Submitted by: Gaurav Ghai Keshie Singh Ravi

8/14/2019 Submitted by: Gaurav Ghai Keshie Singh Ravi

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Submitted By:

Gaurav Ghai (09020541067)

Keshie Singh (09020541070)

Ravi Somvanshi (09020541086)

Swapna Sagar (09020541101)

Vinay Acharya (09020541106)

Yogendra Singh Rathore (09020541114)


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GSM is an acronym that stands for Global System for Mobile

Communications. The original french acronym stands forGroupe Spcial

Mobile.

It was originally developed in 1984 as a standard for a mobile telephone

system that could be used across Europe. GSM is now an international standard for mobile service. It offers high

mobility. Subscribers can easily roam worldwide and access any GSM

network.

It also allowed for a more optimal allocation of the radio spectrum,

which therefore allows for a larger number of subscribers. GSM offers a number of services including voice communications, Short

Message Service (SMS), fax, voice mail, and other supplemental services

such as call forwarding and caller ID.

INTRODUCTION


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GSM frequency bands or frequency ranges are the cellularfrequencies designated by the ITU for the operation of the GSM for

mobile phones. Currently there are several bands in use in GSM. 450

MHz, 850 MHZ, 900 MHz, 1800 MHz, and 1900 MHz are the most

common ones. Some bands also have Extended GSM (EGSM) bands added to

them, increasing the amount of spectrum available for each band.

GSM makes use of Frequency Division Multiple Access (FDMA)and Time Division Multiple Access (TDMA).


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Why GSM?

Improved spectrum efficiency. International roaming. Low-cost mobile sets and base stations (BSs). High-quality speech.

Compatibility with Integrated Services Digital Network (ISDN)and other telephone company services. Support for new services.


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GSM is mature; this maturity means a more stable network with robustfeatures. Less signal deterioration inside buildings. Ability to use repeaters. Talktime is generally higher in GSM phones due to the pulse nature of

transmission.

The availability of Subscriber Identity Modules allows users to switchnetworks and handsets at will. GSM covers virtually all parts of the world so international roaming is not

a problem.

Advantages of 2G GSM

Pulse nature of TDMA transmission used in 2G interferes with

some electronics, especially certain audio amplifiers.

GSM has a fixed maximum cell site range of 35 km, which is

imposed by technical limitations.

Disadvantages of 2G GSM


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GSM900 at 900 MHz

124 carriers @ 2x25 MHz bandGSM1800 at 1800 MHz

375 carriers @ 2x75 MHz band

GSM1900 at 1900 MHz300 carriers @ 2x60 MHz band


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Uplinks/Downlinks & Reverse Forward

GSM allows for use of duplex operation. Each band has a frequency rangefor the uplink (cell phone to tower) and a separate range for the downlink

(tower to the cell phone). The uplink is also known as the Reverse and the

downlink is also known as the Forward. In this tutorial, I will use the terms

uplink and downlink.


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Numbering System (Identifiers)

Mobile Subscriber ISDN (MSISDN)The MSISDN is the subscriber's phone number. It is the number thatanother person would dial in order to reach the subscriber. The MSISDN iscomposed of three parts:

Country Code (CC)National Destination Code (NDC)Subscriber Number (SN)

MSISDN

Country Code (CC) - This is the international dialing code for whichevercountry the MS is registered to.

National Destination Code (NDC) - In GSM, an NDC is assigned to eachPLMN. In many cases, a PLMN may need more than one NDC.

Subscriber Number (SN) - This is a number assigned to the subscriber by

the service provider (PLMN).


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The combination of the NDC and the SN is known as the National

(significant) Mobile Number. This number identifies a subscriber withinthe GSM PLMN.

National (significant) Mobile Number


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International Mobile Subscriber Identity (IMSI)The IMSI is how the subscriber is identified to the network. It uniquely identifiesthe subscriber within the GSM global network. The IMSI is burned into the SIM

card when the subscriber registers with PLMN service provider. The IMSI is

composed of three parts:

Mobile Country Code (MCC)

Mobile Network Code (MNC)

Mobile Subscriber Identification Number (MSIN)

IMSI

Mobile Country Code (MCC) - This number identifies which country thesubscriber's network is in. It has 3 digits.

