computer-network-organization-framework-module

summary

1. COMPUTER
NETWORKS[BCS502]
By: Prof. SHRUTI PATIL
GNDEC, BIDAR

2. Transmission medium and physical Transmission medium and physical
layerlayer
Figure :Transmission medium and physical layer

3. Transmission medium and physical Transmission medium and physical
layerlayer

The transmission medium can be defined as a The transmission medium can be defined as a
pathway pathway that can that can transmit information transmit information from a from a
sender to a receiver.sender to a receiver.

Transmission media are located Transmission media are located belowbelow the the
physical layer physical layer and are and are controlledcontrolled by the by the
physical layer.physical layer.

4. Figure : Classes of transmission media

5. 7.5

6. 1. GUIDED MEDIA1. GUIDED MEDIA
Guided media, which are those that provide a Guided media, which are those that provide a conduitconduit from from
one device to another, include twisted-pair cable, coaxial one device to another, include twisted-pair cable, coaxial
cable, and fiber-optic cable.cable, and fiber-optic cable.
Guided transmission media are also called Guided transmission media are also called bounded bounded
media media or or wired mediawired media..
Twisted-Pair Cable
Coaxial Cable
Fiber-Optic Cable
Topics discussed in this section:Topics discussed in this section:

7. Figure : Twisted-pair cable

8. 1. Twisted-Pair Cable1. Twisted-Pair Cable

Twisted pair is a physical media made up of a Twisted pair is a physical media made up of a
pair of pair of cables twisted cables twisted with each other. with each other.

A twisted pair consists of two A twisted pair consists of two insulated copper insulated copper
wires arranged in a regular spiral pattern.wires arranged in a regular spiral pattern.

The degree of reduction in noise interference is The degree of reduction in noise interference is
determined by the determined by the number of turns per footnumber of turns per foot. .
Increasing the number of turns per foot Increasing the number of turns per foot
decreases noise interference.decreases noise interference.

9. Figure : UTP and STP cables

10. UnshieldedUnshielded and Shielded TPand Shielded TP

Unshielded Twisted Pair (UTP)Unshielded Twisted Pair (UTP)

Ordinary telephone wireOrdinary telephone wire

Less expensiveLess expensive

Weak immunity against noise and interferenceWeak immunity against noise and interference

Suffers from external EM interferenceSuffers from external EM interference

Shielded Twisted Pair (STP)Shielded Twisted Pair (STP)

An extra metallic sheath on each pairAn extra metallic sheath on each pair

Relatively more expensiveRelatively more expensive

Provide better performance than UTPProvide better performance than UTP

Increased Data rateIncreased Data rate

Increased BandwidthIncreased Bandwidth

11. 1. Twisted-Pair Cable1. Twisted-Pair Cable

ApplicationsApplications

Telephone networksTelephone networks

LANs (Local Area Networks)LANs (Local Area Networks)

DSL (Digital Subscriber Line) connectionsDSL (Digital Subscriber Line) connections

Home and office networksHome and office networks

12. 
AdvantagesAdvantages

InexpensiveInexpensive

Easy to installEasy to install

Flexible and lightweightFlexible and lightweight

Suitable for short to medium distancesSuitable for short to medium distances

DisadvantagesDisadvantages

Susceptible to electromagnetic interference (EMI)Susceptible to electromagnetic interference (EMI)

Lower bandwidth compared to coaxial and fiber Lower bandwidth compared to coaxial and fiber
opticsoptics

Shorter transmission distance & Less secureShorter transmission distance & Less secure

13. 2. Coaxial Cable2. Coaxial Cable

Coaxial cable is very commonly used Coaxial cable is very commonly used
transmission media, for example, transmission media, for example, TV wire TV wire is is
usually a coaxial cable.usually a coaxial cable.

The The namename of the cable is coaxial as it contains of the cable is coaxial as it contains
two conductors parallel two conductors parallel to each other.to each other.

It has a It has a higher frequency higher frequency as compared to as compared to
Twisted pair cable.Twisted pair cable.

14. Figure : Coaxial cable

15. 2. Coaxial Cable2. Coaxial Cable

The The inner conductor inner conductor of the coaxial cable is of the coaxial cable is
made up of made up of coppercopper, and the , and the outer conductor outer conductor is is
made up of made up of copper meshcopper mesh. The . The middle core middle core is is
made up of made up of non-conductivenon-conductive cover that cover that
separates the inner conductor from the outer separates the inner conductor from the outer
conductor.conductor.

The The middle core middle core is responsible for the is responsible for the data data
transferringtransferring whereas the whereas the copper mesh copper mesh
prevents from the prevents from the EMIEMI(Electromagnetic (Electromagnetic
interference).interference).

16. ApplicationsApplications

Cable TV systemsCable TV systems

Internet broadband connectionsInternet broadband connections

CCTV (Closed-Circuit Television)CCTV (Closed-Circuit Television)

Satellite communicationsSatellite communications

17. AdvantagesAdvantages

Better Better shieldingshielding than twisted pair than twisted pair

Supports higher bandwidthSupports higher bandwidth

Less susceptible to Less susceptible to EMIEMI

Can transmit over Can transmit over longer distances longer distances than than
twisted pairtwisted pair

18. DisadvantagesDisadvantages

Bulkier and harder to installBulkier and harder to install

More More expensiveexpensive than twisted pair than twisted pair

Signal loss over long distancesSignal loss over long distances

Not suitable for very high-speed modern Not suitable for very high-speed modern
networksnetworks
7.18

19. Figure : Bending of light ray

20. Figure : Optical fiber

21. Figure : Propagation modes

22. Figure Modes

23. a. Multimode, Step Indexa. Multimode, Step Index

Structure: Structure: Has a core with a uniform Has a core with a uniform
refractive index and a sharp boundary with refractive index and a sharp boundary with
the cladding.the cladding.

