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authorRefik Hadzialic2012-08-24 15:50:01 +0200
committerRefik Hadzialic2012-08-24 15:50:01 +0200
commit8cfa0da161a006d96ae80c09d06bd5adf1ad6970 (patch)
tree617af6885ba5eec896df7118d9b7755507762916
parentGSM last section (diff)
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Results
-rw-r--r--vorlagen/thesis/maindoc.pdfbin6931523 -> 6935692 bytes
-rw-r--r--vorlagen/thesis/src/kapitel_x.tex75
2 files changed, 63 insertions, 12 deletions
diff --git a/vorlagen/thesis/maindoc.pdf b/vorlagen/thesis/maindoc.pdf
index 1ce7a3a..aa2aa68 100644
--- a/vorlagen/thesis/maindoc.pdf
+++ b/vorlagen/thesis/maindoc.pdf
Binary files differ
diff --git a/vorlagen/thesis/src/kapitel_x.tex b/vorlagen/thesis/src/kapitel_x.tex
index f28a102..d4c2e16 100644
--- a/vorlagen/thesis/src/kapitel_x.tex
+++ b/vorlagen/thesis/src/kapitel_x.tex
@@ -250,7 +250,7 @@ depicted in figure \ref{img:WiFiTag}, where the MS in this particular example is
1, 2 and 4 are visible at the same time stamp.
This technique works efficiently indoors as well as outdoors in cities since
ranges of wireless networks 801.11 b/g are not more than 30-150 m, though the new standard 801.11 n has a wider coverage area.
-A simple overview of all the mentioned techniques is given in
+A simple overview of all the discussed techniques is given in
table \ref{tbl:overviewLoc}.
\begin {table}[tp!]
@@ -376,7 +376,7 @@ models.
\label{sec:gpsDataAndSignal}
The aim of this section is to give the reader an overview of the transmitted GPS data and
to understand what type of processing takes place on the GPS satellite itself.
-As mentioned in the paragraph earlier, to estimate the position of the GPS receiver, it is
+As discussed in the paragraph earlier, to estimate the position of the GPS receiver, it is
important to know the position of the satellite at the moment of signal transmission. Prior to
releasing the data in the athmosphere, they need to be modulated in order for the GPS receiver
to receive and demodulate them.
@@ -870,7 +870,7 @@ further explained in the following section \ref{sec:2dSearch}.
\subsection{Implementation of the 2D search space problem}
\label{sec:2dSearch}
In the following paragraphs an introduction shall be given on
-the implementation problems of the previously mentioned concepts.
+the implementation problems of the previously discussed concepts.
As it can be seen,
from subsections \ref{sec:Carrierdemod} and
\ref{sec:CAdemod}, decoding the GPS navigation message is a 2D
@@ -998,7 +998,7 @@ first time the GPS receiver is turned on. It is known under the name of cold sta
There are three different working modes when it comes to searching
for the GPS satellites. If no information are known,
when some information are known and when almost all information are
-known. These three modes are known as \textit{cold} (as mentioned earlier),
+known. These three modes are known as \textit{cold} (as discussed earlier),
\textit{warm} and \textit{hot} start. They differ from each other by the amount of known
information by the GPS receiver. Cold start indicates the GPS receiver
has no almanac, ephemeris,
@@ -1020,7 +1020,7 @@ known (time ought to be known in accuracy of submilliseconds).
\section{Distance and position estimation}
\label{sec:distanceAndPosition}
In this section the focus is set on distance and position estimation inside of the GPS receiver.
-GPS system, as mentioned earlier, takes advantage of the TOA ranging concept
+GPS system, as discussed earlier, takes advantage of the TOA ranging concept
to determine user position. Time is measured how long it takes for a signal to arrive from a
known location.
\begin{figure}[ht!]
@@ -1045,7 +1045,7 @@ given in equation \eqref{eq:rMag}.
r=\Vert s-u\Vert
\end{equation}
The geometric distance of $r$ is computed by measuring the signal propagation time, this is illustrated in figure \ref{img:TimingLoc}
-and it was mentioned in section \ref{sec:CAdemod}. The PRN code generated on the GPS satellite
+and it was discussed in section \ref{sec:CAdemod}. The PRN code generated on the GPS satellite
at time $t_1$ arrives at the time $t_2$, the difference between these two time stamps, $\Delta t$, represents the
propagation time. By multiplying the propagation time, $\Delta t$, with the speed of light, $c$, the
geometric distance $r$ is computed, as given in equation \eqref{eq:rDist}.
@@ -1077,7 +1077,7 @@ Equation \eqref{eq:rMag} can be rewritten as \eqref{eq:rhoR} with respect to equ
\label{eq:rhoR}
\rho - c(t_{u}-\delta t) = \Vert s-u\Vert
\end{equation}
-Offset of the satellite clock from the system time, $\delta t$, is updated from Earth, as mentioned in \ref{sec:SigDemod}
+Offset of the satellite clock from the system time, $\delta t$, is updated from Earth, as discussed in \ref{sec:SigDemod}
and for that reason it can be removed for sake of simplicity, i.e. it is not an unknown term anymore,
then the eqaution \eqref{eq:rhoR} can be rewritten as \eqref{eq:rhoNew}.
\begin{equation}
@@ -1091,7 +1091,7 @@ has to be solved, where $i$ is the index of visible satellites at the moment of
\label{eq:rhoSats}
\rho_i= \Vert s_i-u\Vert + ct_u
\end{equation}
-The estimated position of the user, $\vec{u}=(x_u,y_u,z_u)$, is a three dimensional vector and as mentioned
+The estimated position of the user, $\vec{u}=(x_u,y_u,z_u)$, is a three dimensional vector and as stated
above the clock offset, $t_u$, is unknown as well. This four dimensional space requires to have at least four pseudorange
equations \eqref{eq:rhoSats} to find all the four unknown terms.
