Wireless Computer Networking Melanie Hanson May 6, 2002.
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Transcript of Wireless Computer Networking Melanie Hanson May 6, 2002.
![Page 1: Wireless Computer Networking Melanie Hanson May 6, 2002.](https://reader036.fdocuments.us/reader036/viewer/2022082816/56649d0c5503460f949e0f9f/html5/thumbnails/1.jpg)
Wireless Computer Networking
Melanie Hanson
May 6, 2002
![Page 2: Wireless Computer Networking Melanie Hanson May 6, 2002.](https://reader036.fdocuments.us/reader036/viewer/2022082816/56649d0c5503460f949e0f9f/html5/thumbnails/2.jpg)
Outline
Types of NetworksLayers of a networkData transfer techniquesFrequency HoppingDirect Sequence Spread Spectrum InfraredOrthogonal Frequency Division
Multiplexing
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Network Types
Cellular Controlled by a base
station
Ad Hoc No base station No specific structure
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Network Layers
7 layers in the traditional network
Physical layer contains hardware
Applications layer is user software
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Types of Data Transfer
Spread SpectrumFrequency HoppingDirect Sequence Spread Spectrum
Infrared
Orthogonal Frequency Division Multiplexing
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Spread Spectrum
Allows multiple access
Little interference due to other systems
Uses ISM band Industrial 902MHz to 928MHz Scientific 2.4GHz to 2.4853Ghz Medical 5.727GHz to 5.85GHz
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Frequency Hopping
Frequency is periodically changed
Generates narrow band signals
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Direct Sequence Spread Spectrum
Carrier is modulated following a specific sequence of bits
For ‘0’ the chip sequence is used
For ‘1’ the inverse chip sequence is used
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Infrared
Intensity Modulation with Direct Detection (IM/DD) Signal is modulated onto the instantaneous
power of the carrier signal Direct detection aspect describes the process of
a photodetector
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Orthogonal Frequency Division Multiplexing
Break signal into small orthogonal parts
Transmit stepsSerial to parallel conversionModulation Inverse Fourier transformParallel to serial conversionDigital to analog conversion
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Which is best?
Depends on situation and environment