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Introductory Lecture
TE-306 Wireless Communication and RF planning (2 + 0)
Instructor
Engr. Dr. Farzana Kulsoom
Assistant Professor TED
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Recommended Textbooks
1) Wireless Communications , Andrea Goldsmith
2) Theodore Rappaport, Wireless Communications:
Principles and Practice, Second Edition, Prentice Hall,
2003 ISBN:
3) Wireless communication & networks by William
Stallings
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Electromagnetic waves and
communication
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Wireless Communication
• Transmitting voice and data using electromagnetic waves
• Electromagnetic waves
• Travel at speed of light (c = 3x108 m/s)
• Has a frequency (f) and wavelength (l) c=fl
• Higher frequency means higher energy and short wavelength
• The higher the energy the more penetrating is the radiation
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Electromagnetic Spectrum
104 102 100 10-2 10-4 10-6 10-8 10-10 10-12 10-14 10-16 λ (m)
Radio Micro Cosmic
IR UV X-Rays
Spectrum wave Rays
104 106 108 1010 1012 1014 1016 1018 1020 1022 1024 f(Hz)
1MHz ==100m
100MHz ==1m
10GHz ==1cm
Visible light
1) Radio Waves: These are long wavelength, small frequency waves; AM, FM, TV,
Radar, Microwave.
2) Infrared : Emit by all objects at room temp, usually used in TV remote.
3) Visibile Light: This is the spectrum range for which our eyes are sensitive, they
can sense colors.
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Uses
4) Ultra-Violent : Have short wavelength and frequency than visible light. Freq after
this has more energy and dangerous to humans.
5) X-rays : Given off by stars naturally. Used In medical applications.
6) Gamma-Rays: Most energetic and shortest wave , given off by radio active
elements and stars
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https://www.youtube.com/watch?v=cfXzwh3KadE
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Elements of Wireless system
The information from transmitter to receiver is carried over
a well defined frequency band over a certain medium or
channel, like air, water or a substance.
Signal gets faded over distance
attenuated because of multiple paths and
Reflection, Diffraction
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Communication mode
• Simplex :When the signal is sent in one
direction.
• This is called simplex transmission,
For example keyboard and monitor.
• Half duplex mode, the signal is sent in both
directions, but one at a time.
walkie-talkie
• Full duplex mode. both parties can
communicate with each other
simultaneously, mobile phones network
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Duplex Communication - FDD
FDD: Frequency Division Duplex
Frequency-division duplexing (FDD) which is a method for establishing
a full duplex communication link that uses two different radio
frequencies for transmitter and receiver operation.
Mobile Forward Channel Base Station
Terminal B
Reverse Channel
M
Forward Channel and Reverse Channel use different frequency
Bands.
Complex to install----pairs of frequencies are required
Low latency----- as no time switching is required
Training overhead problem in 5G forward channel
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Duplex Communication - TDD
TDD: Time Division Duplex
• TDD is a method for emulating full-duplex communication over a half-duplex
communication link.
•
Mobile Base Station
Terminal M B M B M B
B
M
Same frequency is used. The channel is divided into time
slots.
Mobile station and base station transmits on the time slots
alternately.
• High Latency because of switching
• Spectral efficient
• Pilot contamination problem in 5 G
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What is Mobility
Initially Internet and Telephone Networks is designed
assuming the user terminals are static
• No change of location during a call/connection
• A user terminals accesses the network always
from a fixed location
Mobility and portability
– Portability means changing point of attachment to the
network offline
– Mobility means changing point of attachment to the
network online
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Degrees of Mobility
• Walking Users------------low mobility
• Low speed
• Small roaming area
• Usually uses high-bandwith/low-latency access
• Vehicles ------------high mobility
• High speeds
• Large roaming area
• Usually uses low-bandwidth/high-latency access
• Uses sophisticated terminal equipment (cell phones)
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Wireless/Mobile Networking
• Ubiquitous Computing
– Connectivity Anywhere, anytime computing and communication
• You don’t have to go to the lab to work on your lab computer.
– Pushing the computers more into background
• Focus on the task and life, not on the computer
smart home
• Use computers seamlessly to help you and to make your life more
easier.
– Computers should be location aware
• Adapt to the current location, discover services
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Some Example Applications of Ubiquitous
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Computing
• You walk into your office and your computer
automatically authenticates you through your
active badge and logs you into the Unix system
• You go to a foreign building and your PDA
automatically discovers the closest public printer
where you can print your schedule and give to
your friend
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More Examples
You walk into a Conference room or a shopping Mall
with your PDA and your PDA is smart enough to collect
and filter the public profiles of other people that are
passing nearby
Of course other people should also have smart
PDAs.
The cows in a village are equipped with GPS and GPRS
devices and they are monitored from a central location
on a digital map
No need for a person to guide and feed them
You can find countless examples
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What is PCS
• Personal Communication Services
– A wide variety of network services that includes
wireless access and personal mobility services
– Provided through a small terminal
– Enables communication at any time, at any place,
and in any form.
• The market for such services is tremendously big
– Think of cell-phone market
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THANK
YOU
