From a7c67a1838333228a647a8d783bd6acfd8ae7f23 Mon Sep 17 00:00:00 2001 From: Philipp Le Date: Mon, 4 May 2020 01:22:22 +0200 Subject: Finishing chapter 1 --- chapter01/NetworkTopologies.svg | 1904 +++++++++++++++++++++++++++++++++++++++ chapter01/content_ch01.tex | 118 ++- 2 files changed, 1993 insertions(+), 29 deletions(-) create mode 100644 chapter01/NetworkTopologies.svg (limited to 'chapter01') diff --git a/chapter01/NetworkTopologies.svg b/chapter01/NetworkTopologies.svg new file mode 100644 index 0000000..325c51c --- /dev/null +++ b/chapter01/NetworkTopologies.svg @@ -0,0 +1,1904 @@ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + image/svg+xml + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + Ring + Mesh + Star + Fully Connected + Bus + Tree + Line + + diff --git a/chapter01/content_ch01.tex b/chapter01/content_ch01.tex index b294529..6f514cc 100644 --- a/chapter01/content_ch01.tex +++ b/chapter01/content_ch01.tex @@ -287,7 +287,7 @@ The carrier of information in an electronic communication system are electromagn \begin{figure}[H] \centering \includegraphics[width=0.8\linewidth]{svg/ch01_EM_Spectrum_Properties.pdf} - \caption[Diagram of the electromagnetic spectrum]{Diagram of the electromagnetic spectrum. \licensequote{\cite{Inductiveload2007}}{''Inductiveload''}{\href{https://creativecommons.org/licenses/by-sa/3.0/deed.en}{CC-BY-SA 3.0}}} + \caption{Diagram of the electromagnetic spectrum. \licensequote{\cite{Inductiveload2007}}{''Inductiveload''}{\href{https://creativecommons.org/licenses/by-sa/3.0/deed.en}{CC-BY-SA 3.0}}} \end{figure} Electromagnetic waves have different properties and applications, depending on the frequency. The most interesting range for communication is from radio waves to visible light. @@ -296,46 +296,77 @@ Electromagnetic waves have different properties and applications, depending on t \item Radio waves and microwaves can be generated by electronics and are radiated by antennas. They have advantages over light like a wider range or their ability to penetrate walls. \end{itemize} +Instead of the frequency, the \index{wavelength} \textbf{wavelength} $\lambda$ can be given. It is inverse proportional to the frequency with the proportionality constant $c_0$, the speed of light. The wavelength is the distance in which one period of the oscillating electromagnetic wave fits. The higher the frequency, the short the distance which a wave travels until the next period starts. +\begin{equation} + \lambda = \frac{c_0}{f} = \frac{2 \pi c_0}{\omega} +\end{equation} + \begin{figure}[H] \centering \includegraphics[width=0.5\linewidth]{svg/ch01_Electromagnetic-Spectrum.pdf} - \caption[Zooming into the radio spectrum as apart of the electromagnetic spectrum]{Zooming into the radio spectrum as apart of the electromagnetic spectrum. \licensequote{\cite{Penubag2012}}{"Penubag" and Victor Blacus}{\href{https://creativecommons.org/licenses/by-sa/3.0/deed.en}{CC-BY-SA 3.0}}} + \caption{Zooming into the radio spectrum as apart of the electromagnetic spectrum. \licensequote{\cite{Penubag2012}}{"Penubag" and Victor Blacus}{\href{https://creativecommons.org/licenses/by-sa/3.0/deed.en}{CC-BY-SA 3.0}}} \end{figure} -Radio waves are used as a information carrier since the beginning of the 20th century. They can be further divided in accordance with their properties. The radio spectrum is split into \index{bands} \textbf{bands}. +Radio waves are used as a information carrier since the beginning of the 20th century. They can be further divided in accordance with their properties. The radio spectrum is split into \index{band} \textbf{bands}. +\renewcommand{\arraystretch}{1.5} \begin{table}[H] \centering \caption[ITU radio band plan]{\ac{ITU} radio band plan} - \begin{tabular}{|l|l|} + \begin{tabular}{|l|l|l|l|} \hline - Band & Abbreviation \\ + Band & Frequency & Properties & Example Applications \\ \hline \hline - Extremely low frequency & ELF \\ + \acs{ELF} & \SIrange{3}{30}{Hz} & \multirow{3}{*}{\begin{minipage}{0.25\textwidth}can penetrate water,\\ follows earth curvature\end{minipage}} & \multirow{3}{*}{\begin{minipage}{0.25\textwidth}submarine communication\end{minipage}} \\ + \cline{1-2} + \acs{SLF} & \SIrange{30}{300}{Hz} & & \\ + \cline{1-2} + \acs{ULF} & \SIrange{300}{3000}{Hz} & & \\ + \cline{1-4} + \acs{VLF} & \SIrange{3}{30}{kHz} & \multirow{3}{*}{\begin{minipage}{0.25\textwidth}follows