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+++ b/vorlagen/thesis/src/kapitel_x.tex
@@ -2631,9 +2631,9 @@ all of them employing different modulation/demodulation procedures and frequency
built using an SDR platform that is within the domain of the SDR hardware.
The exploited SDR platform in this thesis was the Universal Software
-Radio Peripheral (USRP) that already had an GSM and RRLP implementation.
-The GSM network software used on USRP was OpenBTS, a Linux application written in C++
-employing the SDR platform to provide a GSM air interface \citep{openBTS}. Once the
+Radio Peripheral (USRP) by Ettus Research. USRP had already a GSM and RRLP software
+implementation. The GSM network software used on USRP was OpenBTS, a Linux
+application written in C++ employing the SDR platform to provide a GSM air interface \citep{openBTS}. Once the
system has been successfully configured and set in operation it was followed by tests
to verify if it was operating correctly. Initially, the system was
tested with 2G cell phones (Nokia 3310 and Siemens M50) and its correctness was verified.
@@ -2673,23 +2673,25 @@ inside of this set up because the system itself was unstable and had an unpredic
behaviour. The conducted tests with OpenBTS thus lead to a logical decision to
employ dedicated BTS hardware with a tested and calibrated clock oscillator only
for GSM. On the other hand, the Erlang RRLP module was a starting point to understand
-the RRLP protocol. The generated assistance data packets by the module were used as
-a template and comparison to build author's RRLP assistance data generator. The nanoBTS
+the RRLP protocol. The generated assistance data packets by the module were used
+for comparison and a template to build author's RRLP assistance data generator. The nanoBTS
is operated by OpenBSC which is explained in the following section.
\section{OpenBSC}
-OpenBSC is an open source implementation of a GSM network by Osmocom. It was developed
-for experimentation and security research of the GSM netowrks \citep{obsc1}.
+OpenBSC is an open source implementation of a GSM network software by Osmocom.
+It was developed for experimentation and security research of the GSM networks \citep{obsc1}.
OpenBSC is ``implementing the minimal necessary parts to build a small,
self-contained GSM network'' \citep{obsc}. This self-contained GSM network
consists of following functional components: Base Station Controller (BSC),
Mobile Switching Center (MSC), Home Location Register (HLR),Authentication
Center (AUC), Visitor Location Register (VLR) and Equipment Identity
-Register (EIR). OpenBSC was written in C and operates on Linux. It connects
+Register (EIR). OpenBSC was written in C and operates on Linux. OpenBSC connects
to the BTS using the Abis or Abis/IP interface. At the moment OpenBSC
-supports Voice calls, SMS and some other features not of the interest
-for this work.
+supports Voice calls, SMS, handovers, support for multiple BTS and other features
+not of the interest for this work. OpenBSC has an implemented module for sending only
+RRLP requests however without assistance data. This module was tested
+\section{RRLP assistance data generator application}
At the point of writing this thesis there was no working open source
implementation of generating RRLP assistance data.
@@ -2701,6 +2703,14 @@ protocol\footnote{Kurtis Heimerl's
code can be found on \url{https://github.com/ttsou/RRLP}}! More details shall be given in the following
sections. OpenBSC is an open source implementation of
+
+\begin{figure}[hb]
+ \centering
+ \includegraphics[scale=0.4]{img/algorithmRRLP.pdf}
+ \caption{Flowchart for the RRLP assistance data generators}
+\label{img:RRLPAlgFlowchart}
+\end{figure}
+
-from rinex conversion\\
explain rinex form \\
explain a bit ephemeris data and almanac \\