This is the training report of the work i did in BSNL, Agartala

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A REPORT OF FOUR WEEKS INDUSTRIAL TRAINING
IN
BASIC TELECOM
AT
BHARAT SANCHAR NIGAM LIMITED
Submitted in Partial Fulfillment of the
Requirement for Award of the Degree
Of
BACHELOR OF TECHNOLOGY
In
ELECTRONICS & COMMUNICATION ENGINEERING
Submitted By: - ARIJIT ROY
REGISTERATION NO: -11710188
SECTION: -E1722
ROLL NO: -RE1722B45
Under the Guidance of
Mr. Vishal Polowalia
DEPARTMENT OF ELECTRICAL & ELECTRONICS ENGINEERING
LOVELY PROFESSIONAL UNIVERSITY
PHAGWARA, PUNJAB (INDIA) -144402
2017-18

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Lovely Professional University Jalandhar, Punjab
CERTIFICATE
I hereby certify that the work which is being presented in the industrial summer training
entitled Basic Telecom in partial fulfillment of the requirement for the award of degree of
Bachelor of Technology and submitted in Department of Electronics & Communication
Engineering, Lovely Professional University, Punjab is an authentic record of my own work
carried out during period of summer training under the supervision of Mr.Vishal Polowalia,
Junior Telecom Officer, BSNL, Udaipur, Tripura-799120.
The matter presented in this summer training has not been submitted by me anywhere
for the award of any other degree or to any other Institute.
Date:-09/07/2018 Arijit Roy

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ACKNOWLEDGEMENT
“It is not possible to prepare a project report without the assistance &
Encouragement of other people. This one is certainly no exception.”
On the very outset of this report, I would like to extend my sincere & heartfelt
obligation towards all the personages who have helped me in this endeavour. Without
their active guidance, help, cooperation & encouragement, I would not have made
headway in the project.
I am ineffably indebted to Mr. VISHAL POLOWALIA for conscientious guidance and
Encouragement to accomplish this assignment.
I am extremely thankful and pay my gratitude to department of BSNL for their
Valuable guidance and support on completion of this project in its presently.
I extend my gratitude to LPU for giving me this opportunity. I also acknowledge with a
deep sense of reverence, my gratitude towards my Parents and member of my family,
who has always supported me morally as well as economically.
At last but not least gratitude goes to all of my friends who directly or indirectly
Helped me to complete this project report.
Any omission in this brief acknowledgement does not mean lack of gratitude.
Thanking You
Arijit Roy

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ABSTRACT
Spending a period of four weeks with the Telecommunication Networking. The report on how
the BSNL Basic Telecom Network work and how to exchange work and how the company work
with telecommunication Network. This Report also contains the basic telecommunication that
work with all team work of employees and the exchange work.
I was in direct selling and, I realized that it is very difficult to understand the behaviour of
customers. I am saying this because even though I was associated with a brand, sometimes it
was difficult to convince the custom BSNL has a Quality telecommunication system which is
demonstrated through its ability to consistently provide product and services that meets
customer and applicable regulatory requirements. It aims to enhance customer satisfaction
through its effective services.
Previously electro mechanically exchange for use in India namely Strowger type exchange,
cross bar exchange was there. These Manual telephone exchanges suffered from some
disadvantages.
To overcome these an automatic exchange was introduced in this system. In this system 1980’s
PITHROTHA LTD. Introduced “C-DOT “exchange in India. Besides C-DOT exchange ILT
exchange, E-10B exchange also proved of mild stone in Telecommunication Sector to replace
electromechanical exchanges, which were most sophisticated and modern latest techniques
electronics exchanges. There after it was OCB-283 exchange which proved very important
exchange in this series to replace electromechanical exchanges.
Now it is “WLL” & “GSM” mobiles which is also proved a mild stone in telecommunication
sector. It was 31st march 2002 when BSNL started these GSM mobile and today it has provided
almost 35 lacks mobiles in all over country.

