09-SpreadSpectrum

09 spreadspectrum

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Unformatted text preview: Data and Computer Communications Communications Chapter 9 – Spread Spectrum Eighth Edition by William Stallings Lecture slides by Lawrie Brown Spread Spectrum Spread All creative people want to do the unexpected. —Ecstasy and Me: My Life as a Woman, Hedy Lamarr Spread Spectrum Spread important encoding method for wireless important communications communications analog & digital data with analog signal spreads data over wide bandwidth makes jamming and interception harder two approaches, both in use: Frequency Hopping Direct Sequence General Model of Spread Spectrum System Spectrum Spread Spectrum Advantages Spread immunity from noise and multipath immunity distortion distortion can hide / encrypt signals several users can share same higher several bandwidth with little interference bandwidth CDM/CDMA Mobile telephones Pseudorandom Numbers Pseudorandom generated by a deterministic algorithm not actually random but if algorithm good, results pass reasonable but tests of rando...
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