From 8d6cd3c3abaabb42cc7842cd897a424fa5fbc739 Mon Sep 17 00:00:00 2001
From: Refik Hadzialic
Date: Wed, 22 Aug 2012 17:22:39 +0200
Subject: GSM last section

---
 vorlagen/thesis/src/kapitel_x.tex | 22 +++++++++++++++++++++-
 1 file changed, 21 insertions(+), 1 deletion(-)

(limited to 'vorlagen/thesis/src/kapitel_x.tex')

diff --git a/vorlagen/thesis/src/kapitel_x.tex b/vorlagen/thesis/src/kapitel_x.tex
index baebf75..f28a102 100644
--- a/vorlagen/thesis/src/kapitel_x.tex
+++ b/vorlagen/thesis/src/kapitel_x.tex
@@ -1308,7 +1308,7 @@ AGPS receivers work on the equivalent idea as warm/hot start on GPS receivers.
 Instead of loading the recently saved data from the EEPROM, an external
 information transfer medium is used to deliver the equivalent type of information that are known 
 at a warm/hot start \citep{755159}, \citep{901174}, \citep{springerlink:10.1007/s10291-002-0028-0}.
-In this work, the external transfer medium is air and the information are transfered using electromagnetic
+In this work, the external transfer medium is air and the information are transferred using electromagnetic
 waves. The existing GSM interface was utilised for the purpose of delivering the data to the smart phone
 with an AGPS receiver. The basic scenario can be seen in figure \ref{img:agpsPrinciple}.
 
@@ -1600,7 +1600,27 @@ Random access channel&RACH&Request from MS to BTS for a communication& MS$\right
 \end {tabular}
 \end {table}
 
+The protocol scenario occuring in this work can be seen in figure \ref{img:SDCCHReq} \citep{0470844574}.
+In order for the assistance data to be delivered to the MS, an SDCCH channel has to be initialized. 
+This occurs in the following procedure, the BTS where the MS has been lastly active or idle
+broadcast a paging request (PCH channel) to the selected MS. After the MS obtains the paging request, the MS shall
+try to send a random access request (RACH channel) using the Slotted Aloha protocol. Another MS could 
+transmit a random access request in the same time slot allowing collisions to occur. In case there was no collision,
+if the BTS successfully received the random access request and at the moment of reception has a free SDCCH channels, 
+it will immediatelly reserve an SDCCH channel and send the MS an assignment request (AGCH channel) back. 
+After the MS obtains the assignment request, the SDCCH channel is initialized and data can be transferred in both 
+directions, in this case assistance data to the MS and acknowledgements, errors or the position from the MS back 
+to the BTS. In the case if all SDCCH channels are reserved, the network will queue an SDCCH request for later assignment
+or it may send an assignment reject. While the SDCCH channel connection has been established assistance data can be
+transmitted to the MS. While an active SDCCH conecction exists, the MS will receive and transmit
+radio link control messages (signal strength and synchronization data) on the SACCH channel \citep{0470844574}.
 
+\begin{figure}[ht!]
+  \centering
+  \includegraphics[scale=0.50]{img/SDCCHRequest.pdf}
+  \caption{Initializing an successful SDCCH channel..}
+\label{img:SDCCHReq}
+\end{figure}
 
 
 
-- 
cgit v1.2.3-55-g7522

