Hidden and exposed terminal problems in Wi-Fi

The hidden and exposed terminal/node problems in wireless communications, commonly encountered with Wi-Fi networks.

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% Hidden and exposed terminal problems in Wi-Fi
% Author: Philip Withnall
\documentclass{article}
\usepackage{tikz}
\usepackage[active,tightpage]{preview}
\PreviewEnvironment{center}
\setlength\PreviewBorder{10pt}%
\usetikzlibrary{decorations.pathreplacing} % for expanding waves
% Style for radio transmission paths.
\tikzstyle{transmission}=[decorate, decoration={expanding waves, angle=7,
                          segment length=2}]
% Path definition for a base station. Parameters
%  1. Node name.
%  2. Node label.
%  3. Path graphic options.
\newcommand{\basestation}[3]{%
    \path[draw, thick, #3] (0, 0) node(#1){#2}
            (0*120+90:0.5cm) --
            (1*120+90:0.5cm) --
            (2*120+90:0.5cm) -- cycle
}
\begin{document}
\begin{center}
\begin{tikzpicture}
    % Shade the intersection where signals collide.
    \begin{scope}
        \clip (-2, 0) circle [radius=2.5];
        \fill[fill=purple!20] (2, 0) circle [radius=2.5];
    \end{scope}
    % Signal radii.
    \draw[red] (-2, 0) circle [radius=2.5]; % A
    \draw[dashed, green] (0, 0) circle [radius=2.5]; % B
    \draw[blue] (2, 0) circle [radius=2.5]; % C
    % Base stations.
    \basestation{BS1}{A}{red, shift={(-2, 0)}};
    \basestation{BS2}{B}{green};
 
 
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