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-rw-r--r--vorlagen/thesis/src/kapitel_x.tex16
1 files changed, 9 insertions, 7 deletions
diff --git a/vorlagen/thesis/src/kapitel_x.tex b/vorlagen/thesis/src/kapitel_x.tex
index c839f46..0623f5d 100644
--- a/vorlagen/thesis/src/kapitel_x.tex
+++ b/vorlagen/thesis/src/kapitel_x.tex
@@ -1111,7 +1111,8 @@ to estimate the rough position of the satellites, therefore the Doppler effects
roughly estimated. As a consequence of the known Doppler effect, the frequency bins to
search through to obtain the correlation peak are this time limited \citep[Chapter 3]{diggelen2009a-gps}.
Hot start works in the same manner as warm start however, the ephemeris data and time data are precisely
-known (time is known in accuracy of submilliseconds).
+known (time is known in accuracy of submilliseconds). The process of finding user's position is explained
+in detail in appendix section \ref{sec:distanceAndPosition}.
\section{Assisted GPS in wireless networks}
\label{sec:agps}
@@ -1140,8 +1141,8 @@ off by several seconds and would require additional equipment for synchronizing
\citep{springerlink:10.1007/s10291-002-0028-0}, \citep{901174}. However in CDMA networks the time stamp is
accurate to within $100 \, \mu s$ \citep{springerlink:10.1007/s10291-002-0028-0}. Approximate
location is typically taken to be the location of the BTS from which the target AGPS receiver
-acquires the assistance data. Ephemeris and navigation data obtained by the AGPS receiver in the smart phone
-help it to estimate the positions of the GPS satellites. This method can greatly
+acquires the assistance data. Ephemeris and navigation data obtained from the GSM network provider
+help the smart phone to estimate its position. This method can greatly
enhance the sensitivity of the receiver especially in urban environments \citep{springerlink:10.1007/s10291-002-0028-0}.
Conventional GPS receivers require at least up to extra $18$ to $30\,s$ to receive and decode the navigation data
@@ -1153,8 +1154,8 @@ an antenna with a gain of $3\, \mathrm{dB}$ with respect to an isotropic (omnidi
\citep[Chapter 2]{diggelen2009a-gps}.} (located near ground) at worst normal orientation''
\citep{GPS-Interface-Specification}.
-A simplified AGPS algorithm given in \citep{springerlink:10.1007/s10291-002-0028-0} shall be presented here. This
-algorithm benefits in speed the more assistance data is present. As the first satellites are tracked,
+A simplified AGPS algorithm given in \citep{springerlink:10.1007/s10291-002-0028-0} will be presented. This
+algorithm benefits the more assistance data are known. As the first satellites are tracked,
the AGPS algorithm has an estimation of the feasible region where the target AGPS user might be located.
Consequently, this feasible region shall shrink until the location has been fully estimated
\citep{springerlink:10.1007/s10291-002-0028-0}.
@@ -1168,7 +1169,8 @@ Consequently, this feasible region shall shrink until the location has been full
Although the AGPS algorithms can be seen as a set of equations with more unknown terms being known. It is
straightforward to solve a set of equations when all the terms are known. However, without assistance information
which provide additional information to the GPS receiver,
-it takes more time to obtain (decode) assistance data from the satellite message.
+it takes more time to obtain (decode) assistance data from the satellite message. The set of equations
+to be solved is described in detail in appendix section \ref{sec:distanceAndPosition}.
Numerous AGPS algorithms exist, some do not require the exact time component and navigation data to
be present in the assistance data \citep{998892}.
@@ -1560,7 +1562,7 @@ position and would help weak signals to be detected which in return would minimi
As listed above, almanac, ephemeris, UTC model, ionospheric model and reference location are transmitted to the MS. Reference
location is the location of the BTS and provides the MS with an proximate location which can be used
-for the position determination in equations given in appendix \ref{sec:distanceAndPosition}.
+for the position determination in equations given in appendix section \ref{sec:distanceAndPosition}.
Furthermore, this limits the search space in time and frequency domain for satellites
to lock on. For an illustration, if the AGPS receiver has access to these data it can not expect to see satellites
which send signals on the opposite side of the Earth \citep[Chapter 4]{harper2010server-side}.