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CONTENTS
CHAPTER PARTICULAR PAGE
NO. NO.
Cover Page 1
Certificate 2
Acknowledgement 3
Abstract 4
Contents 5-6
List of Figures 7
Introduction to BSNL 8
Profile of the Company 9
Telecom Network 10-14
Chapter-1 1.1 Call Setup 10-11
1.2 Electronic Exchange 11
1.3 Carrier Room 11
1.3.1 Conventional Leased 11
Line System
1.3.2 Managed Leased Line 12
Network
1.4 Main Distribution Frame 12
1.4.1 Function of MDF 12
1.5 Power Plant 13
1.6 How a Telecom Exchange 13
Work
1.7 Engine and Alternator 14

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1.8 OMC 14
1.9 Switches 14
Chapter-2 Switching 15-18
2.1 C-DOT 16-18
Chapter-3 Mobile Communication 19-22
3.1 Generation Gap 19
3.2 How a call is connected 21-22
Chapter-4 CDMA 23-24
4.1 Advantage of CDMA 24
Chapter-5 GSM 25-28
5.1 GSM Subsystem 26
5.2 GSM Evoulation 27
5.3 Advantages for Operators 28
Chapter-6 Broadband 29-35
6.1 Feature of Broadband 30
6.2 Wire Line Broadband Technologies 30
6.2.1 ADSL 30
6.2.2 DSL 33
6.2.3 ISDN 33
6.2.4 Advantages 34
6.2.5 BPL 34
6.2.6 Applications of 35
Broadband
Chapter-7 Conclusion 36
References 37

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List of Figures
FIGURE Title of Figure Page
NO. No.
FIG 1.1 How Line Reaches From Subscriber to Exchange 10
FIG 1.2 Main Distribution Frame 12
FIG 1.3 Block Diagram of Telephone Exchange 14
FIG 2.1 General Diagram of a Digital Switch 15
FIG 2.2 C-DOT Rax 17
FIG 2.3 The C-DOT DSS MAX Basic Architecture 18
FIG 3.1 Cell Phone and Base Station 20
FIG 4.1 Different b/w CDMA and Other Systems 24
FIG 5.1 GSM Network Architecture 27
FIG 5.2 Evalution of GSM 27
FIG 6.1 Broadband Connection 32

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INTRODUCTION
The telephone is a telecommunication device that is used to transmit and receive
electronically or digitally encoded speech between two or more people conversing. It
is one of the most common household appliances in the world today. Most telephone
network which allows any phone user to communicate with almost any other user.
Telecommunication networks carry information signals among entities, which are
geographically far apart. The entities are involved in the process of information transfer
that may be in the form of a telephone conversation or a file transfer between two
computers or message transfer between two terminals etc.
With the rapidly growing traffic and untargeted growth of cyberspace,
telecommunication becomes a fabric of our life. The future challenges are enormous as
we anticipate rapid growth items of new services and number of user.
Telecommunication has evaluated and growth at an explosive rate in recent years and
will undoubtedly continue to do so. The telecommunication links and switching were
mainly designed for voice communication. With the appropriate
attachments/equipment’s, they can be used to transmit data. A modern society, therefore
needs new facilities including very high bandwidth switched data networks, and large
communication satellites with small, cheap earth antennas.

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COMPANY PROFILE
Bharat Sanchar Nigam Limited is a state-owned telecommunications company
headquartered in New Delhi, India. BSNL is one of the largest Indian cellular service
providers, with over 87.1 million subscribers as of April 2011, and the largest land
line telephone provider in India. BSNL is India’s oldest and largest communication
service provider (CSP). It had a customer base of 90 million as of June 2008. It has
footprints throughout India except for the metropolitan cities of Mumbai and New
Delhi, which are managed by Mahanagar Telephone Nigam Limited (MTNL). As of
June 30, 2010, BSNL had a customer base of 27.45 million wire line and 72.69 million
wireless subscribers. BSNL is the only service provider, making focused efforts and
planned initiatives to bridge the Rural-Urban Digital Divide ICT sector. In fact, there
is no telecom operator in the country to beat its reach with its wide network giving
services in every nook & corner of country and operates across India except Delhi &
Mumbai. Whether it is inaccessible areas of Siachen glacier and North-eastern region
of the country BSNL serves its customers with its wide bouquet of telecom services.
BSNL is numerous operator of India in all services in its license area.
The company offers wide ranging & most transparent tariff schemes designed to suite
every customer. BSNL cellular service, Cell One, has 55,140, 282 2G cellular
customers and 88,493 3G customers as on 30.11.2009. In basic services, BSNL is
miles ahead, with 85 per cent share of the subscriber base and 92 percent share in
revenue terms. BSNL has more than 2.5 million WLL subscribers and 2.5 million
Internet Customers who access Internet through various modes. BSNL has been
adjudged as the NUMBER ONE ISP in the country. BSNL has set up a world class
multi-gigabit, multi-protocol convergent IP infrastructure that provides convergent
services like voice, data and video through the same Backbone and Broadband Access
Network. At present there are 0.6 Million broadband customers.
The company has vast experience in Planning, Installation, network integration and
Maintenance of Switching & Transmission Networks and also has a world class ISO
9000 certified Telecom Training Institute.

