How to increase fontsize inside tables?

Question

Here is the table. I have tried everything possible to increase the font size of the text, but it is not working. The document type is an article.

\begin{table*}
\LARGE\textbf
\centering\caption{Uplink and Downlink Systems with Different Cooperation Methods}\label{Table:systems}
\resizebox{\textwidth }{!}{
\renewcommand{\arraystretch}{1.2}
\begin{tabular}[l]{|l|l|l|l|}
\hline
\Huge{\textbf{Cooperation Method}}&\Huge{\textbf{Downlink}}&\Huge{\textbf{Uplink}}&\Huge{\textbf{Information needed to calculate DL Beamforming vector}}\\
\hline
\Huge{CBF}&\Huge{Each BS transmits to UEs under its own coverage area.}&\Huge{Each UE transmits to only one BS and other BSs treat it as noise.}&\Huge{Each BS needs to know its own channel to all the users.}\\ \hline
\Huge{PDC}&\Huge{Each BS transmits independent data streams to all UEs,}&\Huge{Each UE transmits independent data streams to the BSs,}&\Huge{Each BS needs to calculate $\mathbf{w}_{l, k}$ from~(\ref{Eq:uldlconv}).}\\ \hline
\Huge{JP}&\Huge{The BSs have all the data to be transmitted to UE}&\Huge{No uplink counterpart.}&\Huge{Each BS needs to know all the channels and data symbols.}\\ \hline 
\end{tabular}
}
\end{table*}

Answer 1

Your table is simply to wide to be fit in text with without resizebox. It not only shrink table to desired width but also reduce font size to size which enable to shrink table ... In generally the resizebox should not be used in any circumstances (well, when you desperate what to do, it can be solution of last resort).

Better approach is redesign table. Text in cells had to be broken into more lines which enables to fit table in text width. In this package `tabularx is very handy:

MWE of above table image is:

\documentclass[twocolumn]{article}
\usepackage[showframe]{geometry}  
\usepackage{makecell, tabularx}
    \renewcommand\theadfont{\bfseries}
\usepackage[labelfont=bf]{caption}                   

\begin{document}
\begin{table*}
%\small
\caption{Uplink and Downlink Systems with Different Cooperation Methods}
    \label{Table:systems}
\renewcommand{\arraystretch}{1.2}
\begin{tabularx}{\textwidth}{|l|*{3}{>{\raggedright\arraybackslash}X|}}
\hline
\thead[b]{Cooperation\\ 
          Method}
    &   \thead[b]{Downlink}
        &   \thead[b]{Uplink}
            &   \thead[b]{Information needed\\ 
                          to calculate DL\\ Beamforming vector}        \\
\hline
CBF &   Each BS transmits to UEs under its own coverage area
        &   Each UE transmits to only one BS and other BSs treat it as noise
            &   Each BS needs to know its own channel to all the users. \\ 
    \hline
PDC &   Each BS transmits independent data streams to all UEs
        &   Each UE transmits independent data streams to the BSs,
            &   Each BS needs to calculate $\mathbf{w}_{l, k}$ from~(\ref{Eq:uldlconv}).                                   \\
    \hline
JP  &   The BSs have all the data to be transmitted to UE
        &   No uplink counterpart.
            &   Each BS needs to know all the channels and data symbols.\\ 
    \hline
\end{tabularx}
\end{table*}
\end{document}

From your code snipped is not clear, if you really like to have all text in table in bold face. I according to my test, remove wrongly use of \textbf.

If you like to have column heads vertical˙ly centered, just omit option [b] at \thead. For top aligned replace [b] with [t].

Answer 2

You can use \tiny \scriptsize \footnotesize \small \normalsize \large \Large \LARGE \huge \Huge to control text size in your table.

