principle of mc.ppt
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AITTM
B.TECH(E&T), SEVENTH SEMESTER
Course on Cellular Communication
Topic: Principle Of Mobile Communication
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Evolution of GSM
GSM is offering continuous improvement andmore services.
In 1995 the Phase2recommendations were
frozen.The GSM 900 and GSM 1800specifications were merged and additionalsupplementary services were defined,theshort message services was improved andimprovement in radio access and SIM cardswere introduced.
GSM continuous evolve at full speed.
The number of improvements so large that
together they are called Phase2++ features.
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In 1982CEPT initiated a new cellular system.
* For roaming frequencies are in the band of900 MHz.
1987Memorandum of understanding (MoU).
Allocation of frequencies:-890-915MHz uplink &935-960 MHz downlink
1988- European Telecommunication Standard
Institute (ETSI)was created.
1991- First official call in the world with GSM on
1stJuly.
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1992- Worlds first GSM network launched in
Finland. The first roaming agreement was made.
By December there were 13 networks operating in
7 areas. Australian operators were the first non-
European signatories of the GSM MoU.New frequency allocation for GSM 1800 (DCS
1800)- 1710-1785 MHz (uplink) & 1805-1880
MHz (downlink).
1993- GSM demonstrated for first time in Africa
at Telkom and there was 32 GSM network
operating in 18 areas.
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1994 - The first GSM network in Africa was
launched in South Africa.
1995 -There were 117 GSM networks. Fax,
data, and SMS roaming was
implemented.
* The GSM phase2 standardization was
completed, forGSM 1900 (PCS1900).
1996- There were 120 networks operating.
* The 8K SIM was launched in
addition to prepaid GSM SIM cards.
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1998 - HSCSD (High Speed Circuit Switched Data) trials
in Singapore.
1999The first mobile data call using GPRS(GeneralPacket Radio Service)in a live network was made.
LBS is combined with GPS(Global Positioning System), so
that subscriber can determine his geographical locationextremely accurately.
The 3G mobile communications system UMTS was
specified which is based on the GSM standards to allow asmooth evolution from the 2nd generation to the 3rd
generation.this ought to guarantee an investment protection
for GSM operators.
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2000- The first GPRS network is launched.
2001- The Multimedia Messaging Service (MMS)
was standardized. GSM 700 supported; UL: 747
762 MHz and DL: 777792 MHz.
2002 UMTS/ GSM Rel.5 standardized (IMS) wasstandardized for GSM/GPRS and UMTS.
Smart phones are under development for GSM/GPRS
and UMTS to allow a wide range of mobile service,such as mobile Internet, mobile gambling, enhanced
LDAs, video messaging, agonistic services, etc.
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2003- First commercial starts of UMTS network
operators in Europe.
2004More than one billion people are now
using GSM mobile phones.
More than 200 countries and territories has
adopted GSM and it has become a truly global
standard for mobile communications.
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SUMMARY OF GSM BAND
U / L D / L B/W D/D
GSM90 890-915 MHz 935-960 MHz 25 MHz 45MHz
GSM-1800 (DCS-1800) 1710-1785 MHz 1805-1850 MHz 75 MHz 95MHz
GSM-850 (Support) 824-849 MHz 869-894 MHz 25 MHz 45MHz
GSM-700 (MMS) 747-762 MHz 777-792 MHz 15 MHz 30MHz
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UMTS
UMTS3rdgeneration
It is based on GSM due to two reasons.
1. The GSM technology dominates the market.
2. Great investment made to GSM should be utilized asmuch as possible.
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Some requirements for 3G are :
The system to be developed must be fully
specified(like GSM).The specifications
generated should be valid worldwide.
The system must bring clear added value.it
must be backward compatible at least with
GSM and ISDN.
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Multimedia and all of its components must be supported
throughout the system.
The radio access of 3G must be generic. Radio access
and the network infrastructure must not limit the servicesto be generated. That is the technology platform is one
issue and the service using the platform another issue.
3G system has high data rate, that will allow multimediatraffic through the wireless network.
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Enhanced packet switching and routing techniques are to
be deployed to support video traffic.
The 3G system will use Broadband Integrated Services
Digital Network (B-ISDN) to provide data services
between the exiting data networks and the wireless
network.
The Global 3G Partnership Project (3GPP) incorporating
many organization (ITU-T, ETSI, ARIB, and ANSI) isdeveloping standards for the 3G systems.
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Mobile Communications: Basic Concepts
From ancient to modern times, mankind has been looking
for means of long distance communications.
Fire, flags, horns, etc were used to transmit information
faster.
19th century simplified long distance communications:
Telegraphy and later on Telephony.both technique were
wire line.
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Marconi made economic use of electro-magnetic theory by
developing devices for wireless transmission of Morse
signals(about 1985). Already 6 years later, the first
transatlantic wireless transmission of Morse signal tookplace.
Voice was transmitted the first time in 1906 (R.Fess
Eden),and first radio broadcast transmission 1909 in New
York.
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Economically most successful wireless
application in the first half of the 20thcentury was
radio broadcast. There is one transmitter, the so
called radio station. Information, such as news,
music etc. is transmitted from the radio station tothe receiver equipment, the radio device. This type
of one way transmission is called simplex
transmission.
