current TeX

competition/tex/chapters/wifi.tex

@@ -1,14 +1,18 @@
 \subsection{\docWIFI}
 
-	absolute positioning using wifi (x,y,z)
-	no fingerprinting
-	uses signal-strength prediction model
-	position of access points must be known beforehand
-	only 2 parameters for all APs
-	only vague position estimation
+	the smartphone's \docWIFI{} component provides an absolute location estimation $(x,y,z)^T$ by
+	measuring the signal-strengths of nearby transmitters (\docAP{}) and comparing them with the signal-strengths
+	that should be measurable. The latter are determined using a signal-strength prediction model.
+	Thus, no fingerprinting is required. Solely the positions of the \docAP{}s must be known beforehand.%
+	%
+	Prediction uses the wall-attenuation-factor model \cite{ebner-15}
+	which needs just three parameters: 
+	the senders transmission power, the attenuation based on the distance from the sender, and the attenuation by floors/ceilings.
+	To reduce the setup-time, the same values can be used for all transmitters at the expense of a worse location estimation / higher
+	uncertainties.
 	
 \subsection{\docIBeacon{}s}
 
-	optional
-	same as wifi
-	but only one param: as txp is broadcasted
+	If the building is equipped with \docIBeacon{}s, those may additionally be used as absolute location source.
+	Like \docWIFI{}, measurements are compared with a model prediction based on the known transmitter position.
+	The transmission power of the \docIBeacon{} is transmitted by the beacon itself and does not need any estimation beforehand.