diff options
| -rw-r--r-- | DCS.bib | 23 | ||||
| -rw-r--r-- | chapter07/content_ch07.tex | 67 | ||||
| -rw-r--r-- | common/acronym.tex | 3 |
3 files changed, 86 insertions, 7 deletions
@@ -26,6 +26,28 @@ url = {https://commons.wikimedia.org/wiki/File:Comparison_convolution_correlation.svg} } +@TECHREPORT{en300392, + author = {EN 300 392}, + title = {Terrestrial Trunked Radio ({TETRA}); Voice plus Data ({V+D});}, + institution = {European Telecommunications Standards Institue (ETSI)}, + year = {2020}, + type = {Standard}, + note = {Version 1.2.1}, + owner = {ple}, + timestamp = {2020.06.27} +} + +@TECHREPORT{etsits145002, + author = {ETSI TS 145 002}, + title = {Digital cellular telecommunications system (Phase 2+); Multiplexing and multiple access on the radio path ({3GPP TS} 45.002 version 9.3.0 Release 9)}, + institution = {European Telecommunications Standards Institue (ETSI)}, + year = {2010}, + type = {Standard}, + note = {Version 9.3.0}, + owner = {ple}, + timestamp = {2020.06.27} +} + @MISC{Maksim2011, author = {"Maksim" and "Malyszkz"}, title = {Netowrk topologies}, @@ -161,6 +183,7 @@ owner = {ple}, timestamp = {2020.05.03} } +} @MISC{WikiSemaphore, author = {Unknown}, diff --git a/chapter07/content_ch07.tex b/chapter07/content_ch07.tex index ba494d1..e436e1a 100644 --- a/chapter07/content_ch07.tex +++ b/chapter07/content_ch07.tex @@ -1609,7 +1609,20 @@ Drawbacks: \end{figure} \begin{example}{2G cell phone -- \acs{GSM}} - \todo{GSM example} + The 2G cell phone system (\acf{GSM}) uses a hybrid \acs{TDMA}/\acs{FDMA} scheme. + \begin{itemize} + \item 8 users can share a frequency. + \begin{itemize} + \item The \acs{TDMA} part uses 8 time-slots of $\SI{576.92}{\micro{}s}$ length. + \item The 8 time-slots are arranged in a frame of $8 \cdot \SI{576.92}{\micro{}s} = \SI{4.615}{ms}$ length. + \item Thus, a time-slot for each user repeats every $\SI{4.615}{ms}$. + \item Frames are arranged in multi-frames, which themselves are arranged in super-frames, which themselves are arranged in hyper-frames. + \item Each time-slot (if used for data traffic) can transport $\SI{114}{bit}$. (The frame has actually $\SI{156.25}{bit}$ used for data, synchronization, control information and guard interval.) + \item The theoretical net data rate is $\SI{114}{bit} / \SI{4.615}{ms} = \SI{24.7}{kbit/s}$. This is sufficient to transmit voice. + \item The real number of users is less than 8, because some time-slots are used for control information. + \end{itemize} + \item To enable, more than 8 users, a base station uses more than one frequency. Different users can be assigned different frequencies (\acs{FDMA}). + \end{itemize} \end{example} \subsection{Code-Division Multiple Access} @@ -1887,7 +1900,7 @@ For asynchronous \ac{DS-CDMA}, codes must have good autocorrelation properties. \begin{itemize} \item They shall only have one peak, so that the correlator in the receiver can determine the time-shift and synchronize itself. \item The cross-correlation to other codes shall be close to uero. - \item Good codes are \index{pseudo-random number code} \textbf{\acf{PN codes}}. + \item Good codes are \index{pseudo-random number code} \textbf{\acf{PRN} codes}. \begin{itemize} \item There are equal numbers of $+1$'s and $-1$'s in the code sequence. \item The $+1$'s and $-1$'s are equally distributed. @@ -1901,9 +1914,8 @@ Examples of such codes (without going into detail): \item Kasami codes \end{itemize} -\begin{example}{3G cell phone -- \acs{UMTS}} - Inhalt... -\end{example} +%\begin{example}{3G cell phone -- \acs{UMTS}} +%\end{example} \section{Duplexing} @@ -1938,6 +1950,15 @@ The transmission is perfectly simultaneous. \ac{FDD} is the \emph{duplexing method} derived from \ac{FDMA}. +\begin{remark} + Like in an \ac{FDMA} system, guard bands must be inserted to mitigate inter-carrier interference. +\end{remark} + +Examples: +\begin{itemize} + \item 2G cell phone (\acs{GSM}) according to the \acs{ETSI} TS 145 002 Standard \cite{etsits145002} +\end{itemize} + \subsection{Time-Division Duplex} The \index{time-division duplex} \textbf{\acf{TDD}} uses two sequential time-slots in the same frequency band. @@ -1946,10 +1967,44 @@ The \index{time-division duplex} \textbf{\acf{TDD}} uses two sequential time-slo \item Time-slot 2 is used by device 2 for transmission and by device 1 for reception. \item Afterwards, time-slot 1 starts again. \end{itemize} -In fact, this is a half-duplex method. But, the time-slots are so short that the user will not notice to switching between the time-slots. The duplexing is \emph{quasi-full-duplex}. +In fact, this is a half-duplex method. But, the time-slots are so short that the user will not notice the switching between the time-slots. The duplexing is \emph{quasi-full-duplex}. \ac{TDD} is the \emph{duplexing method} derived from \ac{TDMA}. +\begin{remark} + Like in an \ac{TDMA} system, guard intervals must be inserted to mitigate \ac{ISI}. +\end{remark} + +Examples: +\begin{itemize} + \item \acf{TETRA}: trunked radio system for professional mobile radio according to the \acs{ETSI} EN 300 392 Standard \cite{en300392} +\end{itemize} + +\begin{figure}[H] + \centering + \begin{tikzpicture}[ + x={(1.5cm,0cm)}, + y={(0cm,1cm)}, + ] + \draw[-latex] (-0.5,0) -- (8.5,0) node[below right,align=left]{Time $t$}; + + \foreach \x in {0,2,4,6}{ + \draw[fill=red!50,draw=black] ({(\x)},0) -- ({(\x)+1},0) -- ({(\x)+1},1) -- ({(\x)},1) -- cycle; + %\node[align=center] at({(\x)+0.5},0.5) {User 1 Tx\\ User 2 Rx}; + } + \draw[latex-] (0.5,0.5) -- (0,3) node[above,align=center]{User 1 transmitting\\ User 2 receiving}; + + \foreach \x in {1,3,5,7}{ + \draw[fill=blue!50,draw=black] ({(\x)},0) -- ({(\x)+1},0) -- ({(\x)+1},1) -- ({(\x)},1) -- cycle; + %\node[align=center] at({(\x)+0.5},0.5) {User 1 Rx\\ User 2 Tx}; + } + \draw[latex-] (1.5,0.5) -- (2,2) node[above right,align=left]{User 1 receiving\\ User 2 transmitting}; + + \draw[latex-latex] (1,-0.5) -- node[midway,below,align=center]{\footnotesize Time-slot length\\ $T_{TS}$} (2,-0.5); + \end{tikzpicture} + \caption{Distribution of transmission and reception time-slots (without guard intervals) in a \acs{TDD} system} +\end{figure} + \nocite{ipatov2005} diff --git a/common/acronym.tex b/common/acronym.tex index e5f1446..e8f4658 100644 --- a/common/acronym.tex +++ b/common/acronym.tex @@ -137,7 +137,7 @@ \acro{PLD}{programmable logic device} \acro{PLL}{phase-locked loop} \acro{PM}{phase modulation} - \acro{PN}{pseudo-random number} + \acro{PRN}{pseudo-random noise} \acro{PPDU}{physical layer protocol data unit} \acro{PPM}{pulse-position modulation} \acro{PRF}{pulse repetition frequency} @@ -177,6 +177,7 @@ \acro{SSB-SC}{single-sideband suppressed carrier} \acro{TCXO}{temperature-compensated crystal oscillator} \acro{TCP}{Transmission Control Protocol} + \acro{TETRA}{Terrestrial Trunked Radio} \acro{THSS}{time-hopping spread spectrum} \acro{TH-CDMA}{time-hopping code-division multiple access} \acro{TOA}{time of arrival} |