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diff --git a/vorlagen/thesis/src/kapitel_x.tex b/vorlagen/thesis/src/kapitel_x.tex
index 568e1b7..6c1b697 100644
--- a/vorlagen/thesis/src/kapitel_x.tex
+++ b/vorlagen/thesis/src/kapitel_x.tex
@@ -21,7 +21,7 @@ used some of the LBS on their cell phones, this number is expected to grow in 20
468 million users worldwide \citep{smartPhone2015}. As social networks grow like Facebook,
Twitter or Foursquare (a location based social network), it has become a trend
for the users to share their location with their friends \citep{smartPhone2015}.
-It has been reported that LBS represent a Bonanza opportunity for new startup
+It has been reported that LBS represent a bonanza opportunity for new startup
companies and Global Industry Analysts project by 2015 a global market
worth of \$21 USD billion ($\approx$ \euro17.142 billion) \citep{Bonanza}.
New ideas and algorithms for tracking,
@@ -48,7 +48,7 @@ and their working principle.
When the GSM network was designed, its primary goal was to enable wireless
full duplex telephony service \citep{gsmTelephony}.
Over the past decade the GSM network became more popular and mature compared to the initial GSM standard so
-the demands grew for diffent services. One of the demands, was the demand from emergency services
+the demands grew for different services. One of the demands, was the demand from emergency services
to localize mobile user in emergency situations like snow avalanches or other not
typical daily emergency situations \citep{0849333490}. This demand led to the
devolopment of different approaches that differ in complexity and in the degree of accuracy of position fixes.
@@ -60,12 +60,12 @@ distinguish three different approaches to positioning mobile user's, handset, ne
approach. The handset based techniques are based on one fact, the handset itself tries to estimate its
position using the available information on its own. In the network based approach the network makes
all the required measurements and the handset itself is passive. The last approach, hybrid based, uses
-resources from the handset and network together, both are active participants in the position estimation. In
+resources from the handset and network together, both are active participants in the position estimation process. In
the further text with mobile station the target user one wants to locate is ment. A few different methods,
varying by their complexity and precision, will be presented. First simple and then more advanced techniques
will be presented in their order.
-\subsection{Cell-ID estimation technique}
+\subsection{Cell-ID}
Cell-identification method is the simplest known GSM ranging method \citep[Chapter 8]{0470092319}.
By knowing the geographical location of the base transceiver
station (BTS) one can roughly estimate the position of the mobile station (MS) \citep[Chapter 4]{0470694513}.
@@ -84,6 +84,7 @@ BTS has a unique identifier code name and hence can be distinguished from other
\caption[]{Cell-ID position estimation technique where a mobile user can be connected to only one BTS.}
\label{img:cellid}
\end{figure}
+
Using this method even higher accuracies
can be achieved than the known shape of signal reception \citep[Chapter 8]{0470092319}. Basically, provided that the
\textit{timing advance} (TA) value is known. The TA is the rough prediction of the \textit{round trip time} (RTT), time
@@ -100,7 +101,7 @@ estimation technique, due to the fact that the user may run his/her own applicat
the network operator himself. This estimation technique does not require the MS to be a smart phone, it works with
any type of cell phone.
-\subsection{Received Signal Strength estimation technique}
+\subsection{Received Signal Strength}
The Received Signal Strength (RSS) position estimation technique, as the name states,
uses the signal strength measurement reports to localize the MS. RSS measurement
reports in GSM networks are transmitted from the MS to the BTS and they
@@ -113,7 +114,6 @@ are used to determine if the handover process should be triggered or not \citep{
RSS measurements for two BTS, blue is BTS1 and red is BTS2.}
\label{img:rssLoc}
\end{figure}
-
This method requires mapping the location blocks with RSS of the
covered areas before it can be used \citep{Richard2011Master}. The basic
idea can be seen in figure \ref{img:rssLoc}, where one location region is represented
@@ -130,9 +130,36 @@ is limited to the amount of BTS in range and the manufacturer design of the RF f
in the cell phone. However, this method can be applied on any cell phone and does not
require a smart phone. It is a network based estimation technique.