Mobile Network Code (MNC) - This number identifies the home GSM PLMN of

the subscriber. It has 2 or 3 digits. Some networks may have more than one MNC

allocated to it.

Mobile Subscriber Identification Number (MSIN) - This number uniquely

identifies a user within the home GSM network.


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International Mobile Equipment Identity (IMEI)The IMEI uniquely identifies the Mobile Equipment itself. It is essentially a serialnumber that is burned into the phone by the manufacturer. The IMEI is composed ofthree parts:

Type Allocation Code (TAC) - 8 digitsSerial Number (SNR) - 6 digitsSpare (SP) - 1 digit

IMEI

Type Allocation Code (TAC) - This number uniquely identifies the model of a wirelessdevice. It is composed of 8 digits. Under the new system (as of April 2004), the first two

digits of a TAC are theReporting Body Identifierof the GSMA approved group thatallocated this model type.Serial Number (SNR) - This number is a manufacturer defined serial number for themodel of wireless device.Spare (SP) This number is a check digit known as aLuhn Check Digit. It is omittedduring transmission within the GSM network.On many devices the IMEI number can be retrieved by entering *#06#


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International Mobile Equipment

Identity/Software Version (IMEISV)This is a newer form of the IMEI that omits the Spare digit at the end and

adds a 2-digit Software Version Number (SVN) at the end. The SVN

identifies the software version that the wireless device is using. This results

in a 16-digit IMEI.

Type Allocation Code (TAC) - 8 digits

Serial Number (SNR) - 6 digits

Software Version Number (SVN) - 2 digits

IMEISV


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Network Architecture


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MOBILE STATION= MOBILE EQUIPMENT +

SIMMOBILE EQUIPMENT :-

PHYSICAL PHONE

AVAILABLE INSINGLE,DOUBLE,TRIPLE ANDQUAD BANDS

CONSIST OF IMEI NUMBER

SUBSCRIBER IDENTITY MODULE(SIM):-

SMART CARD CARRIESSUBSCRIBER SPECIFICINFORMATION SUCH AS IMSI,TMSI, Ki, SPN AND LAC

STORES LAST DIALLED ANDRECEIVED NUMBERS (MSIDN)

CAN BE EASILY REMOVED ANDUSE IN OTHER MOBILE QUIPMENT

CONTAINS PIN (4 DIGITS)AND PUK(8 DIGITS)


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BASE TANSRECIVER STATION (BTS)

MOBILE STATION ACCESSPOINT TO NETWORK

CONSIST OF ALL RADIO

EQUIPMENTS NECESSARYFOR RADIO TRANSMISSION

HANDLES SPEECHENCODING, ENCRYPTION,MULTIPLEXING(TDMA) AND

MODULATION/DEMODULATION OF RADIO SIGNALS

CAPABLE OF FREQUENCYHOPPING

HAS A UNIQUE CELLIDENTITY


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MOBILE SWITCHING CENTER(MSC)