\documentclass{article}
\begin{document}
\begin{table*}
\centering\caption{Uplink and Downlink Systems with Different Cooperation Methods}\label{Table:systems}
\small
\begin{tabular}[l]{|l|l|l|l|}
\hline
\textbf{Cooperation Method}&\textbf{Downlink}&\textbf{Uplink}&\textbf{Information needed to calculate DL Beamforming vector}\\
\hline
CBF&Each BS transmits to UEs under its own coverage area.&Each UE transmits to only one BS and other BSs treat it as noise.&Each BS needs to know its own channel to all the users.\\ \hline
PDC&Each BS transmits independent data streams to all UEs,&Each UE transmits independent data streams to the BSs,&Each BS needs to calculate $\mathbf{w}_{l, k}$ from~(\ref{Eq:uldlconv}).\\ \hline
JP&The BSs have all the data to be transmitted to UE&No uplink counterpart.&Each BS needs to know all the channels and data symbols.\\ \hline 
\end{tabular}
\end{table*}
\end{document}

Answer 3

Instead of using tabular you can use tabularx like this

\documentclass{article}
\usepackage{booktabs,tabularx}
\usepackage{ragged2e}
\renewcommand\tabularxcolumn[1]{b{#1}}

%\usepackage[showframe]{geometry}

\begin{document}
\begin{table}[htb]
    \centering
    \large
    \begin{tabularx}{\textwidth}{*{4}{>{\Centering\arraybackslash}X}}
\toprule
\textbf{Cooperation Method}&\textbf{Downlink}&\textbf{Uplink}&\textbf{Information needed to calculate DL Beamforming vector}\\
\midrule
CBF&Each BS transmits to UEs under its own coverage area.&Each UE transmits to only one BS and other BSs treat it as noise.&Each BS needs to know its own channel to all the users.\\ 
\midrule
PDC&Each BS transmits independent data streams to all UEs,&Each UE transmits independent data streams to the BSs,&Each BS needs to calculate $\mathbf{w}_{l, k}$ from~(\ref{Eq:uldlconv}).\\ 
\midrule
JP&The BSs have all the data to be transmitted to UE&No uplink counterpart.&Each BS needs to know all the channels and data symbols.\\
 \bottomrule
\end{tabularx}
    \end{table} 
\end{document}

Result of this is shown in picture below:

If you use \tiny instead:

Answer 4

Here is a solution with a normal font size, based on tabularx, caption and makecell:

\documentclass{article}
\usepackage[utf8]{inputenc}
\usepackage[showframe]{geometry} %
\usepackage{ragged2e}%
\usepackage{tabularx, makecell, booktabs, caption}

\begin{document}

\begin{table*}
\renewcommand{\tabularxcolumn}[1]{>{\RaggedRight\arraybackslash}p{#1}}
\renewcommand{\cellset}{\bfseries\renewcommand\arraystretch{1}}\renewcommand\cellalign{lc}
\setlength\tabcolsep{4pt}
\setcellgapes{3pt}\makegapedcells
\centering\caption{Uplink and Downlink Systems with Different Cooperation Methods}\label{Table:systems}
%\resizebox{\textwidth }{!}{
\renewcommand{\arraystretch}{1.2}
\begin{tabularx}{\linewidth}{|l|*{3}{>{\arraybackslash}X|}}
\hline
 \makecell{Cooperation\\ Method} & \makecell{Downlink} & \makecell{Uplink} & \makecell{Information needed\\ to calculate %
DL\\ Beamforming vector} \\
\hline
 CBF & Each BS transmits to UEs under its own coverage area. & Each UE transmits to only one BS and other BSs treat it as noise. & Each BS needs to know its own channel to all the users. \\ \hline
 PDC & Each BS transmits independent data streams to all UEs, & Each UE transmits independent data streams to the BSs, &{Each BS needs to calculate $\mathbf{w}_{l, k}$ from~(\ref{Eq:uldlconv}).}\\ \hline
 JP & The BSs have all the data to be transmitted to UE & No uplink counterpart. & Each BS needs to know all the channels and data symbols. \\ \hline
\end{tabularx}
%}
\end{table*}

\end{document}