h2.cjk Aim: Case Study on GSM (Global System

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Experiment
No 1
Aim:
Case Study on GSM (Global System for Mobile Communication).
INTRODUCTION:

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GSM is a standard developed by the European Telecommunications
Standards Institute (ETSI) to describe the protocols for second
generation digital cellular networks used by mobile devices such as
tablets, mobile.It was first deployed in Finland in 1991.As it was
better adapted it takes 90% of total market in 193 countries and
territories.

It
was developed to replace the 1G i.e Analog cellular networks.It is
originally described as digital networks with
circuit switching system optimized for full duplex voice
telephony.It was then followed by 3G (UMTS) and then by 4G (LTE).
GSM
Network Structure consists
of number of discrete sections.It includes:

Base Station subsystem

Network and switching Subsystem

GPRS Core Network

Operations Support system (OSS).

FEATURES:

Improved spectrum efficiency

International roaming

Compatibility with integrated services digital network (ISDN)

Support for new services.

SIM phonebook management

Fixed dialing number (FDN)

Real time clock with alarm management

High-quality speech

Uses encryption to make phone calls more secure

Short message
service (SMS)

ARCHITECTURE
OF GSM:
Radio Subsystem:Its
comprises of all radio specific entities ie: MS and and BSS the
connection between RSS and NSS are via ‘A’ interface and the
connection to the OSS via ‘O’ interface
MS(Mobile
Station):
A
GSM network consist of many bss each bs is controlled by bsc,the bss
all functions. MS uses Sim card.Sim card consist of many identity
details,Pin,Puk and Authentication key and IMSI. MS store dynamic
info while lock on to GSM service cypher key,location info,TMSI and
LAR.It can also offer other types of interface to user which consist
of microphone,loudspeaker and services like bluetooth function as
camera,calenders,address book,games etc.
BTS(Base
Transreceiver Station):
As
antenna,amplifiers,signal processsing necessary for radio
transmmision,A BTS can form a radio cell using sectorized antenna
.BTS is connected to MS via linear interface and BSC via ABis
interface
BSC(Base
Station Controller):
It
manages all BTS,it reserves radio frequency,handle from one bts to
another within BSS.BSC also multiplexes the radio channels to fix
network conection at the a interface
NSS(Network
Switching Subsytem):
The
heart of GSM system is form by NSS,it connects wireless network to
standard public network .
It
performs handover switching,between different BSS. It consist of
function for localization

MSC(Mobile Station
Controller):

Msc are high performance
digital,isdn switches,they setup connection to other msc and to the
bsc via a interface

GMSC(GatewayMSC):

A GMSC has additional connections
to the other metwork such as PSTN and ISDN.Using additional
interworking function IWF on msc can also connect to PDN

HLR(Home Location Register):

it is the most important database
in gsm system.it stors all user relevant information.it consist os
static information like subscribed services,call forwarding
,roaming,gprs etc

dynamic information as current
location area of the ms,the mobile subscriber roaming number,current
vlr and msc.hlr can manage million of customer.

VLR(Visitor Location
Register):

VLR is associated with each msc
and store all important information nedded for the ms user.its is
imsi and hlr address address.if a new ms comes into an LA the vlr is
resposibile to copy all relevant information from that hlr.some vlr
are capable of managing 1 billion customer.

OSS(Operation Sub System):

The necessary function forms
network operation and maintenance.it consiste of omc,auc,eir.it
monitorsand controls all the other network entity via O interface
.its function includes traffic monitoring,status report of
network,subscriber and security manager ,accounting,billing etc

AUC(Authentication center):

its is used to protect user
identity and data transmission, it conains algorithm for
authentication as well as keys for encryption and generate the values
nedded for authentication in hlr.

EIR(Equipment Identity
Register):

Its is a database for all imei.it
stores all device identification registration for the network.

SERVICES:

Teleservices
The
abilities of a Bearer Service are used by a Teleservice to transport
data. These services are further transited in the following ways:
Voice
Calls
The
most basic Teleservice supported by GSM is telephony. This includes
full-rate speech at 13 kbps and emergency calls, where the nearest
emergency-service provider is notified by dialing three digits.
Videotext
and Facsmile
Another
group of teleservices includes Videotext access, Teletex
transmission, Facsmile alternate speech and Facsmile Group 3,
Automatic Facsmile Group, 3 etc.
Short
Text Messages
Short
Messaging Service (SMS) service is a text messaging service that
allows sending and receiving text messages on your GSM mobile phone.
In addition to simple text messages, other text data including news,
sports, financial, language, and location-based data can also be
transmitted.
Bearer
Services
Data
services or Bearer Services are used through a GSM phone. to receive
and send data is the essential building block leading to widespread
mobile Internet access and mobile data transfer. GSM currently has a
data transfer rate of 9.6k. New developments that will push up data
transfer rates for GSM users are HSCSD (high speed circuit switched
data) and GPRS (general packet radio service) are now available.
Supplementary
Services
Supplementary
services are additional services that are provided in addition to
teleservices and bearer services. These services include caller
identification, call forwarding, call waiting, multi-party
conversations, and barring of outgoing (international) calls, among
others. A brief description of supplementary services is given here:

Conferencing
: It allows a mobile subscriber to establish a multiparty
conversation, i.e., a simultaneous conversation between three or
more subscribers to setup a conference call. This service is only
applicable to normal telephony.

Call
Waiting : This service notifies a mobile subscriber of an
incoming call during a conversation. The subscriber can answer,
reject, or ignore the incoming call.

Call
Hold : This service allows a subscriber to put an incoming call
on hold and resume after a while. The call hold service is
applicable to normal telephony.

Call
Forwarding : Call Forwarding is used to divert calls from the
original recipient to another number. It is normally set up by the
subscriber himself. It can be used by the subscriber to divert calls
from the Mobile Station when the subscriber is not available, and so
to ensure that calls are not lost.

Call
Barring : Call Barring is useful to restrict certain types of
outgoing calls such as ISD or stop incoming calls from undesired
numbers. Call barring is a flexible service that enables the
subscriber to conditionally bar calls.

Number
Identification : There are following supplementary services
related to number identification:

Calling
Line Identification Presentation : This service displays the
telephone number of the calling party on your screen.

Calling
Line Identification Restriction : A person not wishing their
number to be presented to others subscribes to this service.

Connected
Line Identification Presentation : This service is provided to
give the calling party the telephone number of the person to whom
they are connected. This service is useful in situations such as
forwarding’s where the number connected is not the number dialled.

Connected
Line Identification Restriction : There are times when the
person called does not wish to have their number presented and so
they would subscribe to this person. Normally, this overrides the
presentation service.

Malicious
Call Identification : The malicious call identification service
was provided to combat the spread of obscene or annoying calls. The
victim should subscribe to this service, and then they could cause
known malicious calls to be identified in the GSM network, using a
simple command.

Advice
of Charge (AoC) : This service was designed to give the
subscriber an indication of the cost of the services as they are
used. Furthermore, those service providers who wish to offer rental
services to subscribers without their own SIM can also utilize this
service in a slightly different form. AoC for data calls is provided
on the basis of time measurements.

Closed
User Groups (CUGs) : This service is meant for groups of
subscribers who wish to call only each other and no one else.

Unstructured
supplementary services data (USSD) : This allows
operator-defined individual services.

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