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2020-03-04 09:15:15 +01:00
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@@ -106,24 +106,41 @@ In total there are eight phone AP combinations.
\autoref{fig:DistMeasMeanNucPixel}~\subref{fig:DistMeasMeanNucPixel:a} shows the average measured distance per smartphone in respect to the ground truth distance. \autoref{fig:DistMeasMeanNucPixel}~\subref{fig:DistMeasMeanNucPixel:a} shows the average measured distance per smartphone in respect to the ground truth distance.
Likewise, \autoref{fig:DistMeasMeanNucPixel}~\subref{fig:DistMeasMeanNucPixel:b} depicts the average measured distance per access point. Likewise, \autoref{fig:DistMeasMeanNucPixel}~\subref{fig:DistMeasMeanNucPixel:b} depicts the average measured distance per access point.
The corresponding values of these figures are shown in \autoref{tab:distvaluesPixels} and \autoref{tab:distvaluesNUCs}. The corresponding values of these figures are shown in \autoref{tab:distvaluesPixels} and \autoref{tab:distvaluesNUCs}.
Interestingly, both the wireless cards and the Pixel devices exhibit some tendency regarding the measurement error. Interestingly, both the wireless cards and the Pixel devices exhibit some similar tendency regarding the measurement error.
As seen in \autoref{fig:DistMeasMeanNucPixel}~\subref{fig:DistMeasMeanNucPixel:a} the Pixel3a tends to underestimate the distance. As seen in \autoref{fig:DistMeasMeanNucPixel}~\subref{fig:DistMeasMeanNucPixel:a} the Pixel 3a tends to underestimate the distance.
Only at \SI{6}{m} and \SI{10}{m} the estimated distance is slightly larger compared to the true distance. Only at \SI{6}{m} and \SI{10}{m} the estimated distance is slightly larger compared to the true distance.
The overall The overall error is mostly negative and the mean absolute error is $\SI{1}{m}$.
Contrarily, the Pixel 2 XL tends to overestimates the distance compared to the groundtruth distance.
Here the mean absolute error is $\SI{1.4}{m}$.
However, at the \SI{16}{m} mark the measured mean distance of the Pixel 2 XL significantly increases.
Computing the mean absolute error only in the interval of $[\SI{2}{m}, \SI{16}{m}]$ reduces the Pixel 2 XL error to $\SI{0.6986}{m}$, while the Pixel 3a error changes negligible.
At \SI{16}{m} the Pixel 3a stops to underestimate the distance and the measurements at \SI{18}{m} and \SI{20}{m} are quite close to the true distance.
In contrast, the Pixel 2 XL starts to increasingly overestimate the true distance which results in large error values ($\approx \SI{4}{m}$).
The same behavior is observable for the Intel AC 8260 and 9460 cards.
Again at \SI{16}{m} both cards start to overestimate the true distance.
For distances smaller than \SI{16}{m} the \intelOld also underestimates the distance with a mean absolute error of \SI{1.11}{m} in that range.
Like the \pixelOld the error increases for larger distances, however, somewhat smaller with $\approx \SI{2}{m}$.
In total the \intelNew card tends to provide an accurate distance estimate but has some outliers at \SI{6}{m} and \SI{10}{m} but never underestimates the true distance.
While the mean distance over many measurements is relevant for stationary measure points, in our scenario a pedestrian is moving with the smartphone.
Therefore, only one or a few measurements can be observed at a given position.
A more expressive visualization for this scenario is given with the CDF graph in \autoref{fig:DistMeasMeanNucPixel}~\subref{fig:DistMeasMeanNucPixel:c}.
\begin{figure}[ht] \begin{figure}[ht]
\begin{minipage}{.5\textwidth} \begin{minipage}{.5\textwidth}
\centering \centering
\subfloat[]{\label{fig:DistMeasMeanNucPixel:a}\includegraphics[width=\textwidth]{DistMeasMeanPerPixel.png}} \subfloat[]{\label{fig:DistMeasMeanNucPixel:a}\includegraphics[width=0.8\textwidth]{DistMeasMeanPerPixel.png}}
\end{minipage}% \end{minipage}%
\begin{minipage}{.5\textwidth} \begin{minipage}{.5\textwidth}
\centering \centering
\subfloat[]{\label{fig:DistMeasMeanNucPixel:b}\includegraphics[width=\textwidth]{DistMeasMean.png}} \subfloat[]{\label{fig:DistMeasMeanNucPixel:b}\includegraphics[width=0.8\textwidth]{DistMeasMeanPerNuc.png}}
\end{minipage}\par\medskip \end{minipage}\par\medskip
\centering \centering
\subfloat[CDF of error]{\label{main:c}\includegraphics[width=\textwidth]{DistMeasCDF.png}} \subfloat[CDF of error]{\label{fig:DistMeasMeanNucPixel:c}\includegraphics[width=\textwidth]{DistMeasCDF.png}}
\caption{my fig} \caption{my fig}
\label{fig:DistMeasMeanNucPixel} \label{fig:DistMeasMeanNucPixel}

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@@ -18,6 +18,12 @@
\newcommand{\ieeWifiN} {\mbox{IEEE 802.11n}\xspace} \newcommand{\ieeWifiN} {\mbox{IEEE 802.11n}\xspace}
\newcommand{\ieeWifiAC} {\mbox{IEEE 802.11ac}\xspace} \newcommand{\ieeWifiAC} {\mbox{IEEE 802.11ac}\xspace}
\newcommand{\pixelOld}{Pixel~2~XL\xspace}
\newcommand{\pixelNew}{Pixel~3a\xspace}
\newcommand{\intelOld}{Intel~AC~8260\xspace}
\newcommand{\intelNew}{Intel~AC~9460\xspace}
% keyword macros % keyword macros
\newcommand{\docIBeacon}{iBeacon} \newcommand{\docIBeacon}{iBeacon}