As a result of this fact, at least four satellites have to be visible at
@@ -1547,7 +1547,7 @@ ought to be tracked if they register \citep[Chapter 4]{0890064717}.
\newpage
\section{Logical channels and the SDCCH channel}
In this section more details will be given on logical channels and the procedure to initialize (open) an SDCCH channel (Standalone
-Dedicated Control Channel). As mentioned in section \ref{sec:GSMNetStruct}, logical channels can be divided in two groups,
+Dedicated Control Channel). As stated in section \ref{sec:GSMNetStruct}, logical channels can be divided in two groups,
traffic channels (TCH) and signalling channels (SCH). The former are employed for transfering payload data like speech and message data
and the latter for managing and synchronizing the GSM network \citep[Chapter 4]{0470030704}.
Traffic and signalling channels can be split up by their usage, as given in tables \ref{tbl:tchChannels} and \ref{tbl:cchChannels}.
@@ -2112,8 +2112,7 @@ location in the example listing \ref{lst:RRLPAssisPER} are marked with orange co
have been transmitted to the MS, it shall respond back with an acknowledgement or error depending if the
data were correctly received and parsed by the MS. The acknowledgement shall have the same reference number
as the assistance packet. This can be seen as well in figure \ref{img:RRLPReqProt}.
-In the next section more
-details shall be given on the RRLP response from the MS.
+In the next section more details shall be given on the RRLP response from the MS.
\begin{equation}
\label{eq:latLong}
\begin{array}{l}
@@ -2347,7 +2346,7 @@ constructed in the same manner as the RRLP request and assistance data by follow
ASN.1 rules precisely specified in the RRLP standard. RRLP response is produced by the MS itself.
It may include the estimated position, data for estimating the position on the BTS (if MS assisted was
choosen as the prefered method) or errors indicating that some of the
-previously mentioned assistance data are missing. Missing data and errors are
+previously stated assistance data are missing. Missing data and errors are
specified inside of the RRLP response. The response data shall be PER encoded and require
to be decoded into the ASN.1 notation. In listing \ref{lst:RRLPRespError} an example of an
RRLP response with an error can be seen. The location error bit is set if the location
@@ -2820,6 +2819,58 @@ than 100 m \citep{installnanoBTS}.
\end{figure}
\chapter{Results}
+One of the most important parts of this thesis are the results that
+shall be presented in this chapter. Tests shall be elucidated and how the results
+were obtained. The results will be analysed by the time required to perform a
+localization of a GSM user and the geographical dislocation error using
+Google maps. After the results have been presented,
+a section with criticism demonstraces all the obstacles that may have appeared
+while the tests have been performed and why the results may biased. The criticism
+section represents a vital part of this thesis, aside from the given theoretical and
+mathematical perspective of how AGPS works and why lack of time synchronization inside
+GSM can be of critical value to correctly evaluate the results. It gives an additional
+insight into the complete operation of the built localization system in this thesis.
+The results will
+
+\newpage
+\section{Criticism of performed tests}
+Perhaps the most serious weakness of the presented results
+is that the author had no access to the firmware of the MS while the
+tests have been performed. This would allow the author to see what type
+and how the assistance data are employed by the AGPS in the MS. If access
+could be gained to the internal operation of the AGPS receiver in the MS,
+every bias could be eliminated whether the AGPS receiver uses the transmitted
+assistance data or it might be the case that they are from the memory.
+The whole system represents a black box where an input is delivered and
+an output expected. Another drawback was the lack of information of the
+internal hardware in the MS. This does not allow an exact comparison
+between different cell phones model.
+
+
+Difficulties arise in assessment and comparing the results in this
+thesis with other relevant studies due to the lack of expensive
+hardware equipment used in the studies. In addition, no research has
+been found that surveyed the amount of time required to get a
+position response from a MS where only almanac, ephemeris, UTC model,
+ionospheric model and reference location data have been delivered to
+the MS.
+
+Another limitation of the evaluated results lies in the fact that it has
+only been applied to the stated cell phones and it could not be tested
+with all models. The tests suffer from a major drawback as real time
+movement of satellites, the tests could not be conducted parallely but
+rather in serial manner in time. In other words a satellite visible at
+the moment while the first test is being performed may not be visible
+the second time when the test executed.
+
+Correctness of assistance data in almanac and ephemeris data can not be
+verified. The author had to rely and trust NASA and Trimble as sources
+although errors were confirmed by different studies in \citep{Stanford-Ephem-Errors}
+\citep{NASA-Ephem-Errors}. Errors can be confirmed by the author in
+ephemeris data as well (URA values were out of range specified by the standard).
+
+\section{Future work}
+
Test if it can be tricked out by the software Dennis mentioned (protect my privacy)!
\chapter{Summary}