GSM is a second generation cellular technology developed to provide digital voice and data services using TDMA and FDMA. It initially provided circuit switched services but later added packet switched capabilities with GPRS. The key components of GSM are the mobile station, base station subsystem including base transceiver stations and base station controllers, and the network switching subsystem centered around mobile switching centers and databases like HLR, VLR, EIR and AUC. GSM supports various voice and data services as well as supplementary services and saw continual upgrades over time to improve data capabilities.

1. THE GSM TECHNOLOGY
GLOBAL SYSTEM FOR
MOBILE
COMMUNICATION
By-Wajahat Hussain
EN
1502721112
AKGEC

2. 2G(Second Generation)-
3 most successful variants of 2G are-
• IS-54B and IS-136
• IS-95 CDMA
• GSM

3. GSM History
• In 1982,Conference on European Posts &
Telecommunication setup organization
called Group Speciale Mobile to develop
new digital standards.
• First GSM network was launched in 1991.
• Many countries adopted it so it was
renamed Global System for Mobile
Communication.

4. • Global System for Mobile (GSM) is a second generation
cellular standard developed to cater voice services and
data delivery using digital modulation.
• GSM network operates in 900MHz & 1800MHz bands.
• It uses the digital air interface wherein the analog signals
are converted to digital signals before transmission.
• It initially started as a circuit switching network, but later
packet switching was implemented after integration
General Packet Radio Service (GPRS)
technology(2.5G).
• When 2G system were deployed 9.6kbps was existing
What is GSM?

5. • GSM is TDMA system with Frequency Division
Duplex(FDD).
• GSM uses Gaussian Minimum Shift Keying as modulation
scheme.
• Each RF channel is divided into 8 time slots,from 0 to 7 and
transmitted in a frame structure.
• Each frame lasts approximately 4.62ms such that each time

6. • Fully digital system.
• Security against fraud.
• Enhance privacy.
• Full international roaming capability.
• Support for Short Message service.
• Reduction in operation cost.
Characteristics of GSM-

7. Time division multiple access(TDMA)-
• In this method the signal is divided into
different timeslots. This allows multiple
stations to share the same transmission
medium while using only the part of its
bandwidth.
Frequency division multiple access(FDMA)-
• The assigned frequency band for a network is
divided into sub-bands which are allocated to
a subscriber for the duration of their calls.
Access Methods-

8. • GSM-900 uses
• -890-915MHz to send information from mobile station to
the base station(Uplink).
• -935-960MHz for other direction(Downlink).
• Providing 124 RF channels spaced at 200KHz.
• GSM-1800 uses
• -1710-1785MHz to send information from mobile station
to the base station(Uplink).
• -1805-1880MHz for other direction(Downlink).
• Providing 374 channels.
GSM Frequency-

9. • Tele-services.
• Bearer or Data Services.
• Supplementary services.
GSM Services-

10. • Telecommunication services that enable
voice communication via mobile phones.
• Mobile telephony.
• Emergency calling.
Tele-Services-

11. • Include various data services for information
transfer between GSM and other networks like
ISDN etc at rates from 300 to 9600bps.
• Short Message Service(SMS)-upto 160
characters alphanumeric data transmission.
• Voice mailbox.
• Electronics mail.
Bearer services-

12. • Call Waiting-
• Notification of an incoming call during a conversation.
• Call Hold-
• It allows user to put an incoming call on hold and resume after a while.
• Call Forwarding-
• It is used to divert calls from the original recipient to another number.
• Call Barring-
• Used to restrict certain types of outgoing calls such as ISD or stop incoming
calls from undesired numbers.
• Unstructured supplementary services data (USSD)-
• Used to send text between a mobile and an application program in the network.
Supplementary services-

13. • Mobile Station(MS)
• Base Station Subsystem(BSS)
• Network Switching Subsystem(NSS)
GSM Architecture-

15. • Mobile Equipment.
• Hardware used by the subscriber to access the
network.
• Uniquely identified by IMEI number.
• Subscriber Identity Module (SIM).
• Smartcard containing the International Mobile
Subscriber Identity(IMSI).
• Allows user to send and receive calls and other
subscribed services.
Mobile Station-

16. • Base Transceiver station(BTS)-
• Encodes, Encrypts, Multiplexes,Modulates and feeds the RF signals
to antenna.
• Frequency hopping.
• Communicates with MS and BSC.
• Consists of transceivers units.
• Base Station Controller(BSC)-
• Manage Radio resources for BTS.
• Assign frequency and time slots for all MS’s area
• Radio power control.
• Communicates with MSC and BTS.
Base Station Subsystem(BSS)-

17. • Manages communication between the mobile user
with the other users.
• Consists of different components they are as
follows-
• Mobile Switching Centre(MSC)
• Gateway Mobile Switching Centre(GMSC)
• HLR & VLR
• AUC & EIR
Network Switching Subsystem-

18. • Heart of the GSM network.
• Performs Call routing ,Call set-up and
basic switching functions.
• Generates CDR for each and every call.
• Communicates with HLR, VLR and other
MSC’s.
Mobile Switching Centre(MSC)-

19. • Functions as a gateway between 2
networks.
• Switch to the Public Switch Telephone
Network(PSTN).
Gateway Mobile Switching Centre(GMSC)

20. • Home Location Registers (HLR)
• HLR contains a database for subscriber specific
information such as IMSI.
• Current location of the MS, roaming restrictions etc.
• Subscriber Status.
• Visitor Location Registers(VLR)
• VLR contains a temporary database about all active
subscribers and always integrated with the MSC.
• Reduces number of queries to HLR.
HLR & VLR

21. • Authentication Center(AUC)
• Protects against intruders in air interface.
• Maintains authentication keys and algorithms and
provides security triplets( RAND, SRES,Kc ).
• Equipment Identity Register(EIR)
• It contains a centralized database for validating
the International Mobile Equipment Identity(IMEI)
• It contains three list, they are-
• White list
• Black list
• Grey list
AUR & EIR

22. • Dynamic monitoring and controlling of
network.
• Storage of software and data.
• Fault report and alarm handling.
• Performance Supervision.
• Stores data for minimum one year.
Operation and Maintenance Subsystem-

23. • GSM provide limited data rate capability.
• Many of the technology are patented and should be license
from Qualcomm.
• GSM uses FDMA in which multiple users share the same
bandwidth and will lead to interference when more number
of users are using the GSM service.
• GSM uses pulse based burst transmission technology and
hence it interferes with certain electronics.
Disadvantages of GSM-

24. Future of GSM-
2.5G
• High-Speed Circuit-Switched Data(HSCSD)
 Data rate : 76.8Kbps
• General Packet Radio Services(GPRS)
 Data rate : 14.4-115.2Kbps
• Enhanced Data Rates for Global
Evolution(EDGE)
 Data rate : 547Kbps