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Chapter-1
TELECOM NETWORK
This section includes brief introduction of how a call is processed when
we dial a call from basic telephone to another basic telephone or from
basic to mobile or vice versa.
1.1 CALL SETUP:
 When a subscriber calls to another subscriber first its request goes to
the nearest switching centre that is PSTN (Public Switching
Telecommunication Network). Then it processes the caller and
subscriber’s number if it exists in the same BSC then call setup is
completed.
 If subscriber is not in the same BSC (Base Switching Centre) then
call transfer to MSC (Main Switching Centre) then it transfers the
call to prior BSC then call setup is completed.
 If Caller calls to a mobile subscriber then call transfer is done by
MTSO now call transfer is done on BTSs (Base Transceiver Station)
and call setup is completed.
FIG 1.1 HOW LINE REACHES FROM SUBSCRIBER TO EXCHANGE

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FUNCTION OF EXCHANGE:
 Exchange of information with subscriber lines with other exchange.
This is done by two types of signalling:
1. Inchannel signalling
2. Common channel signalling
 Processing of signalling information and controlling the operation of
signalling network.
 Charging and billing.
1.2: ELECTRONIC EXCHANGE:
 All control functions by series of instructions are stored in memory.
 Memories are modifiable and control program can always be
rewritten. For each call processing step decision is taken according
to class of service.
1.3: CARRIER ROOM:
Leased line connectivity is provided in carrier room. This room has
two parts:
1. Conventional leased line system
2. MLLN
1.3.1: CONVENTIONAL LEASED LINE SYSTEM:
 It consists of modems and routers that are provided by the company
requesting for that network.
 Connectivity of different ATM, banks etc. is provided by BSNL here.
 For this, we have 4 modems (2 in Exchange, 1 at sender and 1 at receiver)
 Modems are used for short distances i.e. trans and receive part are
received here and local lead connection is given to the subscriber.

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 Local lead faults can be handled here but the trans and receive faults can
be handled by the department meant for it.
 Accept 64Kbps or 2 Mbps.
 For long distance communication we have MUXS and data is sent through
optical fibers. MUXS are present at both the ends.
1.3.2: MANAGED LEASED LINE NETWORK:
 No open wiring.
 Route can be changed by the computer software
 In Agra Gate Exchange, we have 3 VMUX of type II.
1.4: MDF (MAIN DISTRIBUTION FRAME):
M.D.F. is a media between switching network and subscriber’s line. It
is a termination point within the local telephone exchange where
exchange equipment and terminations of local loops are connected by
jumper wires.
FIG 1.2 MDF
(REF- 1.4.1)
1.4.1: FUNCTIONS OF MDF:
 All cable copper wires supplying services through user
telephone lines are terminated and distributed through MDF.
 The most common kind of large MDF is a long steel rack
accessible from both sides. Each jumper is a twisted wire.

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 It consists of local connection and broadband connection frames
for the main Exchange area.
 The MDF usually holds central office protective devices including
heat coils and functions as a test point between a line and the
office.
 It provides testing of calls.
 It checks whether fault is indoor or external.
 All lines terminate individually.
1.5: POWER PLANT:
 It provides -48V to the switch rooms and 48V to the connections.
 Batteries are artificially discharged once in a year for their
maintenance.
 Cooling is provided through fans & AC.
 There is earth region too for protection.
1.6: HOW A TELECOM EXCHANGE WORKS:
It requires -48 Vdc.
A telephone exchange or telephone switch is a system of electronic
components that
connects telephone calls. A central office is the physical building used
to house inside plant equipment including telephone switches, which
make telephone calls “work” in the sense of making connections and
relaying the speech information.
The basic block diagram for a telecom exchange is as follows-

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Fig 1.3 : Block diagram of telephone exchange
1.7: Engine and Alternator
It provides AC output in the event of commercial power supply
failure. The diesel engine provides the prime mover to the alternator
so that the alternating current is generated to support the exchange
systems.
150 KV Generator with 6 Cylinder, and it require 24 V DC for Starting
System
1.8: OMC (Operation and Maintenance Control)
It contains input-output processor terminals, visual display units,
printers, cartridges, etc. It controls the entire operation of exchange data
and billing data. The new connections, adding and removing of facilities
to the subscriber is done in the OMC room.
1.9: Switch
It provides the switching facility and connection to the outside of the
exchange. The switch room contains actual telephone switching
hardware such as cabinets, racks, slots and cards. Switching is the most
important part of the exchange process.