HEART OF GSM NETWORK

HANDLES CALL ROUTING,CALL SETUP

HANDLES MULTIPLE BSCs

HANDLES INTER BSCsHANDOVERS


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VISITOR LOCATION REGISTER(VLR) DATABSE CONTAINS SUBSET OF

INFORMATION LOCATED ON HLR

EVERY LOCATION AREA CONTAINSONE VLR

REDUCES THE OVERALL NUMBER OFQUERIES TO HLR

IDENTIFIES LOCAL AREA CODE

ASSIGNS TMSI TO MOBILE STATION


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EQUIPMENT IDENTITY REGISTER(EIR) KEEP RECORD OF HANDSETS IN

NETWORK USING IMEI NUMBER

ONLY ONE EIR IS PRESENT IN ANETWORK

CONTAINS THREE LIST

1. BLACK LIST

2. GRAY LIST

3. WHITE LIST


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AUTHENTICATION CENTER(AuC) HANDLES AUTHENTICATION AND

ENCRYPTION TASK FRO A NETWORK

STORES Ki FOR EACH NETWORK

GENERALY LOCATED AT HLR


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OPERATION AND MAINTENANCE

CENTER(OMC) CONNECTED TO HLR

LOOKS TRAFFIC MONITORING ,ACCOUNTING AND BILLING

GENERATE STATUS REPORT OF NETWORK ENTITIES

ALSO CALLED TELECOM MANAGEMENT


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GSM ARCHITECTURE


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Specifications


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GSM Specifications

GSM 900

Mobile to BTS (uplink): 890-915 Mhz

BTS to Mobile(downlink):935-960 Mhz

Bandwidth : 2* 25 Mhz

GSM 1800

Mobile to BTS (uplink): 1710-1785 Mhz

BTS to Mobile(downlink) 1805-1880 Mhz

Bandwidth : 2* 75 Mhz


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GSM Specification Carrier Separation : 200 Khz

No. of RF carriers : 124

Access Method : TDMA/FDMA

Modulation Method : GMSK

Modulation data rate : 270.833 Kbps


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GSM-Frame Structure


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Call Routing Call Originating from MS

Call termination to MS


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Outgoing Call

1. MS sends dialled number to BSS

2. BSS sends dialled number to MSC

3,4 MSC checks VLR if MS is allowed therequested service.If so,MSC asks BSS to

allocate resources for call.5 MSC routes the call to GMSC

6 GMSC routes the call to local exchangeof called user

7, 8,

9,10 Answer back(ring back) tone is routedfrom called user to MS viaGMSC,MSC,BSS


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Incoming Call

1. Calling a GSM subscribers

2. Forwarding call to GSMC

3. Signal Setup to HLR

4. 5. Request MSRN fromVLR

6. Forward responsible MSC toGMSC

7. Forward Call to currentMSC

8. 9. Get current status of MS

10.11. Paging of MS

12.13. MS answers

14.15. Security checks

16.17. Set up connection


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How does SMS works? Short message service is a mechanism of delivery of short messages over

the mobile networks.

It is a store and forward way of transmitting messages to and from mobiles.

An interesting feature of SMS is return receipts.

Since SMS used signalling channel as opposed to dedicated channels, these

messages can be sent/received simultaneously with the voice/data/fax

service over a GSM network.

The actual limit of size of SMS is 160 characters if Latin alphabets are

used. If non-Latin alphabets like Chinese or Arabic are used, the limit is 70characters.


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Organization of network elements in a GSM network

supporting SMS.


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Short Message Centeris the entity which does the job of store and forward of

messages to and from the mobile station.

Short Message Entity which can be located in the fixed network or a mobile

station, receives and sends short messages.

SMS gateway MSC is a gateway MSC that can also receive short messages.

The gateway MSC is a mobile networks point of contact with other networks.

On receiving the short message from the SMC, GMSC uses the SS7 networkto interrogate the current position of the mobile station form the HLR.

Visitor Location Registercorresponds to each MSC and contains

temporary information about the mobile, information like mobile identification

and the cell (or a group of cells) where the mobile is currently situated. Using

information form the VLR the MSC is able to switch the information (short

message) to the corresponding BSS (Base Station System, BSC + BTSs),

which transmits the short message to the mobile.

This information is passed over the signaling channels so the mobile can

receive messages even if a voice or data call is going on.


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Cellular Concepts


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Cellular Systems--Cellular ConceptsThe cellular concept was a major breakthrough in solving the problem of

spectral congestion and user capacity. It offered very high capacity in a

limited spectrum allocation without any major technological changes.

The cellular concept has the following system level ideas

Replacing a single, high power transmitter with many low power

transmitters, each providing coverage to only a small area.

Neighboring cells are assigned different groups of channels in order to

minimize interference.

The same set of channels is then reused at different geographicallocations.


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Cellular ConceptsWhen designing a cellular mobile communication system, it is important to

provide good coverage and services in a high user-density area.

Reuse can be done once the total interference from all users in the cells

using the same frequency (co-channel cell) for transmission suffers from

sufficient attenuation. Factors need to be considered include:

Geographical separation (path loss)

Shadowing effect


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Cell FootprintThe actual radio coverage of a cell is known as the cell footprint.

