Date post: | 21-Jan-2016 |
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War Walking vs. War War Walking vs. War DrivingDriving
Trying to find the reasons why war Trying to find the reasons why war walking radio map performs betterwalking radio map performs better
War Walking Radio-map Performs War Walking Radio-map Performs BetterBetter
Major Possible Origin of ErrorMajor Possible Origin of Error
Bias on war-driving ground truthsBias on war-driving ground truths Quality of collected WiFi signal patternsQuality of collected WiFi signal patterns
Signal strength and varianceSignal strength and variance Amount of dataAmount of data
GPS as War Driving Ground TruthGPS as War Driving Ground Truth GPS itself suppose to have a 15m errorGPS itself suppose to have a 15m error GPS and WiFi reading does not synchronized in our GPS and WiFi reading does not synchronized in our
experimentexperiment
GPS Lags
Uniformly Shift GPS ReadingsUniformly Shift GPS Readings
Driving Testing TraceDriving Testing Trace Intuition: same manner for training and testing Intuition: same manner for training and testing
leads better resultleads better result
Not in our testsNot in our tests
If “resemblance” does not account for If “resemblance” does not account for difference in war walking and war difference in war walking and war driving, what does?driving, what does?
Signal strengthSignal strength Variance of signalsVariance of signals ……??
Signal StrengthSignal Strength Intuition: Lower strength in radio map Intuition: Lower strength in radio map larger errors larger errors
somewhatsomewhat
Variance of signalsVariance of signals Intuition: Higher variance in signals is better for Intuition: Higher variance in signals is better for
differentiation, so lowering the variance differentiation, so lowering the variance larger errors larger errors
somewhatsomewhat
Number of Access Points in RadiomapNumber of Access Points in Radiomap
Intuition: war walking tend to receive more APs Intuition: war walking tend to receive more APs and those may be criticaland those may be critical
In bothIn both
Only in war walkingOnly in war walkingWar War walking:walking:
Only in war drivingOnly in war drivingWar driving:War driving:
Walking Walking reduced:reduced:
Driving plus:Driving plus:
Signal as recv’d Signal as recv’d by walkingby walking
War driving onlyWar driving only
Signal as recv’d Signal as recv’d by drivingby driving
Signal as recv’d Signal as recv’d by walkingby walking
Signal as recv’d Signal as recv’d by drivingby driving War walking onlyWar walking only
Only in war walkingOnly in war walking
Number of Access Points in RadiomapNumber of Access Points in Radiomap
Intuition: war walking tend to receive more APs Intuition: war walking tend to receive more APs and those may be criticaland those may be critical
The additional APs seems to be redundantThe additional APs seems to be redundant
Number of SamplesNumber of Samples Intuition: war walking tends to receive more samples and Intuition: war walking tends to receive more samples and
it’s criticalit’s critical
it’s not criticalit’s not critical
RecapRecap
Signal quality (strength, variance)Signal quality (strength, variance)
Amount of dataAmount of data