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Chapter-2
SWITCHING
A switch is defined as establishing a temporary connection from the
calling subscriber to the called subscriber. Switch is a device that makes
the connection and breaks the connection. It is a device that channels
incoming data from any of the multiple input ports to the specific input
that will take the data toward its intended destination.
A Digital switching system, in general, is one in which signals are
switched in digital form. These signals may represent speech or data. The
digital signals of several speech samples are time multiplexed on a
common media before being switched through the system.
To connect any two subscribers, it is necessary to interconnect the time-
slots of the two speech samples which may be on same or different PCM
highways. The digitalized speech samples are switched in two modes,
viz., Time Switching and Space Switching.
Fig 2.1 : General Diagram of a Digital Switch

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
AU: Subscriber rack for feeding current and other functionalities

Interface: Interface between main exchange and subscribers/Trunks

Switch: Main switching network and other exchange equipment

MDD: Magnetic Disk Drive for storing data

MTD: Magnetic Tape Drive for backup and regeneration of the exchange

OMT: Operation and Maintenance terminal to issue various commands.

Control: Processor to control peripherals and interfacing Main
Exchange.

Printer: To get hard copy for all the reports.
Different types of Electronic Switches are –
(1) C-DOT: Indian Made
(2) E10B: France Made
(3) OCB: France Made
(4) EWSD: Germany Made
Of these, the most important ones include C-DOT and EWSD, which are
mostly used now a days.
2.1: C-DOT
The Centre for Development of Telematics (C-DOT) was established in
August 1984 as an autonomous body. Its goal was to develop
telecommunication technology to meet the needs of the Indian
telecommunication network.
In the initial years, a telecom revolution in rural India that was
responsible for all-round socio-economic development from global
connectivity. As part of its development process, C-DOT spawned
equipment manufacturers and component vendors. Research and
development facilities were located at its Delhi and Bangalore
campuses.

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Within a very short time, telecom switching products suited to Indian
conditions appeared in the form of small rural automatic exchanges
(RAXs) and medium size switches as SBMs for towns. This was
followed by higher capacity digital switches known as main automatic
exchanges (MAXs). C-DOT technology spread across the country
through its licensed manufacturers.
Beginning with digital switching systems, C-DOT developed products
for optical, satellite and wireless communication from circuit switching
technology, ATM and next generation networks. From a purely
hardware development centre, it diversified into development of telecom
software like IN, NMS, Data Clearing House and from a protected
environment of closed market to an open and competitive market.
While developing the RAX/MAX digital switches, C-DOT also evolved
processes and procedures for manufacturing the switches in Indian
factories which set up an Indian manufacturing vendor base. Later, C -
DOT projects included central monitoring systems for telecom security,
for the Indian government.

Fig 2.2 : C-DOT Rax

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Block diagram :C-DOT DSS MAX exchange can be configured using
four basic modules
 Base Module
 Central Module
 Administrative Module
 Input Output Module
Fig 2.3: The C-DOT DSS MAX Basic Architecture

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Chapter-3
MOBILE COMMUNICATION
A mobile phone, cell phone or hand phone is an electronic device used
to make mobile telephone calls across a wide geographic area, served by
many public cells, allowing the user to be mobile. By contrast, a cordless
telephone is used only within the range of a single, private base station,
for example within a home or an office.
A mobile phone can make and receive telephone calls to and from the
mobile phones also support a wide variety of other services such as text
messaging, MMS, email, Internet access, sh ort range wireless
communications (infrared, Bluetooth), business applications, gaming
and photography. Mobile phones that offer these more general
computing capabilities are referred to as smart phones.
3.1: Generation Gap
Generation#1
 Analog [routines for sending voice]
 All systems are incompatible
 No international roaming
Generation#2
 Digital [voice encoding]
 Increased capacity
 More security
 Compatibility
 Can use TDMA or CDMA for increasing capacity

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Generation#2.5
 Packet-switching
 Connection to the internet is paid by packets and not by connection
time.
 Connection to internet is cheaper and faster [up to 56KBps]
Generation#3
 The present future
 Permanent web connection at 2Mbps
 Internet, phone and media: 3 in 1
 The standard based on GSM is called UMTS.
 The EDGE standard is the development of GSM towards 3G.
The genius of the cellular system is the division of a city into small cells.
This allows extensive frequency reuse across a city, so that millions of
people can use cell phones simultaneously. In a typical analog cell-
phone system, the cell-phone carrier receives about 800 frequencies to
use across the city. The carrier chops up the city into cells. Each cell is
typically sized at about 10squaremiles (26 square 22ilometres). Cells are
normally thought of as hexagons on a big hexagonal grid, like this:
Fig 3.1: Cell Phones and base Stations

