second draft um 2 Uhr wie angekündigt. hehe

tex/chapters/system.tex

@@ -3,7 +3,7 @@
 \label{sec:filtering}
 
 As mentioned before, most smoothing methods require a preceding filtering. 
-In our previous work \cite{Ebner-16}, we consider indoor localisation as a time-sequential, non-linear and non-Gaussian state estimation problem. 
+Similar to our previous works, we consider indoor localisation as a time-sequential, non-linear and non-Gaussian state estimation problem. 
 Therefore, a Bayes filter that satisfies the Markov property is used to calculate the posterior, which is given by
 	%
 	\begin{equation}