% arara: pdflatex
\documentclass{article}
\usepackage{threeparttable}
\usepackage{array} % fixes the corners
\usepackage{caption}
\usepackage{microtype}
\usepackage{chngcntr}
\counterwithin{table}{section}
\begin{document}
\setcounter{section}{3}
\setcounter{table}{5}
\begin{table}[htbp] % only use those if needed.
\caption{Phase control word}\label{table:3.6} % label after caption!
\centering\footnotesize
\renewcommand{\tabcolsep}{2.1pt}
\begin{threeparttable}
\begin{tabular}{|*{18}{c|}@{}}
\hline
& & \multicolumn{16}{c|}{Phase Control Word(Binary)}\\
\hline
Frequ. & Phase & Bit & Bit & Bit & Bit & Bit & Bit & Bit & Bit & Bit & Bit & Bit & Bit & Bit & Bit & Bit & Bit\\
& Control Word & 15 & 14 & 13 & 12 & 11 & 10 & 9 & 8 & 7 & 6 & 5 & 4 & 3 & 2 & 1 & 0\\ \hline
48000 & 16384 & 0 & 1 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0\\
1000 & 341 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 1 & 0 & 1 & 0 & 1 & 0 & 1 & 0 & 1\\
8000 & 2731 & 0 & 0 & 0 & 0 & 1 & 0 & 1 & 0 & 1 & 0 & 1 & 0 & 1 & 0 & 1 & 1\\
14000 & 4779 & 0 & 0 & 0 & 1 & 0 & 0 & 1 & 0 & 1 & 0 & 1 & 1 & 1 & 1 & 1 & 1\\
21000 & 7168 & 0 & 0 & 0 & 1 & 1 & 1 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0\\
\hline
\end{tabular}
\begin{tablenotes}[para,flushleft]
\centering [By University Requirement, no text should be allowed here in this landscape table/picture page. DON'T USE sidewaystable from rotating package, it cannot align landscape title to the left binding side.].
\end{tablenotes}
\end{threeparttable}
\end{table}
\end{document}

You can save some more space by deleting those vertical lines:
% arara: pdflatex
\documentclass{article}
\usepackage{threeparttable}
\usepackage{array} % fixes the corners
\usepackage{caption}
\usepackage{microtype}
\usepackage{chngcntr}
\counterwithin{table}{section}
\usepackage{siunitx}
\usepackage{booktabs}
\usepackage{multirow}
\begin{document}
\setcounter{section}{3}
\setcounter{table}{5}
\begin{table}[htbp] % only use those if needed.
\caption[Phase control word]{Phase Control Word(Binary)}\label{table:3.6} % label after caption!
\centering\footnotesize
\renewcommand{\tabcolsep}{2.39pt}
\begin{threeparttable}
\begin{tabular}{S[table-format=5.0,group-four-digits]*{17}{c}@{}}
\toprule
\multirow{2}{*}{Frequ.} & Phase & Bit & Bit & Bit & Bit & Bit & Bit & Bit & Bit & Bit & Bit & Bit & Bit & Bit & Bit & Bit & Bit\\
& Control Word & 15 & 14 & 13 & 12 & 11 & 10 & 9 & 8 & 7 & 6 & 5 & 4 & 3 & 2 & 1 & 0\\ \midrule
48000 & 16384 & 0 & 1 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0\\
1000 & 341 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 1 & 0 & 1 & 0 & 1 & 0 & 1 & 0 & 1\\
8000 & 2731 & 0 & 0 & 0 & 0 & 1 & 0 & 1 & 0 & 1 & 0 & 1 & 0 & 1 & 0 & 1 & 1\\
14000 & 4779 & 0 & 0 & 0 & 1 & 0 & 0 & 1 & 0 & 1 & 0 & 1 & 1 & 1 & 1 & 1 & 1\\
21000 & 7168 & 0 & 0 & 0 & 1 & 1 & 1 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0\\
\bottomrule
\end{tabular}
\begin{tablenotes}[para,flushleft]
\centering [By University Requirement, no text should be allowed here in this landscape table/picture page. DON'T USE sidewaystable from rotating package, it cannot align landscape title to the left binding side.].
\end{tablenotes}
\end{threeparttable}
\end{table}
\end{document}

threeparttablepackage. See Add notes under the table (which is probably a duplicate.) – Alan Munn Sep 07 '15 at 17:31\multicolumn{16}{c|}{Phase Control Word(Binary)}. To have the note below, follow Alan Munn's link and use there\begin{tablenotes} \small \item\relax\centering [By University Requirement, no text should be allowed here in this landscape table/picture page. DON''T USE sidewaystable from rotating package, it cannot align landscape title to the left binding side.]. \end{tablenotes}– Gonzalo Medina Sep 07 '15 at 17:43\labelmust go after\caption. – Gonzalo Medina Sep 07 '15 at 17:44