Irregular cell structure and irregular placing of the transmitter may be

acceptable in the initial system design. However as traffic grows, where

new cells and channels need to be added, it may lead to inability to

reuse frequencies because of co-channel interference.

For systematic cell planning, a regular shape is assumed for the

footprint.

Coverage contour should be circular. However it is impractical because

it provides ambiguous areas with either multiple or no coverage.Due to economic reasons, the hexagon has been chosen due to its

maximum area coverage.

Hence, a conventional cellular layout is often defined by a uniform grid

of regular hexagons.


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Cell Footprint


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Frequency Reuse

A cellular system which has a total ofSduplex channels.

Schannels are divided amongNcells, with each cell uses unique and

disjoint channels. If each cell is allocated a group ofkchannels, then

S= k N.


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TerminologyCluster size : TheNcells which collectively use the complete set of

available frequency is called the cluster size.

Co-channel cell : The set of cells using the same set of frequencies as thetarget cell.

Interference tier : A set of co-channel cells at the same distance from thereference cell is called an interference tier. The set of closest co-channelcells is call the first tier. There is always 6 co-channel cells in the first tier.


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Designing a cellular systemN=19

(i=3, j=2)


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Designing a cellular systemThe cluster size must satisfy:N= i2 + ij +j2 where i,j are non-negative

integers.


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Handover / HandoffOccurs as a mobile moves into a different cell during an existing call, or

when going from one cellular system into another.

It must be user transparent, successful and not too frequent.

Not only involves identifying a new BS, but also requires that the voiceand control signals be allocated to channels associated with the new BS.

Once a particular signal levelPmin

is specified as the minimum usable

signal for acceptable voice quality at the BS receiver, a slightly stronger

signal levelPHO is used as a threshold at which a handover is made.


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Handover / Handoff

=handoff threshold -

Minimum acceptable

signal to maintain the call

too small:

Insufficient time

to complete handoff

before call is lost

More call losses

too large:

Too many handoffs

Burden for MSC


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Dwell TimeThe time over which a user remains within one cell is called the dwell time.

The statistics of the dwell time are important for the practical design of

handover algorithms.

The statistics of the dwell time vary greatly, depending on the speed of theuser and the type of radio coverage.


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Handover indicatorEach BS constantly monitors the signal strengths of all of its reverse voice

channels to determine the relative location of each mobile user with respect

to the BS. This information is forwarded to the MSC who makes decisions

regarding handover.

Mobile assisted handover (MAHO) : The mobile station measures the

received power from surrounding BSs and continually reports the results of

these measurements to the serving BS.


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Prioritizing Handover

Dropped call is considered a more serious event than call blocking. Channelassignment schemes therefore must give priority to handover requests.

A fraction of the total available channels in a cell is reserved only forhandover requests. However, this reduces the total carried traffic. Dynamicallocation can improve this.

Queuing of handover requests is another method to decrease the probabilityof forced termination of a call due to a lack of available channel. The timespan over which a handover is usually required leaves room for queuinghandover request.


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Practical handoverHigh speed users and low speed users have vastly different dwell timeswhich might cause a high number of handover requests for high speed

users. This will result in interference and traffic management problem.

The Umbrella Cell approach will help to solve this problems. High speed

users are serviced by large (macro) cells, while low speed users are handledby small (micro) cells.


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Practical handover

A hard handover does break before make, ie.The old channel connection is broken before thenew allocated channel connection is setup. This

obviously can cause call dropping. In soft handover, we do make before break,

ie. The new channel connection is establishedbefore the old channel connection is released.This is realized in CDMA where also BSdiversity is used to improve boundary condition.


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System Expansion TechniquesAs demand for wireless services increases, the number of channels assigned

to a cell eventually becomes insufficient to support the required number ofusers. More channels must therefore be made available per unit area.

This can be accomplished by dividing each initial cell area into a

number of smaller cells, a technique known as cell-splitting. It can also be accomplished by having more channels per cell, i.e. by

having a smaller reuse factor. However, to have a smaller reuse factor,the co-channel interference must be reduced. This can be done by usingantenna sectorization.


