2. Group System for Mobile
OR
Global System for Mobiles

3. CONTENTS
 HISTORY
 INTRODUCTION
 CELLULAR COMPONENTS
 GSM COMPONENTS
 NETWORK STRUCTURE
 SUBSCRIBER IDENTITY MODULE
 GSM SECURITY
 ADVANTAGES OF GSM
 DISADVANTAGES OF GSM

4. HISTORY
 The European Conference of Postal and
Telecommunications Administrations
(ECPT) created the Group Special Mobile
(GSM) to develop a standard for a mobile
telephone system that could be used
across Europe.
 The first GSM network was launched in
1991 by Radio-Linja in Finland with joint
technical infrastructure maintenance from
Ericsson.

5. INTRODUCTION
 GSM is a cellular network, which means
that mobile phones connect to it by
searching for cells in the immediate
vicinity.
 Time Division Multiple Access(TDMA)
 Frequency Division Multiple
Access(FDMA)
 3 billion people across more than 212
countries and territories.

7. Cellular Components
 Cell Site(Base Station Equipment)
 Frequency System

8. Cell Site
 Large Cells
• 32 kms
• High Transmission
Power
• Few Subscribers
 Smart Cells
• 0.8 kms
• Urban Areas
• Many Subscribers

9. Cell Types
 There are five different cell sizes in a GSM network—macro,
micro, pico, femto and umbrella cells.
 Macro cells can be regarded as cells where the base station
antenna is installed on a mast or a building above average roof top
level.
 Micro cells are cells whose antenna height is under average roof
top level; they are typically used in urban areas.
 Picocells are small cells whose coverage diameter is a few dozen
meters; they are mainly used indoors.
 Femtocells are cells designed for use in residential or small
business environments and connect to the service provider’s
network via a broadband internet connection.
 Umbrella cells are used to cover shadowed regions of smaller cells
and fill in gaps in coverage between those cells.

10. Frequency System
 GSM operate on four different frequency
ranges.
 GSM operate in 890 MHz - 960 MHz bands.
 In GSM network there are two frequencies:-
1. Uplink Frequency (890 MHz – 915 MHz)
2. Downlink Frequency (935 MHz – 960 MHz)
3. Frequency Channel = 124 (200kHz B/W)

11. GSM Network Components
 The Mobile Station
 The Base Station System
 The Network Switching System

12. Mobile Station (MS)
 Mobile Equipment(ME)
1. Vehicle Mounted
2. Portable Mobile Unit
3. Handportable Unit

13. Subscriber Identity Module
(SIM)
1. International Mobile Subscriber Identity-IMSI
2. Temporary Mobile Subscriber Identity-TMSI
3. Location Area Identity-LAI
4. Subscriber Authentication Key-KI
5. Mobile Station International Services Digital
Network-MSISDN

14. Base Station System
 Connection b/w ME and MSC
 Its Components:-
 Base Station Controller(BSC)
1. Contains 40 BTSs.
2. Handover phone signal without involving
MSC.
 Base Tranreceiver Station(BTS)
 Make connection with mobiles

16. The Network Switching
System
 Mobile Services Switching Centre-MSC
 Home Location Register-HLR
 Visitor Location Register-VLR
 Equipment Identity Register-EIR
 Authentication Centre-AUC
 InterWorking Function-IWF
 Echo Canceller-EC

19.  The network behind the GSM system seen by the
customer is large and complicated in order to provide
all of the services which are required.
 The Base Station Subsystem (the base stations and
their controllers).
 The Network and Switching Subsystem (the part of
the network most similar to a fixed network). This is
sometimes also just called the core network.
 The GPRS Core Network (the optional part which
allows packet based Internet connections).
 All of the elements in the system combine to produce
many GSM services such as voice calls and SMS.

20. NETWORK STRUCTURE

21. Subscriber Identity Module
 One of the key features of GSM is the
Subscriber Identity Module (SIM),
commonly known as a SIM card.
 The SIM is a detachable smart card
containing the user's subscription
information and phonebook. This allows the
user to retain his or her information after
switching handsets

22. GSM SECURITY
 GSM was designed with a moderate level of
security.
 PIN (Personal Identity Number) Password
 PIN2 (Personal Identity Number) Password
 PUK (Personal Unlock Keyword) Password
(e.g.,14468400)

23.  Call Costs are becoming lower and lower everyday.
 Call quality is much more pure and secure in GSM.
 More and more value-added services like GPRS,
EDGE etc are coming everyday.
 Power is less consumed in GSM handsets compared
to CDMA handsets.
 If u have a tri-band GSM phone u can use it in
almost any part of the world.

24.  Call costs will still remain higher compared to
CDMA. Roaming costs are much lower in CDMA
compared to GSM.
 GSM phones can be tampered with. They have
their unique IMEI number which is used to lock
the phone permanently but now a days
software’s are available which can tamper them
too.
 If your SIM is lost then all data is lost unless u
have it stored in the phone’s memory.

25. THANKS
TO
ALL OF YOU