In this transmission takes place in one direction,
from the transmitter to the receiver.
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The first commercial wireless car phony telephony service
started in the late 1946 in St. Louise, Missouri (USA). It
was a car phone service, because at that time, the mobile
phone equipment was bulky and heavy.
Actually, in the start up, it filled the whole back of the
car. But it was real fullduplex solution.
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In the 50ies, several vehicle radio systems were also
installed in Europe.
These systems are now a days called single cell system.
The user data transmission takes place between the
mobile phone and the base station (BS).
A base station transmit and receive user data. While a
mobile phone is only responsible for its users data
transmission and reception, a base station is capable tohandle the calls of several subscribers simultaneously.
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Transmission of user data from base station to the
mobile phone is called downlink (DL).
Transmission from mobile phone to base station is
called uplink (UL).
The area, where the wireless transmission between
mobile phone to the base station can take place, is the
base station supply area,called cell.
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For conversation, a technical solution is required where
information flow can take place in two directions. This
type of transmission is called Duplex transmission.
Walky-talky was already available the early 30ies. This
system already allowed a transmission of user data in twodirections, but there was a limitation: the users were not
allowed to transmit at the same time.
In other words, you could only receive or transmit the userinformation. This type of transmission is often called semi-
duplex transmission.
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For telephony services, a technical solution is required,where subscribers have the impression, that they can
speak (transmit) and hear (receive) simultaneously. This
type of solution is regarded as full- duplex transmission.
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Single cell system are quite limited. The more and
more distant the subscriber is from the base station, thelower the quality of the radio link. If the subscriber is
leaving the supply area of the cell, no communication is
possible any more. In order to over come this limitation,
cellular systems were introduced.
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A cellular mobile communication system consists of
several cells, which can overlap. By doing so a whole
geographical area can be supported with the mobilecommunication service.
But what happens, when a subscriber moves during a
call from one cell to another cell?
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If the subscriber is leaving the cell, and in parallel isentering a new cell, then system makes new radio
resources available in the neighboring cell, and the call is
handed over from one cell to the next one. By doing so,
service continuation is guaranteed, even when thesubscriber is moving. The process is known as
handover(HO).
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A hand over takes place during a call i.e. when amobile in active mode.
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In the idle mode of mobile, the mobile is switched on,but no resources are allocated to it to allow user data
transmission, and the mobile phone is still listening the
information, broadcast by the base station.
Why? Imagine, there is a mobile terminated call. The
mobile phone is then paged in the cell. This means the
phone receive information that there is a mobile
terminated call.
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A cellular system may consists of hundreds of cell. If
the mobile network does not know, in which cell themobile phone is located, it must be paged in all of
them.
To reduce load on networks, paging is done in smallparts of mobile an operators network.
Mobile network operators group cells in
administrative units called location areas (LA).
A mobile phone is paged in only one direction area.
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But How does the cellular system know, in which
location area the mobile phone is located?
In every cell, system information is continuously
transmitted. System information includes the location
area information.
In the idle mode, the mobile phone is listening to this
system information.
If the subscriber moves hereby from one cell to the nextcell, and the new cell belongs to the same location area,
the mobile stays idle.
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If the new cell belongs to a new location area,
then the mobile phone has to become active. Itstarts a communication with the network
informing it about it new location. This is stored
in database with in the mobile network, and if
there is a mobile terminated call, the networkknows where to page the subscriber.
The process, where the mobile phones informs
the network about its new location is calledLocation Update Procedure (LUP).
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First generation mobile communication systems
are:
TACS U.K (Total Access Communication System) 900 MHz band
NMT Scandivanian (Nordic Mobile Telephony) 450 & 900 MHz band
AMPS U.S (Advanced Mobile Phone Service) 800 MHz band
C450
etc.
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All of them launched in the 80s of the last century.
1stgeneration mobile communication systems often
offered national wide coverage. But there was
limitations: Most of them did not support roaming.
Roaming is the ability to use another operators network
infrastructure.
International roaming is the ability to go even to another
country and use the locals operators infrastructure.
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Most 1st
generation mobile communication systemsonly support only speech transmission, but not data
transmission such as fax.
Supplementary services, well known from ISDN,
were not available, such as number indication and
call forwarding, when busy.
The transmission takes place unprotected via the
radio interfaceas a consequence evaesdropping ispossible.
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Finally, mobile communication started to
become a mass market. And the radiointerface is the main bottleneck in terms of
capacity.
Improved solution was urgently required.This led to the inauguration of the second
generation mobile communication systems,
one of which is GSM.
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1980 1990 2000
1G 2G 3G
multi standard analog multi standard digital unified standard digital
voice only prepaid data barrier high speed data rate
low data rate up to 2Mb/sTACS,NMT, IS-95,GSM, WCDMA,UMTS,
AMPS CDMA IMT-2000
Terrestrial Terrestrial Satellite/Terrestrial
CXL, M/W OFC, M/W, Cellular Cellular/Satellite
DAMPSU.S 800 MHz Band
GSM Europe 900 / 1800 / 1900 MHz Band
CDMA U S 900 MHz