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Monday, December 16, 2013

Difference Between CDMA and GSM

Parameter
CDMA
GSM
Acronym for
Code Division Multiple Access and also known as IS-95 or CDMAone.
Global System for Mobile Communication.
Technology Used
This Technology is based on spread spectrum technology and does not require dividing the channel by time. It also allows several users to share same frequency in a given band or space. Users are isolated by bipolar sequences and can share same frequency.
In this technology Carrier is divided into number of time slots. These different time slots are assigned to each user and until ongoing call is not finished, no other user can access this assigned slot.
Concurrent User Access
Same frequency is used by several users on the same time and can accommodate more users per MHz of bandwidth than any other technology.
Each user uses separate time slot that can be used by one user at a time.
Network Portability
No such feature is available and hence international roaming is a Problem and very limited support is available.
The availability of Subscriber Identity Modules (SIM) allows users to switch networks.
Spectrum Frequencies
800MHz(India)
900MHz/1800MHz (India)
Security
CDMA is more secure than GSM. Because Data is transmitted by using PN Codes.
GSM is less secure than CDMA because data is transmitted with no encryption.
Cell Site Range
CDMA has no built-in limit. Hence large no. of phones can be served by smaller no. of cell sites and have economic advantage.
GSM has fixed size cell size range of 120Kms. (Expanded from Old range of 35Kms).
Data Transfer
EVDO/3G/4G/LTE
GPRS/EDGE/3G/4G/LTE
Global Reach
Limited
Worldwide
Voice and Data Simultaneously
NO
Yes , GPRS Class A
Handoff
In CDMA Soft handoff technique is used in which the channel in the source cell is retained and used for a while in parallel with the channel in the target cell.
GSM uses Hard handoff Technique in which the channel in the source cell is released and only then the channel in the target cell is engaged.

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