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System Expansion Techniques--Cell splitting

Cell splitting increases the number of BSs in order to increase capacity.

There will be a corresponding reduction in antenna height and transmitter

power.

Cell splitting accommodates a modular growth capability. This in turn leads

to capacity increase essentially via a system re-scaling of the cellulargeometry without any changes in frequency planning.

Small cells lead to more cells/area which in turn leads to increased traffic

capacity.


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System Expansion Techniques--Cell splitting


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System Expansion Techniques --Sectorization

Keep the cell radius but decrease theD/R ratio. In order to do this, we must

reduce the relative interference without increasing the transmit power.

Sectorization relies on antenna placement and directivity to reduce co-

channel interference. Beams are kept within either a 60 or a 120 sector.


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System Expansion Techniques --Sectorization


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System Expansion Techniques --Micro cellsMicro cells can be introduced to alleviate capacity problems caused by

hotspots.

By clever channel assignment, the reuse factor is unchanged. As for cell

splitting, there will occur interference problems when macro and micro

cells must co-exist.


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Evolution of

Mobile

Communication


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1G1G (or 1-G) is short for first-generation wireless telephone

technology, cellphones.

Uses digital signaling to connect the radio towers to the rest of the

telephone system .Uses analog signaling to communicate between the speakers.

The voice is modulated to higher frequency, typically 150MHz and

up.


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2G

2G (or 2-G) is short for second-generation wirelesstelephone technology.

Commercially launched on the GSM standard.

Three primary benefits of 2G networks :1) Phone conversations were digitally encrypted.

2) More efficient on the spectrum allowing for far greater

mobile phone penetration levels.

3) Introduced data services for mobile, starting with SMS

text messages.


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Advantages of 2G

The lower powered radio signals require less battery power.

Digital error checking increased sound quality by increasing

dynamic range and lowering the noise floor.

The lower power emissions helped address health concerns.

Introduction of digital data services, such as SMS and email.

Greatly reduced fraud.

Enhanced privacy. Digital cellular calls are much harder to

eavesdrop on by use of radio scanners.


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Disadvantages of 2G

In less populous areas, the weaker digital signal may not

be sufficient to reach a cell tower.

Digital signal has a jagged steppy one and has occasional dropouts.

While digital calls tend to be free of static and background noise,

the lossy compression used by the codecs takes a toll; the range of

sound that they convey is reduced.


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Journey from 2G to 3G


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3G Features


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3G Features continued


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3G ISSUES Expensive input fees.

Difference in license in states.

Cost of 3G handsets.

Battery life of 3G handsets.

Lack of coverage in some areas.

Lack of support for some operators.


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GenNext4G!A fully IP-based integrated system.

Will be capable of providing between 100 Mbit/s and 1 Gbit/s

speeds both indoors and outdoors.

Premium quality and high security.


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4G TARGET

High quality service (QOS)

High network capacity.

A data rate of 100 Bits/s between points.

Seamless connectivity and global roaming.

Ip packet, switched network.


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GSM IN INDIA


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From desk of C.O.A.I Cellular operator association of India

Started its operation in 1995

Registered as non profit organization .

Vision with aim to develop and maintain world class infrastructure and tomaintain good communication.

To improve standard and upgrade services with G.S.M India.

To undertake continuous effort to improve customer satisfaction.


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India as G.S.M player India has 335.5 million customers as on September 2009.

The report declared by cellular operators association of India (C.O.A.I)

Bharati Airtel remains top player with market with net subscriber base

of 107.9 million - August 2009.

Second in the list is Vodafone with subscriber base of 80.8 million

August 2009.

Third position lies with government owned BSNL with adding 1.3

million customers- August 2009

Fourth position is taken by idea adding 1.5 million customers

August 2009.


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India as G.S.M player.Market share of various telecom operators as on September 2009.

o Bharti Airtel with top position 32.19%

o

Vodafone on second position with 24.11%o BSNL is at third position with15.5%

o Idea is at fourth position of 14.9%

o Aircel is at fifth position with 7.28%


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G.S.M at glance.


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Thank You

Submitted by: Gaurav Ghai Keshie Singh Ravi

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