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Bhaskaran Raman, Department of CSE, IIT Kanpur Wireless Networks: Principles and Practice, Fall 2005

CS698tWireless Networking:Principles and Practice

Lecture 0202 Aug 2005, Tuesday

Bhaskaran Raman

Department of CSEIndian Institute of Technology, Kanpur

http://www.cse.iitk.ac.in/users/braman/courses/wless-fall2005/

Bhaskaran Raman, Department of CSE, IIT Kanpur Wireless Networks: Principles and Practice, Fall 2005

From Previous Lecture...

Cellular operational frequencies in India

Scribe for today?

Terms: spectrum, bandwidth

Bhaskaran Raman, Department of CSE, IIT Kanpur Wireless Networks: Principles and Practice, Fall 2005

Three Basic Propagation

Phenomena

Reflection Diffraction Scattering

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Bhaskaran Raman, Department of CSE, IIT Kanpur Wireless Networks: Principles and Practice, Fall 2005

Electro-Magnetic Spectrum

103 102 101 100 10-1 10-2 10-3 10-4 10-5 10-6 10-7 10-8 10-9 10-10 10-11 10-12

106 107 108 109 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020

Common

nameLF MF HF VHF UHF SHF EHF

ISM band: 902-928MHz, 2400-2483.5MHz, 5725-5850MHz

Wavelength (m)

Frequency (Hz)

IR UV X-Rays

Radio

TVCellular Propagation depends on:

Distance, environment, frequency

Bhaskaran Raman, Department of CSE, IIT Kanpur Wireless Networks: Principles and Practice, Fall 2005

dB: Relative Measure(to measure propagtion)

Gravitational

force on a mass

m at distance d

Gravitational

force on a mass

m at distance d/2

4 timer more

Gravitational

force on a mass

m at distance 10d

100 times less

6dB more 20dB less

Bhaskaran Raman, Department of CSE, IIT Kanpur Wireless Networks: Principles and Practice, Fall 2005

Measuring Path Loss in dB

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Bhaskaran Raman, Department of CSE, IIT Kanpur Wireless Networks: Principles and Practice, Fall 2005

Measuring Absolute Power indBm

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Bhaskaran Raman, Department of CSE, IIT Kanpur Wireless Networks: Principles and Practice, Fall 2005

Putting Together dB and dBm

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Bhaskaran Raman, Department of CSE, IIT Kanpur Wireless Networks: Principles and Practice, Fall 2005

Antenna Gain

Antenna Gain G: ratio of transmit/receive power in a

particular direction, to that of an isotropic antenna

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Transmit gain == Receive gain

Typically, gain is expressed in dBi

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Bhaskaran Raman, Department of CSE, IIT Kanpur Wireless Networks: Principles and Practice, Fall 2005

Antenna Radiation Pattern

0o

90o

180o

270o

0dB

-3dB

-10dB

-20dB

-30dB

Side-lobe

rejection

levels

Main direction

Side-lobes

Parabolic Grid

Antenna

Other antennas/patterns: http://www.hyperlinktech.com/