Planning%20WiFi%20Networks

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Planning WiFi Networks

• Narayan Mandayam

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Planning WiFi Networks ?

• Goals
• Estimate radio coverage area
• Estimate performance/throughput
• Estimate network design parameters
• Placement of Access Points
• Transmit power assignment
• Channel Assignment

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Interesting Scenarios
At which locations will network performance be
optimized ? What frequencies ? What Powers ?
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Modeling Approach
Stochastic approach (wide-area cellular)
Deterministic approach (indoor wireless)
Ray-tracing (Valenzuela, Rappaport, ...)
Measurements (Greenstein, COST, Rappaport, Hata,
...)
Deterministic-plus-stochastic approach
Ray-tracing AND Measurements

• Predictable user behavior (trajectory)
• Short-range
• No shadowing

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Ray Tracing
PR
d
PT

Model path loss as free space loss between any
2 points that have line-of-sight path between them
Also known as Friis free space formula
Model penetration, absorption and reflection
losses through materials Power/Intensity at each
point in space is sum of all rays through it
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Indoor Signal Measurement
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Project 1 WiFi Planning using SpectraPlan

• Spectraplan is a Ray-Tracing based interactive
  visualization tool that provides spectrum,
  coverage and throughput maps
• Requires Floor-plan of building in question with
  associated information about wall materials etc.
• Goal Optimize Placement of APs in the WINLAB
  modular building for coverage and/or throughput
• Calibrate Spectraplan output with measurements
• Design location tracking algorithms using
  Spectraplan
• Wibhu Technologies (www.wibhu.com) proprietary
  technology