earth curvature\end{minipage}} & \begin{minipage}{0.25\textwidth}time signals, geophysics\end{minipage} \\[1.5em] + \cline{1-2} + \cline{4-4} + \acs{LF} & \SIrange{30}{300}{kHz} & & \begin{minipage}{0.25\textwidth}time signals, maritime navigation, AM broadcasting\end{minipage} \\[1.5em] + \cline{1-2} + \cline{4-4} + \acs{MF} & \SIrange{300}{3000}{kHz} & & \begin{minipage}{0.25\textwidth}AM broadcasting, aviation navigation, avalanche beacon\end{minipage} \\[1.5em] + \cline{1-4} + \acs{HF} & \SIrange{3}{30}{MHz} & \begin{minipage}{0.25\textwidth}reflections at ionosphere\end{minipage} & \begin{minipage}{0.25\textwidth}AM broadcasting, amateur radio, \acs{RFID}, maritime communication, long-distance aviation communication\end{minipage} \\[1.5em] + \cline{1-4} + \acs{VHF} & \SIrange{30}{300}{MHz} & \begin{minipage}{0.25\textwidth}quasi-optical propagation,\\ reflections at ionosphere possible\end{minipage} & \begin{minipage}{0.25\textwidth}FM broadcasting, television broadcasting, maritime and aviation communication, land mobile communication, weather satellites\end{minipage} \\[1.5em] + \cline{1-4} + \acs{UHF} & \SIrange{300}{3000}{MHz} & \multirow{3}{*}{\begin{minipage}{0.25\textwidth}quasi-optical propagation,\\ higher frequencies generally mean higher attenuation and shorter ranges\end{minipage}} & \begin{minipage}{0.25\textwidth}television broadcasting, \acs{WLAN}, \acs{GPS}, communication satellites, cell phones\end{minipage} \\[1.5em] + \cline{1-2} + \cline{4-4} + \acs{SHF} & \SIrange{3}{30}{GHz} & & \begin{minipage}{0.25\textwidth}radio astronomy, communication satellites, radar, satellite television broadcasting\end{minipage} \\[1.5em] + \cline{1-2} + \cline{4-4} + \acs{EHF} & \SIrange{30}{300}{GHz} & & \begin{minipage}{0.25\textwidth}new \acs{WLAN} standard (IEEE\,802.11ad), radar, radio astronomy, imaging (millimeter wave scanners), remote sensing\end{minipage} \\[1.5em] \hline \end{tabular} \end{table} Especially, the bands LF to UHF have been traditionally used in wireless communication. Furthermore, their usage is not limited to wireless systems. For example, cable television uses parts of the VHF or UHF spectra. Cable internet shares the wire with TV broadcasting. -Because of the increasing number of services and growing demands regarding bandwidth and response time, modern communication system advance in the direction of microwaves. The microwave spectrum begins at \SI{3}{GHz}. There are dedicate band plans for microwave applications. Table \ref{tab:ch01:IEEE_radar_bands} IEEE radar bands. - -\begin{table}[H] - \centering - \caption{IEEE radar bands} - \label{tab:ch01:IEEE_radar_bands} - \begin{tabular}{|l|} - \hline - Abbreviation \\ - \hline - \hline - HF \\ - \hline - \end{tabular} -\end{table} - -The services using the electromagnetic spectrum get a \index{frequency allocation} \textbf{frequency allocation}. Usually, a national telecommunication regulation authority is responsible for allocation frequencies to the services. They follow recommendations of the \ac{ITU}, a special agency of the \ac{UN}. In Germany, the regulation authority is the Federal Network Agency (Bundesnetzagentur). +Because of the increasing number of services and growing demands regarding bandwidth and response time, modern communication system advance in the direction of microwaves. The microwave spectrum begins at \SI{3}{GHz}. +%There are dedicate band plans for microwave applications. Table \ref{tab:ch01:IEEE_radar_bands} IEEE radar bands. + +%\begin{table}[H] +% \centering +% \caption{IEEE radar bands} +% \label{tab:ch01:IEEE_radar_bands} +% \begin{tabular}{|l|} +% \hline +% Abbreviation \\ +% \hline +% \hline +% HF \\ +% \hline +% \end{tabular} +%\end{table} + +The services using the electromagnetic spectrum receive a \index{frequency allocation} \textbf{frequency allocation}. Usually, a national telecommunication regulation authority is responsible for allocation frequencies to the services. They follow recommendations of the \ac{ITU}, a special agency of the \ac{UN}. In Germany, the regulation authority is the Federal Network Agency (Bundesnetzagentur). \section{Computer Networks} @@ -458,14 +489,43 @@ This course on digital communication systems mainly considers the physical layer \subsection{Network Topologies} +In the context of