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3.2: HOW A CALL IS CONNECTED
 When you first power up the phone, it listens for an SID on the
control channel. The control channel is a special frequency that the
phone and base station use to talk to one another about things like
call set-up and channel changing. If the phone cannot find any
control channels to listen to, it knows it is out of range and displays
a “no service” message.
 When it receives the SID, the phone compares it to the SID
programmed into the phone. If the SIDs match, the phone knows that
the cell it is communicating with is part of its home system.
 Along with the SID, the phone also transmits a registration request,
and the MTSO keeps track of your phone’s location in a database
this way, the MTSO knows which cell you are in when it wants to
ring your phone.
 The MTSO gets the call, and it tries to find you. It looks in its
database to see which cell you are in.
 The MTSO picks a frequency pair that your phone will use in that
cell to take the call.
 The MTSO communicates with your phone over the control channel
to tell it which frequencies to use, and once your phone and the tower
switch on those frequencies, the call is connected. Now, you are
talking by two-way radio to a friend.
 As you move toward the edge of your cell, your cell’s base station
notes that your signal strength is diminishing. Meanwhile, the base
station in the cell you are moving toward (which is listening and
measuring signal strength on all frequencies, not just its own one-

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seventh) sees your phone’s signal strength increasing. The two base
stations coordinate with each other through the MTSO, and at some
point, your phone gets a signal on a control channel telling it to change
frequencies. This hand off switches your phone to the new cell.
Let’s say you’re on the phone and you move from one cell to another
but the cell you move into is covered by another service provider, not
yours. Instead of dropping the call, it’ll actually be handed off to the
other service provider. If the SID on the control channel does not match
the SID programmed into your phone, then the phone knows it is
roaming. The MTSO of the cell that you are roaming in contacts the
MTSO of your home system, which then checks its database to confirm
that the SID of the phone you are using is valid. Your home system
verify your phone to the local MTSO, which then tracks your phone as
you move through its cells. And the amazing thing is that all of this
happens within seconds.

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Chapter- 4
CDMA
One of the basic concepts in data communication is the idea of allowing
several transmitters to send information simultaneously over a single
communication channel. This allows several users to share a band of
frequencies. This concept is called multiple access.
CDMA employs spread-spectrum technology and a special coding
scheme (where each transmitter is assigned a code) to allow multiple
users to be multiplexed over the same physical channel.
By contrast, time division multiple access (TDMA) divides access by
time, while frequency-division multiple access(FDMA) divides it by
frequency. CDMA is a form of spread spectrum signalling,
since the modulated coded signal has a much higher data bandwidth
than the data being communicated.
FDMA - Different users use different frequency
TDMA - Different user use different time slot of one frequency
CDMA - Different user use same frequency at the same
time, but with different spreading code
CDMA is a spread spectrum multiple access technique. A spread
spectrum technique spreading the bandwidth of the data uniformly for
the same transmitted power. Spreading code is a pseudo-random code
that has a narrow Ambiguity function, unlike other narrow pulse codes.
In CDMA a locally generated code runs at a much higher rate than the
data to be transmitted. Data for transmission is combined via bitwise
XOR(exclusive OR) with the faster code.
Each user in a CDMA system uses a different code to modulate their
signal. Choosing the codes used to modulate the signal is very important
in the performance of CDMA systems. The best performance will occur
when there is good separation between the signal of a desired user and

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the signals of other users. The separation of the signals is made by
correlating the received signal with the locally generated code of the
desired user. If the signal matches the desired user’s code then the
correlation function will be high and the system can extract that signal.
If the desired user’s code has nothing in common with the signal the
correlation should be as close to zero as possible (thus eliminating the
signal); this is referred to as cross correlation. If the code is correlated
with the signal at any time offset other than zero, the correlation should
be as close to zero as possible. This is referred to as auto-correlation and
is used to reject multi-path interference.
4.1: Advantages of CDMA
 Frequency reuse factor is 1. Network design and expanding
become much easier.
 Large Coverage, almost 2 times than GSM, saves money for operators.
 High spectrum capacity 8—10 times than AMPS, 4²6 times than GSM.
 High privacy, hard to wiretapping.
 Perfect Power Control and voice activation make the MS power
low, healthy for body green mobile phone.
 Use soft handoff, decreases call-drop rate.
CDMA – “make before break”---soft handoff
Other systems – “make after break”---hard handoff
Fig 4.1: Differences b/w CDMA and other systems

