History:
1946 -First Car Phone by St. Louis
1973-First hand held mobile by Martin Cooper
1980's
• 1G Cellular Technology launched
• TACS,NMT,AMPS etc. analog systems launched in America & UK countries.
1990's
• Digital 2G Cellular technology launched.
• GSM,CDMA etc. launched with GSM being standard.
In 2001 the first commercial launch of 3G was
done in Japan. With 3G following services are
available
Video Conferencing
online games
net surfing..
Introduction:
Global System for Mobile (GSM) is a second generation cellular standard
developed to cater voice services and data delivery using digital modulation.
GSM Services
TELE SERVICES : Includes mobile phones, emergency calling etc.
DATA SERVICES : Includes SMS (Short message service), fax,
voicemail, electronic mail.
SUPPLYMENTARY SERVICES : I/C & O/G calls, call forwarding,
call hold, call waiting, conference, etc.
ADVANTAGES OF GSM
Communication
– mobile, wireless communication, support for voice and data services
Total mobility
– international access, chip-card enables use of access points of different
providers.
Worldwide connectivity
– one number, the network handles every location.
High capacity
– better frequency efficiency, smaller cells, more customers per cell.
High transmission quality
-high audio quality and reliability for wireless, uninterrupted phone calls at
higher speeds (e.g., from cars, trains).
GSM SPECIFICATION
GSM 900
Mobile to BTS (uplink): 890-915 MHz CARRIER SEPARATION:200KHZ
RF Spectrum DUPLEX DISTANCE:45 MHZ
BTS to Mobile(downlink):935-960 MHz NO. OF RF CARRIERS:124
Bandwidth : 2* 25 ACCESS METHOD:TDMA/FDMA
GSM 1800 MODULATION METHOD:GMSK
Mobile to BTS (uplink): 1710-1785 MHz MODULATION DATA RATE:270.833
BTS to Mobile(downlink) 1805-1880 MHz kbps
Bandwidth : 2* 75 MHz
NETWORK SUBSYSTEM:
Performs call processing and subscriber related functions.
It includes:
MSC : Mobile Switching Centre
HLR : Home Location Register
VLR : Visitor Location Register
AuC : Authentication Centre
EIR : Equipment Identity Register
GMSC:Gateway MSC.
Mobile switching centre
• It is included in the GSM system for call-switching. Its overall purpose is the
same as that of any telephone exchange.
The functions carried out by the MSC are listed below:
• Call Processing
Includes control of data/voice call setup, inter-BSS and inter-MSC handovers
and control of mobility management (subscriber validation and location).
• Operations and Maintenance Support
Includes database management, traffic metering and measurement, and a
man–machine interface.
• Internetwork Interworking
Manages the interface between the GSM network and the PSTN.
When the MSC provides the interface with the other networks in the
GSM network it is known as a Gateway MSC.
Home location register
Reference database for subscriber parameters.
• Subscriber ID (IMSI & MSISDN).
• Current location of subscriber.
• Subscriber status (registered/unregistered)
• Authentication key and AUC functionality.
• Mobile subscriber roaming number.
Visitor location register
• It provides local database for the subscribers wherever they are physically
located within a PLMN, this may or may not be the “home” system. It is a
local database and contains copy of most of the data stored in HLR.
It contains:
• Mobile status(busy/free/no ans)
• Location area identity(LAI)
• TMSI AND MSRN
Authentication centre
• It provides authentication and encryption parameters for verification of
subscriber identity.
• It ensures confidentiality of each cell.
• It protects network operators from frauds in today's cellular world.
• It is associated with HLR.
• The authentication process will usually take place each time the subscriber
“initializes” on the system.
EQUIPMENT IDENTITY REGISTER
• The EIR contains a centralized database for validating the International
Mobile Equipment Identity (IMEI).
• It contains three lists:
White List
Contains those IMEIs which are known to have been assigned to valid MS
equipment.
Black List
Contains IMEIs of MS which have been reported stolen or which are to be denied
service for some other reason.
Grey List
Contains IMEIs of MS which have problems (for example, faulty software).
These are not, however, sufficiently significant to warrant a ‘‘black listing”.
Radio Subsystem
• Management of radio network and is controlled by a MSC . One MSC controls
many radio subsystem.
It consists of :
• BSC: Base station controller.
• BTS: Base transceiver station.
BASE STATION CONTROLLER
-It is connected to MSC.
- Controls one or more BTS.
-Switches traffic and signaling to/from
BTSs and MSC.
-Connects terrestrial circuits and
channels on air interface.
-Controls handover performed by BTS.
-Frequency allocation and power control.
base transceiver station
• Maintains air interface and minimize transmission problems.
• Paging information.
• Radio level power control.
• BTS identification.
• Ciphering
• Speech processing.
GSM- FRAME STRUCTURE
OUTGOING CALL
1.MS sends dialed number to BSS
2.BSS sends dialed number to MSC
3,4 MSC checks VLR if MS is allowed the requested service. If so, MSC asks BSS
to allocate resources for call.
MSC routes the call to GMSC
GMSC routes the call to local exchange of called user
7, 8,
9,10 Answer back(ring back) tone is routed from called user to MS via
GMSC,MSC,BSS
INCOMING CALL
1.Calling a GSM subscribers
2.Forwarding call to GSMC
3.Signal Setup to HLR
4,5. Request MSRN from VLR
5.Forward responsible MSC to GMSC
6.Forward Call to current MSC
7,9. Get current status of MS
8,11. Paging of MS
9,13. MS answers
10,15. Security checks
11,17. Set up connection
FUTURE OF GSM
2nd Generation
GSM -9.6 Kbps (data rate)
2.5 Generation ( Future of GSM)
HSCSD (High Speed ckt Switched data)
Data rate : 76.8 Kbps (9.6 x 8 kbps)
GPRS (General Packet Radio service)
Data rate: 14.4 - 115.2 Kbps
EDGE (Enhanced data rate for GSM Evolution)
Data rate: 547.2 Kbps (max)
3 Generation
WCDMA(Wide band CDMA)
Data rate : 0.348 – 2.0 Mbps
