documentclass[conference]{IEEEtran}
usepackage{array}
newcolumntype{P}[1]{>{centeringarraybackslash}p{#1}}
newcolumntype{M}[1]{>{centeringarraybackslash}m{#1}}

begin{document}

begin{table}
caption{(A)}label{Tab_a}
centering
begin{tabular}{|M{1.5cm}|M{1.5cm}|M{1.5cm}|}
hline
No. & Col.2  \ hline
1 & AA   \ hline
2 & BB   \ hline
3 & CC   \ hline
end{tabular}
end{table}

begin{table}
caption{(B)}label{Tab_b}
centering
begin{tabular}{|M{1.5cm}|M{1.5cm}|M{1.5cm}|}
hline
M & P & Q \ hline
M1 & A & 2, 3  \ hline
M2 & B & 1, 2  \ hline
M3 & C & 1, 2, 3  \ hline
end{tabular}
end{table}

end{document}