-\subsection{Enhanced Observed Time Difference estimation technique}
+\subsection{E-OTD and UL-TDOA}
+E-OTD and UL-TDOA are two similarly working positioning techniques and for this reason have been grouped
+as one. E-OTD stands for Enhanced Observed Time Difference. This technique requires the GSM network to be
+clock synchronized. The clock synchronization of the GSM network can be achieved with
+a location measurement unit (LMU) \citep{ETSI.TS.125.111}. LMU's provide the precise time to the BTS's
+by having an atomic clock synchronized with the BTS on a seperate location from the BTS or
+by providing a special GPS device at the BTS location that can provide precise time \citep{ETSI.TS.125.111}.
+The clock synchronization of the MS and the BTS is required becase the E-OTD technique
+takes advantage of measuring signal propagation time.
+A data signal with current time information is transmitted from two or more BTS's at the same time
+and then propagation time is measured on the MS \citep{200mRangeEOTD}. Once the difference in time is known between the time point
+when the signal was transmitted and when it was received, it is easy to estimate the relative position
+to the BTS's with trilateration \citep{200mRangeEOTD}. In order to estimate the absolute position, it is required to know
+the absolute location of the BTS's. The basic idea can be seen in figure \ref{img:eotdLoc}.
+
+\begin{figure}[ht!]
+ \centering
+ \includegraphics[scale=1.20]{img/EOTD.pdf}
+ \caption[]{Basic idea of the E-OTD positioning technique. Current time information
+ are transmitted from 3 different BTS's at the same time.Then the MS observes the difference of time when
+ the information arrive and using trilateration technique calculates the relative position of
+ the MS.}
+\label{img:eotdLoc}
+\end{figure}
+
+E-OTD requires the cell phone to be equiped with the firmware software to perform the measurements but does
+not require new or external hardware. The accuracy of this method lies in the range between 50-200 m, depending
+on the location of the MS \citep{malik2009rtls}. This method is not resistant to the multipath signal reflection problem.
-\subsection{Assisted-GPS estimation technique}
+\subsection{Assisted-GPS}
Another positioning technique named Assisted-GPS (AGPS) is recently gaining on popularity
because of the great number of smart phones with an embedded AGPS receiver and the introduction.
of 3G/4G networks. These networks are clock synchronized since
@@ -180,11 +207,11 @@ since it will provide strong evidence on the advantages and limitations
of this method. This will provide the correlation for the observed results.
Once the GPS and GSM working principles have been explained, the author will proceed with introducing the reader
-to the Radio Resource Location services Protocol (RRLP)\footnote{At this point RRLP can be seen as
-the connection point between the AGPS and GSM subsystems.}, responsible for obtaining the location
-and transmission of the assistance data to the cell phone. Furthermore, the reader will be introduced to
+to the Radio Resource Location services Protocol (RRLP), responsible for obtaining the location
+and transmission of the assistance data to the cell phone\footnote{RRLP can be seen as
+the connection point between the AGPS and GSM subsystems.}. Furthermore, the reader will be introduced to
the software development process and the hardware connection schemes will be provided.
-In the last part of this thesis, test results and summary of the entire system will be discussed.
+In the last part of this thesis, test results are reported and summary of the entire system is presented.
@@ -1213,7 +1240,7 @@ Consequently, this feasible region will shrink until the location has been fully
and time data.
\item For each visible satellite $SV_i$, the code phase, $\tau_i$, is estimated.
\item Pseudoranges are calculated for each visible satellite $SV_i$.
- \item Triangulate the position out of the pseudoranges $\rho_i$.
+ \item Trilaterate the position out of the pseudoranges $\rho_i$.
\end{enumerate}
Although the AGPS algorithms can be seen as a set of equations, with more unknowns terms known it is
straightforward to solve the set of equations. However, with more of the unknown terms it takes more