Planning WiFi Networks Narayan Mandayam

Planning WiFi Networks ? Goals Estimate radio coverage area Estimate performance/throughput Estimate network design parameters 1.Placement of Access Points 2.Transmit power assignment 3.Channel Assignment

Interesting Scenarios At which locations will network performance be optimized ? What frequencies ? What Powers ?

Modeling Approach Deterministic approach (indoor wireless) Ray-tracing (Valenzuela, Rappaport,...) Stochastic approach (wide-area cellular) Measurements (Greenstein, COST, Rappaport, Hata,...) Deterministic-plus-stochastic approach Ray-tracing AND Measurements Predictable user behavior (trajectory) Short-range No shadowing

Ray Tracing PTPT PRPR d Isotropic power density Power density along the direction of maximum radiation Power received by Antenna 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

Indoor Signal Measurement

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 ( proprietary technologywww.wibhu.com