  The light-cone (LC) effect causes the Epoch of Reionization (EoR) 21-cm
signal $T_{\rm b} (\hat{\bf{n}}, \nu)$ to evolve significantly along the line
of sight (LoS) direction $\nu$. In the first part of this paper, we present a
method to properly incorporate the LC effect in simulations of the EoR 21-cm
signal that include peculiar velocities. Subsequently, we discuss how to
quantify the second order statistics of the EoR 21-cm signal in the presence of
the LC effect. We demonstrate that the 3D power spectrum $P({\bf{k}})$ fails to
quantify the entire information because it assumes the signal to be ergodic and
periodic, whereas the LC effect breaks these conditions along the LoS.
Considering a LC simulation centered at redshift $8$ where the mean neutral
fraction drops from $0.65$ to $0.35$ across the box, we find that $P({\bf{k}})$
misses out $\sim 40 \%$ of the information at the two ends of the $17.41 \,
{\rm MHz}$ simulation bandwidth. The multi-frequency angular power spectrum
(MAPS) ${\mathcal C}_{\ell}(\nu_1,\nu_2)$ quantifies the statistical properties
of $T_{\rm b} (\hat{\bf{n}}, \nu)$ without assuming the signal to be ergodic
and periodic along the LoS. We expect this to quantify the entire statistical
information of the EoR 21-cm signal. We apply MAPS to our LC simulation and
present preliminary results for the EoR 21-cm signal.
