% !TeX root = ../main.tex

\chapter{What is communication}
We'll talk about the definition of communication.

\section{In the ancient}
It is an action for people to communicate with each other. One man talks to another man.

\section{In nowadays}
I would say it's a concept of information exchange.

\section{The principle of communication}
If I have to use one word to describe it, that'll be 'Stable'.

During the transmission process, you shouldn't lose any information that was originally sent.

And also, it should be as fast as possible. Say, if you have an urgent message to send to others, you definitely don't wanna others to receive that message ten days later.

And also, security is important too. You don't wanna send your message to a wrong guy, it'll cause you a lot of trouble.

\subsection{A table for the principle of communication}
\begin{table}[H]
  \centering
  %\caption[title]{long title}
    \begin{tabularx}{\linewidth}{lX}
      \toprule[1.5pt]
      {\heiti principles} & {\heiti description} \\\midrule[1pt]
      integrity & never lose information \\
      speed & provide information at time \\
      security & make sure no one else could see it! \\
      \bottomrule[1.5pt]
    \end{tabularx}
\end{table}

\subsection{Exceptions}
But there are still have a few communication types that only follow 1 or 2 principles of communication. 

For example, broadcast. As long as you send the message out, whether the audience gets that message or not, it's not your business. Because the user have a choice about when to listen to your broadcast, when not to.

Radio for entertainment doesn't need security, but radio for the military does need to secure its message.

\section{Classification of communications}

\subsection{Distinguish by the number of end devices}
Some people like to classify communication with the number of sender or receiver.

\begin{table}[ht]
  \begin{minipage}{0.4\linewidth}
    \centering
    \caption*{1}
    \label{tab:badtabular}
      \framebox(150,50)[c]{
        one to one
      }
  \end{minipage}%
  \hfill%
  \begin{minipage}{0.4\linewidth}
    \centering
    \caption*{2}
    \label{tab:badfigure}
    \framebox(150,50)[c]{
        one to many
    }
  \end{minipage}
\end{table}

It's OK for doing that classification. 'One to one' also called 'Peer to Peer', 'One to many' also called broadcast.

\subsection{Distinguish by the type of information}
Some other people like to classify communication with the type of information being transferred.

\begin{table}[ht]
  \begin{minipage}{0.4\linewidth}
    \centering
    \caption*{1}
    \label{tab:badtabular}
      \framebox(150,50)[c]{
        audio chat
      }
  \end{minipage}%
  \hfill%
  \begin{minipage}{0.4\linewidth}
    \centering
    \caption*{2}
    \label{tab:badfigure}
    \framebox(150,50)[c]{
        video chat
    }
  \end{minipage}
\end{table}

\section{The machine language}
At the above Explanation, we only covered the basics of communication. Or how humans understood that.

In this section, I'll talk about how a machine sees that problem. Because in the end, in modern society, communication is based on computers, not humans.

For a computer, he itself is a computer, the one that he communicates with, is also a computer. So the speed of communication can be very high. At least it'll faster than human-being.

Then the problem left is how a computer could understand each other, and most importantly, to cooperate in the right way so information can flow freely and correctly. 

\begin{example}
For example, if we got a phone and a computer, how do we communicate with each other? (A phone itself is also a computer actually.)

We need to create a certain method for communicating, that method is called \emph{protocol}.
\end{example}

\begin{example}
How to make sure all the information we sent is correctly received by others?

We need to create a certain method to make sure the integrity of information in transferring, that method is a subsection of a \emph{protocol}.
\end{example}

\begin{problem}
Is there a best \emph{protocol} for using?

No! For different scenarios, there are different transmission protocols to choose from.
\end{problem}

\section{Reference}
For more information, check this Wikipedia ~\cite{wiki-communication}