2. TRANSMISSION MEDIA
THE TRANSMISSION MEDIUM IS THE PHYSICAL PATH BY WHICH A MESSAGE
TRAVELS FROM SENDER TO RECEIVER.
COMPUTERS AND TELECOMMUNICATION DEVICES USE SIGNALS TO REPRESENT
DATA.
THESE SIGNALS ARE TRANSMITTED FROM A DEVICE TO ANOTHER IN THE FORM
OF ELECTROMAGNETIC ENERGY.
4. GUIDED MEDIA AND ITS TYPES:
Consists of physical connection between source and destination via a wire or a
cable.
There are three basic types of guided media :
• Twisted pair cable
• Co-axial cable
• Fiber-optic cable
5. TWISTED PAIR CABLE
Consists of two copper wires insulated from each other by plastic.
The twisting helps to reduce the interference (noise) and crosstalk.
Low frequency transmission medium
6. TYPES OF TWISTED PAIR CABLE
STP (shielded twisted pair)
the pair is wrapped with metallic foil or braid to insulate the pair from electromagnetic interference
UTP (unshielded twisted pair)
each wire is insulated with plastic wrap, but the pair is encased in an outer covering
7. ADVANTAGES AND DISADVANTAGES OF TWISTED PAIR:
Advantages:
Inexpensive and readily available
Flexible and light weight
Easy to work with and install
Disadvantages:
Susceptibility to interference and noise
Attenuation problem
• For analog, repeaters needed every 5-6km
• For digital, repeaters needed every 2-3km
Relatively low bandwidth (3000Hz)
8. COAXIAL CABLE (OR COAX):
Used for cable television, LANs, telephony
Has an inner conductor surrounded by a braided mesh
Both conductors share a common center axial, hence the
term “co-axial”
9. ADVANTAGES AND DISADVANTAGES OF COAXIAL
CABLE:
Advantages:
Higher bandwidth
Can be tapped easily
Much less susceptible to interference than twisted pair
Disadvantages:
High attenuation rate makes it expensive over long distance
Bulky
11. • These are similar to coaxial cable. It uses electric signals to transmit data. At
the centre is the glass core through which light propagates.
• Fiber optic cable has bandwidth more than 2 gbps (Gigabytes per Second)
12. ADVANTAGES :
• Speed of transmission
• Noise control
• Used for analog and digital signals
• Long distance transmission
• Low data loss
15. WHAT IS UNBOUNDED TRANSMISSION MEDIA?
• Unlabelled media of transmission of data
• Unguided or wireless media sends the data through air (or water)
• Use of antenna for transmission of signal
16. WHY DO WE USE UNBOUNDED TRANSMISSION
MEDIA
• High-Frequency Radiotelephone
• Microwave Radio
• Satellite Radio link Systems
• Commercial Satellites
17. EXAMPLES OF UNBOUNDED TRANSMISSION MEDIA
• Microwave
• Radio waves
• Infrared waves
• Satellites
18. RADIO WAVE
• Signals are sent by modulation of electromagnetic waves with frequencies
below those of visible light
19. ADVANTAGES :
• carry a message instantaneously over a wide area.
• Cheaper(message are sent through air)
• Simple in transmission
20. DISADVANTAGES
• Travel in a straight line, so repeater stations may be needed
• The range of frequencies that can be accessed by existing technology is
limited
• Competition among companies to get the frequency
21. MICROWAVE
• the transmission of information or energy by electromagnetic
waves whose wavelengths are conveniently measured in
small numbers of centimeter.
• radio spectrum ranges across frequencies of roughly 1.0
gigahertz (GHz) to 300 GHz.
• requires line of sight in order to work properly
• to allow two way communications two frequencies are
used(that doesn’t mean it requires two antenna)
• to increase this coverage each antenna has a built-in repeater
that regenerates the signal before passing it on to the next
antenna in line
23. PRINCIPLE
• Use of radio frequency to achieve the transmissions
(operating between 1Ghz to 170Ghz)
• Clear line-of-sight with no obstacles in the way
• Regular relay stations required due to line of site and cost
considerations
24. ADVANTAGES AND DISADVANTAGES
Advanatages
• No cables needed
• Multiple channels available
• Wide bandwidth
Disadvantages
• Line-of-sight will be disrupted if any obstacle, such as new buildings,
are in the way
• Signal absorption by the atmosphere. Microwaves suffer from
attenuation due to atmospheric conditions.
• Towers are expensive to build
25. BLUETOOTH
• It is an always on, low power, short ranged radio link for
communication between mobile devices
• Developed in 1994 by the Swedish company Ericsson to enable
laptops make calls over mobile phones
• Also known as 802.15, it employs the 2.4 GHz unlicensed band, the
same as 802.11b wireless, but does not interfere with it
• Provides data rates of up to 720 Kbps
• Power output is around 1 milliwatt, compared to the average cell
phone’s 500 milliwatt power output
26. BLUETOOTH CHARACTERISTICS
• Allows up to 8 devices to communicate in a local network called a Piconet,
• Because of its low power consumption, its range is limited to 10 m.
• However, range can be increased to 100 m by employing a scatternet topology or a higher
powered Antenna
• Three classes of Bluetooth devices
• Class 1 – 100 m = 20 dBm power
• Class 2 – 10m = 4 dBm power
• Class 3 – 10 cm @ 0 dBm power
27. BLUETOOTH DEVICES
• Bluetooth exists in many products, such as telephones, tablets, media
players, robotics systems, handheld, laptops and console gaming
equipment, and some high definition headsets, modems, and
watches.
28. APPLICATIONS
• A typical Bluetooth mobile phone headset.
• Wireless control of and communication between a mobile phone and a handsfree headset.
This was one of the earliest applications to become popular.
• Wireless control of and communication between a mobile phone and a Bluetooth compatible
car stereo system.
• Wireless control of and communication with tablets and speakers such as iOS and Android
devices.
• Wireless Bluetooth headset and Intercom. Idiomatically, a headset is sometimes called "a
Bluetooth".
29. WIMAX
• Worldwide Interoperability for Microwave Access (WiMAX)
• One of the hottest broadband wireless technologies around today.
• Broadband wireless is a technology that promises high-speed
connection over the air.
• Based on IEEE 802.16 specification
30.
31. A WiMAX system consists of two parts:
• A WiMAX tower, similar in concept to a cell-phone
tower(can provide coverage to a very large area as
~8,000 square km).
• A WiMAX receiver - The receiver and antenna could be
a small box or PCMCIA card, or they could be built into
a laptop the way WiFi access is today.
32. APPLICATIONS
• Providing portable mobile broadband connectivity across cities and countries
through a variety of devices.
• Providing a wireless alternative to cable and digital subscriber line (DSL) for
"last mile" broadband access.
• Providing data, telecommunications (VoIP) and IPTV services (triple play).
• Providing a source of Internet connectivity as part of a business continuity
plan
33. FEATURES
• Very high peak data rates
• Scalable bandwidth and data rate support
• Adaptive modulation and coding (AMC)
• Flexible and dynamic per user resource allocation
• Quality-of-service support
• Robust security