Author Topic: different between CDMA & GSM  (Read 2323 times)

Offline sumit

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different between CDMA & GSM
« on: January 12, 2010, 02:26:06 AM »
Its must that, we all know at least something about the term CDMA and GSM.Though it is very common term but its very important to know the differences  between these two term.We have some friends here who knows it very well, though i want to tell here something on this because its very important in wireless technology.. ......

  The questions that arises in here is:
            1.What is the difference between CDMA & GSM?

            2.Is it possible to use GSM sim card in CDMA handsets?

            3.What is  GSM & CDMA stands for?

1.Ans:
                   These  two different means of mobile communication being presently used world wide.The basic difference lies in the Multiplexing method.


                  CDMA uses Code Division Multiple Assess as the name itself indicates, for example if you are in a hall room occupied with number of people speaking different language. You will find that the one language you are knowing will be heard by you and the otherggs will be treated like noise. In the same manner each CDMA mobile communication takes place with a "code" communicating between them and the other end if one is knowing that code then only it can listen to the data being transmitted i.e. the communication is in the coded form.
                 

      In CDMA we allocate a unique code for every user saparately and allocate bandwidth to user.


                       On the other hand GSM is stands for global system for mobile communication. it use TDMA  & FDMA techniques as access mechanism . in GSM  we devide bandwidth in to time slots for better utilization of bandwidth.GSM uses narrowband TDMA, which allows eight simultaneous calls on the same radio frequency.
                         

                            In GSM only 30 or 35 peoples can call at at time in a single carrier but In CDMA
 apprx 70  peoples can call in a single carrier at a time.

                            CDMA  has been traditionally faster than GSM, though both technologies continue
to rapidly leapfrog along this path.

                            In CDMA technology adjacent channel interference is very  low compared to GSM.
In CDMA  the power consumption is very low it takes 23 to 30 dBm.But in GSM the power
consumption  is very high comparitive to CDMA the lower limit is 30 dbm.
             
                           The range of each technology is different, and they also have different rates and modulation schemes, and that is why handsets are different between the two technologies. GSM uses SIM cards (Subscriber Identity Module) whereas, CDMA based phones use the RUIM (Removable User Identity Module).So it is give you the answer of 2.






Offline arefin

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Re: different between CDMA & GSM
« Reply #1 on: January 15, 2012, 10:12:37 PM »
In the context of Bangladesh, GSM gives better performance than CDMA.
“Allahumma inni as'aluka 'Ilman naafi'an, wa rizqan tayyiban, wa 'amalan mutaqabbalan”

O Allah! I ask You for knowledge that is of benefit, a good provision and deeds that will be accepted. [Ibne Majah & Others]
.............................
Taslim Arefin
Assistant Professor
Dept. of ETE, FE
DIU