\documentclass{standalone}

\usepackage{tikz}

\begin{document}
\begin{tikzpicture}
  \foreach \y in {7,6,...,0} {
    \draw (0,\y) node {$\xi_\y$};
    \draw (.3, \y) -- (.7,\y);
    \draw (6.4, \y) -- (7, \y);
    \draw (7.05, \y) circle (0.05);
    \draw (.25, \y) circle (0.05);

    \draw (8.95, \y) -- (10.25, \y);
    \draw (9.25,\y+0.3) node {$W_N^\y$};
    \draw (10.3, \y) circle (0.05);
    \draw (10.7,\y) node {$x_\y$};
  }

  \foreach \y in {0, 1, 2, 3} {
    \draw (6.8,\y+4+0.3) node {$O_\y$};
    \draw (6.8,\y+0.3) node {$E_\y$};
    \draw[->,red] (7.1, \y) -- (8.95, \y+4);
    \draw[->, blue] (7.1, \y+4) -- (8.95, \y);

    \draw[->, blue] (7.1, \y) -- (8.95, \y);
    \draw[->, red] (7.1, \y+4) -- (8.95, \y+4);

    \draw[->] (.7, 2 * \y) -- (2.2, \y);
    \draw (2.25, \y + 4) circle (0.05);
    \draw (2.3, \y + 4) -- (3, \y + 4);

    \draw[->] (.7, 2 * \y + 1) -- (2.2, \y+4);
    \draw (2.25, \y) circle (0.05);
    \draw (2.3, \y) -- (3, \y);
  }

  \draw (3, -.2) rectangle  (6.4, 3.2);
  \draw (3, 3.8) rectangle  (6.4, 7.2);
  \draw (.7, 8) rectangle  (9.7, -1);
  \draw (4.6, 1.5) node {$N/2$-FFT};
  \draw (4.6, 5.5) node {$N/2$-FFT};
\end{tikzpicture}
\end{document}