networks, +\begin{itemize} + \item the devices are called \index{node} \textbf{nodes} and + \item the communication channels between the nodes are called \index{link} \textbf{links}. +\end{itemize} + +Nodes of a network can be arranged in various ways. The structures being formed are \index{network topology} \textbf{network topologies}. Basic topologies are: +\begin{itemize} + \item \textbf{Line} or chain -- The nodes are connected in series. A packet is passed on by each node until reaches its destination. + \item \textbf{Ring} -- An extension of the line where the outer nodes are interconnected, too. A packet is passed by every node to its destination. The failure of a single node does not split the network into two segments, which increases the fault tolerance. + \item \textbf{Bus} -- All nodes are connected to a central cable, the bus. Each node can receive the signals transmitted. As a drawback, only one device may occupy the bus simultaneously for transmission. + \item \textbf{Star} -- A central node (a hub or switch) relays the packets to its destination. + \item \textbf{Tree} -- Tree structure is a hybrid network of star networks interconnected by a bus. Because there a no loops in the network, the nodes can be graphically re-ordered to a tree graph. + \item \textbf{Mesh} -- The nodes are interconnected directly. Nodes may have many direct connections to other nodes, while there is no hierarchy. There are many loops in the network. Usually, mesh networks are re-organized dynamically in mobile systems. A node discovers all nodes which it can reach and establishes a link. A special form is the \emph{Full Mesh}, where all nodes are interconnected with every other one. +\end{itemize} + +\begin{figure}[H] + \centering + \includegraphics[width=0.7\linewidth]{svg/ch01_NetworkTopologies.pdf} + \caption{Network topologies. \licensequote{\cite{Maksim2011}}{``Maksim'' and ``Malyszkz''}{Public Domain}} +\end{figure} + +The network topology is a concern of the physical and data link layers of the \ac{OSI} model. It can be physical or logical. +\begin{itemize} + \item The \index{network topology!physical topology} \textbf{physical topology} refers to the placement of the hardware. For example, in a cable network, the physical topology is defined by the cables which interconnect the devices. The topology is mainly implemented in the physical layer. + \item The \index{network topology!logical topology} \textbf{logical topology} models the data flow in the network. For example, in a wireless network, each node can receive the signals of all other nodes in range. By addressing the devices and filtering out packets with wrong destination addresses, a logical network is created on top of the physical wireless interface. The topology is mainly implemented in the data link layer. +\end{itemize} + +A network must fulfil requirements, which determine the network topology, in the end. The use case and constraints must be considered by the engineer. For example: \begin{itemize} - \item \textbf{Ring} - \item \textbf{Star} - \item \textbf{Tree} - \item \textbf{Chain} - \item \textbf{Bus} - \item \textbf{Mesh}, special form \emph{Full Mesh} + \item Lines and trees lack in reliability. The failure of one node divides the network into two segments and the remaining nodes cannot communicate with each other. + \item The ring is an improvement of the line with respect to reliability. Lines and rings require that all nodes have equal power. Otherwise, the weakest node would be a bottleneck with respect to network bandwidth. + \item Mesh and fully connected topologies are fault tolerant. The failure of one node does not corrupt the whole network. Furthermore, high data rates and lower latencies may be reached due to a higher number of links. + \item Mesh and fully connected topologies increase the cost of the networks. Each link consumes energy, space and money. + \item Buses and stars reduce the cost by maintaining a reasonable amount of reliability. The failure of one device has no major impact on the network, but a disturbance of the bus may. Buses can only be occupied by one node simultaneously. The results in lower data rate and higher latency compared to meshes. \end{itemize} +An optimal topology may mix the basic forms. \phantomsection \addcontentsline{toc}{section}{References} -- cgit v1.1