\section{Collected type of Data}
This section describes the different characteristics that are considered when generating the signal map for this thesis work.

\subsection{Location}

In order to map the collected data to a point in the signal map a location of where the data was collected must be defined. There are several ways to determine a location of a mobile device but the accuracy of these techniques vary. Getting location by \gls{gps} is easy to implement in Android and generally provides high accuracy without having to do location prediction such as in \citet{yin2008learning}. The energy consumption is considered as a secondary issue when collecting data.
%The \gls{gps} does consume a lot of energy but since we do not care about the energy consumption while logging.

\subsection{RSS}

The \gls{rss} comes free since it is utilized for deciding when the mobile device needs to either amplify the signal to the cell tower or send larger packets of data to the \gls{wifi} access point (\gls{ap}).

\subsection{Data Rate}

% source needed

The collection of data rates has a impact on the data sent and received from the device it is tested on, this is due to that in order to measure the data rate the device must send and receive data. In order to properly be able to estimate the achievable data rate the size of the data sent or received must be known before the transfer occur, the estimation is then just a matter of dividing the file size with the time spent transmitting data.

The size of the transmitted data also matters and generally a greater file size results in a more accurate estimate. The reason for this is that errors and delays of a transfer is distributed over a larger set and thus estimates the real transfer speed better.

% picture with packet loss in small transfer vs big


\subsection{Other Interesting Characteristics}

Since a mobile device can be connected to several different types of network it is interesting to see which network is used for data transmission. This comes in handy when evaluating the transfer speeds since just checking the connection to a mobile network such as \gls{3g} or \gls{lte} does not mean that the data is being transmitted over that specific interface. It is for example possible to be connected to both \gls{lte} and \gls{wifi} at the same time.

Carrier and cell tower id is also interesting to log since these controls how the \gls{ue} communicate through the cellular network.


% cite sonntag2013mobile

% Cell tower id regional code etc

% 