Time Division Multiple Access) technology.(GSM)Global System for Mobile communication is an international organization founded in 1987 which is dedicated to developing , providing , overseeing the worldwide wireless standard of GSM.This is the leading techology used around the globle in more than 100 countries .GSM operates in four seperate frequencies. 900MHz and 1,800MHz bands in Europe and Asia and 850MHz and 1,900MHz(1.9GHz) bands in North America and Latin America. This technology allows you to send digital data and allows several callers to share the same channel at the same time.

CDMA : CDMA (Code Divison Multiple Access) is a proprietary standard designed by Qualcomm in the UnitedStates and has been dominant network standard for North America and parts of Asia. Unlike GSM/TDMA  CDMA spreads data out over the channel after the channel is digitized.Multiple calls can then be overlaid on top of one another across the entire with dedicated sequence code to keep the signal distinct.CDMA was actually invented for military during World War II for field communications.