an industrial training taken at BSNL CTTC Kolkata covered the whole syllabus of the training (Switching system, SDH, Optical Fibre Cable, GSM, CDMA, ISDN, IN networks, PCM, Broadband DSL Technology, IP fundamentals) Overviews of the total topics all the advantages and Disadvantages. -Dhrubajyoti Adak(Camellia Institute of Technolgy)

1. Presented by:-
Dhrubajyoti Adak

2.  Bharat Sanchar Nigam Limited (BSNL) was formed in the year
of 2000 to took over the service providers role from DOT.
 Today BSNL has customer base over 9 crores.
 It is the fourth largest telecom operator in India.
 BSNL is the market leader in broadband, landline and
national transmission network.
 BSNL is the only operator covering 5 lakh villages in the
country.
 The area of operation of BSNL is all India except Delhi and
Mumbai.

3.  Introduction
 History
 Signal multiplexing Techniques
 PCM
 OFC
 SDH
 GSM
 CDMA
 Broadband DSL Technology
 IP fundamentals
 Intelligent networks
 ISDN

4.  In 1885 the Indian Telegraph Act has been amended in which the
country is divided into various circles.
 In 1984 C-DOT was formed for developing of indigenous
technologies and customer service premises equipment.
 In 1986 the VSNL (Videsh Sanchar Nigam Limited) and MTNL
(Mahanagar Telecom Nigam Limited) were set up. The telecom
commission was established in 1989.
 TRAI (Telecom Regulatory Authority of India) was formed in 1997 to
assure the investors that the sector would be regulated in a balance
fair manner.
 In 2000 DOT corporatized its services wings and created BSNL.

5.  FDM:- The FDM techniques is the process of translating individual
speech circuits (300-3400 Hz) into pre-assigned frequency slots
within the bandwidth of the transmission medium. The frequency
translation is done by amplitude modulation of the audio frequency
with an appropriate carrier frequency. At the output of the modulator
a filter network is connected to select either a lower or an upper side
band. Since the intelligence is carried in either side band, single side
band suppressed carrier mode of AM is used.
 TDM:- Basically, time division multiplexing involves nothing more
than sharing a transmission medium by a number of circuits in time
domain by establishing a sequence of time slots during which
individual channels (circuits) can be transmitted. Thus the entire
bandwidth is periodically available to each channel. Normally all
time slots1 are equal in length. Each channel is assigned a time slot
with a specific common repetition period called a frame interval.

6.  PCM systems use TDM technique to provide a number of circuits on the
same transmission medium viz open wire or underground cable pair or a
channel provided by carrier, coaxial, microwave or satellite system.
 To devolve a PCM system few steps are required- Filtering, Sampling,
Quantization, Encoding, Line Coding.
 Filtering:- Filters are used to limit the signal between 300-3400Hz.
 Sampling:- The amplitude of the sample is depend upon the amplitude of the
input signal at the instant of sampling. The duration of these sampled pulses
is equal to the duration for which the switch S is closed.
 Quantization:- Quantization can be defined as a process of breaking down a
continuous amplitude range into a finite number of amplitude values or
steps.
 Encoding:- Conversion of quantised analogue levels to binary signal is
called encoding.

7. Optical Fibre is new medium, in which information (voice,
Data or Video) is transmitted through a glass or plastic
fibre, in the form of light, following the transmission
sequence give below :
 (1) Information is encoded into electrical signals.
 (2) Electrical signals are converted into light signals.
 (3) Light travels down the fibre.
 (4) A detector changes the light signals into electrical
signals.
 (5) Electrical signals are decoded into information.

8.  Optical fibers are dielectric.
 It is immune to electromagnetic interference.
 It has larger bandwidth.
 Loss is low and same at all operating speeds.
 These are small light weight cables.
 Cause it is dielectric it cannot cause fire.

9.  The optical fiber has two concentric layers called the core and the cladding.
The inner core is the light carrying part. The surrounding cladding provides
the difference refractive index that allows total internal reflection of light
through the core. The index of the cladding is less than 1%, lower than that
of the core. Typical values for example are a core refractive index of 1.47
and a cladding index of 1.46. Fiber manufacturers control this difference to
obtain desired optical fiber characteristics.
The specific characteristics of light propagation through a fiber depends on
many factors, including
 - The size of the fiber.
 - The composition of the fiber.
 - The light injected into the fiber.

