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GSM System Overview & Features

GSM is an international standard for digital cellular networks that was developed to address fragmentation issues with earlier cellular standards. It aims to provide improved spectrum efficiency, high quality speech, international roaming, and compatibility with other networks. The GSM system architecture consists of base transceiver stations, base station controllers, and a transcoder and adaptation unit. It uses TDMA technology and supports various services and features like emergency calling, SMS, and encryption.

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1K views17 pages

GSM System Overview & Features

GSM is an international standard for digital cellular networks that was developed to address fragmentation issues with earlier cellular standards. It aims to provide improved spectrum efficiency, high quality speech, international roaming, and compatibility with other networks. The GSM system architecture consists of base transceiver stations, base station controllers, and a transcoder and adaptation unit. It uses TDMA technology and supports various services and features like emergency calling, SMS, and encryption.

Uploaded by

api-3743621
Copyright
© Attribution Non-Commercial (BY-NC)
We take content rights seriously. If you suspect this is your content, claim it here.
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Download as PPT, PDF, TXT or read online on Scribd
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GSM

BY:
PRASHANT
CSE-2

GSM
INTRODUCTION
 GSM FACTS

 GOALS OF GSM

 SERVICES & FEATURES

 SYSTEM ARCHITECTURE

 CHANNEL TYPES

 FRAME STRUCTURE

 SIGNAL PROCESSING
INTRODUCTION
• GSM :- ESTI standard for 2G pan- European
digital cellular with international roaming.

• Developed to solve the fragmentation problem of


first cellular system.

• First introduced in European market in 1991.


GSM F ACTS

- Used in over 170 countries


- Over 400 GSM TDMA
network operators pdk
- Over 550 million GSM
People Were
550 CDMA
million
90 million
subscribers to GSM
GO AL S OF G SM

• Improved spectrum efficiency


• High quality speech
• International roaming
• Low cost mobile set & base station
• Support for new services
• Compatibility with ISDN & other telephone
company services
SER VICE S
User servi ce s :
# Telephone services - emergency calling &
facsimile.
# Bearer services or data services – packet
switched protocols data rates from 300bps to
9.6kbps.
# Supplementary ISDN services – call diversion ,
caller identification SMS
FEATURES

• SIM :- Memory device stores


information( subscriber’s identification no. ,
networks , countries)
• On air privacy :- made possible by
encrypting the digital bit stream sent by
GSM transmitter
SYS TEM

ARCHI TECTUR E
Consist of three major parts :

# base transceiver station


# base station controller
# the transcoder & adaptation unit
SYS TEM
ARCH ITECTU RE

HLR VLR AUC

BSC
PSTN

MSC ISDN

BSC
DATA

OMC

NETWORK SWITCHING PUBLIC


BASE STATION SUBSYSTEM SUBSYSTEM NETWORK
BASE TRAN SRECI VER
STATI ON

- Serves a single cell


- Usually placed in center
of a cell
- Coding
- Crypting
- Multiplexing
- Modulating
- synchronizing
BASE STATI ON
CO NTR OLLER
BTS
BSC
• Translates the 13 kbps
voice
• Frequency hopping To MSC
• Time and frequency
2
• Power management
mbps
• Time delay
measurement
Abis
TRA NS CODE R &
AD APT ATION
UNIT
• (13 kbps speech or data +
3 kbps additional
synchronizing data) *4 =
64 kbps (TRAU) standard
rate
BSD

64 kbps

TRAU

MSC
The va rio us i nte rfa ces u sed
in GS M
MS
BTS

BTS BSC MSC PSTN

MS
SS7
BTS A interface
(standardized)

GSM radio air


interface Abis interface
FRA ME STRU CTU RE
6.12
SUPERFRAME 51 MULTIFRAME

120
MULTI 26 FRAME
FRAME

4.615
FRAME 8 TIME
0 1 2 4 5 6
3 7 SLOTS

576.92
T
M 3 57 1 26 1 57 3 8.25
SI GN AL PROC ESSI NG
• Speech coding
• Channel coding for data channels
• Channel coding for control channels
• Interleaving
• Ciphering
SPEECH SPEECH
Digitizing & Source decoding
source coding

Channel coding Channel decoding

interleaving
De- interleaving

Burst formatting Burst formatting

ciphering De- ciphering

Radio
channel demodulation
modulation

GSM o per ation s fro m s peec h inp ut to s pee ch


CONCLUSION

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