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Chapter-5
GSM
GSM (Global System for Mobile Communications) is a standard set
developed by the European Telecommunications Standards Institute
(ETSI) to describe technologies for second generation (or “2G”) digital
cellular networks. Developed as a replacement for first generation analog
cellular networks, the GSM standard originally described a digital,
circuit switched network optimized for full duplex voice telephony. The
standard was expanded over time to include first circuit switched data
transport, then packet data transport via GPRS. Packet data transmission
speeds were later increased via EDGE. The GSM standard is succeeded
by the third generation (or “3G”)UMTS standard developed by the
3GPP. GSM networks will evolve further as they begin to incorporate
fourth generation (or “4G”) LTE Advanced standards.”GSM” is a
trademark owned by the GSM Association.
GSM is a cellular network, which means that mobile phones connect to
it by searching for cells in the immediate vicinity. There are five different
cell sizes in a GSM network² macro, micro, pico, femto and umbrella
cells. The coverage area of each cell varies according to the
implementation environment. Macro cells can be regarded as cells where
the base station antenna is installed on a mast or a building above average
roof top level. Micro cells are cells whose antenna height is under
average roof top level; they are typically used in urban areas. Pico cells
are small cells whose coverage diameter is a few dozen metres; they are
mainly used indoors. Femto cells are cells designed for use in residential
or small business environments and connect to the service provider’s
network via a broadband internet connection. Umbrella cells are used to
cover shadowed regions of smaller cells and fill in gaps in coverage
between those cells.

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Cell horizontal radius varies depending on antenna height, antenna gain
and propagation conditions from a couple of hundred meters to several
tens of kilometres. The longest distance the GSM specification supports
in practical use is 35 kilometres (22 mi). There are also several
implementations of the concept of an extended cell,
where the cell radius could be double or even more, depending on the
antenna system, the type of terrain and the timing advance.
Indoor coverage is also supported by GSM and may be achieved by
using an indoor microcell base station, or an indoor repeater with
distributed indoor antennas fed through power splitters, to deliver the
radio signals from an antenna outdoors to the separate indoor distributed
antenna system. These are typically deployed when a lot of call capacity
is needed indoors; for example, in shopping centres or airports.
However, this is not a prerequisite, since indoor coverage is also
provided by in-building
penetration of the radio signals from any nearby cell. The modulation used
in GSM is Gaussian minimum-shift keying (GMSK), a kind of
continuous-phase frequency shift keying. In GMSK, the signal to be
modulated onto the carrier is first smoothened with a Gaussian low-pass
filter prior to being fed to a frequency modulator, which greatly reduces
the interference to neighbouring channels (adjacent-channel
interference).
5.1: GSM subsystems
Network Subsystem: includes the equipment and functions related to
end-to-end call.
Radio Subsystem: includes the equipment and functions related to the
management of the connections on the radio path.
Operations and Maintenance subsystem: includes the operation and
maintenance of GSM equipment for the radio and network interface.

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Fig 5.1: GSM Network Architecture
5.2: GSM Evolution
Fig 5.2.: Evolution of GSM

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5.3: Advantages for Operators
More revenue : By providing more than a mobile connection. Also
operator can charge on the basis of type and amount of content accessed.
Huge Potential Market for Data Services: Mobile Phone and Internet,
both are fastest growing technologies and GPRS is the merger of two.
Fast Roll-out and Continuous Network Expansion: GPRS is an
integral part of GSM.
GPRS uses excess voice capacity for data: GPRS Packets are
transmitted in short, free periods between busy hour calls.