10. SDH is a standard technology for
synchronous data transmission on optical
media. It is the international equipment of
optical network. This technology provides
faster and less expensive network
interconnection than traditional PDH
(plesiochronous digital hierarchy).
SDH uses the following synchronous
transport modules (STM) and rates, STM-
1(155 megabits per second), STM-
2(622Mbps) and STM-64(10gbps).

11.  SDH defines a number of “Containers”, each corresponding to
an existing plesiochronous rate.
 Each container has a “Path Overhead” added to it. POH
provides network management capability.
 All equipment is synchronised to a national clock.
 When STM–1 payload is full, more network management
capability is added to form the “Section Overhead”.
 SOH remains with payload for the fibre section between
synchronous multiplexers
 SOH bytes provide communication channels to cater for
OA&M facilities.
user channels.
protection switching.
section performance
frame alignment
other functions.

12.  Global System for mobile 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, fax, voicemail,
electronic mail.
• Supplementary services:- I/C & O/G calls, Call
forwarding, call waiting, conference, hand off etc.

14. 1 MS sends dialed number to
BSS.
2 BSS sends dialed number to
MSC.
3,4 MSC checks VLR if MSC
allows the service. If so , MSC
asks BSS to allocate the call.
5 MSC routes the call to GMSC
6 GMSC routes the call to local
exchange of called user.
7,8,9,10 Answer back or ring back
tone is routed from the called user
to MS vai GMSC, BSS.

15.  Code division multiple access (CDMA) is a standard
digital air interface claiming 8 to 15 times the capacity of
analog.
 Multiple access in CDMA:-
• Each users is assigned a unique PN code.
• Each users transmit with information by spreading with
unique code
• Spread spectrum technology is used.
• Users are separated by codes not by time or
frequency slots.

17.  Broadband DSL allows digital data to be transferred
through copper telephone wires. This does not interfere
with the telephone service itself as the data is transmitted
at a higher frequency than a voice pone call.
 This technology transmits signals to a computer over
short-range radio waves. No wiring is required.

19.  Internet protocol(IP) specifies the format of the packets,
and the addressing scheme. Most networks combine IP
with higher level protocol called Transmission Control
Protocol(TCP), which establishes a virtual connection
between a destination and a source.
 It allows us to address a package and drop it in the
system, but there is no direct link between the recipent
and the sender.
 TCP/IP, on the other hand establishes a connection
between two hosts so the can send messages back and
forth for a period of time.

20.  Each IP address has two components
• Header
• Payload

21.  Intelligent Network is one concept to specify telecom
services, and it has emerged from technical, buisness
and protocol engineering point of view.
 Intelligent networks are used by teleoperators for
creation and management of value added services in
telecom networks.
 Originally, IN has been applied in telephone and voice
services, but today its meaning is also growing in the
service integration of mobile and fixed telephone
networks and as gateway to internet based networks.

23.  Integrated Services Digital Network (ISDN) is a set of
communication standards for simultaneous digital
transmission of voice, video, data, and other network
services over the traditional circuits of the PSTN.
 It provides a faster data transmission rate than modems
by using 64-kbps bearer channel. And also offers faster
call set-up.
 ISDN consists of some devices
• Terminal Adapter(TA)
• Terminal Equipment Type 1(TE1)
• Terminal Equipment Type 2(TE2)
• Network Termination type 1 & 2(NT1 and NT2)

25.  Basic Rate interface (BRI)
• Two 64 kbps b channels, one 16 kbps D channel, and 48
kbps framing and synchronization.
• Available data bandwidth: 128 kbps(2x64 kbps)
• User bandwidth: 144 kbps(128 kbps + a 16kbps D channel)
• Total line capacity: 192 kbps(144 kbps + 48 kbps framing)
Each B channel can be used foe separate applications
such as internet and voice
Allows individual B channels to be aggregated together
into a Multilink channel.