\documentclass[a4paper,12pt]{standalone} \usepackage{ifxetex,ifluatex} \ifnum 0\ifxetex 1\fi\ifluatex 1\fi=0 % if pdftex \usepackage[T1]{fontenc} \usepackage[utf8]{inputenc} \else % if luatex or xelatex \ifxetex \usepackage{mathspec} \else \usepackage{fontspec} \fi \defaultfontfeatures{Ligatures=TeX,Scale=MatchLowercase} \fi \ifxetex \usepackage{fontspec} \setmainfont[Ligatures=Historic]{TeX Gyre Pagella} \newfontfamily\FiraCode{Fira Code} \fi %% TikZ \usepackage{tikz} \usetikzlibrary{snakes,arrows,shapes} % https://tex.stackexchange.com/a/226974/ \tikzset{ font={\fontsize{10pt}{10}\selectfont} } \begin{document} \begin{figure}[h!] \begin{tikzpicture}[>=latex',line join=bevel,scale=2] % \node (C) at (0,2) [draw,rectangle,thick, text width=8cm,text centered] {Channel selection and access policy}; \node (S) at (1.16667,1) [draw,rectangle,thick, text width=3cm,text centered] {Spectrum Sensing}; \node (R) at (0,0) [draw,rectangle,thick, text width=8cm,text centered] {RF Environment}; % \draw [black,->] (C.354) to node[near start,right,text centered,black] {Channel selection} (S.35); \draw [black,->] (C.186) to node[near start,left,text centered,black] {Channel access} (R.160); \draw [black,->] (R.140) to node[near start,right,text centered,black] {Reward} (C.188); \draw [black,->] (S.130) to node[near start,left,text centered,black] {Free/busy} (C.350); \draw [black,->] (R.10) to node[near start,right,text centered,black] {Observation} (S.south); % \end{tikzpicture} % \caption{\small Test.} \label{fig:test} \end{figure} \end{document}