Light Behavior: Light Behavior: Light rays bounce off the Light rays bounce off the
core-cladding boundary at different angles core-cladding boundary at different angles
(zigzag paths).(zigzag paths).

Result: Result: Because rays travel different Because rays travel different
distances, they arrive at the destination at distances, they arrive at the destination at
different times → signal distortion.different times → signal distortion.

24. b. Multimode, Graded Indexb. Multimode, Graded Index

Structure: Structure: Core has a gradually changing Core has a gradually changing
refractive index (highest in the center, refractive index (highest in the center,
decreasing towards the edges).decreasing towards the edges).

Light Behavior: Light Behavior: Light bends smoothly in Light bends smoothly in
curved paths instead of bouncing sharply.curved paths instead of bouncing sharply.

Result: Result: Different rays are “balanced out” so Different rays are “balanced out” so
they reach the destination more simultaneously they reach the destination more simultaneously
→ less distortion compared to step index.→ less distortion compared to step index.

25. c. Single Modec. Single Mode

Structure: Structure: Very thin core, only allows one Very thin core, only allows one
light path (mode).light path (mode).

Light Behavior: Light Behavior: Light travels in a straight Light travels in a straight
line.line.

Result: Result: No modal dispersion → clean signal No modal dispersion → clean signal
with minimal distortion, best for high-speed with minimal distortion, best for high-speed
and long-distance communication.and long-distance communication.

26. Figure : Fiber construction

27. 3. Optical fiber3. Optical fiber

1. Core: 1. Core: This is the light-carrying part of the This is the light-carrying part of the
fiber made of glass or plastic.fiber made of glass or plastic.

2. Cladding: 2. Cladding: Surrounds the core and reflects Surrounds the core and reflects
light back into the core using total internal light back into the core using total internal
reflection it is also glass or plastic, but with a reflection it is also glass or plastic, but with a
lower refractive index than the core.lower refractive index than the core.

3. Buffer Coating (Coating Layer): 3. Buffer Coating (Coating Layer): Protects Protects
the fiber from moisture, physical damage, and the fiber from moisture, physical damage, and
abrasion made from soft polymer materials.abrasion made from soft polymer materials.

28. 3. Optical fiber3. Optical fiber

4. Strength Member: 4. Strength Member: Provides mechanical Provides mechanical
strength, protecting the fiber from pulling and strength, protecting the fiber from pulling and
stress.stress.

5. Outer Jacket (Sheath): 5. Outer Jacket (Sheath): The outermost The outermost
protective layer of the cable made of tough protective layer of the cable made of tough
plastic like PVC or PE.plastic like PVC or PE.

29. ApplicationsApplications

High-speed internet (FTTH)High-speed internet (FTTH)

Long-distance telecommunicationLong-distance telecommunication

Backbone networks (ISP, data centers)Backbone networks (ISP, data centers)

Military and medical imagingMilitary and medical imaging

30. AdvantagesAdvantages

Extremely high bandwidthExtremely high bandwidth

Very long-distance transmissionVery long-distance transmission

Immune to EMIImmune to EMI

Highly secure data transmissionHighly secure data transmission

Lightweight and durableLightweight and durable

31. DisadvantagesDisadvantages

Higher initial costHigher initial cost

Fragile compared to copper cablesFragile compared to copper cables

Requires specialized installation and Requires specialized installation and
maintenancemaintenance

More difficult to splice and connectMore difficult to splice and connect

32. Figure : Fiber-optic cable connectors

33. 2 UNGUIDED MEDIA: WIRELESS2 UNGUIDED MEDIA: WIRELESS
Unguided media transport electromagnetic waves Unguided media transport electromagnetic waves
without using a physical conductor. This type of without using a physical conductor. This type of
communication is often referred to as wireless communication is often referred to as wireless
communication.communication.
Radio Waves
Microwaves
Infrared
Topics discussed in this section:Topics discussed in this section:

34. Figure Electromagnetic spectrum for wireless communication

35. Figure : Propagation methods

36. Figure : Wireless transmission waves

37. Figure : Omnidirectional antenna

38. Radio waves are used for multicast
communications, such as radio and
television, and paging systems.
Note

39. Figure Unidirectional antennas

40. Microwaves are used for unicast
communication such as cellular
telephones, satellite networks,
and wireless LANs.
Note

41. Infrared signals can be used for short-
range communication in a closed area
using line-of-sight propagation.
Note

42. Questions
1)Define Transmission Media. [2]
2)List the applications of guided and unguided media. [6]
3)What is the principle of refraction? Write a short note on
Fiber optics. Clearly state its types, advantages and
disadvantages. [6]
4)Provide the classification of Transmission media. Explain
in detail each one of them. [10]
5)Explain physical description and application of
Microwave, Broadcast Radio and Fiber optics. [10]
6)Explain the types of guided and unguided media with
suitable diagrams. [10]
7)Discuss in detail about the physical description,
application and transmission characteristics of the
guided Media. [10]

43. THANK YOU.
Solve these questions before moving forward.