This document compares GSM and CDMA mobile technologies. It outlines that GSM uses TDMA and FDMA to allow multiple users to access frequencies, while CDMA uses direct sequence spread spectrum and unique codes to separate users on the same frequency. The document discusses features of each technology such as frequency reuse in GSM. It analyzes advantages of both such as better voice quality in CDMA due to use of entire spectrum, and international roaming capability in GSM. Overall, the document provides a technical overview comparing key aspects of GSM and CDMA mobile networks.

1. GSM vs CDMATECHNOLOGY
SHAFAQUE GHAYAS SATTAR
ECE11030
4th Year 7th Semester

2. Outline of the Presentation
• GSMTechnology
• Techniques used in GSM
• Features of GSM
• CDMATechnology
• Features of CDMA
• CDMA vs GSM
• Advantages of CDMA:
• Disadvantages of CDMA
• Advantages of GSM
• Disadvantages of GSM
• Reference

3. WHAT IS GSM?
• 1982 – European Telecommunications Standards Institute (ETSI) formed Grouped Special
Mobile(GSM) to develop a public land mobile system.
• Later named as Global System for Mobile Communications.
GSMTECHNOLOGY

4. Techniques used in GSM
In the GSM system, TDMA in combination with FDMA is used .Thus, only a
single mobile is using a given frequency/timeslot combination at any particular
time.
Frequency D iv isio n M ult iple A ccess ( FD M A ) :
Each call is carried on a separate frequency channel. Provides multiuser
access by separating the used frequencies.

5. Time Div isio n Multiple Access (TDMA):
Each frequency channel is further divided into a set of timeslots; each timeslot carries
the data of a voice call. Provides multiuser access by chopping up the channel into
sequential time slices.

6. FREQUENCY REUSE
• There are total 124 carriers in GSM
• Each carrier has 8 timeslots and if 7 can be used for traffic then a maximum of 868 ( 124
X 7 ) calls can be made. This is not enough and hence frequencies have to be reused.
• The same RF carrier can be used for many conversations in several different cells at the
same time.
• The radio carriers available are allocated according to a regular pattern which repeats
over the whole coverage area.
• The pattern to be used depends on traffic requirement
and spectrum availability. 2
1
FEATURES OF GSM
6
4
3
7
2
5
1
2
1

7. CDMATechnology
What is CDMA Technology?
Code division multiple access (CDMA) is a channel access method used by various radio
communication technologies. CDMA is an example of multiple access, which is where
several transmitters can send information simultaneously over a single communication
channel
Multiple Access in CDMA:
• Each user is assigned a unique PN code.
• Each user transmits its information by spreading with unique code.
• Direct Sequence spread spectrum is used.
• Users are separated by code not by time slot and frequency slot.

8. FEATURES OF CDMA
• Concept of CDMA
Users share same
bandwidth
User axis shows
cumulative signal strength
of all users Code 1
Code2
Code 3
Code 4
Freq
User

10. CDMA vs GSM
Comparison between CDMA and GSM:
 InTDMA Band width available for transmission is
small which leads to compromise in quality of
transmission. Whereas in CDMA systems entire
spectrum is used which enhances voice quality.
 InTDMA/FDMA, cell design requires more
frequency planning which is tough job.Whereas in
CDMA frequency planning is minimal.
 TDMA is Band limited system. CDMA is Power
limited system

11. Advantages of CDMA:
• Increased cellular communications security.
• Simultaneous conversations.
• Increased efficiency, meaning that the carrier can serve more subscribers.
• Low power requirements and little cell-to-cell coordination needed by operators.
• Extended reach - beneficial to rural users situated far from cells.
Disadvantages of CDMA
• Due to its proprietary nature, all of CDMA's flaws are not known to the engineering
community.
• CDMA is relatively not popular, and the network is not as mature as GSM.
• CDMA cannot offer international roaming, a large GSM advantage.

12. ADVANTAGES OF GSM
• Less signal deterioration inside buildings.
• Talk time is generally higher in GSM phones due to the pulse nature of transmission.
• The availability of SIM allows users to switch networks and handsets at will, aside from
a subsidy lock.
• GSM covers virtually all parts of the world so international roaming is not a problem.
• GSM is already used worldwide with over 450 million subscribers.The much bigger number
of subscribers globally creates a better network effect for GSM handset makers, carriers and
end users.

13. DISADVANTAGES OF GSM
• Released and Missed Calls
Conferring to Cellular Newscast, call superiority difficulties, with dropped calls and missed
calls are shared difficulties with GSM expertise.
• Safety Issues
ZDNet UK GSM has a grave safety flaw, established by a hacker who was capable to
interrupt telephone calls from an amount of GSM-based cellular headphones.

14. The GSM Association is an international organization
founded in 1987, dedicated to providing, developing, and
overseeing the worldwide wireless standard of GSM.
 CDMA, a proprietary standard designed by Qualcomm in
the United States, has been the dominant network standard
for North America and parts of Asia.
However, GSM networks continue to make inroads in
the United States, as CDMA networks make progress in
other parts of the world.

16. MARKET SHARE BYTWOTECHNOLOGY

17. Reference
• http://en.wikipedia.org/
• Mobile Computing Technology, Applications and Service
Creation – Asoke K Talukder, Hasan Ahmed, Roopa R
yavagal
• http://www.howstuffworks.com/

18. Thank you