The document presents a comprehensive overview of transmission media in data communication, detailing wired (bound) and wireless (unbound) media, circuit switching, telephone networks, digital subscriber lines (DSL), cable modems, and synchronous optical networking (SONET). It explains the characteristics, advantages, and disadvantages of each type of transmission media, as well as their applications in telecommunications. The presentation is structured to inform an academic audience about the principles and technologies underpinning modern communication networks.

1. Welcome
to
the presentation
Submitted To:
AHSAN ULLAH
Lecturer
CSE Department
World University of Bangladesh

2. Presentation Outline
Transmission Media
Circuit Switching
Telephone Network
Digital Subscriber Line(DSL)
Cable Modems
Synchronous optical networking (Sonet)
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3. Transmission Media
In data communication,
Transmission media is a pathway that carries the
information from sender to receiver.
We use different types of cables or waves to transmit data.
Data is transmitted normally through electrical or
electromagnetic signals.
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4. Types of Transmission Media
Transmission media is broadly classified into two groups.
1. Wired or Guided Media or Bound Transmission Media
2. Wireless or Unguided Media or Unbound Transmission Media
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5. Types of Transmission Media
1.Bound Transmission Media:
Bound Transmission Media are the cables that have physical existence and are
limited by the physical geography. Popular Bound Transmission Media in use are
twisted pair cable, co-axial cable and fiber optical cable. Each of them has its own
characteristics like transmission speed, effect of noise, physical appearance, cost
etc.
2.Unbound transmission media: Unbound transmission media are the ways of
transmitting data without using any cables. These media are not bounded by
physical geography. This type of transmission is called Wireless communication.
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6. Circuit Switching
A circuit-switched network is made of a
set of switches connected by physical
links, in which each link is
divided into n channels.
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7. As a trivial example, let us use a circuit-switched network
to connect eight telephones in a small area.
Communication is through 4-kHz voice channels. We
assume that each link uses FDM to connect a maximum of
two voice channels. The bandwidth of each link is then 8
kHz. Figure 8.4 shows the situation. Telephone 1 is
connected to telephone 7; 2 to 5; 3 to 8; and 4 to 6. Of
course the situation may change when new connections are
made. The switch controls the connections.
Example
Circuit Switching
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8. Figure: Circuit-switched network used in Example
Circuit Switching
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9. Telephone Network
The earliest electronic network is the telephone system. This telephone network commonly uses
analog technology that was quite different from digital technology used in the computer-based
networks.
A telephone network is a telecommunications network used for telephone calls between two or more parties . A
landline network where the telephones must be directly wired into a single telephone exchange. This is known
as the public switched telephone network or PSTN.
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10. There are a number of different types of telephone network: A landline network where the
telephones must be directly wired into a single telephone exchange. This is known as the public
switched telephone network or PSTN.
The telephone is connected to Public switched telecommunications network (PSTN) for local,
national, and international voice communications
The same connections can carry data and image information (television)
The connection to the PSTN may be via local exchange carriers (LEC)
End-users, nodes, and connectivities
Types of Telephone Network
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11. Advantages and Disadvantages of Telephone Networks
Advantages
It is circuit-switching network, therefore, any receiver can be
selected and' there is virtually no transmission delay.
As it is widely spread therefore it is available at a low price.
Disadvantages
It requires a long time for connection. A dial-up operation is
necessary before the line can be connected to the receiver. This
dial-up time is too long to use in data communication systems.
It has low transmission speed.
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12. Digital Subscriber Line(DSL)
Digital Subscriber Line (DSL) is a high-speed Internet service for homes
and businesses that competes with cable and other forms of broadband
Internet. DSL provides high-speed networking over ordinary phone lines
using broadband modem technology. The technology behind DSL enables
Internet and telephone service to work over the same phone line without
requiring customers to disconnect either their voice or Internet
connections.
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13. Digital Subscriber Line(DSL)
DSL Speed :
Basic DSL supports maximum download data rates ranging
between 1.544 Mbps and 8.448 Mbps. Actual speeds vary in
practice depending on the quality of the copper phone line
installation involved.
Symmetric vs. Asymmetric DSL :
Most types of DSL service are asymmetric also known as ADSL.
ADSL offers higher download speeds than upload speeds, a
tradeoff that most residential providers make to better match
up with the needs of typical households who generally do much
more downloading.
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14. Digital Subscriber Line(DSL)
Business DSL Service:
Besides its popularity in homes, many businesses also rely on DSL for their
Internet service. Business DSL differs from residential DSL in several key
respects:
Symmetric DSL is typically used as businesses tend to generate
much higher volumes of outgoing traffic than a typical home.
Problems with DSL:
DSL Internet service only works over a limited physical distance and
remains unavailable in many areas where the local telephone
infrastructure does not support DSL technology.
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15. Cable Modems
What is cable modem ?
• A cable modem is a hardware device that allows your
computer to communicate with an Internet Service
Provider over a landline connection. It converts an analog
signal to a digital signal for the purpose of granting access
to broadband Internet. A cable modem works by connecting
a coaxial cable to a jack in the wall and then
a Cat5 (Ethernet) cord from the modem to a computer or
a network router. Network routers are used to share your
Internet connection between multiple computers.
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16. How Do Cable Modems Work ?
• Cable modems receive digital information carried over the cable TV
network and passes it through to the computer via a standard
10BaseT Ethernet interface.
• The Cable Modem Termination System (CMTS) can talk to all the
Cable Modems, but the Cable Modems can only talk to the CMTS.
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17. Inside the cable modem
Cable modems can be either internal or external to the computer.
In some cases, the cable modem can be part of a set-top cable box,
requiring that only a keyboard and mouse be added for Internet
access. In fact, if your cable system has upgraded to digital cable,
the new set-top box the cable company provides will be capable of
connecting to the Internet, whether or not you receive Internet
access through your CATV connection. Regardless of their outward
appearance, all cable modems contain certain key components:
• A tuner
• A demodulator
• A modulator
• A media access control (MAC) device
• A microprocessor
Figure: Inside cable modem

18. Cable Modem Connection
Figure: Cable Modem ConnectionPage - 17

19. Synchronous optical networking (Sonet)
Synchronous optical networking (SONET) is a
standardized digital communication protocol that
is used to transmit a large volume of data over
relatively long distances using a fiber optic
medium. With SONET, multiple
digital data streams are transferred at the same
time over optical fiber using LEDs and laser
beams.
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20. SONET LAYERS
SONET defines four layers: path, line, section, and
photonic
-Path layer is responsible for the movement of a signal
from its optical source to its optical destination
-Line layers is for the movement of a signal across a
physical line
-Section layer is for the movement of a signal across a
physical section, handling framing, scrambling, and error
control
-Photonic layer corresponds to the physical layer of OSI
model
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21. SONET Networks
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22. Thank you so much for being
with us up to now.
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23. Have any question?
Please
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