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Chapter-6
BROADBAND
An “always-on” data connection that is able to support interactive
services including Internet access and has the capability of the minimum
download speed of 256 kilobits per second (kbps) to an individual
subscriber from the Point Of Presence (POP) of the service provider is
called Broadband.
Data rates are defined in terms of maximum download because network and
server conditions significantly affect the maximum speeds that can be
achieved and because common consumer broadband technologies such
as ADSL are “asymmetric” supporting much lower maximum upload
data rate than download. In practice, the advertised maximum bandwidth
is not always reliably available to the customer; physical
Link quality can vary, and ISPs usually allow a greater
number of subscribers than their backbone connection or neighbourhood
access network can handle, under the assumption that most users will
not be using their full connection capacity very frequently. This
aggregation strategy (known as a contended service) works more often
than not, so users can typically burst to their full bandwidth most of the
time however, peer-to-peer (P2P) filesharing systems, often requiring
extended durations of high bandwidth usage, violate these assumptions,
and can cause major problems for ISPs. In some cases, the contention
ratio, or a download cap, is agreed in the contract, and businesses and
other customers, who need a lower contention ratio or even an
uncondensed service, are typically charged more. When traffic is
particularly heavy, the ISP can deliberately throttle back user traffic, or
just some kinds of traffic. This is known as traffic shaping. Careful use
of traffics happing by the network provider can ensure quality of service
for time critical services even one extremely busy networks, but overuse
can lead to concerns about network neutrality if certain types of traffic
are severely or completely blocked.

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6.1: FEATURES OF BROADBAND
 Fast connection to the Internet
Access to the services which would otherwise be impossible on a slower
dial up connection. These include facilities such as downloading music
or video footage, listening to your favourite radio station or downloading
(or sending) large attached files with emails.
 “Always-on” connection
Means that you are permanently connected to the internet; hence no need
to dial up connection every time you want to surf the web, send email,
etc.
 Flat-rate billing
If you choose an uncapped rate there will be no additional charges for
the time you are online. You can use it as much or as little as you would
like, for a fixed fee. Some connections are available at a lower cost, but
limit you to the amount of data being downloaded (known as ‘capped
rate’).
 Dedicated connection
Simultaneous use of both telephone & data line.
6.2: WIRE LINE BROADBAND TECHNOLOGIES:
6.2.1: ADSL (A symmetric Digital Subscriber Line)
ADSL exploits the copper wires which have a much greater bandwidth or
range of frequencies than that demanded for voice without disturbing the line’s
ability to carry phone conversations. The A stands for asymmetric, meaning
that data transmission rate is not the same in both directions i.e., more
bandwidth, or data-carrying capacity, is devoted to data travelling
downstream-from the Internet to your PC-than to upstream data travelling

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from your PC to the Internet. The reason for the imbalance is that,
generally upstream traffic is very limited to a few words at a time, like
for example ±an URL request and downstream traffic, carrying graphics,
multimedia, and shareware program downloads needs the extra capacity.
An ADSL circuit connects an ADSL modem on each end of a twisted
pair telephone line, creating three information channels
1. A high speed downstream channel
2. A medium speed duplex channel
3. A basic telephone service channel:- The basic telephone service
channel is split off from the digital modem by filters, thus
guaranteeing uninterrupted basic telephone service, even if ADSL
fails.
6.2.1.1: Features of ADSL
 Allows simultaneous access to the line by the telephone and the
computer
 In case of power/ADSL failure, data transmission is lost but basic
telephone service will be operational
 ADSL Provides 16-1000 kbps upstream and 1.5-24 Mbps
downstream. It can work up to a distance of 3.7 to 5.5 km depending
upon the speed required.
6.2.1.2: Advantages of ADSL
 You can leave your Internet connection open and still use the phone
line for voice calls.
 The speed is much higher than a regular modem
 DSL doesn’t necessarily require new wiring; it can use the phone
line you already have.
In BSNL, Broadband Access Network, there has to be an ADSL modem on
either end of the telephone line. One end of the line, terminated at Subscriber’s
premises is first connected to the splitter which filter out the low

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frequency voice to be connected to the telephone instrument. The higher
frequency, which carries the data is connected to the modem. The
connectivity is shown in the figure 1 given below.
Fig 6.1: Broadband Connections
The other end is terminated at service providers end which also has
similar arrangement. But at service providers point, numerous ADSL
lines are terminated and there has to be equal number of splitters and
ADSL modems. So instead of separate splitters & modems, it is
aggregated into single nit called Digital Subscriber Line Access
Multiplexer (DSLAM). So, one side of the DSLAM interfaces the
subscriber lines and the other side interfaces to the core network through
several LAN switches. Before being given access to the subscriber,
subscriber is authenticated based on username and password by the
BRAS. After authentication (verification of username & password),
subscriber is authorised to access the Providers core network and in turn
is connected to whatever service or content the subscriber demands and
accounting is initiated based on either time based or volume-based
billing. The LAN Switch collocated with the Core router is termed as

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tier ± 1 Switch and all other LAN switches which aggregate the DSLAM
are called Tier -2 switches. DSLAMs can also be aggregated to Tier -
1switch.
The various components in the Broadband Access Network are
 Customer Premises Equipment(CPE) (ADSL Modem & Splitter)
 Digital Subscriber Line Access Multiplexer (DSLAM)
 LAN Switches: for aggregating DSLAM (Tier -1 & Tier -2 Switch)
 Broadband Remote Access Server (BRAS)
6.2.2: DSL
DSL is a family of technologies that provides digital data transmission
over the wires of a local telephone network. DSL originally stood for
digital subscriber loop. In telecommunications marketing, the term
Digital Subscriber Line is widely understood to mean Asymmetric
Digital Subscriber Line (ADSL), the most commonly installed technical
variety of DSL. DSL service is delivered simultaneously with regular
telephone on the same telephone line. This is possible because DSL uses
a higher frequency. These frequency bands are subsequently separated
by filtering. The data throughput of consumer DSL services typically
ranges from 256 Kb/s to 20 Mbit/s in the direction to the customer
(downstream), depending on DSL technology, line conditions, and
service-level implementation. In ADSL, the data throughput in the
upstream direction, (i.e. in the direction to the service provider) is lower,
hence the designation of asymmetric service. In Symmetric Digital
Subscriber Line (SDSL) service, the downstream and upstream data rates
are equal.
6.2.3: ISDN
Integrated Service Digital Network (ISDN) is one of the oldest
broadband digital access methods for consumers and businesses to
connect to the Internet. It is a telephone data service standard. A basic

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rate ISDN line (known as ISDN-BRI) is an ISDN line with 2 data
“bearer” channels (DS0 -64 Kbit/s each). Using ISDN terminal adapters
(erroneously called modems), it is possible to bond together 2 or more
separate ISDN-BRI lines to reach bandwidths of 256 Kbit/s or more. The
ISDN channel bonding technology has been used for video conference
applications and broadband data transmission.
6.2.4: Advantages:
 Constant data rate at 64 Kbit/s for each DS0 channel.
 Two way broadband symmetric data transmission, unlike ADSL.
 One of the data channels can be used for phone conversation without
disturbing the data transmission through the other data channel. When a
phone call is ended, the bearer channel can immediately dial and re-
connect itself to the data call.
 Call setup is very quick.
 Low latency
 ISDN Voice clarity is unmatched by other phone services.
 Caller ID is almost always available for no additional fee.
 Maximum distance from the central office is much greater than it is
for DSL.
6.2.5: BPL
Broadband over power lines (BPL), also known as power -line Internet
or power band, is the use of PLC technology to provide broadband
Internet access through ordinary power lines. A computer (or any other
device) would need only to plug a BPL “modem” into any outlet in an
equipped building to have high-speed Internet-access. BPL my offer
benefits over regular cable or DSL connections: the extensive
infrastructure already available appears to allow people in remote
locations to access the Internet with relatively little equipment

35. 35
investment by the utility. Also, such ubiquitous availability would make
it much easier for other electronics, such as televisions or sound systems,
to hook up. Cost of running wires such as Ethernet in many buildings
can be prohibitive; Relying on wireless has number of predictable
problems including security, limited maximum throughput and inability
to power devices efficiently.
6.2.6: APPLICATIONS OF BROADBAND
 Basic WWW browsing and Email access
 Run Servers (Web / FTP)
 Business tariff, can depend on company
 Some technologies are asymmetric (cable, ADSL)
 Video on Demand (VOD)
 Audio Streams (Internet Radio)
 Fast File Transfers (Possibility of downloading large files in short period
of time)

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Chapter-7
CONCLUSION
Bharat Sanchar Nigam Ltd. Formed in October 2000 is the world’s 7th
largest Telecommunications company providing comprehensive range
of telecom services in India: Wired-line, CDMA mobile, GSM mobile,
Internet, Broadband, Carrier Service, MPLS-VPN, VSAT, VoIP
services, IN services, etc. Presently it is one of the largest and leading
public-sector units in India.
The training was aimed at providing the students with basic knowledge
about telecommunications and the working of telecom exchanges. The
various aspects regarding the working of telecommunications, the
various modules in the telecom exchange and their importance in the
exchange process was explained. Both wired and wireless (mobile)
communication aspects were dealt with. Mobile communication ± both
CDMA and GSM ± was extensively covered. Also, information about
broadband internet and its requirements was provided. Along with
technical lecture sessions, practical sessions were also conducted where
the telecom exchanges and their equipment were shown and explained.

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REFERENCES
 BSNL In-plant training material
 www.bsnl.co.in
 www.wikipedia.org
 Telecommunication system engineering by Roger L Freeman